NUREG/CR-7236, Vol. 1

Results of Open Testing for 

the Program to Assess the 

Reliability of Emerging 

Nondestructive Techniques 

Office of Nuclear Regulatory Research

Results of Open Testing for 

the Program to Assess the 

Reliability of Emerging 

Nondestructive Techniques 

NUREG/CR-7236, Vol. 1 

Office of Nuclear Regulatory Research

Manuscript Completed: December 2016 

Date Published: August 2017 

Prepared by: 

R. M. Meyer, A. E. Holmes, and P. G. Heasler 

Pacific Northwest National Laboratory 

P.O. Box 999 

Richland, WA 99352 

I. Prokofiev and B. Lin, NRC Project Managers 

NRC Job Code V6286 

iii

ABSTRACT

The U.S. Nuclear Regulatory Commission (NRC) has established the Program to Assess the 

Reliability of Emerging Nondestructive Techniques (PARENT) whose goal was to investigate 

the performance of current emerging and perspective novel nondestructive examination (NDE) 

procedures and techniques to find flaws in nickel-alloy welds and base materials. This was 

performed by conducting a series of open and blind international round-robin tests on a set of 

nickel alloy piping components that include large-bore dissimilar metal welds (LBDMW), smallbore dissimilar metal welds (SBDMW), and bottom-mounted instrumentation (BMI) penetration 

welds. The project was split into open and blind testing portions for the purpose of separating 

the evaluation of novel techniques that are at a stage of relative immaturity for field testing and 

which were implemented by teams that may not have significant experience in conducting field 

examinations (open testing) from the evaluation of more established techniques implemented by 

commercial inspection vendors (blind testing). This report is focused on documenting the open 

testing activity and results. The motivation for evaluating emerging NDE techniques includes the 

desire to identify more effective methods for detecting and characterizing rapidly growing forms 

of degradation, such as primary water stress corrosion cracking (PWSCC) and interdendritic 

stress corrosion cracking (IDSCC).

PARENT was a follow-on to the Program for Inspection of Nickel Alloy Components (PINC), 

which was based on the Bilateral International Agreements with participants and the in-kind 

contribution of resources from organizations of Finland, Japan, Republic of Korea, Sweden, and 

the United States of America to evaluate several nondestructive techniques for detection and 

characterization of PWSCC and IDSCC in SBDMW and BMI components. In February 2012, the 

NRC conducted new agreements with VTT Technical Research Centre of Finland, Nuclear 

Regulation Authority of Japan, Korea Institute of Nuclear Safety, Swedish Radiation Safety 

Authority, and Swiss Federal Nuclear Safety Inspectorate to establish PARENT to conduct a 

series of round-robin tests on SBDMWs, BMIs, and LBDMWs. The open testing portion of 

PARENT was performed with knowledge of true-state information in the open test blocks 

provided to teams conducting tests. As a result, no detection performance analyses were 

performed on open test data. Thus, the evaluation of open test data is based on statistical 

analyses of sizing data and qualitative review of data response images.

v 

FOREWORD

Leakage events due to primary water stress corrosion cracking (PWSCC) or interdendritic 

stress corrosion cracking (IDSCC) have been recorded in the United States and internationally. 

This cracking has been observed at several weld locations in reactor coolant systems including 

penetrations to the reactor vessel (e.g., control rod drive mechanism [CRDM] penetrations, 

bottom-mounted instrumentation [BMI] penetrations, and nozzle penetrations), and nozzle 

penetrations on steam generator and pressurizer components. Inservice inspections (ISI) are 

conducted at nuclear power plants to detect cracks before leakage occurs. The effectiveness of 

ISI is dependent on several factors such as the frequency with which periodic examinations 

occur, human factors, the performance capability of the nondestructive examination (NDE) 

procedures and techniques used, etc. Leakage events, both domestic and internationally, have 

indicated a need for additional research to evaluate the performance of NDE procedures and 

techniques for the detection and sizing of PWSCC and IDSCC flaws in reactor components. 

In February 2012, the U.S. Nuclear Regulatory Commission executed agreements with 

organizations in Finland, Japan, Republic of Korea, Sweden, Switzerland, and the United States 

to establish the Program to Assess the Reliability of Emerging Nondestructive Techniques 

(PARENT) to investigate the performance of current and emerging NDE techniques to find flaws 

in nickel-alloy welds and base material. This assessment was performed by conducting a series 

of open and blind international round-robin tests on a set of mockups. The project was split into 

open and blind testing to separate the evaluation of novel techniques implemented by 

nonqualified teams from the evaluation of more established techniques implemented by 

commercial inspection service providers. The objective of the blind testing was to obtain 

quantitative empirical estimates of the performance of contemporary NDE inspection 

procedures and techniques used within the industry to determine which may be more reliable for 

detecting and accurate sizing PWSCC or IDSCC flaws. The objective of the open testing was to 

evaluate the performance of novel NDE procedures and techniques that have not yet reached 

the maturity level for field testing. The motivation for evaluating novel NDE procedures and 

techniques was to explore their potential for improving the performance of NDE in comparison 

to established techniques. Analysis of the open test data included a quantitative evaluation of 

sizing performance and qualitative evaluation of signal response images. 

The purpose of this report was to publish the results of the sizing analyses and the qualitative 

evaluation of signal response images for data collected in open testing for PARENT. The open 

test assessed several novel and non-standard NDE procedures and techniques such as 

nonlinear ultrasonic testing (NLUT) and advanced phased array UT (ADVPAUT). Some 

highlights obtained from the results of the sizing analysis include observations that ADVPAUT 

and NLUT procedures exhibited more consistent depth sizing error over the range of flaw 

depths sampled in comparison to established PAUT procedures. Further, sub-harmonic NLUT 

procedures exhibited better overall depth sizing performance than higher-harmonic NLUT 

procedures. Highlights of the qualitative analysis of data response images included the 

observation that identifying stress corrosion crack tip signals with established PAUT procedures 

can be difficult and that crack tip signal identification by image analysis is, in part, a subjective 

determination. Further, for both PAUT and ADVPAUT procedures, data response images 

illustrate the difficulty in distinguishing noise from SCC crack tip responses. The results obtained 

in open testing can be considered optimistic to what would be anticipated under blind test 

conditions or field conditions. Thus, the PARENT open test results have illustrated that NDE 

procedures and techniques are limited to less than ideal performance by their fundamental 

capability and that overall ISI effectiveness could benefit from NDE technology advancements 
vi

that improve upon fundamental capability. Finally, the data generated from PARENT open 

testing provides an understanding of the state of art in NDE capabilities and can be used to 

evaluate emerging inspection techniques in the future.
vii

TABLE OF CONTENTS

ABSTRACT...............................................................................................................................iii

FOREWORD .............................................................................................................................. v

LIST OF FIGURES...............................................................................................................................xi

LIST OF TABLES....................................................................................................................xix

EXECUTIVE SUMMARY .........................................................................................................xxiii

ACKNOWLEDGMENTS.......................................................................................................xxvii

ACRONYMS AND ABBREVIATIONS...................................................................................xxix

1 INTRODUCTION ...........................................................................................................1-1

1.1 Laboratory Grown SCC Specimens....................................................................1-2

1.2 Open NDE Techniques Report...........................................................................1-2

1.3 Atlas Information Tool ........................................................................................1-3

1.4 PARENT Organization........................................................................................1-3

1.5 Organization of Report .......................................................................................1-3

2 TEST BLOCK DESCRIPTIONS ....................................................................................2-1

2.1 Full Circumference Large Bore and Small Bore Dissimilar Metal Weld Test 

Blocks ................................................................................................................2-1

2.2 Partial Circumference Large Bore Dissimilar Metal Weld Test Blocks ................2-4

2.3 Flat Bar Test Blocks ...........................................................................................2-5

2.4 Bottom-Mounted Instrumentation Test Blocks ....................................................2-7

2.5 Simulated Flaw Types ........................................................................................2-9

2.5.1 Laboratory-Grown SCC (P12, P28, P29, P31, P32, and P38) ............. 2-10

2.5.2 Thermal Fatigue Cracks (P1, P4, and P5) ........................................... 2-14

2.5.3 Weld Solidification Cracks (P7, P37, and P41).................................... 2-14

2.5.4 Electrical Discharge Machined Notches (P1, P12, P42, P21, P22, 

P23, and P24) ..................................................................................... 2-15

2.5.5 Mechanical Fatigue Cracks (P30)........................................................ 2-15

2.5.6 Welding Defects (P37)......................................................................... 2-15

2.6 True-State Determination..................................................................................2-15

3 TECHNIQUE DESCRIPTIONS ......................................................................................3-1

3.1 Ultrasonic Techniques........................................................................................3-1

3.1.1 Through Transmission of Longitudinal Waves .......................................3-1

3.1.2 Phased Array Ultrasonic Testing ...........................................................3-3

3.1.3 Three-Dimensional Synthetic Aperture Focusing Technique .................3-4

3.1.4 Phased Array Time Reversal Technique ...............................................3-6

3.1.5 Phased Array Asymmetrical Beam Time of Flight Diffraction.................3-7

3.1.6 Phased Array Twin Probe......................................................................3-9

3.1.7 Subharmonic Phased Array................................................................. 3-10

3.1.8 Large Amplitude Excitation Subharmonic ............................................ 3-13

3.1.9 Higher Harmonic Ultrasonic Technique ............................................... 3-13
viii

3.1.10 Nonlinear Resonant Ultrasound Spectroscopy .................................... 3-15

3.1.11 Guided Ultrasonic Waves .................................................................... 3-16

3.1.12 Laser Ultrasound Visualization ............................................................ 3-18

3.1.13 Ultrasound Infrared Thermography...................................................... 3-18

3.2 Eddy Current Techniques................................................................................. 3-20

3.2.1 Exciter-Pickup Eddy Current Techniques ............................................ 3-20

3.2.2 Controlled Excitation ECT ................................................................... 3-21

3.2.3 Orthogonal Coil Array Eddy Current Technique................................... 3-23

3.2.4 Pulsed Excitation Eddy Current Technique.......................................... 3-23

3.3 Other Techniques............................................................................................. 3-24

3.3.1 Microwave Near Field Microscope....................................................... 3-24

3.3.2 Radiography Techniques..................................................................... 3-25

4 DATA OVERVIEW.........................................................................................................4-1

4.1 Data Reporting ...................................................................................................4-1

4.2 Records Collection Overview Summary .............................................................4-5

4.3 Procedure Type Categorization ..........................................................................4-5

4.4 Scoring Procedure Used for PARENT Open Testing..........................................4-5

4.5 Substitution for X1, X2, Y1, and Y2 Indication Fields..........................................4-9

4.6 Multiple Indications Associated with One Flaw ................................................. 4-11

4.7 Analysis of PARENT Open Round Robin Data................................................. 4-12

5 DATA ANALYSIS RESULTS ........................................................................................5-1

5.1 DMW Depth Sizing Results ................................................................................5-1

5.1.1 Depth Sizing Regression Plots for ADVPAUT Procedure Types............5-5

5.1.2 Depth Sizing Regression Plots for NLUT Procedure Types ...................5-9

5.1.3 Depth Sizing Regression Plots for PAUT Procedure Types................. 5-11

5.1.4 Depth Sizing Regression Plots for RT Procedure Types...................... 5-13

5.1.5 Depth Sizing Regression Plots for UIR Procedure Types ....................5-15

5.1.6 Depth Sizing Regression Plots for Conventional UT Procedure 

Types .................................................................................................. 5-17

5.2 DMW Length Sizing Results............................................................................. 5-19

5.2.1 Length Sizing Regression Plots for ADVPAUT Procedure Types ........ 5-21

5.2.2 Length Sizing Regression Plots for NLUT Procedure Types................ 5-22

5.2.3 Length Sizing Regression Plots for PAUT Procedure Types ............... 5-23

5.2.4 Length Sizing Regression Plots for Conventional UT Procedure 

Types .................................................................................................. 5-25

5.2.5 Length Sizing Regression Plots for ECT Procedure Types.................. 5-26

5.2.6 Length Sizing Regression Plots for MM Procedure Types ................... 5-27

5.3 BMI Data Analysis Results ............................................................................... 5-28

5.4 Indication Plots................................................................................................. 5-28
ix

6 ANALYSIS OF RESULTS .............................................................................................6-1

6.1 Comparison of ADVPAUT and PAUT Procedure Types .....................................6-1

6.2 Comparison of NLUT with PAUT and ADVPAUT Procedure Types....................6-7

6.3 Analysis of FB Test Block Results .................................................................... 6-11

6.4 Comparison of Linear and Sectorial PAUT by Team 122.................................. 6-15

6.5 UIR Results...................................................................................................... 6-17

6.6 RT, Conventional UT, and ECT Results ........................................................... 6-18

6.7 Analysis of Data Response Images from FB Test Blocks ................................. 6-21

6.7.1 Comparison of PAATOFD.29.2 Responses from P42, P30, and 

P32...................................................................................................... 6-21

6.7.2 Comparison of SAFT.17 Responses from P42, P30, and P32............. 6-24

6.7.3 PAUT.122.1 Responses from SCC Flaws............................................6-31

6.7.4 Team 22 SAFT and PATRT Responses from P29............................... 6-38

6.7.5 SAFT.17 Depth Measurement on P46................................................. 6-40

6.8 Procedures with Sparsely Populated Datasheets ............................................. 6-44

6.9 Discussion of Test Block Appropriateness........................................................ 6-48

6.10 Techniques to Consider for Blind Testing ......................................................... 6-49

7 CONCLUSIONS AND FUTURE WORK ........................................................................7-1

8 REFERENCES ..............................................................................................................8-1

APPENDIX A 11th ICNDE PAPERS .................................................................................. A-1

APPENDIX B SUMMARY TABLE OF OPEN NDE TECHNIQUES ................................... B-1

APPENDIX C SUMMARIES OF OPEN NDE TECHNIQUES............................................. C-1

APPENDIX D TEST BLOCK INFORMATION ................................................................... D-1

APPENDIX E TRUE-STATE SUMMARY .......................................................................... E-1

APPENDIX F DEPTH SIZING RESULTS.......................................................................... F-1

APPENDIX G LENGTH SIZING RESULTS ....................................................................... G-1

APPENDIX H INDICATION PLOTS .................................................................................. H-1

xi

LIST OF FIGURES

Figure 1.1 Organization Chart for Steering Committee and Task Groups .............................1-3

Figure 2.1 Coordinate System Definition for SBDMW Test Blocks P41 and 

LBDMW Test Block P37 ......................................................................................2-2

Figure 2.2 Coordinate System Definition for SBDMW Test Blocks P1...................................2-3

Figure 2.3 Coordinate System Definition for SBDMW Test Blocks P4...................................2-4

Figure 2.4 Coordinate System Definition and Illustration of LBDMW Partial 

Circumference Test Block P12.............................................................................2-5

Figure 2.5 Coordinate System Definition and Illustration of LBDMW Partial 

Circumference Test Blocks P23 and P24.............................................................2-5

Figure 2.6 Coordinate System Definition, Dimensions, and Illustrations of FB Test 

Blocks P28, P29, P30, P31, P32, P42, and P46 ..................................................2-6

Figure 2.7 Coordinate System Definition, Dimensions, and Illustrations of FB Test 

Block P38 ............................................................................................................2-6

Figure 2.8 Coordinate System Used for BMI Test Blocks: P5 and P7 ...................................2-7

Figure 2.9 Depiction of Configuration for BMI Test Blocks P21 and P22 with 

Coordinate System and Dimensions Labeled ......................................................2-8

Figure 2.10 Depiction of Configuration for BMI Test Blocks P5 and P7 with Labeled 

Dimensions..........................................................................................................2-9

Figure 2.11 Depiction of the Approach Used to Produce a Laboratory-Grown SCC in 

Test Block P12................................................................................................... 2-11

Figure 2.12 Flowchart of the Process Used to Produce a Laboratory-Grown 

PWSCC/IDSCC ................................................................................................. 2-11

Figure 2.13 Photograph and Depiction of FB Test Block Cut Out into Standard 

Fracture Mechanic Specimen from Reactor Pressure Vessel Material............... 2-12

Figure 2.14 Depiction of laboratory Autoclave Set-up for Growing SCC Flaws in FB 

Specimens under BWR and PWR Conditions.................................................... 2-12

Figure 2.15 Typical Micro-Fractographic Appearance of Laboratory-Grown SCC in 

FB Specimens ................................................................................................... 2-13

Figure 2.16 Uncracked Ligaments and Finger-Like Local Laboratory SCC Crack 

Growth in Destructively Analyzed FB Specimen ................................................ 2-14

Figure 3.1 Illustration of Mechanized Scanning Through-Transmission Longitudinal 

Pitch/Catch Technique.........................................................................................3-2

Figure 3.2 The C-scan Shows the Received Amplitude Color Coded (0% full 

screen height, FSH [white] to 100% FSH [red])....................................................3-2

Figure 3.3 Illustration of Time Delay Sequencing of Excitation of PAUT Transducer 

Elements to Achieve Beam Steering and Focusing..............................................3-3

Figure 3.4 PAUT Data Represented as A-scan (top left), C-scan (top right), B-scan 

(bottom left), and D scan (bottom right) ................................................................3-4
xii

Figure 3.5 2D Illustration of SAFT Correction for Focusing Distortion in Ultrasonic 

Inspections (left); B-scan Illustrating Distortion Caused by Beam 

Focusing Effects (right) ........................................................................................3-5

Figure 3.6 Implementation of 3D SAFT Using a Matrix Array Transducer. Individual 

elements are excited in sequence, while all elements “listen” for echoes.............3-6

Figure 3.7 Illustration of the Time Reversal Technique Concept for Focusing 

Ultrasonic Energy ................................................................................................3-7

Figure 3.8 Schematic Illustration of the PAATOFD Technique..............................................3-8

Figure 3.9 Data from Multiple Scan Angles and Depths of Focus are Synthesized 

in PAATOFD to Help Discriminate Crack Tip Signals from Noise.........................3-8

Figure 3.10 Schematic Illustration of the PATP Technique .....................................................3-9

Figure 3.11 Data from Multiple Scan Angles and Depths of Focus are Synthesized 

in PATP to Help Discriminate Crack Tip Signals from Noise .............................. 3-10

Figure 3.12 Illustration of the Crack Face “Clapping” Phenomena that is the Basis 

for Subharmonic Generation when Elastic Waves are Applied to Tight 

Cracks ............................................................................................................... 3-11

Figure 3.13 Illustration of SPACE Implementation in SAW Mode to Assess 

Detection and Length Sizing Capability and in Bulk Wave Mode to 

Assess Depth Sizing Capability ......................................................................... 3-12

Figure 3.14 Illustration of SHPA Data Analysis for Length and Depth Sizing of Flaws .......... 3-12

Figure 3.15 Depiction of the LASH Technique Implementation ............................................. 3-13

Figure 3.16 Illustration of Higher Harmonic Generation Because of the CAN 

Phenomenon ..................................................................................................... 3-14

Figure 3.17 Illustration of HHUT Implementation in PE (left) and TR (right) Modes............... 3-14

Figure 3.18 Resonance Frequency Shift in a Compact Tension Specimen in the 

Early Stage of Crack Initiation (top) and a Compact Tension Specimen 

with Crack Length of 7.0 mm (bottom) ............................................................... 3-15

Figure 3.19 Schematic Drawing of Possible Piezoelectric Sensor Configuration................... 3-16

Figure 3.20 Illustration of GUW Formation and Propagation in Test Material........................ 3-16

Figure 3.21 Guided Wave Dispersion Curves on Cylindrical Coordinate: (a) phase 

velocity dispersion curve; (b) group velocity dispersion curve ............................ 3-17

Figure 3.22 Schematic of the Envisioned LUV System ......................................................... 3-18

Figure 3.23 Illustration of the UIR Concept ........................................................................... 3-19

Figure 3.24 UIR Image of a Test Specimen with Crack......................................................... 3-19

Figure 3.25 Depiction of a Single Coil Eddy Current Probe with an Alternating 

Current Excitation, Induced Magnetic Fields, and Induced Eddy 

Currents. Disturbance of eddy current flow can be caused by existence 

of a defect.......................................................................................................... 3-21

Figure 3.26 Schematic Illustration of an Eddy Current Probe with Separate Coils for 

Field Excitation and for Signal Detection............................................................ 3-21
xiii

Figure 3.27 Illustration Showing that the Phase Response of CEECT has a 

Significant Correlation to Flaw Depth over a Large Range of Flaw Depth 

Values, Including for Deep Cracks..................................................................... 3-22

Figure 3.28 Illustration of the CEECT Probe for Measuring the Depth of Flaws .................... 3-22

Figure 3.29 Illustration of Orthogonal Coil Pair and Relative Orientation to Surface 

Crack Profiles .................................................................................................... 3-23

Figure 3.30 Comparison of Pulsed Excitation for PECT (left) to Continuous SineWave Excitation for Conventional ECT (right) and Illustration of the 

Frequency Spectrum Associated with Each Type of Excitation Source.............. 3-24

Figure 3.31 Illustration of the MM Technique for Crack Detection......................................... 3-25

Figure 3.32 Illustration of a Radiographic Examination and Interaction of Source Xrays with Density Discontinuities such as Flaws................................................. 3-26

Figure 3.33 Illustration Depicting the Sensitivity of Conventional Radiography Signal

to Planar Flaw Orientation ................................................................................. 3-27

Figure 4.1 Technique Datasheets for Techniques ET400Hz and TOFD.Ax for 

Fictitious Inspection 12.P89.1 ..............................................................................4-3

Figure 4.2 Technique Datasheet for Technique TOFD.Circ for Fictitious Inspection 

12.P89.1 ..............................................................................................................4-4

Figure 4.3 Inspection Summary Datasheet for Fictitious Inspection 12.P89.1.......................4-4

Figure 4.4 Diagram Illustrating How Procedures are Classified by Procedure Types 

for Data Analysis Purposes..................................................................................4-8

Figure 4.5 Illustration of Tolerance (δX and δY) Applied Flaw True-State (in red) 

Dimensions for the Purpose of Scoring in PARENT.............................................4-9

Figure 4.6 Depiction of Indication Plot Illustrating 2-D Representation of Test 

Block. The red filled rectangles represent the true-state (actual flaws), 

while red empty rectangles surrounding the flaws depict the scoring 

tolerance. Indications are shown as black empty rectangles................................4-9

Figure 4.7 Inspection Summary Datasheet for Inspection of Test block P1 by 

Procedure LASH.18 showing unpopulated X1, X2, Y1 and Y2 fields ................. 4-10

Figure 4.8 Indication Plot for Procedure LASH.18 Applied to Test Block P1 in 

PARENT Open Testing (X – Y view).................................................................. 4-11

Figure 4.9 Indication Plot for Procedure LASH.18 Applied to Test Block P1 in 

PARENT Open Testing (X – Z view).................................................................. 4-11

Figure 4.10 Indication Plot Illustrating Two Indications Intersecting the Region 

Bounded by the Tolerance Box.......................................................................... 4-12

Figure 4.11 Illustration of Tolerance Divided Between Flaw and Multiple Indications 

Intersecting the Region Bounded by the Flaw Tolerance Box ............................ 4-12

Figure 4.12 Indication Plot for Procedure HHUT.27 Inspection of Test Block P1 .................. 4-14

Figure 4.13 Length Sizing Regression for ADVPAUT Procedures on LBDMW Test 

Blocks in PARENT Open Testing (O.D. access) ................................................ 4-14
xiv

Figure 4.14 Depth Sizing Regression (in mm) for Procedure PAUT.131.1 on 

SBDMW Test Blocks in PARENT Open Testing (O.D. access – w/ FB 

test blocks) ........................................................................................................ 4-15

Figure 4.15 Depth Sizing Regression for NLUT Procedures on SBDMW Test Blocks 

in PARENT Open Testing (O.D. access – w/ FB test blocks)............................. 4-16

Figure 4.16 Depth Sizing Regression (in mm) for Procedure HHUT.30 on SBDMW 

Test Blocks in PARENT Open Testing (I.D. access – w/ FB test blocks)............ 4-16

Figure 5.1 Depth Sizing Regression for ADVPAUT Procedures on SBDMW Test 

Blocks in PARENT Open Testing (O.D. access – w/ FB test blocks)....................5-6

Figure 5.2 Depth Sizing Regression for ADVPAUT Procedures on SBDMW Test 

Blocks in PARENT Open Testing (O.D. access – w/o FB test blocks)..................5-6

Figure 5.3 Depth Sizing Regression for ADVPAUT Procedures on FB Test Blocks 

in PARENT Open Testing (O.D. access)..............................................................5-7

Figure 5.4 Depth Sizing Regression for ADVPAUT Procedures on FB Test Blocks 

in PARENT Open Testing (I.D. access) ...............................................................5-7

Figure 5.5 Depth Sizing Regression for ADVPAUT Procedures on LBDMW Test 

Blocks in PARENT Open Testing (O.D. access) ..................................................5-8

Figure 5.6 Depth Sizing Regression for ADVPAUT Procedures on LBDMW Test 

Blocks in PARENT Open Testing (I.D. access)....................................................5-8

Figure 5.7 Depth Sizing Regression for NLUT Procedures on SBDMW Test Blocks 

in PARENT Open Testing (O.D. access – w/ FB test blocks)...............................5-9

Figure 5.8 Depth Sizing Regression for NLUT Procedures on SBDMW Test Blocks 

in PARENT Open Testing (O.D. access – w/o FB test blocks)........................... 5-10

Figure 5.9 Depth Sizing Regression for NLUT Procedures on FB Test Blocks in 

PARENT Open Testing (O.D. access) ............................................................... 5-10

Figure 5.10 Depth Sizing Regression for PAUT Procedures on SBDMW Test Blocks 

in PARENT Open Testing (O.D. access – w/ FB test blocks)............................. 5-11

Figure 5.11 Depth Sizing Regression for PAUT Procedures on SBDMW Test Blocks 

in PARENT Open Testing (O.D. access – w/o FB test blocks)........................... 5-12

Figure 5.12 Depth Sizing Regression for PAUT Procedures on FB Test Blocks in 

PARENT Open Testing (O.D. access) ............................................................... 5-12

Figure 5.13 Depth Sizing Regression for PAUT Procedures on LBDMW Test Blocks 

in PARENT Open Testing (I.D. access) ............................................................. 5-13

Figure 5.14 Depth Sizing Regression for RT Procedures on SBDMW Test Blocks in 

PARENT Open Testing (O.D. access – w/ FB test blocks)................................. 5-14

Figure 5.15 Depth Sizing Regression for RT Procedures on SBDMW Test Blocks in 

PARENT Open Testing (O.D. access – w/o FB test blocks)............................... 5-14

Figure 5.16 Depth Sizing Regression for RT Procedures on FB Test Blocks in 

PARENT Open Testing (O.D. access) ............................................................... 5-15

Figure 5.17 Depth Sizing Regression for UIR Procedures on SBDMW Test Blocks in 

PARENT Open Testing (O.D. access – w/ FB test blocks)................................. 5-16
xv 

Figure 5.18 Depth Sizing Regression for UIR Procedures on FB Test Blocks in 

PARENT Open Testing (O.D. access) ............................................................... 5-16

Figure 5.19 Depth Sizing Regression for Conventional UT Procedures on SBDMW 

Test Blocks in PARENT Open Testing (O.D. access – w/ FB test blocks).......... 5-17

Figure 5.20 Depth Sizing Regression for Conventional UT Procedures on SBDMW 

Test Blocks in PARENT Open Testing (O.D. access – w/o FB test 

blocks)............................................................................................................... 5-18

Figure 5.21 Depth Sizing Regression for Conventional UT Procedures on FB Test 

Blocks in PARENT Open Testing (O.D. access) ................................................ 5-18

Figure 5.22 Length Sizing Regression for ADVPAUT Procedures on SBDMW Test 

Blocks in PARENT Open Testing (O.D. access) ................................................ 5-21

Figure 5.23 Length Sizing Regression for ADVPAUT Procedures on LBDMW Test 

Blocks in PARENT Open Testing (O.D. access) ................................................ 5-22

Figure 5.24 Length Sizing Regression for NLUT Procedures on SBDMW Test 

Blocks in PARENT Open Testing (O.D. access) ................................................ 5-23

Figure 5.25 Length Sizing Regression for PAUT Procedures on SBDMW Test 

Blocks in PARENT Open Testing (O.D. access) ................................................ 5-24

Figure 5.26 Length Sizing Regression for PAUT Procedures on LBDMW Test 

Blocks in PARENT Open Testing (O.D. access) ................................................ 5-24

Figure 5.27 Length Sizing Regression for PAUT Procedures on LBDMW Test 

Blocks in PARENT Open Testing (I.D. access).................................................. 5-25

Figure 5.28 Length Sizing Regression for Conventional UT Procedures on SBDMW 

Test Blocks in PARENT Open Testing (O.D. access) ........................................ 5-25

Figure 5.29 Length Sizing Regression for ECT Procedures on SBDMW Test Blocks 

in PARENT Open Testing (I.D. access) ............................................................. 5-26

Figure 5.30 Length Sizing Regression for ECT Procedures on LBDMW Test Blocks 

in PARENT Open Testing (I.D. access) ............................................................. 5-27

Figure 5.31 Length Sizing Regression for MM Procedures on LBDMW Test Blocks 

in PARENT Open Testing (I.D. access) ............................................................. 5-27

Figure 6.1 Depth Sizing Regression for ADVPAUT Procedures on SBDMW Test 

Blocks in PARENT Open Testing (O.D. access – w/o FB test blocks)..................6-2

Figure 6.2 Depth Sizing Regression for PAUT Procedures on SBDMW Test Blocks 

in PARENT Open Testing (O.D. access – w/o FB test blocks).............................6-3

Figure 6.3 Depth Sizing Regression for ADVPAUT Procedures on FB Test Blocks 

in PARENT Open Testing (O.D. access)..............................................................6-3

Figure 6.4 Depth Sizing Regression for PAUT Procedures on FB Test Blocks in 

PARENT Open Testing (O.D. access) .................................................................6-4

Figure 6.5 Length Sizing Regression for PAUT Procedures on SBDMW Test 

Blocks in PARENT Open Testing (O.D. access) ..................................................6-6

Figure 6.6 Length Sizing Regression for ADVPAUT Procedures on SBDMW Test 

Blocks in PARENT Open Testing (O.D. access) ..................................................6-7
xvi

Figure 6.7 Depth Sizing Regression Plot for HHUT.27.1 Applied to SBDMW Test 

Blocks (w/o FB test blocks) with O.D. Access ......................................................6-8

Figure 6.8 Depth Sizing Regression Plot for SHPA.6.1 Applied to SBDMW Test 

Blocks (w/o FB test blocks) with O.D. Access ......................................................6-9

Figure 6.9 Depth Sizing Regression Plot for LASH.18 Applied to SBDMW Test 

Blocks (w/o FB test blocks) with O.D. Access ......................................................6-9

Figure 6.10 Depth Sizing Regression Plot for HHUT.27.2 Applied to FB Test Blocks 

with O.D. Access ............................................................................................... 6-10

Figure 6.11 Depth Sizing Regression Plot for SHPA.6.3 Applied to FB Test Blocks 

with O.D. Access ............................................................................................... 6-10

Figure 6.12 Depth Sizing Regression Plot for LASH.18 Applied to FB Test Blocks 

with O.D. Access ............................................................................................... 6-11

Figure 6.13 Depth Sizing Regression for Procedure PAUT.122.1 (Linear) for FB 

Test Blocks by O.D. Access............................................................................... 6-16

Figure 6.14 Depth Sizing Regression for Procedure PAUT.122.2 (Sectorial) FB Test 

Blocks by O.D. Access....................................................................................... 6-16

Figure 6.15 UIR Image of FB Test Block P29 (view from side surface)................................. 6-17

Figure 6.16 UIR Image of FB Test Block P29 (view from side surface)................................. 6-17

Figure 6.17 UIR Image of FB Test Block P29 (view of surface from which crack 

initiates) ............................................................................................................. 6-17

Figure 6.18 Length Sizing Regression Plot for Procedure AECT.33 Applied to 

SBDMW Test Blocks with I.D. Access ............................................................... 6-19

Figure 6.19 Length Sizing Regression Plot for Procedure ECT.16 Applied to 

SBDMW Test Blocks with I.D. Access ............................................................... 6-20

Figure 6.20 Length Sizing Regression Plot for Procedure AECT.33 Applied to 

LBDMW Test Blocks with I.D. Access................................................................ 6-20

Figure 6.21 PAATOFD.29.2 Inspection of P42 (EDM) from O.D. .......................................... 6-21

Figure 6.22 PAATOFD.29.2 Inspection of P42 (EDM) from I.D............................................. 6-22

Figure 6.23 PAATOFD.29.2 Inspection of P30 (MFC) from O.D. .......................................... 6-22

Figure 6.24 PAATOFD.29.2 Inspection of P30 (MFC) from I.D. ............................................ 6-23

Figure 6.25 PAATOFD.29.2 Inspection of P32 (SCC) from O.D. .......................................... 6-23

Figure 6.26 PAATOFD.29.2 Inspection of P32 (SCC) from I.D. ............................................ 6-24

Figure 6.27 Data Images of Responses Obtained by SAFT-17 on Test Block P42 

with EDM Notch................................................................................................. 6-25

Figure 6.28 Data Images of Responses Obtained by SAFT-17 on Test Block P30 

with MFC Flaw................................................................................................... 6-26

Figure 6.29 Data Images of Responses Obtained by SAFT-17 on Test Block P32 

with SCC Flaw ................................................................................................... 6-27

Figure 6.30 Indication Depth Profile Obtained by SAFT-17 on Test Block P42 with 

EDM Notch ........................................................................................................ 6-28
xvii

Figure 6.31 Indication Depth Profile Obtained by SAFT-17 on Test Block P30 with 

MFC Flaw .......................................................................................................... 6-29

Figure 6.32 Indication Depth Profile Obtained by SAFT-17 on Test Block P32 with 

SCC Flaw .......................................................................................................... 6-30

Figure 6.33 Indication Plot for Procedure SAFT.17 Applied to Test Block P42 in 

PARENT Open Testing (X – Z view).................................................................. 6-30

Figure 6.34 Indication Plot for Procedure SAFT.17 Applied to Test Block P30 in 

PARENT Open Testing (X – Z view).................................................................. 6-31

Figure 6.35 Indication Plot for Procedure SAFT.17 Applied to Test Block P32 in 

PARENT Open Testing (X – Z view).................................................................. 6-31

Figure 6.36 Data Image Response for PAUT.122.1 Inspection of SCC Flaw in P28 

Viewed from the Right Side of Weld. The Inspection was performed by 

linear scanning with longitudinal wave modes from TRL probe at 60°. 

Two possible crack tip signals are highlighted by arrows in the image. .............. 6-32

Figure 6.37 Data Image Response for PAUT.122.1 Inspection of SCC Flaw in P28 

Viewed from the Right Side of Weld. The Inspection was performed by 

linear scanning with longitudinal wave modes from TRL probe at 50°. 

The likely crack tip signal is identified with the white circle................................. 6-33

Figure 6.38 Data Image Response for PAUT.122.1 Inspection of SCC Flaw in P32 

Viewed from the Right Side of Weld. The inspection was performed by 

linear scanning with longitudinal wave modes from TRL probe at 50°. 

The white circle indicates that it is difficult to separate the tip response 

from noise.......................................................................................................... 6-34

Figure 6.39 Data Image Response for PAUT.122.1 Inspection of SCC Flaw in P32 

Viewed from the Left Side of Weld. The inspection was performed by 

linear scanning with longitudinal wave modes from TRL probe at 55°. 

The white arrow highlights a weak signal considered to be the crack tip 

response............................................................................................................ 6-35

Figure 6.40 Data Image Response for PAUT.122.1 Inspection of SCC Flaw in P32 

Viewed from the Left Side of Weld. The inspection was performed by 

linear scanning with longitudinal wave modes from TRL probe at 45°. 

The white circle highlights the signal considered to be the crack tip 

response............................................................................................................ 6-36

Figure 6.41 Data Image Response for PAUT.122.1 Inspection of MFC Flaw in P30 

Viewed from the Left Side of Weld. The inspection was performed by 

linear scanning with longitudinal wave modes from TRL Probe at 50°. 

The white circle highlights the signal considered to be the tip response............. 6-37

Figure 6.42 Data Image Response for PAUT.122.1 Inspection of EDM Notch in P42 

Viewed from the Right Side of Weld. The inspection was performed by 

linear scanning with longitudinal wave modes from TRL probe at 50°. 

The white circle highlights the signal considered to be the tip response............. 6-38

Figure 6.43 Image of Response for Team 22 SAFT Response with L-waves ....................... 6-39
xviii

Figure 6.44 Image of Response for Team 22 SAFT Response with S-waves ....................... 6-39

Figure 6.45 Image of Response for Team 22 PATRT Response with L-waves ..................... 6-39

Figure 6.46 Image of Response for Team 22 PATRT Response with S-waves..................... 6-40

Figure 6.47 Coordinate System Definition, Dimensions, and Illustrations of FB Test 

Block P46 .......................................................................................................... 6-40

Figure 6.48 Data Images of Responses Obtained by SAFT-17 on Test Block P46 

from y-position 103.6 mm .................................................................................. 6-41

Figure 6.49 Indication Depth Profile Obtained by SAFT-17 on Test Block P46 from 

y-position 103.6 mm........................................................................................... 6-42

Figure 6.50 Data Images of Responses Obtained by SAFT-17 on Test Block P46 

from y-position 120 mm ..................................................................................... 6-43

Figure 6.51 Indication Depth Profile Obtained by SAFT-17 on Test Block P46 from 

y-position 120 mm ............................................................................................. 6-44

Figure 6.52 Example of Datasheet Submission for Procedures MM.28.1 and 

MM.28.2 with Non-Numerical Data in X, Y, and Z Fields for Indications............. 6-45

Figure 6.53 Example of Datasheet Submission for Procedure GUW.21 with Blank X, 

Y, and Z Fields for Indications............................................................................ 6-46

Figure 6.54 Example of Datasheet Submission for Procedures PECT.11 with NonNumerical Data in X, Y, and Z Fields for Indications .......................................... 6-47

Figure 6.55 Example of Datasheet Submission for Procedures NRUS.11 with NonNumerical Data in X, Y, and Z Fields for Indications .......................................... 6-48
xix

LIST OF TABLES

Table 1.1 Summary of Members of the PARENT Steering Committee, NDE Task 

Group, Atlas Task Group, and Invigilator/DAG.....................................................1-4

Table 2.1 Summary of Categories into which Test Blocks for Open Testing are 

Classified.............................................................................................................2-1

Table 2.2 Summary of Dimensions for LBDMW Full Circumference Test Blocks.................2-2

Table 2.3 Summary of Dimensions for SBDMW Full Circumference Test Blocks ................2-3

Table 2.4 Summary of Dimensions for LBDMW Partial Circumference Test Blocks.............2-5

Table 2.5 Tabulation of BMI Test Block P5 and P7 Dimensions ..........................................2-9

Table 2.6 Summary of Flaw Simulation Methods Used for Each Test Block and 

Quantities of Each Type of Simulated Flaw........................................................ 2-10

Table 4.1 Definitions of Data Fields for “Technique Datasheets” and “Inspection 

Summary Datasheets” .........................................................................................4-2

Table 4.2 Number of Inspection Summary Records by Procedure and Test Block 

Type ....................................................................................................................4-6

Table 4.3 Number of Inspection Summary Records for Procedure Types and 

Block Types by Access........................................................................................4-7

Table 4.4 Summary of Number of Flaw Observations (NOBS) for Different Flaw 

Types in Each Test Block Type............................................................................4-7

Table 4.5 Summary of Number of Flaw Observations (NOBS) by Flaw Orientation 

in Each Test Block Type ......................................................................................4-7

Table 5.1 Depth Sizing Results for Procedure Types Applied to SBDMW Test 

Blocks with O.D. Access w/ FB Test Blocks.........................................................5-1

Table 5.2 Depth Sizing Results for Procedure Types Applied to SBDMW Test 

Blocks with O.D. Access w/o FB Test Blocks.......................................................5-2

Table 5.3 Depth Sizing Results for Procedure Types Applied to SBDMW Test 

Blocks with O.D. Access (only FB test blocks) .....................................................5-2

Table 5.4 Depth Sizing Results for Procedure Types Applied to SBDMW Test 

Blocks with I.D. Access (only FB test blocks).......................................................5-2

Table 5.5 Depth Sizing Results for Procedure Types Applied to LBDMW Test 

Blocks with O.D. Access ......................................................................................5-2

Table 5.6 Depth Sizing Results for Procedure Types Applied to LBDMW Test 

Blocks with I.D. Access........................................................................................5-3

Table 5.7 Depth Sizing Results for Procedures Applied to SBDMW Test Blocks 

with O.D. Access w/ FB Test Blocks ....................................................................5-3

Table 5.8 Depth Sizing Results for Procedures Applied to SBDMW Test Blocks 

with O.D. Access w/o FB Test Blocks ..................................................................5-4

Table 5.9 Depth Sizing Results for Procedures Applied to SBDMW Test Blocks 

with O.D. Access (only FB blocks) .......................................................................5-4
xx 

Table 5.10 Depth Sizing Results for Procedures Applied to SBDMW Test Blocks 

with I.D. Access (only FB test blocks) ..................................................................5-5

Table 5.11 Depth Sizing Results for Procedures Applied to LBDMW Test Blocks 

with O.D. Access .................................................................................................5-5

Table 5.12 Depth Sizing Results for Procedures Applied to LBDMW Test Blocks 

with I.D. Access ...................................................................................................5-5

Table 5.13 Length Sizing Results for Procedure Types Applied to SBDMW Test 

Blocks with O.D. Access .................................................................................... 5-19

Table 5.14 Length Sizing Results for Procedure Types Applied to SBDMW Test 

Blocks with I.D. Access...................................................................................... 5-19

Table 5.15 Length Sizing Results for Procedure Types Applied to LBDMW Test 

Blocks with O.D. Access .................................................................................... 5-19

Table 5.16 Length Sizing Results for Procedure Types Applied to LBDMW Test 

Blocks with I.D. Access...................................................................................... 5-20

Table 5.17 Length Sizing Results for Procedures Applied to SBDMW Test Blocks 

with O.D. Access ............................................................................................... 5-20

Table 5.18 Length Sizing Results for Procedures Applied to SBDMW Test Blocks 

with I.D. Access ................................................................................................. 5-20

Table 5.19 Length Sizing Results for Procedures Applied to LBDMW Test Blocks 

with O.D. Access ............................................................................................... 5-20

Table 5.20 Length Sizing Results for Procedures Applied to LBDMW Test Blocks 

with I.D. Access ................................................................................................. 5-21

Table 5.21 Length Sizing Results for Procedures Applied to BMI Test Blocks with 

J-Groove Weld Surface Access ......................................................................... 5-28

Table 6.1 Summary of Depth Sizing RMSEs for ADVPAUT and PAUT Techniques 

Applied to SBDMW and LBDMW Test Blocks with O.D. and I.D. Access.............6-2

Table 6.2 Summary of Depth Sizing Performances for ADVPAUT Procedure 

Types Applied to SBDMW Test Blocks with O.D. Access w/o FB Test 

Blocks ..................................................................................................................6-5

Table 6.3 Summary of Depth Sizing Performances for ADVPAUT Procedure 

Types Applied to FB Test Blocks with O.D. Access .............................................6-5

Table 6.4 Summary of Depth Sizing Performances for PAUT Procedure Types 

Applied to SBDMW Test Blocks with O.D. Access w/o FB Test Blocks................6-5

Table 6.5 Summary of Depth Sizing Performances for PAUT Procedure Types 

Applied to FB Test Blocks with O.D. Access ........................................................6-5

Table 6.6 Summary of Length Sizing RMSEs for ADVPAUT and PAUT 

Techniques Applied to SBDMW and LBDMW Test Blocks with O.D. 

Access .................................................................................................................6-6

Table 6.7 Summary of Length Sizing Performances for ADVPAUT Procedure 

Types Applied to SBDMW Test Blocks with O.D. Access w/o FB Test 

Blocks..................................................................................................................6-6
xxi

Table 6.8 Summary of Length Sizing Performances for PAUT Procedure Types 

Applied to SBDMW Test Blocks with O.D. Access w/o FB Test Blocks................6-6

Table 6.9 Comparison of Depth Sizing Performances for FB Test Blocks.......................... 6-12

Table 6.10 Depth Sizing Results for P28 by Procedure Type for I.D. Access ...................... 6-12

Table 6.11 Depth Sizing Results for P29 by Procedure Type for I.D. Access ...................... 6-12

Table 6.12 Depth Sizing Results for P30 by Procedure Type for I.D. Access ...................... 6-12

Table 6.13 Depth Sizing Results for P31 by Procedure Type for I.D. Access ...................... 6-12

Table 6.14 Depth Sizing Results for P32 by Procedure Type for I.D. Access ...................... 6-13

Table 6.15 Depth Sizing Results for P38 by Procedure Type for I.D. Access ...................... 6-13

Table 6.16 Depth Sizing Results for P42 by Procedure Type for I.D. Access ...................... 6-13

Table 6.17 Depth Sizing Results for P28 by Procedure Type for O.D. Access..................... 6-13

Table 6.18 Depth Sizing Results for P29 by Procedure Type for O.D. Access..................... 6-13

Table 6.19 Depth Sizing Results for P30 by Procedure Type for O.D. Access..................... 6-14

Table 6.20 Depth Sizing Results for P31 by Procedure Type for O.D. Access..................... 6-14

Table 6.21 Depth Sizing Results for P32 by Procedure Type for O.D. Access..................... 6-14

Table 6.22 Depth Sizing Results for P38 by Procedure Type for O.D. Access..................... 6-15

Table 6.23 Depth Sizing Results for P42 by Procedure Type for O.D. Access..................... 6-15

Table 6.24 Summary of Depth Sizing Performances for Procedures PAUT.122.1 

and PAUT.122.2 ................................................................................................ 6-15

xxiii

EXECUTIVE SUMMARY 

The U.S. Nuclear Regulatory Commission (NRC) has established the Program to Assess the 

Reliability of Emerging Nondestructive Techniques (PARENT) whose goal is to investigate the 

performance of current emerging and perspective novel nondestructive examination (NDE) 

procedures and techniques to find flaws in nickel-alloy welds and base materials. This was

performed by conducting a series of open and blind international round-robin tests on a set of 

piping components that include large-bore dissimilar metal welds (LBDMW), small-bore 

dissimilar metal welds (SBDMW), and bottom-mounted instrumentation (BMI) penetration welds. 

In February 2012, the NRC entered into agreements with VTT Technical Research Centre of 

Finland, Nuclear Regulation Authority of Japan (NRA), Korea Institute of Nuclear Safety (KINS), 

Swedish Radiation Safety Authority (SSM), and Swiss Federal Nuclear Safety Inspectorate 

(ENSI) to establish PARENT to conduct a series of round-robin tests on SBDMWs, BMIs, and 

LBDMWs. PARENT activities were split into blind testing and open testing activities. Blind 

testing was performed in PARENT to quantitatively estimate the performance of established 

NDE methods in the nuclear power industry and the results from blind testing are documented 

in another report that is under preparation. This report is focused on documenting the open

testing activity and results.

Open testing was performed on a set of test blocks with true-state information that was open 

and provided to teams performing the testing. The objective of open testing was to evaluate the 

performance of emerging NDE techniques, which are still in relatively early stages of 

development. The performances of emerging NDE techniques were evaluated based on 

quantitative sizing analyses and qualitative analysis of data response images. The motivation 

for evaluating emerging NDE techniques includes the desire to identify more effective methods 

for detecting and characterizing rapidly growing forms of degradation, such as primary water 

stress corrosion cracking (PWSCC) and interdendritic stress corrosion cracking (IDSCC). 

Inspections with emerging NDE techniques were carried out by a variety of organizations 

including universities, industry organizations, and government research organizations. 

This report describes open testing performed in PARENT including a description of the test

blocks used, an overview of the NDE techniques applied, and analysis of the data. Data were 

collected for procedures incorporating novel NDE techniques on SBDMW, LBDMW, and BMI 

test blocks. There were 226 inspections performed on 4 BMI test blocks, 4 LBDMW test blocks, 

and 11 SBDMW test blocks. Some significant conclusions drawn for the results documented in 

this report include:

• A general trend was observed for oversizing shallow flaws and undersizing deep flaws with

the exception of advanced phased array ultrasonic testing (ADVPAUT) procedure types and

non-linear ultrasonic testing (NLUT) procedure types based on sub-harmonic techniques,

which exhibit a more consistent error over the range of flaw depths considered.

• NLUT procedures incorporating sub-harmonic techniques exhibited better depth sizing

performance than NLUT procedures incorporating higher harmonic techniques based on

overall root mean square error (RMSE) and regression analysis.

• ADVPAUT procedure types did not exhibit better overall depth sizing accuracy than phased

array ultrasonic testing (PAUT) procedure types in this study based on RMSE.
xxiv

• Overall, NLUT procedure types did not exhibit better overall depth sizing accuracy in 

comparison to ADVPAUT and PAUT procedure types based on RMSE.

• PAUT procedures exhibited a more consistent length sizing error over the range of flaw 

lengths considered for SBDMW test blocks in comparison to ADVPAUT, which exhibited a 

tendency to oversize short flaws and undersize long flaws.

• Better depth sizing performance was observed on flat bar (FB) test blocks (most with 

laboratory-grown SCC flaws) for ADVPAUT, NLUT, and conventional UT procedure types in 

comparison to SBDMW test blocks (with weld solidification cracks). PAUT procedure types 

exhibited better depth sizing performance on SBDMW test blocks in comparison to FB test 

blocks.

• Eddy current testing (ECT) exhibits a more consistent length sizing error over the range of 

flaw lengths considered for SBDMW test blocks in comparison to ”Advanced” ECT 

procedures (AECT.33), which tend to oversize short flaws and undersize long flaws.

• Depth sizing data for ultrasound infrared thermography (UIR) was obtained in a way that 

would not be practical in a field environment. However, the results indicated a capability for 

flaw detection and flaw length sizing.

• Data response images for ADVPAUT techniques illustrate that SCC flaws result in weaker 

crack tip responses in comparison to mechanical fatigue crack (MFC) and electro-discharge 

machine (EDM) notch flaws.

• Data response images for PAUT techniques illustrate that identifying crack tip signals with 

PAUT can be difficult and that crack tip signal identification by image pattern analysis is, in 

part, a subjective determination.

• Data response images for ADVPAUT and PAUT techniques illustrate difficulty in 

distinguishing noise from crack tip responses.

• Tip diffraction signals with low signal-to-noise ratio (SNR) were easier to detect under open 

testing conditions with flaw information provided to test participants. Detecting tip diffraction 

signals with low SNR under blind test conditions will be more challenging. 

Based on the results documented in this report and the conclusions outlined above, the 

following recommendations can be made:

• Blind testing of some of the open test procedures described in this report could be 

conducted based on the open testing results to obtain an estimate of detection performance 

and more realistic estimates of sizing performance. The specific techniques for which blind 

testing is recommended are summarized below:

− ADVPAUT

○ PAATOFD.29.0

○ PAATOFD.29.1

○ PAATOFD.29.2

○ PAATOFD.29.3

○ PATP.29
xxv 

○ PATRT.22

○ SAFT.17

− NLUT

○ SHPA.6.1

○ SHPA.6.2

○ SHPA.6.3

○ LASH.18

○ HHUT.27.1

○ HHUT.27.2

○ HHUT.30

− ECT

○ ECT.7

○ AECT.33

○ ECT.6

• Procedures UIR.20 and LUV.170 incorporated stand-off inspection techniques that have the 

potential for deployment during reactor operation. Evaluation of these procedures should be 

based on test pieces subject to relevant field conditions. 

• NLUT procedure types, which incorporated techniques that are sensitive to degradation in

early stages (i.e., before large cracks form), should be evaluated using test blocks with 

simulated early degradation to better evaluate their potential.

• Procedure GUW.21 had difficulty detecting flaws due to the geometrical limitations of the 

test blocks used in PARENT. Future efforts to evaluate GUW testing should ensure the 

dimensions of the test blocks are sufficient so that boundaries do not significantly influence 

the response.

xxvii 

ACKNOWLEDGMENTS

There have been significant contributions made by a number of people and organizations to

accomplish this work. The authors express appreciation to Iouri Prokofiev, Stephen Cumblidge, 

and Aladar Csontos, of the NRC for their leadership in helping to organize and start the Program 

to Assess the Reliability of Emerging Nondestructive Techniques (PARENT) program; to David 

Rudland of the NRC for his continued commitment to PARENT; to Stephen Cumblidge for 

continuing to provide technical and philosophical input to PARENT; and to Iouri Prokofiev for his 

continuous leadership of PARENT. Brett Braatz was the original Project Manager for PARENT 

and was responsible for the complex task of organizing and executing test block shipping and 

data collection. The authors also acknowledge the tireless efforts of the PARENT invigilators—

Tommy Zetterwall (Europe), Ichiro Komura (Japan), and Kyung-cho Kim (South Korea)—who

reviewed inspection procedures and monitored the work of inspection teams in their respective 

regions. The author also acknowledges contributions to the open testing portion of PARENT 

from the following organizations:

 Organizations from Japan

 Nuclear Regulation Authority (NRA)

 Ultrasonic Materials Diagnosis Laboratory (UMDL)

 Institute of Nuclear Safety System, Incorporated (INSS)

 Tohoku University 

 Nagoya University 

 Toyama University

 Japan Power Engineering and Inspection Corporation (JAPEIC)

 Organizations from Europe

 Swedish Radiation Safety Authority (SSM)

 Swiss Federal Nuclear Safety Inspectorate (ENSI)

 Swedish Qualification Center (SQC)

 Swiss Association for Technical Inspections, Nuclear Inspectorate (SVTI)

 VTT Technical Research Centre of Finland Ltd.

 Alstom Power Products [Switzerland]

 Swiss Federal Laboratories for Materials Science and Technology (EMPA)

 Chalmers Institute of Technology [Sweden]

 Paul Scherer Institute (PSI) [Switzerland]

 Organizations from Korea

 Korea Institute of Nuclear Safety (KINS)

 Korea Plant Service KPS

 Korea Atomic Energy Research Institute (KAERI)

 Korea Research Institute of Standards and Science (KRISS)

 Pusan National University (PNU)

 Sungkyunkwan University (SKKU)

 Hanyangg University (HYU)

 Organizations from the USA

 Nuclear Regulatory Commission (NRC)
xxviii 

 IHI Southwest Technologies and Southwest Research Institute (SwRI)

 AlphaSense

 Pacific Northwest National Laboratory (PNNL)

Finally, the authors thank Ms. Kay Hass for typing and editing versions and revisions of this 

document. 
xxix

ACRONYMS AND ABBREVIATIONS

2D two-dimensional 

3D three-dimensional

ADVPAUT advanced phased array ultrasonic testing

AECT advanced ECT technique 

BMI bottom-mounted instrumentation

BWR boiling water reactor

CAN contact acoustic nonlinearity 

CCD charge coupled device

CEECT controlled excitation eddy current technique 

CT computed tomography 

DMW dissimilar metal weld

ECT eddy current techniques

EDM electrical discharge machining 

EPRI Electric Power Research Institute

FB flat bar

FFT Fast Fourier Transform 

FSH full screen height

GUW guided ultrasonic waves 

HHUT higher harmonic ultrasonic technique

I.D. inner diameter

ID identification

IGSCC intergranular stress corrosion cracking 

IQI image quality indicators 

IR infrared 

ISI inservice inspection 

LASH large amplitude excitation subharmonic UT

LBDMW large bore dissimilar metal weld

LOB lack of bond 

LOF lack of fusion 

LUV laser ultrasound visualization 

MA Method Multi-angle Synthesis Method 

MFC mechanical fatigue crack 

MM microwave near-field microscopy 

NDE nondestructive examination 
xxx 

NLUT nonlinear ultrasonic testing

NOBS number of observations

NRUS nonlinear resonant ultrasound spectroscopy 

O.D. outer diameter

OCECT orthogonal coil eddy current technique 

PA phased array

PAATOFD phased array asymmetrical beam time-of-flight diffraction 

PARENT Program to Assess the Reliability of Emerging Nondestructive 

Techniques

PATP phased array twin probe 

PAUT phased-array ultrasonic techniques 

PC pitch/catch 

PE pulse-echo 

PECT pulsed excitation eddy current technique 

photo-emf photo electromotive force 

PINC Program for the Inspection of Nickel Alloy Components

POD probability of detection

PWR pressurized water reactor 

PWSCC primary water stress corrosion cracking

PZT piezoelectric transducer 

RMSE root mean square error

SAFT synthetic aperture focusing technique 

SAW surface acoustic waves 

SBDMW small bore dissimilar metal weld

SC weld solidification cracks

SCC stress corrosion cracking

SHPA subharmonic phased array 

SI slag inclusion 

SPACE subharmonic phased array for crack evaluation 

stdev standard deviation

TFC thermal fatigue cracks 

TOFD time-of-flight diffraction 

TR transmit-receive 

TRL transmit-receive longitudinal

PATRT phased array time reversal technique 

UIR ultrasound infrared thermography 

w/ with

w/o without
xxxi 

Definitions

Bottom-mounted 

instrumentation (BMI) 

A cylindrical penetration in the bottom head of a nuclear reactor 

pressure vessel, into which a tube is welded. Typical inside 

diameters are a few centimeters. 

Dendrite weld grain (columnar or tree-like)

Dissimilar metal weld 

(DMW)

Weldments joining components made of different alloys. In the 

context of PINC and PARENT, refers primarily to nozzle welds.

Heat-affected zone a volume of base metal, adjacent to the fusion zone, changed by 

the heat of welding

Interdendritic between the tree-like grains, such as can form in castings or 

weld metal

Intergranular between the metal crystals rather than through them

J-groove weld a weld with profile shaped as the letter “J,” the seal weld of a 

CRDM or BMI penetration

Lack of fusion missing metallic bond either between the sidewall of a weld with 

the base metal or between weld passes (inter-run)

Partial penetration weld the weld preformed to eliminate leakage paths, also called a seal 

weld

Primary water stress 

corrosion cracking 

(PWSCC)

The intergranular or interdendritic cracking of nickel-base alloys 

that occurs in service and originates from the surfaces of a 

component that are wetted by the primary water of a pressurized 

water reactor (PWR)

Program for the 

Inspection of Nickel-Alloy 

Components (PINC)

An international cooperative research program, The purpose of 

PINC is to assess the capabilities of current and emerging NDE 

techniques to detect and size flaws associated with PWSCC in 

nuclear reactors. This information tool is the definitive source of 

information on PINC.

Round-robin test (RRT) a test performed independently several times (usually at multiple 

testing facilities)

1-1 

1 INTRODUCTION

The U.S. Nuclear Regulatory Commission (NRC) has established the Program to Assess the 

Reliability of Emerging Nondestructive Techniques (PARENT) whose goal is to identify and 

quantitatively assess current emerging and perspective novel nondestructive examination 

(NDE) procedures and techniques for detecting, characterizing, and sizing of flaws in nickelalloy welds and base materials. This was performed by conducting a series of open and blind 

international round-robin tests on a set of piping components that include large-bore dissimilar 

metal welds (LBDMW), small-bore dissimilar metal welds (SBDMW), and bottom-mounted 

instrumentation (BMI) penetration welds. PARENT was a follow-on to the Program for 

Inspection of Nickel Alloy Components (PINC) (Cumblidge et al. 2010) based on the Bilateral 

International Agreements with participants and the in-kind contribution of resources from 

organizations of Finland, Japan, Republic of Korea, Sweden, and the United States of America 

to evaluate several nondestructive techniques for detection and characterization of primary 

water stress corrosion cracks (PWSCC) in SBDMW and BMI components. In February 2012, 

the NRC entered into new agreements with VTT Technical Research Centre of Finland, Nuclear 

Regulation Authority of Japan (NRA), Korea Institute of Nuclear Safety (KINS), Swedish 

Radiation Safety Authority (SSM), and Swiss Federal Nuclear Safety Inspectorate (ENSI) to 

establish PARENT to conduct a series of round-robin tests on SBDMWs, BMIs, and LBDMWs.

PARENT activities were split into blind testing and open testing activities. Blind testing was 

performed in PARENT to quantitatively estimate the performance of established NDE methods 

in the nuclear power industry and the results from blind testing are documented in NUREG/CR7235 (Meyer and Heasler 2017). This report is focused on documenting the open testing activity 

and results.

Open testing was performed on a set of test blocks with true-state information that was open 

and provided to teams performing the testing. The objective of open testing was to evaluate the 

performance of emerging NDE techniques, which are still in relatively early stages of 

development. The motivation for evaluating emerging NDE techniques is the desire to identify 

more effective methods for detecting and characterizing rapidly growing forms of degradation, 

such as PWSCC. Many of the emerging NDE techniques evaluated in open testing were

explored for their potential to be implemented for on-line monitoring or inspections. Other 

techniques were explored for their potential to improve on detection and characterization 

performance compared to more established techniques. Inspections with emerging NDE 

techniques were carried out by a variety of organizations including universities, industry 

organizations, and government research organizations. This contrasts with the blind testing 

portion of PARENT, which focused only on evaluating the latest commercially used NDE 

inspection techniques and only included inspectors and procedures provided by commercial

vendors. This report describes open testing performed in PARENT including a description of the 

test blocks used, an overview of the NDE techniques applied, and analysis of the data. A 

separate report is under development for the blind testing portion of PARENT.

The open testing portion of PARENT collected data from 226 inspections performed on 4 BMI 

test blocks, 4 LBDMW test blocks, and 11 SBDMW test blocks (8 of these test blocks are 

referred to as “flat bar” test blocks discussed in the next subsection). The data was collected by 

23 teams using 37 procedures. An overview of the inspections performed for each test block 

type is provided in Section 4 and tabulated summaries of NDE procedures and techniques 

applied to each test block are provided in Appendix B. 
1-2 

The open testing was performed with knowledge of true-state information in the open test blocks 

provided to teams conducting tests. As a result, no detection performance analyses were 

performed on open test data. Thus, the evaluation of open test data is based on statistical sizing 

analyses and qualitative review of data response images. Although the sizing analyses provide 

some objective measures of performance, the sample sizes are often limited and the results of 

sizing analyses are only able to provide an approximate measure of performance. This is 

appropriate for an open test evaluation because the focus is on establishing basic capability of 

techniques to justify further development and more detailed assessments of performance. For 

this reason, sizing analyses results for axial and circumferential flaws are not separated and no 

attempt is made to analyze outliers in the sizing plots. However, several data response images 

provided by test participants are qualitatively analyzed to supplement the sizing data. In 

reviewing sizing analyses results, emphasis should be placed on relative comparisons within 

open testing instead of the absolute values. Data was collected using established phased array 

ultrasonic testing (PAUT) techniques to provide a benchmark for comparison. Readers are 

cautioned against comparing sizing results from open testing with sizing results from blind 

testing because of the different conditions associated with each test. 

1.1 Laboratory Grown SCC Specimens

PARENT open testing was performed on several block types, including SBDMWs. A subset of 

the SBDMW test blocks used for open testing were manufactured by growing stress corrosion 

cracks (SCC) into fracture mechanics specimens in a laboratory autoclave and then machining 

off the tabs. These test blocks are described in Section 2.3. The specimens do not have 

curvature like other SBDMW test blocks and the flaws extend the full width of the specimens so 

that analysis of length sizing performance cannot be conducted with these test blocks. In 

addition, the weld in these test blocks is used to join pieces of similar reactor vessel steel. This 

contrasts with other SBDMW test blocks that join stainless steel components with carbon steel 

components. These factors provide the basis for distinguishing these test blocks as flat bar (FB) 

test blocks. They are still considered a subset of SBDMW test blocks in this report because the 

FB test blocks are similar to SBDMW test blocks dimensionally (i.e., they have similar 

thicknesses). Therefore, for the results in Section 5 and in Section 6, depth sizing results for 

SBDMW test blocks are noted in figure and table captions to indicate if the data results include 

data from FB test blocks or if the analysis was conducted by excluding data from FB test blocks.

As noted, length sizing analysis cannot be performed on the FB test blocks, so figure and table 

captions related to length sizing performance do not indicate inclusion or exclusion of FB test 

block data. 

1.2 Open NDE Techniques Report

An intermediate report was prepared to document the variety of NDE techniques evaluated in 

PARENT open testing (Meyer 2014). Much of the information in the report was provided by 

teams applying the techniques in PARENT open testing. The main body of the report included a 

basic description of the techniques, while specific information on how the techniques were 

applied in PARENT open testing are included as appendices to the report. Information from the 

main body of that report is included as Section 3 here, while the appendices are collected in

Appendix C of this report. A summarized tabulation of the NDE procedures and techniques 

applied to LBDMWs, SBDMWs, FBs, and BMIs is included in Appendix B of this report.
1-3 

1.3 Atlas Information Tool

An information tool is under development as part of PARENT and is referred to as the PARENT 

Atlas. The information tool is designed to contain data from PARENT open testing and 

information about the test blocks, as well as information on experiences of NDE applied in the 

field to inspect components for PWSCC. At the time of writing this report, only data from 

PARENT open testing and information about the open test blocks has been incorporated into 

the Atlas. Further discussions will be held with PARENT participants regarding additional 

information to incorporate into the Atlas.

1.4 PARENT Organization

PARENT is organized with a Steering Committee, a Task Group on NDE, a Task Group on the 

PARENT Atlas, and an Invigilator/Data Analysis Group (DAG) following a convention used in 

PINC and as shown in Figure 1.1. The objectives of these groups for PINC are described in 

Section 1.0 of NUREG-7019 (Cumblidge et al. 2010) and are similar to PARENT, although 

personnel have changed. A summary of the members of the Steering Committee, Task Group 

on NDE, Task Group on the PARENT Atlas, and the Invigilator/DAG is provided in Table 1.1. 

PARENT participants meet twice per year with one meeting in the United States and the other 

meeting rotated among the remaining participant countries. The first PARENT meeting was held 

June 1–3, 2010, at Pacific Northwest National Laboratory (PNNL) in Richland, Washington. 

Figure 1.1 Organization Chart for Steering Committee and Task Groups

1.5 Organization of Report

Section 2 of this report includes a description of the test blocks used in PARENT open testing, 

including dimensional information, a description of true states, and types of flaws used in each 

test block. Section 3 provides a description of the NDE techniques applied in PARENT open

testing, while Section 4 provides an overview of how data was recorded and a breakdown of 

inspections by procedure, test block, flaw type, and flaw orientation. Section 4 also describes 

how the depth and length sizing analysis was performed. Results of data analysis are presented 

in Section 5 with presentation of the results organized by block type and access (outer diameter 

[O.D.] versus inner diameter [I.D.]). Section 6 includes a discussion of the results in Section 5. 

Finally, additional conclusions and recommendations for future work are provided in Section 7. 
1-4

Table 1.1 Summary of Members of the PARENT Steering Committee, NDE Task Group, Atlas Task Group, and 

Invigilator/DAG

PARENT Committee Members

Organization Steering NDE Task Group Atlas Task Group Invigilator/Data Analysis Task Group

Member Name

FinlandVTT Esa Leskelä Esa Leskelä Esa Leskelä Aalto University Hannu HänninenJapan

NRA/JNES Kazunobu Sakamoto

Kikuo Takeshima

Kazunobu SakamotoKikuo Takeshima

Kenjiro AonoKikuo Takeshima

Kensaku AraiKikuo Takeshima

JAPEIC Ichrio Komura

Toshihiro Yamamoto

Ichiro KomuraToshihiro Yamamoto

Japanese PWR Industry Group

Yusuke Kono (MHI)Takehiko Yamaguchi 

(MHI)

Takayoshi Tsuruta (MHI)

(Rotating Member)Tomonori Shichida (MHI)Yasuto Nagoshi (MHI)Takehiko Sera (Kansai)Yasukazu Takada (Kansai)Seiji Asada (MHI)Junichiro Nishida (MHI)

Tohoku University Tetsuya Uchimoto

Korea 

KINS Sung-Sik Kang Kyung Cho Kim Kyung Cho KimKPS ES DohKHNP Yong-Sik Kim KAERI Hong-Pyo KimDOOSAN DS Lee, Joo Youl HongSKKU Hak-Joon Kim

SwedenSSM Richard Sundberg Giselle García Roldán SQC Tommy Zetterwall Tommy Zetterwall (all of Europe) Ulf Hjern (only invigilation) - Switzer

land

ENSI Klaus Germerdonk Klaus GermerdonkSVTI Hardy Ernst

USA

PNNL (Non-Voting) Brett Braatz, Rob Harris

Ryan M. Meyer

Brett Braatz, Ryan M. Meyer

Darren Curtis, Robert HarrisRyan M. Meyer

Steven Doctor, Brett BraatzJack Spanner – DAG (Open Only)Ryan M. Meyer NRC Iouri Prokofiev Stephen Cumblidge

EPRI Jack Spanner Jack Spanner

DOOSAN – Doosan Heavy Industries & Construction KAERI – Korea Atomic Energy Research Institute PNNL – Pacific Northwest National LaboratoryENSI – Swiss Federal Nuclear Safety Inspectorate Kansai – The Kansai Electric Power Company, Inc. SKKU – Sungkyunkwan UniversityEPRI – Electric Power Research Institute KHNP – Korea Hydro & Nuclear Power SQC – Swedish Qualification Center

JAPEIC – Japan Power Engineering and Inspection KINS – Korea Institute of Nuclear Safety SSM – Swedish Radiation Safety Authority

Corporation KPS – Korea Plant Service SVTI – Swiss Association for Technical Inspections,

JNES – Japan Nuclear Energy Safety MHI – Mitsubishi Heavy Industries, Ltd. Nuclear Inspectorate

Organization NRC – US Nuclear Regulatory Commission VTT – Technical Research Centre of Finland Ltd
2-1 

2 TEST BLOCK DESCRIPTIONS

The following section provides an overview of the test blocks used in the open testing activity of 

PARENT. The categories of test blocks that were used in the open testing study are 

summarized in Table 2.1. The categories include large bore dissimilar metal weld (LBDMW) test 

blocks, small bore dissimilar metal weld (SBDMW) test blocks, flat bar (FB) test blocks, and 

bottom mounted instrumentation (BMI) test blocks. A total of 19 test blocks were contributed for 

the open testing. Table 2.1 also indicates the typical weldment in each test block category, test 

block diameter and wall thickness dimensions, and the identifications (IDs) of test blocks in each 

category. Descriptions of the test blocks in each category are provided in Sections 2.1–2.4, 

while the flaw fabrication methods are described in Section 2.6. True-state information for the 

flaws in each test block is summarized in Section 2.7. 

Table 2.1 Summary of Categories into which Test Blocks for Open Testing are Classified

Category

Typical 

Weldment in 

Category

Diameter/Thickness 

Range

Test 

Block IDs

Test Block 

Photographs

LBDMW Full 

Circumference

DMW piping 

welds, PWR

Diameter (outer): 897 mm

Thickness: 78.5 mm

P37 Appendix D.3

LBDMW Partial 

Circumference

Diameter (outer): 852.5,

Thickness: 77 mm

P12, P23, 

P24

SBDMW Full 

Circumference

DMW piping 

welds, BWR

Diameter range (outer): 

286 mm–387 mm

Thickness range: 

32 mm–47 mm

P1, P4, 

P41

Appendix D.2

FB Diameter: Flat

Thickness: 30.3 mm

P28, P29, 

P30, P31, 

P32, P38, 

P42, P46,

Appendix D.2

BMI J-groove weld Tube OD: 38–45 mm P21, P22, 

P5, P7

Appendix D.1

2.1 Full Circumference Large Bore and Small Bore Dissimilar Metal Weld Test 

Blocks

One LBDMW full circumference test block and three SBDMW full circumference test blocks 

were used in PARENT open testing. The coordinate system defined for acquiring and reporting 

data on LBDMW test block P37 and SBDMW test block P41 is provided in Figure 2.1. The zero 

point is defined as that location on the test block where X=0, Y=0, and Z=0. Figure 2.1 also 

provides the definitions for the directional vectors X+, Y+, and Z+ in relation to the zero point 

and with respect to the material construction of the test block. The location for Z=0, Y=0 is at the 

outer diameter surface of the test block, at the center of the weld, and is located a distance “D” 

from the face edge of the carbon steel section. The X=0 location is indicated by a punch 

marking on the test block outer surface. A summary of dimensions for P37 and P41 are 

provided in Table 2.2 and Table 2.3, respectively. The locations, sizes, and types of flaws in test 

blocks P37 and P41 are provided in the true-state table in Appendix E. 
2-2 

Figure 2.1 Coordinate System Definition for SBDMW Test Blocks P41 and LBDMW Test 

Block P37

Table 2.2 Summary of Dimensions for LBDMW Full Circumference Test Blocks

Test Block ID

Inner Diameter, 

mm

Outer Diameter, 

mm D, mm

Test Block 

Length, mm

Circumferential 

Extent, degrees

P37 740 897 300 --- 360
2-3 

Table 2.3 Summary of Dimensions for SBDMW Full Circumference Test Blocks

Test Block ID

Inner Diameter, 

mm

Outer Diameter, 

mm D, mm

Test Block 

Length, mm

Circumferential 

Extent, degrees

P1 260–284 324–349 89 256 360

P4 257–290 324–387 208 583 360

P41 222 286 215 --- 360

The coordinate systems defined for acquiring and reporting data on SBDMW test blocks P1 and 

P4 are provided in Figure 2.2 and Figure 2.3, respectively. The zero point is defined as the 

location on the test blocks where X=0, Y=0, and Z=0. Figure 2.2 and Figure 2.3 also provide the 

definitions for the directional vectors X+, Y+, and Z+ in relation to the zero point and with 

respect to the material construction of the test block. The location for Z=0, Y=0 is at the outer 

diameter surface of the test block, at the center of the weld, and is located a distance “D” from 

the face edge of the carbon steel section. The X=0 locations are indicated by punch markings 

on the outer surface of the test blocks. A summary of dimensions for P1 and P4 are provided in 

Table 2.3. The locations, sizes, and types of flaws in test blocks P1 and P4 are provided in the 

true-state table in Appendix E. 

Figure 2.2 Coordinate System Definition for SBDMW Test Blocks P1
2-4 

Figure 2.3 Coordinate System Definition for SBDMW Test Blocks P4

2.2 Partial Circumference Large Bore Dissimilar Metal Weld Test Blocks

Three partial circumference LBDMW test blocks (P12, P23, and P24) were used in the open 

testing activities as indicated in Table 2.1. These test blocks use a similar coordinate system 

definition as the full circumference test blocks; however, the X=0 point is defined at a sector 

edge rather than a punch marking on the surface. Figure 2.4 depicts the coordinate system 

defined for P12 and Figure 2.5 depicts the coordinate system defined for P23 and P24. A 

summary of dimensions for P12, P23, and P24 test blocks is provided in Table 2.4. 
2-5 

Figure 2.4 Coordinate System Definition and Illustration of LBDMW Partial 

Circumference Test Block P12

Figure 2.5 Coordinate System Definition and Illustration of LBDMW Partial 

Circumference Test Blocks P23 and P24

Table 2.4 Summary of Dimensions for LBDMW Partial Circumference Test Blocks

Test Block 

ID

Inner Diameter, 

mm

Outer Diameter, 

mm D, mm

Test Block 

Length, mm

Circumferential 

Extent, degrees

P12 698.5 852.5 100 200 32.8

P23 736.6 912 306 600 88.8

P24 736.6 912 306 600 89.5

2.3 Flat Bar Test Blocks

A total of eight FB test blocks were used in PARENT open testing, as summarized in Table 2.1. 

However, unlike the partial circumference LBDMWs, these test blocks are not cut-outs from full 

circumference pieces. These specimens are fabricating by modifying fracture mechanics 

specimens used in autoclaves for growing laboratory flaws. As a result, the test blocks are flat 

bars that are cut out from reactor vessel material. The coordinate system and dimensions of test 

blocks P28, P29, P30, P31, P32, P42, and P46 are provided in Figure 2.6. In this case, the weld 

area is in the middle of the specimen and exhibits symmetry. Also, the flaws (one flaw in each 

block) are located at the middle of the specimens and extend across the full width of the 

specimens, except for P46, which is blank. Test block P38, illustrated in Figure 2.7, is slightly 

different as the weld area does not exhibit symmetry with respect to the Y direction. The 

dimensions for P38 and its weld area are included in Figure 2.7. 
2-6 

Figure 2.6 Coordinate System Definition, Dimensions, and Illustrations of FB Test 

Blocks P28, P29, P30, P31, P32, P42, and P46

Figure 2.7 Coordinate System Definition, Dimensions, and Illustrations of FB Test Block 

P38
2-7 

2.4 Bottom-Mounted Instrumentation Test Blocks

As Table 2.1 indicates, four BMI test blocks were used in open testing (P21, P22, P5 and P7). 

The coordinate system defined for acquiring and reporting data on these test blocks is provided 

in Figure 2.8 for P5 and P7 and Figure 2.9 for P21 and P22. These figures show that a 

cylindrical coordinate system is defined for BMI test blocks with the azimuthal coordinate, θ, 

increasing in the clockwise direction when viewed from the top of the test block (above the 

wetted surface) with the zero-point marked on the test block. The radial coordinate, R, is defined 

such that R=0 at the center of the penetration tube. R increases outward from this point along a 

plane that is parallel with the top (wetted) surface. The Z coordinate is defined as perpendicular 

to the J-groove weld surface such that Z=0 at the top (wetted) surface and increases into the Jgroove material. The dimensions of test blocks P21 and P22 are labeled in Figure 2.9, while the 

configuration of test blocks P5 and P7 are represented in Figure 2.10, and the dimensions for 

P5 and P7 are tabulated in Table 2.5. 

Figure 2.8 Coordinate System Used for BMI Test Blocks: P5 and P7
2-8 

Figure 2.9 Depiction of Configuration for BMI Test Blocks P21 and P22 with Coordinate 

System and Dimensions Labeled
2-9 

Figure 2.10 Depiction of Configuration for BMI Test Blocks P5 and P7 with Labeled 

Dimensions

Table 2.5 Tabulation of BMI Test Block P5 and P7 Dimensions

Test 

Block ID Figure Ref.

A,

mm

B,

mm

C,

mm

D (angle),

degrees

E (I.D.),

mm

F (O.D.),

mm

H,

mm

P5 Figure 2.10 100.0 215 × 222 240 89.5 15.9 44.2 100.0

P7 Figure 2.10 97.0 215 × 217 218 87.0 15.9 44.2 97.0

I.D. = inner/inside diameter

O.D. = outer/outside diameter

2.5 Simulated Flaw Types

Field flaws were simulated in PARENT open test blocks using similar methods as those used in 

PINC. Simulation flaw types include laboratory-grown SCC, weld solidification cracks (SC), 

thermal fatigue cracks (TFC), a mechanical fatigue crack (MFC), electrical discharge machining 

(EDM) notches, implanted welding defects such as lack of fusion (LOF), lack of bond (LOB), 

and slag inclusion (SI). A summary of the type and quantity of simulated flaws used in each test 

block is provided in Table 2.6. Brief descriptions of the flaw simulation types are provided in the 

following sections with the objective of highlighting some of the advantages and limitations of 
2-10

each flaw simulation type with respect to representing PWSCC/IDSCC for assessing NDE 

performance.

Table 2.6 Summary of Flaw Simulation Methods Used for Each Test Block and 

Quantities of Each Type of Simulated Flaw

Flaw Type Test Block ID (Quantity) Total Flaws

Laboratory-Grown SCC P12 (1), P28 (1), P29 (1), P31 (1), P32(1), P38(1) 6

TFC P5(3), P1 (4), P4 (2) 9

MFC P30(1) 1

SC P7(4), P41(12), P37 (9) 25

Welding Defects P37 (2) 2

EDM P4(2), P42(1), P12(1), P21(3), P22(3), P23(3), P24(4) 17

Total 60

2.5.1 Laboratory-Grown SCC (P12, P28, P29, P31, P32, and P38) 

Laboratory methods for introducing SCC flaws allow for the deliberate introduction of realistic 

flaws into test pieces at desired locations. However, even in a controlled laboratory 

environment, the dimensions of SCC flaws can be difficult to control. In addition, it can be 

difficult to grow SCC flaws into complex geometries because it can be difficult to generate the 

necessary stresses to promote SCC growth. Nonetheless, laboratory-grown SCC was 

introduced into several test blocks. The configuration used to grow SCC in P12 is shown in 

Figure 2.11. The bending loading setup shown in Figure 2.11 was used to introduce SCC flaws 

of shallow and medium depth. The process used is depicted as a flowchart in Figure 2.12. 

A different procedure is used for growing SCC flaws into test blocks P28, P29, P31, P32, and 

P38. Initially, these test blocks are fabricated by forming a standard fracture mechanics

specimen from a sample of pressurized water reactor (PWR) vessel material, including weld 

material, and then exposing the specimens to PWR environments in an autoclave facility. When 

desired crack growth is completed, the tabs of the fracture mechanics specimen are cut off so 

that a flat rectangular bar geometry remains. This is illustrated through a series of photographs 

in Figure 2.13. A depiction of the laboratory autoclave facility growing SCC flaws is provided in 

Figure 2.14. 

In addition to test blocks P28, P29, P31, P32, and P38, another FB specimen was prepared with 

the laboratory-grown SCC process depicted in Figure 2.14. This test block was destructively 

analyzed to study the SCC morphology produced. A photograph of the crack surface depicting 

the micro-fractographic appearance of the flaws is provided in Figure 2.15 and Figure 2.16. 

Observed features of the laboratory-grown SCC flaws considered relevant to NDE included the 

presence of “fingers” on the crack growth front and the presence of uncracked ligaments. The 

“fingers” may have an impact on depth sizing because they creates an irregular crack front and 

it may be difficult to identify the deepest part of the crack. The uncracked ligaments indicate 

regions where ultrasound would be transmitted across the crack faces, increasing the 

transparency of the crack to inspection by ultrasound. 
2-11

Figure 2.11 Depiction of the Approach Used to Produce a Laboratory-Grown SCC in 

Test Block P12

Figure 2.12 Flowchart of the Process Used to Produce a Laboratory-Grown 

PWSCC/IDSCC
2-12

Figure 2.13 Photograph and Depiction of FB Test Block Cut Out into Standard Fracture 

Mechanic Specimen from Reactor Pressure Vessel Material

Figure 2.14 Depiction of laboratory Autoclave Set-up for Growing SCC Flaws in FB 

Specimens under BWR and PWR Conditions
2-13

Figure 2.15 Typical Micro-Fractographic Appearance of Laboratory-Grown SCC in FB 

Specimens
2-14

Figure 2.16 Uncracked Ligaments and Finger-Like Local Laboratory SCC Crack Growth

in Destructively Analyzed FB Specimen

2.5.2 Thermal Fatigue Cracks (P1, P4, and P5) 

Thermal fatigue cracks can be introduced directly into test blocks without welding or machining. 

A single crack or a network of cracks can be induced in the base material and welded areas 

without artificial crack initiators. A total of nine TFCs were introduced into PARENT open test 

blocks P5 (BMI), P1, and P4. Analysis of TFC flaws in blind test blocks P6, P8, and P9 has 

indicated that the TFCs are wider than a typical SCC flaw. Further, flaw clusters have been 

observed in several test blocks. The clusters may make certain flaws easier to detect than they 

would be otherwise. In addition, flaw clusters introduce difficulty in depth sizing because of the 

interference caused by several crack tips in close proximity.

2.5.3 Weld Solidification Cracks (P7, P37, and P41) 

Weld solidification cracks may be used to simulate service-type defects such as IDSCC or 

PWSCC. The region where the cracks are fabricated are excised and filled with a “poisoned” 

weld metal that is designed to crack upon cooling. Care must be taken when SCs are to be 

used to determine the capability of NDE methods because the region of flaw fabrication may be 

too obvious by examination, similar to flaws that are implanted. This may be more of an issue 

for base material compared to weld material, and for this reason, SC type flaws are 

recommended for implantation into weld material. A total of 25 SC defects were used to 

simulate PWSCC flaws in test blocks P7, P37, and P41.
2-15

2.5.4 Electrical Discharge Machined Notches (P1, P12, P42, P21, P22, P23, and P24) 

A total of 17 EDM notches are included in test blocks P1, P12, P42, P21, P22, P23, and P24. 

Electrical discharge machining works by eroding the material in the path of electrical discharges that 

form between an electrode and the work piece. EDM notches are relatively easy to make and 

control the dimensions of, but they are often criticized for limited representation of real flaw features. 

EDM notches have a well-defined rectangular or semi-elliptical shape and lack the branching 

characteristic that SCC flaws often exhibit. In addition, the width of an EDM notch is dependent on 

the depth of the notch, with greater surface opening required with increasing depth.

2.5.5 Mechanical Fatigue Cracks (P30) 

One MFC is included in test block P30. MFCs are formed by cyclic mechanical loading of a test 

block or piece of material that is then implanted into a larger test block. In this case (P30), the 

MFC is grown into a test block whose geometry has been designed to accommodate controlled 

cyclic mechanical loading. MFCs typically have wider crack openings than SCC type flaws and 

the crack faces generally are not in contact except when under compression. Further, MFCs do 

not exhibit the branching behavior that is more common for SCC flaws.

2.5.6 Welding Defects (P37) 

Two welding defects including LOF and SI are included in test block P37. These defects are not 

surface-breaking.

2.6 True-State Determination

Information on flaw true states for each test block were documented on test block drawings by 

the test block contributors based on information documented in the flaw fabrication process and 

by fingerprinting. A summary of true states for all test blocks is provided in Appendix E.

3-1 

3 TECHNIQUE DESCRIPTIONS

The technique descriptions provided in this section have been documented in the main body of 

an intermediate report (PNNL-23387; Meyer 2014). The appendices of PNNL-23387 contain 

more information about specific implementation of open NDE techniques in PARENT and these 

appendices are compiled in Appendix C of this report. A tabulated summary of the open NDE 

techniques and procedures is included in Appendix B organized by test block type. The rest of 

this section is organized such that brief overview descriptions of ultrasonic techniques are 

provided in Section 3.1, while brief overview descriptions of the eddy current techniques used in 

the open testing are included in Section 3.2. Overview descriptions for other techniques are 

provided in Section 3.3, which includes descriptions for microwave near-field microscopy (MM) 

and radiographic techniques.

3.1 Ultrasonic Techniques

This section documents ultrasonic techniques employed in the open testing portion of PARENT 

by providing brief overview descriptions of the techniques. This section is roughly organized by 

first providing the description for a variant of conventional ultrasonic testing involving singleelement transducers, then by providing the description for phased array and other array 

transducer-based techniques. This is followed by overview descriptions for non-linear ultrasonic 

techniques, and overview descriptions for long-range or stand-off ultrasonic inspection 

techniques are provided last.

3.1.1 Through Transmission of Longitudinal Waves

A specific variant of conventional ultrasonic testing was assessed during the open testing based 

on a pitch/catch-type transducer arrangement for transmission and reception of longitudinal waves 

(UT-P/C). Mechanized scanning and encoding of transducer position and data was used to 

enhance flaw characterization ability. Identical angle beam (40° to 45°) transducers are used for 

both transmission and reception. Like most conventional ultrasonic techniques, the transducers 

are mounted on the outer surface of the component under inspection. A single reflection off of the 

backwall is required to direct the sound beam to the receiver located on the outer surface. The 

distance between the transmitter and receiver is such as to optimize this received signal. As the 

pair of transducers is scanned linearly over a flaw, shadowing of the transmitted signal by the flaw 

will result in a drop in the signal received (see Figure 3.1). Flaw characterization can be performed 

by analyzing C-scan images of the data like Figure 3.2. The depth of flaws can be determined 

from the C-scans as shown in Figure 3.2 with the aid of the formula in Figure 3.1. A detailed 

description of how the conventional UT-P/C technique was implemented in PARENT can be found 

in Appendix C.2.1. As reported in Appendix C.2.1.5, this technique is relatively insensitive to flaw 

surface roughness and to flaw orientation. In addition, material grain boundaries introduce very 

low noise, enabling the use of higher frequencies. However, inspection results can be heavily 

influenced by the presence of cladding and the technique can be difficult to implement when the

I.D. surface is not parallel with the O.D. surface.
3-2 

Figure 3.1 Illustration of Mechanized Scanning Through-Transmission Longitudinal 

Pitch/Catch Technique

Figure 3.2 The C-scan Shows the Received Amplitude Color Coded (0% full screen 

height, FSH [white] to 100% FSH [red])
3-3 

3.1.2 Phased Array Ultrasonic Testing

Phased array ultrasonic testing (PAUT) techniques have been gaining increased acceptance for 

performing inservice inspection of nuclear power plants. PAUT uses a transducer consisting of 

multiple piezoelectric or piezocomposite elements in contrast to conventional UT, which uses 

transducers with only a single-element. Electronic beam steering and focusing is achieved by 

careful time delay sequencing of excitation signals to the individual elements in the PAUT

transducers to create complex constructive and destructive interference patterns to intensify the 

sound field in a desired location (see Figure 3.3). PAUT data is often presented in A-scan, 

B-scan, C-scan, and D-scan image form for analysis. In this way, the linear dimensions of a flaw 

are characterized based on image analysis. Figure 3.4 shows an example of PAUT data 

representation as A-scan, B-scan, C-scan, and D-scan images. A PowerPoint overview of how 

several PAUT techniques were implemented in PARENT can be found in Appendix C.1.3 while 

a more detailed description of how the techniques were implemented can be found in Appendix 

C.2.2–C.2.5.

Figure 3.3 Illustration of Time Delay Sequencing of Excitation of PAUT Transducer 

Elements to Achieve Beam Steering and Focusing
3-4 

Figure 3.4 PAUT Data Represented as A-scan (top left), C-scan (top right), B-scan 

(bottom left), and D scan (bottom right) 

There are many parameters to consider in tailoring PAUT to a specific application including the 

size, number, and orientation of elements in a PAUT transducer as well as frequency. In 

addition, probes for PAUT may operate in pulse-echo mode or include separate arrays for 

transmitting and receiving. Like conventional UT, PAUT can be implemented with automated 

and encoded or can be performed manually. The significant advantage of PAUT over 

conventional UT is that it enables rapid examination of flaws from multiple angles resulting in 

more accurate and complete flaw characterization. However, the equipment (including the 

transducers, excitation electronics, and signal processing equipment) is more complex and 

costly in comparison to equipment for conventional UT exams. This increased complexity also 

requires a greater amount of personnel expertise to implement. PAUT can be applied for O.D. 

or I.D. inspections.

3.1.3 Three-Dimensional Synthetic Aperture Focusing Technique

Synthetic aperture focusing technique (SAFT) is a signal processing technique to correct for 

distortions in scanning images as a result of transducer focusing distortion, to obtain images 

with improved resolution. Similar to PAUT, SAFT enables electronic control over transducer 

focus and can greatly improve inspection performance compared to conventional UT. However, 

with SAFT, this control is implemented through post-processing of collected data. The basis for 

SAFT is easiest to illustrate for the two-dimensional (2D) scenario, as shown in Figure 3.5. 
3-5 

Figure 3.5 2D Illustration of SAFT Correction for Focusing Distortion in Ultrasonic 

Inspections (left); B-scan Illustrating Distortion Caused by Beam Focusing 

Effects (right) 

In this figure, an unfocused transducer located at x1 transmits a signal and receives an echo 

from the defect located at x2. As the transducer is scanned along x over the location of the 

defect, the B-scan image is created illustrating the distortion of the actual defect as a result of 

poor focusing. This distortion can be corrected with knowledge of the incident beam width and 

path traveled by ultrasound through the test piece (Elbern and Guimaraes 1999), 

( )   = −−    

1/2 2 2

2 1 12 d d xx . (3.1) 

SAFT can also be implemented with a transducer array in which each element in the transducer 

can be individually excited in sequence while all elements “listen” for echo signals. Using a 

matrix array transducer allows SAFT imaging to be performed in three dimensions (3D) (see 

Figure 3.6). An obvious advantage of implementing SAFT with array transducers is that it 

enables flaws to be characterized much faster and reduces the amount of mechanical scanning 

required for the transducer. Data from 3D-SAFT can be presented in the form of a variety of 

images including A-scans, B-scans, C-scans, and D-scans. Thus, analysis procedures are 

similar to those for PAUT. A PowerPoint overview of how the 3D-SAFT was implemented in 

PARENT can be found in Appendix C.1.2, while a more detailed description of how the 

3D-SAFT technique was implemented in PARENT can be found in Appendix C.5.2. 

3D-SAFT is a powerful technique in that it enables near arbitrary focusing and rapid 

characterization of defects through post processing of data. Similar to PAUT, 3D-SAFT requires 

the use of sophisticated probes and data recording and processing equipment.
3-6 

Figure 3.6 Implementation of 3D SAFT Using a Matrix Array Transducer. Individual 

elements are excited in sequence, while all elements “listen” for echoes.

3.1.4 Phased Array Time Reversal Technique

The phased array time reversal technique (PATRT) is a means for transmitting electronically 

focused ultrasonic energy through even non-homogenous media (Fink 1992; Fink 1999). 

PATRT is an iterative technique in which the reflection of ultrasonic energy from a target is 

interpreted as the emission of a weak ultrasonic signal from the target, which is detected by an 

array transducer. Under this interpretation, the target acts as a localized source and the sound 

field spreads as it propagates away from the target towards the array transducer. After 

digitization and recording of the signals at the transducer, they are time reversed and retransmitted to generate a sound field that becomes more focused as it travels from the array 

transducer back to the target (see Figure 3.7). As the process is repeated, the focusing of the 

sound field improves. Formally, the basis for PATRT lies in the reciprocity property of the wave 

equation. A PowerPoint overview of how PATRT was implemented in PARENT can be found in 

Appendix C.1.1 and a more detailed description of how PATRT was implemented in PARENT 

can be found in Appendix C.3.6.

A significant advantage of PATRT is its ability to adaptively focus in non-homogenous media. In 

contrast to SAFT, knowledge of the actual path that ultrasonic signals travel through the test 

material is not required. Similar to SAFT and PAUT, PATRT requires relatively sophisticated 

equipment and expertise for data recording and processing, in comparison to conventional UT. 

The techniques should be capable of performing both I.D. and O.D. inspections.
3-7 

Figure 3.7 Illustration of the Time Reversal Technique Concept for Focusing Ultrasonic 

Energy

3.1.5 Phased Array Asymmetrical Beam Time of Flight Diffraction

The phased array asymmetrical beam time-of-flight diffraction (PAATOFD) technique is 

implemented using a pair of 2D matrix array probes, with one probe serving as the transmitter 

and the other probe serving as the receiver (Ishida and Kitasaka 2013). Each probe is mounted 

on opposite sides of the flaw under investigation, similar to a regular time-of-flight diffraction 

(TOFD) configuration. However, the PAATOFD technique is based on the direct insonification of 

the crack tip as opposed to listening for the crack tip response when the base of the crack is 

insonified. With PAATOFD, the scan angle and focal depth of the transmitting and receiving 

probes may be arbitrarily adjusted, as indicated in Figure 3.8, to obtain the tip echo of the flaw 

from multiple scan angles. This enables improved discrimination of tip echo signals from 

sources of noise through synthesis (by the method named Multi-angle Synthesis Method (MA 

Method)) of the data from multiple scan angles and depths of focus as illustrated in Figure 3.9. 

A PowerPoint overview of how the PAATOFD technique was implemented in PARENT can be 

found in Appendix C.1.2, and a more detailed description of how PAATOFD was implemented in 

PARENT can be found in Appendix C.5.1.

In principle, the PAATOFD technique could be applied on the component O.D. or I.D. and could 

handle geometrical complexities such as weld crowns or unlevel surfaces, although this would 

likely complicate the analysis. The PAATOFD technique focuses on detecting crack tip signals 

and, thus, should be very accurate at depth sizing. The disadvantages of this technique include its 

large footprint with two matrix array probes, which may make it difficult to implement for certain 

components. Also, the technique could take a significant amount of time to implement as one 

must systematically scan through multiple depths of focus to identify the crack tip signal. However, 

if the technique is implemented in tandem with PAUT or conventional UT for initial flaw detection 

and rough sizing, it is possible that the scan volume could be significantly reduced.
3-8 

Figure 3.8 Schematic Illustration of the PAATOFD Technique

Figure 3.9 Data from Multiple Scan Angles and Depths of Focus are Synthesized in 

PAATOFD to Help Discriminate Crack Tip Signals from Noise
3-9 

3.1.6 Phased Array Twin Probe

The phased array twin probe (PATP) method is very similar to the PAATOFD method except 

that both the transmitter and receiver are oriented in the direction perpendicular to the scan 

direction as opposed to parallel to the scan direction for the PAATOFD technique. An illustration 

of the PATP technique is provided in Figure 3.10. With PATP, the scan angle and focal depth of 

the transmitting and receiving probes may be arbitrarily adjusted to enable improved 

discrimination of tip signals from sources of noise through synthesis (by MA method) of the data 

from multiple scan angles and depths of focus as illustrated Figure 3.11. The selection of the 

PAATOFD or PATP method will depend significantly on access conditions. For situations in 

which only single-sided access is available, the PATP could be implemented whereas 

PAATOFD may require access to both sides of a weld. A PowerPoint overview of how the PATP

technique was implemented in PARENT can be found in Appendix C.1.2, and a more detailed 

description of how PATP was implemented in PARENT can be found in Appendix C.5.1.

Figure 3.10 Schematic Illustration of the PATP Technique
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Figure 3.11 Data from Multiple Scan Angles and Depths of Focus are Synthesized in 

PATP to Help Discriminate Crack Tip Signals from Noise

3.1.7 Subharmonic Phased Array

Subharmonic phased array (SHPA), or subharmonic phased array for crack evaluation 

(SPACE), is an advanced ultrasonic testing technique that is based on the observation of 

nonlinear acoustic responses from material damage and phased array imaging techniques. 

More specifically, for crack evaluation, SHPA is based on the periodic contact (clapping) of the 

faces of tight cracks during the compressional period of an applied elastic wave, also referred to 

as contact acoustic nonlinearity (CAN). In this case, the clapping can occur if the amplitude of 

the elastic displacement is greater than the crack face separation (see Figure 3.12). In 

comparison to observations of higher harmonic generations, observations of subharmonic 

responses exhibit better selectivity to closed cracks (Ohara et al. 2008). 
3-11

Figure 3.12 Illustration of the Crack Face “Clapping” Phenomena that is the Basis for 

Subharmonic Generation when Elastic Waves are Applied to Tight Cracks

SHPA provides fundamental array images at fundamental frequency f and subharmonic array 

images at the subharmonic frequency f/2, visualizing the open and closed parts of cracks, 

respectively. In PARENT, SHPA was implemented in a surface acoustic waves (SAW) mode to 

assess flaw detection and length sizing capability and in a bulk wave mode to assess flaw depth 

sizing capability (see Figure 3.13). As the figure shows, SAW mode requires mounting of the 

transducer on the same surface as the flaw’s surface-breaking feature, while bulk wave mode is 

implemented similar to the way conventional UT and PAUT would typically be performed in the 

field with the transducer mounted on the component O.D. surface.
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Figure 3.13 Illustration of SPACE Implementation in SAW Mode to Assess Detection 

and Length Sizing Capability and in Bulk Wave Mode to Assess Depth 

Sizing Capability

For PARENT, SHPA was implemented using a single phased array transducer for transmitting 

and receiving and using short burst waves for excitations. SHPA data analysis can be 

performed in a similar fashion to data analysis for regular phased array examinations. That is, 

through examination of A-scan data and image analysis of B-scans, C-scans, and D-scans (see 

Figure 3.14).

Figure 3.14 Illustration of SHPA Data Analysis for Length and Depth Sizing of Flaws
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As noted, SHPA is particularly selective to closed or tight formed cracks but would not be useful 

for characterizing open cracks. Thus, characterization of both closed and open portions of 

cracks must be performed by analyzing images of data at the fundamental frequency, f (like 

regular phased array), in addition to the subharmonic image analysis. Otherwise, SHPA may be 

performed very similarly to regular phased array (PAUT) examinations, with similar equipment 

requirements and data analysis procedures. A variant of SHPA, referred to as large amplitude 

excitation subharmonic UT (LASH), described in the next subsection, uses a large amplitude 

excitation pulse to enable characterization of flaws with larger crack openings using 

subharmonic data. A PowerPoint overview describing how the SHPA technique was 

implemented for PARENT can be found in Appendix C.1.2, and a more detailed description of 

how SHPA was implemented in PARENT can be found in Appendix C.5.3.

3.1.8 Large Amplitude Excitation Subharmonic

LASH is a variant of SHPA, described in the previous subsection, utilizing a large amplitude 

excitation pulse to generate elastic waves with larger displacement so that selectivity for flaws 

with larger crack openings that may be more relevant to field conditions can be obtained. 

Implementation of LASH differs in comparison to the implementation described for SHPA in the 

last subsection in that a transmit/receive arrangement is used to facilitate use of separate 

high-voltage transducer for excitation of elastic waves with large displacement. Data analysis 

can be performed similar to SHPA and PAUT through analysis of A-scans, B-scans, C-scans, 

and D-scans.

As shown in Figure 3.15, this variant of LASH requires a separate high-voltage transducer for 

excitation in addition to the array transducer for signal reception. A PowerPoint overview of how 

LASH was implemented in PARENT can be found in Appendix C.1.2, and a more detailed 

description of how LASH was implemented in PARENT can be found in Appendix C.5.4.

Figure 3.15 Depiction of the LASH Technique Implementation

3.1.9 Higher Harmonic Ultrasonic Technique

The higher harmonic ultrasonic technique (HHUT) for crack detection is also based on the 

phenomenon of CAN, as illustrated in Figure 3.12. Higher harmonics are generated, in addition 

to subharmonics, because of the nonlinearity induced in signals as they interact with the crack 

faces (illustrated in Figure 3.16). As a result, the acoustic waveform becomes distorted and the 

higher harmonic frequency components are generated in the transmitted wave or in the 

reflected wave from the crack.
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Figure 3.16 Illustration of Higher Harmonic Generation Because of the CAN Phenomenon

Thus, it would be possible to detect closed cracks by monitoring the magnitude of the higher 

harmonic frequency component generated in the transmitted or the reflected wave. Usually, the 

relative nonlinear parameter (β′) defined by the ratio of the second order harmonic frequency 

magnitude to the power of the fundamental frequency magnitude is used as the monitoring 

parameter (Jhang 2000), although the generation of higher order harmonics can provide useful 

monitoring parameters as well. Overviews of how HHUT was implemented in PARENT can be 

found in the Appendices B.1.1 and B.1.2. More detailed descriptions of how HHUT was 

implemented in PARENT can be found in Appendices C.3.7 and C.5.5.

HHUT can be implemented in pulse-echo (PE) or transmit-receive (TR) modes as shown in 

Figure 3.17. The technique could be implemented on the component I.D. or O.D. To ensure 

sufficient interaction with the crack faces, the transducers should be mounted at an angle with 

respect to the crack faces, or perpendicular to them. The advantage of this technique compared 

to conventional UT is its sensitivity to closed cracks. However, compared to the subharmonic 

techniques described previously, higher harmonics are not as selective for closed cracks, 

although this may not necessarily be viewed as a drawback for all applications. A disadvantage 

of HHUT is that physical understanding of the technique is incomplete. As a consequence, 

quantitative characterization of flaws by HHUT will be difficult with a single measurement and 

may require relative comparison to responses obtained from already well characterized flaws.

Figure 3.17 Illustration of HHUT Implementation in PE (left) and TR (right) Modes
3-15

3.1.10 Nonlinear Resonant Ultrasound Spectroscopy

Nonlinear resonant ultrasound spectroscopy (NRUS) is another acoustic technique, in addition 

to the SHPA, LASH, and HHUT techniques described earlier, in which material characterization 

or damage assessment is based on the observation of nonlinear acoustic/ultrasonic responses. 

With NRUS, signals are applied over a wide frequency sweep to specimens to observe material 

nonlinearity as a result of damage manifested as a shift in resonant frequency and damping of 

the resonant peak amplitude as the excitation signal amplitude increases. An illustration of this 

for cyclic fatigue crack growth in a compact tension (CT) is shown in Figure 3.18. 

Figure 3.18 Resonance Frequency Shift in a Compact Tension Specimen in the Early 

Stage of Crack Initiation (top) and a Compact Tension Specimen with Crack 

Length of 7.0 mm (bottom) 

NRUS can be implemented by permanent mounting of piezoelectric sensors on specimen 

surfaces, as illustrated in Figure 3.19. Resonant peaks can be generated through application of 

swept frequency excitation and the resonant modes can be identified with an iterative solver that 

matches observed spectra with predicted spectra. A PowerPoint overview of how NRUS as 

implemented in PARENT can be found in Appendix C.1.1 and a more detailed description of the 
3-16

implementation can be found in Appendix C.3.1. An advantage of NRUS is that it can be 

sensitive to very early stages of degradation like other nonlinear acoustic/ultrasonic techniques. 

Another advantage is that it is suitable for continuous monitoring and can monitor damage 

progression over an extended region without mechanical scanning of the sensors. However, 

physical models of nonlinear elastic responses in materials are incomplete at this stage; thus, it 

may be difficult to characterize damage based on a single measurement. In addition, because 

NRUS may be implemented to monitor over an extended region, it may be difficult to precisely 

locate the detected damage by NRUS.

Figure 3.19 Schematic Drawing of Possible Piezoelectric Sensor Configuration

3.1.11 Guided Ultrasonic Waves

Guided ultrasonic waves (GUW) refers to an emerging class of techniques based on the 

propagation of low frequency acoustic/ultrasonic signals through materials. Analogous to the 

propagation of electromagnetic waves in bounded media, GUW are formed when the 

dimensions of the test material and wavelength are on similar order of magnitude or when the 

dimensions of the test material are much less than the wavelength of the probing 

acoustic/ultrasonic energy. In this regime, the interactions of the waves with material boundaries 

is very significant and the multiple reflecting waves constructively and destructively interfere 

such that new modes of propagation are generated with velocity that is dependent on 

component geometry, dimensions, and frequency (see Figure 3.20). This is in contrast to bulk 

ultrasonic wave propagation in which only two modes (longitudinal and shear) propagate 

through materials with a velocity that is independent of the component geometry, dimensions, 

and frequency. The topic of GUW is treated in multiple textbooks including the book by Rose 

(1999). 

Figure 3.20 Illustration of GUW Formation and Propagation in Test Material
3-17

The dependence of GUW mode velocity on frequency is a phenomena known as dispersion. 

The design of GUW inspection procedures and the analysis of GUW data is greatly assisted by 

the calculation of dispersion curves for a given applications. The dispersion curves show the 

relationship between the phase velocity and group velocity for several modes as a function of 

frequency, as illustrated in Figure 3.21. Like conventional UT, it is possible to implement GUW

techniques in PE or P/C mode and it can also perform both I.D. and O.D. inspections. A 

PowerPoint overview of how GUW was implemented in PARENT can be found in 

Appendix C.1.1 while a more detailed description of its implementation can be found in 

Appendix C.3.5.

Figure 3.21 Guided Wave Dispersion Curves on Cylindrical Coordinate: (a) phase 

velocity dispersion curve; (b) group velocity dispersion curve

The first widespread application of GUW for NDE was in the long-range inspection of 

petrochemical pipelines for corrosion (Lowe et al. 1998). Since then, the number of GUW

applications has increased, and in the nuclear power industry, GUW have been given serious 

consideration for the inspection of buried pipelines (EPRI 2008). These applications highlight 

the major benefits of GUW, which is the ability to perform fast inspections over a large distance 
3-18

in test materials, and the ability to inspect regions that may be inaccessible by conventional 

NDE equipment. However, GUW can be complex to implement in practice, often requiring 

systems tailored for specific applications. In addition, the analysis of GUW signals can be 

complicated, especially if multiple modes are propagated in the test material simultaneously.

3.1.12 Laser Ultrasound Visualization

Laser ultrasound is a technique in which ultrasound is transmitted and/or received in a material, 

similar to a traditional piezoelectric transducer (PZT). However, laser ultrasound allows the 

ultrasound to be transmitted and received from a distance, and without actual physical contact 

with the component under testing. A laser can be used to introduce the ultrasound via 

thermoelastic or ablative effects in the material surface (Murray and Wagner 1999; Rose 1984). 

A laser system can also be used to detect ultrasound via interferometry, photo electromotive 

force (photo-emf) detectors, or the optical beam deflection technique (Murfin et al. 2000). The 

laser ultrasound visualization (LUV) technique implemented in PARENT uses PZT sensors 

mounted on the component at discrete locations for signal detection. A laser is raster scanned 

over the surface of the test component and the received signals can be mapped with the laser 

ultrasound generated at different points. After a complete scan, the data can be processed and 

displayed as a movie clip for evaluation (see Figure 3.22). A more detailed description of the 

proposed LUV technique can be found in Appendix C.4.4.

Figure 3.22 Schematic of the Envisioned LUV System

The obvious advantage of LUV is the stand-off mode of ultrasound generation, which can 

enable inspection of components that are otherwise difficult to access by more conventional 

means. Enhanced visualization schemes promise to make detection and characterization 

easier. Laser ultrasound techniques, in general, can be used to detect cracks that break the 

illuminated surface. However, depth sizing with laser ultrasound is more difficult and the ability 

of laser ultrasound to do so is undetermined. LUV is most suited for O.D. applications.

3.1.13 Ultrasound Infrared Thermography

Ultrasound infrared thermography (UIR) is based on the detection of thermal energy generated 

when elastic energy is absorbed by a defect and converted to thermal energy through thermo 

elastic effects. An illustration of the general concept is provided in Figure 3.23. The result is an 
3-19

infrared image in the test specimen to which standard image analysis techniques may be 

applied to characterize defects based on temperature differences (see Figure 3.24). The main 

UIR techniques include pulsed, phase lock-in, or a combination of both (Dillenz et al. 2000; 

Maldague 2001). A PowerPoint overview of how UIR was implemented in PARENT can be 

found in Appendix C.1.1, while a more detailed description is provided in Appendix C.3.4.

Figure 3.23 Illustration of the UIR Concept

Figure 3.24 UIR Image of a Test Specimen with Crack

With lock-in phase UIR, amplitude and phase information about the thermal waves emitted from 

the specimen is preserved for several frequencies. The advantage of this is that it enables 

characterizing the depth of a source of thermal emissions within the test component. With 

pulsed phase lock-in thermography, broadband thermal signals arriving at each pixel of an 

infrared detector camera are analyzed using Fast Fourier Transform analysis. The advantage of 

UIR is that it potentially enables more rapid examination of large areas based on camera 

images in contrast to techniques that would require a point-by-point raster scan. The technique 

is significantly more sensitive to cracks on the visually accessible surface (normally O.D. 
3-20

surface). The potential disadvantage of the technique is that it requires a low thermal noise 

background so that flaws could be imaged reliably.

3.2 Eddy Current Techniques

Overview descriptions for eddy current techniques employed in the open testing portion of 

PARENT are provided in this section including a description of exciter-pickup eddy current 

techniques, which refer to eddy current techniques that employ a coil for generating an 

excitation field and separate sensor to detect perturbations in the field because of flaws. This 

contrasts with conventional ECT in which the same coil may be used for both field excitation 

and detection. The controlled excitation eddy current technique (CEECT) is also a variant of the 

pulsed excitation eddy current technique (PECT) but is described separately here because the 

probe is configured specifically to enhance its ability for characterizing deep flaws. Finally, 

overview descriptions for the orthogonal coil eddy current technique (OCECT) and PECT is 

included. In addition to CEECT, PECT can be distinguished from conventional ECT in that it is 

often implemented for the purpose of characterizing flaws in the depth dimension.

3.2.1 Exciter-Pickup Eddy Current Techniques

In practice, an eddy current probe consists of one or more coils with the axis alignment most 

often perpendicular or parallel to the inspection surface normal. An alternating current source is 

applied to the one or more coils, generating magnetic fields. These magnetic fields induce eddy 

currents in the conducting materials when the probe is positioned nearby (see Figure 3.25). 

Flaws and defects in the test material impede the flow of eddy currents manifesting as a change 

in the measurable eddy current coil impedance. An important parameter for eddy current testing 

is the skin depth,

1

f

δ

π σμ = (3.2) 

which provides a measure of the depth to which eddy current fields can penetrate in a test 

material. As can be seen from Eq. (3.2), this quantity depends on the coil frequency, f, and 

electrical conductivity, σ, of the test material (μ is the magnetic permeability). Thus, in metal 

components, the depth of penetration is usually small and the eddy current technique is often 

limited to surface examinations. Multi-coil techniques include separate coils for the generation of 

eddy current fields in the test material and for detection of the fields at the surface, as illustrated 

in Figure 3.26. These types of probes may also be referred to as reflection probes, driverpickup, exciter-pickup, or send-receive probes. This contrasts with conventional ECT in which 

the same coil is used for both field generation and for signal reception. In PARENT, two teams 

applied basic multi-coil techniques. A PowerPoint overview of how one of the techniques was 

implemented in PARENT can be found in Appendix C.1.4, while a more detailed description can 

be found in Appendix C.4.1. A PowerPoint overview of how the second technique (referred to as 

the advanced ECT technique [AECT]) was implemented can be found in Appendix C.1.2, and a 

more detailed description of how AECT was implemented in PARENT can be found in 

Appendix C.5.7.

The advantage of eddy current techniques over ultrasonic techniques is that they are usually 

more sensitive to small defects and the probes do not require coupling to the test material 

surface. As noted, a significant disadvantage of eddy current techniques is that they are often 

relegated to surface inspections and are not very useful for characterizing the depth of flaws
3-21

beyond 1 or 2 mm. In addition, the increased sensitivity of ECT can make it more prone to false 

calls from the pick-up of signals from superficial surface imperfections (such as scratches) and 

ECT techniques can be sensitive to lift-off variations and variations in material conductivity.

Figure 3.25 Depiction of a Single Coil Eddy Current Probe with an Alternating Current 

Excitation, Induced Magnetic Fields, and Induced Eddy Currents. 

Disturbance of eddy current flow can be caused by existence of a defect.

Figure 3.26 Schematic Illustration of an Eddy Current Probe with Separate Coils for 

Field Excitation and for Signal Detection

3.2.2 Controlled Excitation ECT

Controlled excitation eddy current (CEECT) is another type of exciter-pickup technique with 

coils configured so that eddy current response can be correlated with crack depth, even for 

deep cracks. In particular, the probe is designed such that the phase response shows 
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correlation with depth for deep cracks, as illustrated in Figure 3.27. A schematic of the particular 

CEECT probe implementation for PARENT is provided in Figure 3.28. This particular probe has 

two exciter coils oriented with their axes perpendicular to the test surface normal and a pick-up 

sensor is located between the two exciter coils. A PowerPoint overview of CEECT and how it 

was implemented in PARENT is included in Appendix C.1.2, and a more detailed description of 

its implementation can be found in Appendix C.5.8.

The phase response of the CEECT to deep cracks is a significant advantage of CEECT over 

other eddy current techniques. However, the phase response is also dependent on other flaw 

parameters such as length, cross section, etc. More information is needed to fully understand 

the effects of other flaw parameters on the phase response. In addition, the footprint of the 

CEECT can be quite large, because the pick-up sensor must be separated sufficiently from the 

exciter coils. This may limit the ability to deploy the technology on component regions with poor 

accessibility.

Figure 3.27 Illustration Showing that the Phase Response of CEECT has a Significant 

Correlation to Flaw Depth over a Large Range of Flaw Depth Values, 

Including for Deep Cracks

Figure 3.28 Illustration of the CEECT Probe for Measuring the Depth of Flaws
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3.2.3 Orthogonal Coil Array Eddy Current Technique

The orthogonal coil array eddy current technique (OCECT) was implemented in PARENT using 

a commercial eddy current probe with an array of orthogonal coil pairs. The single orthogonal 

coil pair configuration has also been referred to as “plus-point” because when viewed from the 

test piece the intersecting orthogonal coils look similar to a plus sign (Figure 3.29). The OCECT

technique is a differential eddy current technique meaning that the output of one coil is 

referenced to the output of the other coil. Differential eddy current probes are typically less 

sensitive to lift-off and surface irregularities. One advantage of OC-ECT is that it has directional 

sensitivity to flaws, making it possible to distinguish between axial and circumferential defects. 

The orthogonal coil configuration helps minimize the influence of flaw orientation with respect to 

the probe performance as defects that are parallel to the current flow can be missed. Rotation of 

the OCECT probe can also be performed to further minimize the influence of flaw orientation. 

A PowerPoint overview of how OCECT was implemented in PARENT can be found in 

Appendix C.1.2, and a more detailed description of its implementation can be found in 

Appendix C.5.6.

Figure 3.29 Illustration of Orthogonal Coil Pair and Relative Orientation to Surface 

Crack Profiles

3.2.4 Pulsed Excitation Eddy Current Technique

Pulsed excitation eddy current technique (PECT) is an eddy current technique that relies on low 

duty cycle pulse excitations (Lebrun et al. 1997). This contrasts with most ECT concepts, which 

are based on continuous sinusoidal wave excitation at a single frequency (see Figure 3.30). The 

low duty cycle pulse results in a wide frequency band excitation field that allows deeper 

penetration into a test component owing to the lower frequency components (up to 30 mm) (Lee 

et al. 2012). The penetration depth can be tuned by changing the duty cycle of these pulses, 

with wider pulses containing stronger low-frequency components (Abidin et al. 2009). Besides 

the ability to penetrate significant depth, PECT has other advantages over conventional ECT 

techniques such as lower power consumption and the ability to generate a richer set of data. 

However, the instrumentation used to drive pulsed sources can be more complex than for a 

conventional ECT system. In addition the interpretation of PECT signals can require 

considerable expertise. A PowerPoint overview describing how PECT was implemented in 

PARENT can be found in Appendix C.1.1. A more detailed description of how PECT was 

implemented in PARENT can be found in Appendix C.3.2.
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Figure 3.30 Comparison of Pulsed Excitation for PECT (left) to Continuous Sine-Wave 

Excitation for Conventional ECT (right) and Illustration of the Frequency 

Spectrum Associated with Each Type of Excitation Source

3.3 Other Techniques

This section describes other techniques implemented in the open testing portion of PARENT 

and includes the microwave near field microscopy technique and radiographic techniques.

3.3.1 Microwave Near Field Microscope

Microwave near field microscope (MM) is an electromagnetic NDE technique that is based on 

sensing impedance changes as a result of the obstruction of surface excitation currents from 

discontinuities. In this respect, MM is similar to ECT, but operates at much higher frequencies 

such that the electromagnetic field does not penetrate the surface. Whereas ECT may operate 

approximately from 0.1 to 10 MHz, MM may be performed in a frequency range from 

approximately 1 GHz to over 100 GHz (Zoughi and Kharkovsky 2008). MM sensing is based on 

open-ended waveguides in which the standing wave pattern in the waveguide will change in 

response to the terminating impedance. Thus, when the tip of an MM probe is placed near a 

conducting surface and a surface-breaking discontinuity disrupts the flow of currents, it 

represents a change in the terminating impedance and will alter the standing wave pattern (see 

Figure 3.31).
3-25

Figure 3.31 Illustration of the MM Technique for Crack Detection

Zoughi and Kharkovsky (2008) describe two types of interactions through which MM can not 

only indicate crack detection, but also provide information about crack width and depth. In 

dominant mode interaction (for instance, transverse electromagnetic mode), MM is performed 

primarily by observing the perturbations in the dominant mode as a result of interactions with 

surface-breaking discontinuities. In addition to affecting the dominant mode, the presence of 

cracks will result in the generation of higher order modes. Thus, MM can be used to 

characterize flaws based on both the analysis of dominant mode perturbations and higher order 

mode generations. MM is able to detect very tight cracks and is able to sense cracks that may 

be masked by layers of paint or corrosion products. Similar to conventional ECT, MM is 

primarily a surface inspection technique, although its ability to characterize the width and depth 

of flaws sets it apart from conventional ECT. A PowerPoint overview of how MM was 

implemented in PARENT is provided in Appendix C.1.2, and a more detailed description of its 

implementation can be found in Appendix C.5.9.

3.3.2 Radiography Techniques

A radiographic inspection system uses a source of radiation (x-rays or gamma rays) to irradiate 

the specimen under test. X- or gamma rays penetrate the specimen, and are absorbed, 

scattered or otherwise attenuated when passing through the material. A detector of some form 

is used to collect and record the transmitted rays as illustrated in Figure 3.32. Several different 

sources are available (with different energy levels) (Halmshaw 1987) enabling the inspection of 

specimens with different thicknesses. The inspection itself requires a balance between the 

source energy, source-to-specimen distance, source-to-detector distance, and exposure time. 

Conventional radiographic inspection requires access to both sides of the specimen, with the 

source and detector placed on either side of the test specimen. The quality of the radiographs is 

usually determined through the use of image quality indicators (IQI) or penetrameters. Details 

on radiographic inspection, along with information on the choice of IQI devices, may be found in 

several publications, for instance Cartz (1995). 
3-26

Figure 3.32 Illustration of a Radiographic Examination and Interaction of Source X-rays 

with Density Discontinuities such as Flaws

In conventional radiography, the location and orientation of the specimen is fixed relative to the 

source and detector location. The result is a radiograph where the orientation of any flaws is 

fixed with respect to the source and detector locations. The effectiveness of conventional 

radiography techniques for inspection of planar flaws is especially sensitive to the flaw 

orientation (see Figure 3.33). An alternative approach is to subject each region on the specimen 

to multiple radiographic inspections. Each inspection is performed with the specimen oriented at 

a different angle relative to the source and/or detector. While this technique improves the 

information on flaws (potentially enabling better detection and through-wall sizing), the approach 

tends to have higher costs. A common variation on this approach is computed tomography (CT), 

where multiple view angles are used, and the resulting two-dimensional data combined to 

create 3D images of the specimen. Typically, CT scans require a computer-controlled scanner 

system to obtain precision control of view angles (Ewert et al. 2007). A description of how 

radiography techniques were implemented in PARENT can be found in the Appendices C.2.7

and C.2.8. 
3-27

Figure 3.33 Illustration Depicting the Sensitivity of Conventional Radiography Signal to 

Planar Flaw Orientation

4-1 

4 DATA OVERVIEW

This section provides information on what data was recorded and reported during PARENT 

open round-robin testing and how the data is analyzed. Section 4.1 provides a description of 

data reporting by describing the datasheets used to record and report test data. Section 4.2

provides an overview summary of inspection records collected, and Section 4.3 describes how 

procedures are categorized in procedure type categories. Finally, Section 4.4 includes a 

discussion of how data is analyzed. 

4.1 Data Reporting

This section provides an example of the completed data forms for one inspection. In this 

inspection, Team 12 has inspected test block P89 using Procedure 12.1. Procedure 12.1 uses 

three techniques in the inspection, identified as ET400kHz, TOFD.Ax, and TOFD.Circ. 

Consequently, this inspection generates three Technique Datasheets, and one Inspection 

Summary Datasheet. Illustrations of Technique Datasheets and an Inspection Summary 

Datasheet are provided in Figures 4.1 through 4.3. Information in the Inspection Summary 

Datasheet is based on data recorded in Technique Datasheets. For the example provided, 

techniques TOFD.Ax and TOFD.Circ are used for depth sizing and characterization while 

technique ET400kHz is used for detection, length sizing, and positioning. This information is 

combined in completion of the Inspection Summary Datasheet. Similar data fields are included in 

Technique Datasheets and Inspection Summary Datasheets. A summary of descriptions for all of 

the data fields is provided in Table 4.1. Figures 4.1 through 4.3 show that datasheets include a 

table where information about each observed indication is recorded. The information includes a 

series of coordinates (X1, X2, Y1, Y2, Z1, Z2) that describe a cuboid that envelopes an observed 

indication, allowing for comparison of its position and size to true-state information for both 

detection and sizing analysis. In addition, fields “Ymax/Xmax,” “Amp dB,” and “Surface Breaking” 

are included to allow recording of the location where a maximum signal response is observed, the 

value of that signal, and whether or not an observed indication is surface-breaking.
4-2 

Table 4.1 Definitions of Data Fields for “Technique Datasheets” and “Inspection 

Summary Datasheets”

Field Name Description

Procedure ID This has format of Team-ID.seq-no and uniquely identifies this procedure in 

the round robin test. This ID originates from the Procedure Summary Data 

Sheet that describes this technique.

Team ID This is a unique number assigned to each participating team in the test to 

maintain anonymity. 

Tech ID This is a unique alpha-numeric identifier assigned to each technique on the 

data form. This ID originates from the Procedure Summary Data Sheet and 

identifies the technique being applied.

Inspection ID This ID identifies each unique inspection performed. One inspection ID is 

common to all inspections made on a specific test block, by a specific test 

team, for all the Technique IDs applied within a specific Procedure ID. 

Format: Team-id.Block-id.seq-no.

Test Block ID ID of the test block being inspected.

Access This field indicates if access is obtained from I.D. or O.D. If access is from 

both sides, “I.D. and O.D.” can be entered.

Date Date of inspection

Detection This field should contain “yes” if at least one of the techniques in the 

procedure is able to detect flaws. Otherwise, it should contain “no.”

Length Sizing This field should contain “yes” if at least one of the techniques in the 

procedure is able to length size flaws. Otherwise, it should contain “no.”

Depth Sizing This field should contain “yes” if at least one of the techniques in the 

procedure is able to depth size flaws. Otherwise, it should contain “no.”

Weld Volume Inspected Coordinates of the volume of material inspected. 

Defect No. Uniquely identifies each observed indications

X1, X2, Y1, Y2, Z1, Z2 These coordinates describe a cuboid that contains the observed indication. 

Ymax/Xmax This identifies the location at which a maximum signal is observed.

Amp dB The amplitude of the signal observed at Ymax/Xmax is recorded here.

Surface Breaking Indicate whether or not a flaw is surface breaking. 

Comments To include useful information about each indication found. 
4-3 

Figure 4.1 Technique Datasheets for Techniques ET400Hz and TOFD.Ax for Fictitious 

Inspection 12.P89.1
4-4 

Figure 4.2 Technique Datasheet for Technique TOFD.Circ for Fictitious Inspection 

12.P89.1

Figure 4.3 Inspection Summary Datasheet for Fictitious Inspection 12.P89.1
4-5 

4.2 Records Collection Overview Summary

The number of inspection summary datasheets collected (equivalent to the number of 

inspections) for each block type (i.e., BMIs, LBDMWs, SBDMWs, FBs) is tabulated in Table 4.2

according to procedure ID. Procedure ID is expressed here as “Tech.TeamID” where Tech 

represents the type of technique used for a given procedure ID. The possible techniques are 

described in Section 3. Table 4.3 breaks down the number of inspections by access type (i.e., 

O.D. vs. I.D.) for BMIs, SBDMWs, LBDMWs, and FBs test blocks for each procedure type 

classification. Table 4.4 tabulates the number of inspections by flaw type and Table 4.5

tabulates number of inspections by flaw orientation. Flaw orientation is considered axial if the 

axial dimension of the flaw is 3x the circumferential dimension or greater. Flaw orientation is 

considered circumferential if the circumferential dimension of the flaw is 3x the axial dimension 

or greater. If neither of these criteria is met, the flaw is classified as diagonal. In this case, the 

term diagonal is used to distinguish from axial and circumferential orientation and reflect that the 

flaw does not have a dominant orientation in the axial or circumferential direction based on 

dimensions. Only two flaws were classified as diagonal based on this criterion—one flaw in BMI 

test block P22 and another flaw in BMI test block P7.

4.3 Procedure Type Categorization

Individual procedures can be organized into procedure type categories. For instance, 

procedures PAUT.20 and PAUT.122 can be classified as PAUT procedure types. In PARENT 

open testing, the majority of procedures can be classified as PAUT or advanced PAUT 

(ADVPAUT) procedures. The next largest procedure type is ECT. Several procedures included 

in the ECT procedure type category could be considered advanced ECT techniques. However, 

due to the limited amount of data, conventional ECT and advanced ECT procedure types are 

combined into a single procedure type category. A diagram illustrating procedure type 

categories and how procedures are classified by procedure type categories for the purpose of 

data analysis is included in Figure 4.4. 

4.4 Scoring Procedure Used for PARENT Open Testing

The same scoring procedure was utilized in PARENT open testing as was used in PARENT 

blind testing and in PINC, which is described in Section 4.1 of NUREG/CR-7019 (Cumblidge et 

al. 2010). Although detection performance is not analyzed for open test data, scoring was 

required to associate indications to flaws for sizing analysis purposes. A tolerance was added to 

flaw true-state dimensions to limit systematic positioning error resulting in legitimate detections 

being classified as misses. Once the tolerance is defined, δX and δY, then the flaw cuboid, X1, 

X2; Y1, Y2; Z1, Z2, becomes,

(X X,X X,Y Y,Y Y,Z ,Z 1 2 1 2 12 − +−+ δ δδ δ ) (4.1) 

An illustration of tolerance applied to flaw true-state (solid red) dimensions is provided in 

Figure 4.5 resulting in an enlarged region represented by white space with a red border. 

Indications that intersect any portion of this enlarged region are classified as hits. Tolerance 

values of δX = δY = 10 mm were utilized, which is consistent with PARENT blind testing and 

PINC. An illustration of an indication plot is provided in Figure 4.6. The red rectangles represent 

the “true-state” (actual flaws) with the surrounding tolerance box. Indications are shown as 

empty rectangles. 
4-6 

Table 4.2 Number of Inspection Summary Records by Procedure and Test Block Type

BMIs LBDMWs SBDMWs FBs

AECT.33 2 2 1 8

CEECT.5.1 1 0 2 0

CEECT.5.2 0 1 0 0

ECT.16 2 1 3 7

ECT.7 4 0 0 0

GUW.21 1 0 1 0

HHUT.27.1 0 0 2 0

HHUT.27.2 0 0 0 8

HHUT.30 0 0 0 3

LASH.18 0 1 1 5

LUV.170 6 0 4 0

MM.28.1 1 3 3 0

MM.28.2 0 0 0 5

NRUS.11 0 0 0 3

PAATOFD.29.0 0 4 2 0

PAATOFD.29.1 0 4 0 16

PAATOFD.29.2 0 1 0 16

PATP.29 0 4 2 0

PATRT.22 0 0 0 1

PAUT.114 0 0 3 7

PAUT.122.1 0 0 0 7

PAUT.122.2 0 0 0 7

PAUT.131.1 0 0 0 7

PAUT.131.2 0 0 3 0

PAUT.131.4 0 0 1 0

PAUT.150 0 2 0 0

PAUT.20 0 0 1 6

PAUT.7 0 2 0 0

PECT.11 0 0 0 3

RT.109 0 0 0 6

RT.112 0 0 1 3

SAFT.17 0 4 2 8

SHPA.6.1 0 0 1 1

SHPA.6.2 0 0 1 0

SHPA.6.3 0 0 0 4

UIR.20 0 0 0 6

UT.104 0 0 1 8

TOTAL 17 29 35 145
4-7 

Table 4.3 Number of Inspection Summary Records for Procedure Types and Block 

Types by Access

BMIs

LBDMWs 

I.D.

LBDMWs 

O.D.

SBDMWs 

I.D.

SBDMWs 

O.D.

FBs 

I.D.

FBs 

O.D.

ADVPAUT 0 5 12 0 6 16 25

ADVPAUT, NLUT 0 0 1 0 3 0 10

ECT 9 4 0 6 0 15 3

GUW 1 0 0 0 1 0 0

LUV 6 0 0 0 4 0 0

MM 1 3 0 3 0 5 0

NLUT 0 0 0 0 2 3 11

PAUT 0 2 2 0 8 2 32

RT 0 0 0 0 1 0 9

UIR 0 0 0 0 0 0 6

UT 0 0 0 0 1 0 8

TOTAL 17 14 15 9 26 41 105

ADVPAUT = advanced phased-array ultrasonic testing; NLUT = nonlinear ultrasonic testing

Table 4.4 Summary of Number of Flaw Observations (NOBS) for Different Flaw Types in 

Each Test Block Type

BMIs FBs LBDMW SBDMWs TOTAL

EDM 18 28 83 24 153

LOB/LOF 0 0 11 0 11

MFC 0 52 0 0 52

SC 41 0 126 300 467

SCC 0 216 26 0 242

SI 0 0 11 0 11

TFC 31 0 0 124 155

TOTAL 90 296 257 448 1091

Table 4.5 Summary of Number of Flaw Observations (NOBS) by Flaw Orientation in 

Each Test Block Type

BMIs FBs LBDMWs SBDMWs TOTAL

A 40 0 140 150 330

C 16 296 117 298 727

Vol 34 0 0 0 34

TOTAL 90 296 257 448 1092
4

-8

Figure 4.4 Diagram Illustrating How Procedures are Classified by Procedure Types for Data Analysis Purposes
4-9 

Figure 4.5 Illustration of Tolerance (GX and GY) Applied Flaw True-State (in red) 

Dimensions for the Purpose of Scoring in PARENT 

Figure 4.6 Depiction of Indication Plot Illustrating 2-D Representation of Test Block. The 

red filled rectangles represent the true-state (actual flaws), while red empty 

rectangles surrounding the flaws depict the scoring tolerance. Indications 

are shown as black empty rectangles. 

4.5 Substitution for X1, X2, Y1, and Y2 Indication Fields 

For some open testing inspections, X1, X2, Y1, and Y2 fields were not populated because a 

procedure may have only been assessed for depth sizing and the location of flaws was known. 

An example is provided in Figure 4.7 for LASH.18 examination of P1. To facilitate depth sizing 

analysis, the X1, X2, Y1, and Y2 fields were populated with the values for the true state. This 
4-10

was necessary so that the data in the Z1 and Z2 fields for the indications would be correlated to 

the correct flaw. The indication plots appear as Figure 4.8 and Figure 4.9 in this scenario. As 

Figure 4.8 shows, the indication and flaw dimensions (X1, X2, Y1, and Y2) are identical. A 

collection of indication plots for all of the open inspections performed in PARENT is included in 

Appendix H. 

Figure 4.7 Inspection Summary Datasheet for Inspection of Test block P1 by Procedure 

LASH.18 showing unpopulated X1, X2, Y1 and Y2 fields
4-11

Figure 4.8 Indication Plot for Procedure LASH.18 Applied to Test Block P1 in PARENT 

Open Testing (X – Y view)

Figure 4.9 Indication Plot for Procedure LASH.18 Applied to Test Block P1 in PARENT 

Open Testing (X – Z view)

4.6 Multiple Indications Associated with One Flaw

In a few cases, multiple indications may intersect the region bounded by the tolerance box for 

the same flaw as illustrated in Figure 4.10. For these scenarios, it is necessary to select one of 

the indications for performing the sizing analysis. The selection is based on the indication with 

the largest intersecting area with the tolerance region. To accommodate indications that may 

have no width defined in one dimension (i.e., X or Y), and thus have no area, the tolerance is 

divided between the flaw and the indications with values of δX/2 and δY/2 (refer to Figure 4.5). 

This is illustrated in Figure 4.11. The indication whose tolerance boundaries form the largest 

region of intersection with the area defined by the flaw tolerance boundaries is selected as the 

indication to associate with the flaw for sizing analysis purposes.
4-12 

Figure 4.10 Indication Plot Illustrating Two Indications Intersecting the Region 

Bounded by the Tolerance Box 

Figure 4.11 Illustration of Tolerance Divided Between Flaw and Multiple Indications 

Intersecting the Region Bounded by the Flaw Tolerance Box 

4.7 Analysis of PARENT Open Round Robin Data 

PARENT used the same scoring criteria as PINC, which is described in Section 4.1 of 

NUREG/CR-7019 (Cumblidge et al. 2010). However, probability of detection is not emphasized 

for open test data as teams were provided with true-state information for flaws prior to 

performing measurements. Linear regression was used to analyze sizing data (depth and 

length) in PARENT Open testing. An error relation between the measured and true sizes of the 

flaws is defined by the following regression formula: 

M BBTE i i  u 1 2 i (4.2) 
4-13

where Mi represents the measured size associated with flaw i

Ti represents the true size of flaw i

Ei represents the measurement error in sizing flaw i 

B1 and B2 are the regression parameters usually associated with the Y intercept and slope of 

the linear regression. Ideal performance for sizing would occur when B1 = 0, B2 = 1, and Ei = 0. 

To compare two different regression fits, and to order a set of regression fits (from most 

accurate to least accurate as an example), the metric of root mean square error (RMSE) is 

used. RMSE is a statistic that summarizes the three deviations of regression analyses from their 

respective ideals. RMSE is defined by 

( ) −

=

∑ 2

2

i i

i

M T

RMSE

n

(4.3) 

where all the variables are the same as in the preceding descriptions and n is the total number 

of measurements. RMSE can also be represented in terms of bias and standard deviation as

= + 22 2 RMSE bias StDev . (4.4) 

In this formula, standard deviation is represented with the variable StDev. The bias and StDev

represent systematic and random components to the error and are calculated with the following 

formulas,

( ) −

=

∑

bias

i i

i

M T

n , (4.5) 

( ) 2

bias

StDev

i i

i

M T

n

  − −  

=

∑ . (4.6) 

The length of an indication is determined by the maximum of its circumferential and axial 

dimensions. While this is adequate for most of the inspections, this definition of length lead to 

counterintuitive results for procedure HHUT.27 inspection of test block P1. The indication plot 

for this inspection is provided in Figure 4.12. The indications in Figure 4.12 have axial 

dimensions that are greater than their circumferential dimensions. However, the flaws are 

circumferentially oriented. In this case, the sizing algorithm compares the axial dimension of the 

indication to the circumferential dimension in the analysis of length sizing error.
4-14

Figure 4.12 Indication Plot for Procedure HHUT.27 Inspection of Test Block P1

An example of a sizing regression curve is provided in Figure 4.13 for length sizing performed 

on flaws in LBDMW test blocks from the O.D. surface for ADVPAUT procedure types. The dark 

line represents the regression fit while the red dashed lines above and below the regression fit 

are the 95% confidence intervals. In this case, the “A’s” represent the axial flaw data points and

“C” is used to represent circumferential flaw data points. 

Figure 4.13 Length Sizing Regression for ADVPAUT Procedures on LBDMW Test 

Blocks in PARENT Open Testing (O.D. access)

The sizing analysis was performed by an algorithm that was implemented in an automated 

fashion and generally combined data for axially and circumferentially oriented flaws. In addition, 

outliers were not analyzed in detail and were not removed from the analysis. However, the 
4-15

objective of open testing was in establishing basic capability of techniques to justify further 

development and more detailed assessments of performance. Thus, only approximate 

measures of depth and length sizing performance were sought in open testing. Some specific 

sizing examples are provided below to illustrate the consequences of these analyses decisions 

and to emphasize to the reader to interpret the results of sizing analysis cautiously. The data 

provided by the sizing analysis was meant to serve as a rough assessment of performance 

capability, and was not intended to provide a precise measure of performance capability.

Figure 4.14 shows a regression curve for the depth sizing performance of procedure 

PAUT.131.1 applied to SBDMW test blocks and FB test blocks with a negative slope. This result 

is most likely an artifact of an outlier datapoint, which is circled in red. If the outlier datapoint 

were removed, the slope of the regression line would likely be positive. Another example 

provided in Figure 4.15 shows a positive regression fit to circumferential and axial flaw 

datapoints for NLUT procedures applied to SBDMW and FB test blocks. Red and green lines 

are superimposed to illustrate that the regression fits to circumferential and axial flaw datapoints 

would be much different. In this case, it is apparent that the axial datapoints would have resulted

in a negatively sloped curve.

In addition, for some presentations of sizing results, plots such as Figure 4.16 are provided. In 

this case, no regression fit is displayed because four data points are required to provide a fit for 

the model in Eq. (4.2).

Figure 4.14 Depth Sizing Regression (in mm) for Procedure PAUT.131.1 on SBDMW 

Test Blocks in PARENT Open Testing (O.D. access – w/ FB test blocks)
4-16

Figure 4.15 Depth Sizing Regression for NLUT Procedures on SBDMW Test Blocks in 

PARENT Open Testing (O.D. access – w/ FB test blocks)

Figure 4.16 Depth Sizing Regression (in mm) for Procedure HHUT.30 on SBDMW Test 

Blocks in PARENT Open Testing (I.D. access – w/ FB test blocks)
5-1 

5 DATA ANALYSIS RESULTS

This section presents the results of data analysis performed for open test data collected in 

PARENT. The primary data analysis performed includes depth sizing analysis and length sizing 

analysis. Section 5.1 includes the depth sizing analysis results for DMW test blocks, including 

LBDMWs and SBDMWs and FB test blocks. The results are presented separately for O.D. and 

I.D. access of LBDMWs and SBDMWs, and where relevant, SBDMW results are presented with 

(w/) and without (w/o) FB data. In some cases, data is presented just for FB test blocks. 

Tabulated summaries of depth sizing results for procedure types and individual procedures are 

included in Section 5.1. Plots of regression curves for depth sizing data from ADVPAUT, NLUT, 

PAUT, RT, UIR, and conventional UT procedure types are included in Sections 5.1.1 through 

5.1.6, respectively. Section 5.2 summarizes length sizing results for DMWs, again presenting 

results separately for LBDMW and SBDMW test blocks, and according to test block access. In 

this case, FB test block data is not included in the length sizing analysis because flaws extend 

the full width of FB test blocks. Tabulated summaries of length sizing results for procedure types 

and individual procedures are included in Section 5.2. Plots of regression curves for length 

sizing data from ADVPAUT, NLUT, PAUT, conventional UT, ECT, and MM procedure types are 

included in Sections 5.2.1 through 5.2.6, respectively. Finally, BMI results are summarized in 

Section 5.3, consisting of the results of length sizing analysis of inspections conducted from the 

J-groove weld surface.

5.1 DMW Depth Sizing Results

The results of depth sizing analysis are summarized in this section by tabulating RMSE and

Bias for procedures and procedure types. The table column heading “NOBS” refers to the 

number of observations, which represents the number of depth size measurements. Tabulated 

summaries of depth sizing results for procedure types applied to SBDMW and FB test blocks by 

O.D. access are included in Tables 5.1 through 5.3 for SBDMW test blocks with FB test blocks, 

only SBDMW test blocks, and only FB test blocks, respectively. Table 5.4 includes the same 

summary for procedure types with I.D. access, which is only relevant to FB test blocks. Finally, 

depth sizing summaries for procedure types applied to LBDMW test blocks are included in

Tables 5.5 and 5.6 for O.D. and I.D. access, respectively.

Table 5.1 Depth Sizing Results for Procedure Types Applied to SBDMW Test Blocks 

with O.D. Access w/ FB Test Blocks

NOBS Bias (mm) RMSE (mm)

ADVPAUT 57 2.7 5.3

NLUT 38 0.7 6.7

PAUT 79 0.3 3.4

RT 14 −0.2 2.0

UIR 6 1.0 3.4

UT 11 −0.0 2.1

All 205 1.0 4.6
5-2 

Table 5.2 Depth Sizing Results for Procedure Types Applied to SBDMW Test Blocks 

with O.D. Access w/o FB Test Blocks

NOBS Bias (mm) RMSE (mm)

ADVPAUT 36 2.5 5.5

NLUT 21 0.7 7.7

PAUT 47 −0.1 2.4

RT 6 0.2 2.2

UT 4 −0.4 3.2

All 114 0.9 4.8

Table 5.3 Depth Sizing Results for Procedure Types Applied to SBDMW Test Blocks 

with O.D. Access (only FB test blocks) 

NOBS Bias (mm) RMSE (mm)

ADVPAUT 21 3.2 5.0

NLUT 17 0.7 5.2

PAUT 32 0.9 4.5

RT 8 −0.5 1.8

UIR 6 1.0 3.4

UT 7 0.2 0.9

All 91 1.2 4.4

Table 5.4 Depth Sizing Results for Procedure Types Applied to SBDMW Test Blocks 

with I.D. Access (only FB test blocks)

NOBS Bias (mm) RMSE (mm)

ADVPAUT 14 2.0 3.1

NLUT 3 −0.9 2.0

PAUT 2 −0.5 1.2

All 19 1.3 2.8

Table 5.5 Depth Sizing Results for Procedure Types Applied to LBDMW Test Blocks 

with O.D. Access

NOBS Bias (mm) RMSE (mm)

ADVPAUT 36 2.0 9.1

NLUT 1 −1.1 1.1

PAUT 3 2.9 5.1

All 40 2.0 8.7
5-3 

Table 5.6 Depth Sizing Results for Procedure Types Applied to LBDMW Test Blocks 

with I.D. Access

NOBS Bias (mm) RMSE (mm)

ADVPAUT 8 2.3 6.7

PAUT 8 −1.4 5.2

All 16 0.4 6.0

The tabulation of depth sizing results for individual procedures is provided in Tables 5.7 through 

5.12. The summary for individual procedures applied to SBDMW test blocks and FB test blocks 

with O.D. access is provided in Table 5.7. Table 5.8 provides a summary for SBDMW test 

blocks without FB test blocks with O.D. access and Table 5.9 provides a summary for FB test 

blocks with O.D. access. Table 5.10 provides a summary for SBDMW test blocks with ID 

access, while Tables 5.11 and 5.12 provide depth sizing summaries for individual procedures 

applied to LBDMW test blocks with O.D. and I.D. access, respectively.

Table 5.7 Depth Sizing Results for Procedures Applied to SBDMW Test Blocks with O.D. 

Access w/ FB Test Blocks

NOBS Bias (mm) RMSE (mm)

HHUT.27.1 9 3.2 11.1

HHUT.27.2 7 3.1 7.1

LASH.18 9 −1.7 3.3

PAATOFD.29.0 13 0.8 4.6

PAATOFD.29.1 7 3.6 5.5

PAATOFD.29.2 7 3.9 5.8

PATP.29 9 2.4 6.6

PAUT.114 26 0.2 2.8

PAUT.122.1 7 0.4 0.9

PAUT.122.2 7 −0.0 1.1

PAUT.131.1 5 4.1 8.8

PAUT.131.2 16 0.3 0.6

PAUT.131.4 8 −0.1 0.4

PAUT.20 10 −0.6 5.4

RT.109 5 −0.3 2.1

RT.112 9 −0.1 1.9

SAFT.17 21 3.3 4.8

SHPA.6.1 5 1.6 1.9

SHPA.6.2 4 −5.2 5.4

SHPA.6.3 4 1.0 1.4

UIR.20 6 1.0 3.4

UT.104 11 −0.0 2.1

All 205 1.0 4.6
5-4 

Table 5.8 Depth Sizing Results for Procedures Applied to SBDMW Test Blocks with O.D. 

Access w/o FB Test Blocks

NOBS Bias (mm) RMSE (mm)

HHUT.27.1 9 3.2 11.1

LASH.18 4 0.0 1.0

PAATOFD.29.0 13 0.8 4.6

PATP.29 9 2.4 6.6

PAUT.114 19 0.2 3.3

PAUT.131.2 16 0.3 0.6

PAUT.131.4 8 −0.1 0.4

PAUT.20 4 −3.1 3.7

RT.112 6 0.2 2.2

SAFT.17 14 4.0 5.4

SHPA.6.1 4 1.8 2.1

SHPA.6.2 4 −5.2 5.4

UT.104 4 −0.4 3.2

All 114 0.9 4.8

Table 5.9 Depth Sizing Results for Procedures Applied to SBDMW Test Blocks with O.D. 

Access (only FB blocks)

NOBS Bias (mm) RMSE (mm)

HHUT.27.2 7 3.1 7.1

LASH.18 5 −3.0 4.3

PAATOFD.29.1 7 3.6 5.5

PAATOFD.29.2 7 3.9 5.8

PAUT.114 7 0.1 0.8

PAUT.122.1 7 0.4 0.9

PAUT.122.2 7 −0.0 1.1

PAUT.131.1 5 4.1 8.8

PAUT.20 6 1.0 6.2

RT.109 5 −0.3 2.1

RT.112 3 −0.8 1.1

SAFT.17 7 2.0 3.5

SHPA.6.1 1 1.0 1.0

SHPA.6.3 4 1.0 1.4

UIR.20 6 1.0 3.4

UT.104 7 0.2 0.9

All 91 1.2 4.4
5-5 

Table 5.10 Depth Sizing Results for Procedures Applied to SBDMW Test Blocks with I.D. 

Access (only FB test blocks)

NOBS Bias (mm) RMSE (mm)

HHUT.30 3 −0.9 2.0

PAATOFD.29.1 7 2.4 3.2

PAATOFD.29.2 7 1.5 3.0

PAUT.131.1 2 −0.5 1.2

All 19 1.3 2.8

Table 5.11 Depth Sizing Results for Procedures Applied to LBDMW Test Blocks with O.D. 

Access

NOBS Bias (mm) RMSE (mm)

LASH.18 1 −1.1 1.1

PAATOFD.29.0 12 −1.5 4.7

PATP.29 15 −2.5 5.6

PAUT.150 3 2.9 5.1

SAFT.17 9 14.1 15.7

All 37 2.3 8.9

Table 5.12 Depth Sizing Results for Procedures Applied to LBDMW Test Blocks with I.D. 

Access

NOBS Bias (mm) RMSE (mm)

PAATOFD.29.1 8 2.3 6.7

PAUT.7 8 −1.4 5.2

All 16 0.4 6.0

5.1.1 Depth Sizing Regression Plots for ADVPAUT Procedure Types

Plots of regression curves fit to depth sizing data for ADVPAUT procedure types are provided in 

Figures 5.1 through 5.6. Figure 5.1 provides the curve for ADVPAUT procedure types applied to 

SBDMW and FB test blocks with O.D. access; Figure 5.2 provides the curve for ADVPAUT

procedure types applied only to SBDMW test blocks with O.D. access; and Figure 5.3 provides

the curve for ADVPAUT procedure types applied only to FB test blocks with O.D. access. 

Figure 5.4 provides the curve for ADVPAUT procedure types applied to FB test blocks with I.D. 

access. Figure 5.5 provides the curve for ADVPAUT procedure types applied to LBDMW test 

blocks with O.D. access. Finally, Figure 5.6 provides the depth sizing regression plot for 

ADVPAUT procedure types applied to LBDMW test blocks with I.D. access. A compilation of all 

depth sizing regression plots for individual ADVPAUT procedures and for ADVPAUT procedure 

types applied to SBDMW, FB, and LBDMW test blocks with I.D. and O.D. access is provided in 

Appendix F. 
5-6 

Figure 5.1 Depth Sizing Regression for ADVPAUT Procedures on SBDMW Test Blocks 

in PARENT Open Testing (O.D. access – w/ FB test blocks)

Figure 5.2 Depth Sizing Regression for ADVPAUT Procedures on SBDMW Test Blocks 

in PARENT Open Testing (O.D. access – w/o FB test blocks)
5-7 

Figure 5.3 Depth Sizing Regression for ADVPAUT Procedures on FB Test Blocks in 

PARENT Open Testing (O.D. access)

Figure 5.4 Depth Sizing Regression for ADVPAUT Procedures on FB Test Blocks in 

PARENT Open Testing (I.D. access)
5-8 

Figure 5.5 Depth Sizing Regression for ADVPAUT Procedures on LBDMW Test Blocks 

in PARENT Open Testing (O.D. access)

Figure 5.6 Depth Sizing Regression for ADVPAUT Procedures on LBDMW Test Blocks 

in PARENT Open Testing (I.D. access)
5-9 

5.1.2 Depth Sizing Regression Plots for NLUT Procedure Types

Plots of regression curves fit to depth sizing data for NLUT procedure types are provided in 

Figures 5.7 through 5.9. Figure 5.7 provides the curve for NLUT procedure types applied to 

SBDMW and FB test blocks with O.D. access; Figure 5.8 provides the curve for NLUT 

procedure types applied only to SBDMW test blocks with O.D. access; and Figure 5.9 provides

the curve for NLUT procedure types applied only to FB test blocks with O.D. access. A 

compilation of all depth sizing regression plots for individual NLUT procedures and for NLUT 

procedure types applied to SBDMW, FB, and LBDMW test blocks with I.D. and O.D. access is 

provided in Appendix F. 

Figure 5.7 Depth Sizing Regression for NLUT Procedures on SBDMW Test Blocks in 

PARENT Open Testing (O.D. access – w/ FB test blocks)
5-10

Figure 5.8 Depth Sizing Regression for NLUT Procedures on SBDMW Test Blocks in 

PARENT Open Testing (O.D. access – w/o FB test blocks)

Figure 5.9 Depth Sizing Regression for NLUT Procedures on FB Test Blocks in PARENT 

Open Testing (O.D. access)
5-11

5.1.3 Depth Sizing Regression Plots for PAUT Procedure Types

Plots of regression curves fit to depth sizing data for PAUT procedure types are provided in 

Figures 5.10 through 5.13. Figure 5.10 provides the curve for PAUT procedure types applied to 

SBDMW and FB test blocks with O.D. access; Figure 5.11 provides the curve for PAUT 

procedure types applied only to SBDMW test blocks with O.D. access; and Figure 5.12 provides 

the curve for PAUT procedure types applied only to FB test blocks with O.D. access. Finally, 

Figure 5.13 provides the depth sizing regression plot for PAUT procedure types applied to 

LBDMW test blocks with I.D. access. A compilation of all depth sizing regression plots for 

individual PAUT procedures and for PAUT procedure types applied to SBDMW, FB, and 

LBDMW test blocks with I.D. and O.D. access is provided in Appendix F. 

Figure 5.10 Depth Sizing Regression for PAUT Procedures on SBDMW Test Blocks in 

PARENT Open Testing (O.D. access – w/ FB test blocks)
5-12

Figure 5.11 Depth Sizing Regression for PAUT Procedures on SBDMW Test Blocks in 

PARENT Open Testing (O.D. access – w/o FB test blocks)

Figure 5.12 Depth Sizing Regression for PAUT Procedures on FB Test Blocks in 

PARENT Open Testing (O.D. access)
5-13

Figure 5.13 Depth Sizing Regression for PAUT Procedures on LBDMW Test Blocks in 

PARENT Open Testing (I.D. access)

5.1.4 Depth Sizing Regression Plots for RT Procedure Types

Plots of regression curves fit to depth sizing data for RT procedure types are provided in 

Figures 5.14 through 5.16. Figure 5.14 provides the curve for RT procedure types applied to 

SBDMW and FB test blocks with O.D. access; Figure 5.15 provides the curve for RT procedure 

types applied only to SBDMW test blocks with O.D. access; and Figure 5.16 provides the curve 

for RT procedure types applied only to FB test blocks with O.D. access. A compilation of all 

depth sizing regression plots for individual RT procedures and for RT procedure types applied to 

SBDMW, FB, and LBDMW test blocks with I.D. and O.D. access is provided in Appendix F. 
5-14

Figure 5.14 Depth Sizing Regression for RT Procedures on SBDMW Test Blocks in 

PARENT Open Testing (O.D. access – w/ FB test blocks)

Figure 5.15 Depth Sizing Regression for RT Procedures on SBDMW Test Blocks in 

PARENT Open Testing (O.D. access – w/o FB test blocks)
5-15

Figure 5.16 Depth Sizing Regression for RT Procedures on FB Test Blocks in PARENT 

Open Testing (O.D. access)

5.1.5 Depth Sizing Regression Plots for UIR Procedure Types

Plots of regression curves fit to depth sizing data for UIR procedure types are provided in 

Figures 5.17 and 5.18. Figure 5.17 provides the curve for UIR procedure types applied to 

SBDMW and FB test blocks with O.D. access and Figure 5.18 provides the curve for UIR 

procedure types applied only to FB test blocks with O.D. access. A compilation of all depth 

sizing regression plots for individual UIR procedures and for UIR procedure types applied to 

SBDMW, FB, and LBDMW test blocks with I.D. and O.D. access is provided in Appendix F. 
5-16

Figure 5.17 Depth Sizing Regression for UIR Procedures on SBDMW Test Blocks in 

PARENT Open Testing (O.D. access – w/ FB test blocks)

Figure 5.18 Depth Sizing Regression for UIR Procedures on FB Test Blocks in PARENT 

Open Testing (O.D. access)
5-17

5.1.6 Depth Sizing Regression Plots for Conventional UT Procedure Types

Plots of regression curves fit to depth sizing data for conventional UT procedure types are 

provided in Figures 5.19 through 5.21. Figure 5.19 provides the curve for conventional UT

procedure types applied to SBDMW and FB test blocks with O.D. access; Figure 5.20 provides 

the curve for conventional UT procedure types applied only to SBDMW test blocks with O.D. 

access; and Figure 5.21 provides the curve for conventional UT procedure types applied only to 

FB test blocks with O.D. access. A compilation of all depth sizing regression plots for individual

conventional UT procedures and for conventional UT procedure types applied to SBDMW, FB, 

and LBDMW test blocks with I.D. and O.D. access is provided in Appendix F. 

Figure 5.19 Depth Sizing Regression for Conventional UT Procedures on SBDMW Test 

Blocks in PARENT Open Testing (O.D. access – w/ FB test blocks)
5-18

Figure 5.20 Depth Sizing Regression for Conventional UT Procedures on SBDMW Test 

Blocks in PARENT Open Testing (O.D. access – w/o FB test blocks)

Figure 5.21 Depth Sizing Regression for Conventional UT Procedures on FB Test 

Blocks in PARENT Open Testing (O.D. access)
5-19

5.2 DMW Length Sizing Results

The results of length sizing analysis are summarized in this section by tabulating RMSE and

Bias for procedures and procedure types. Tabulated summaries of length sizing results for 

procedure types applied to SBDMW test blocks by O.D. and I.D. access are included in 

Tables 5.13 and 5.14, respectively, and for LBDMW test blocks by O.D. and I.D. access in 

Tables 5.15 and 5.16, respectively. The tabulation of length sizing results for individual 

procedures is provided in Tables 5.17 through 5.20. The summary for individual procedures

applied to SBDMW test blocks with O.D. and I.D. access is provided in Tables 5.17 and 5.18, 

respectively. Tables 5.19 and 5.20 provide summaries for LBDMW test blocks with O.D. and 

I.D. access, respectively. No length sizing analysis was performed on FB test blocks as the 

flaws extend the full width of the specimens.

Table 5.13 Length Sizing Results for Procedure Types Applied to SBDMW Test Blocks 

with O.D. Access

NOBS Bias (mm) RMSE (mm)

ADVPAUT 14 3.9 14.0

NLUT 17 −10.9 17.0

PAUT 49 1.0 9.3

UT 4 1.2 2.4

All 84 −0.9 11.9

Table 5.14 Length Sizing Results for Procedure Types Applied to SBDMW Test Blocks 

with I.D. Access

NOBS Bias (mm) RMSE (mm)

ECT 32 1.2 9.0

Table 5.15 Length Sizing Results for Procedure Types Applied to LBDMW Test Blocks 

with O.D. Access

NOBS Bias (mm) RMSE (mm)

ADVPAUT 9 9.0 15.2

PAUT 4 10.8 20.8

All 13 9.5 17.1
5-20

Table 5.16 Length Sizing Results for Procedure Types Applied to LBDMW Test Blocks 

with I.D. Access

NOBS Bias (mm) RMSE (mm)

ECT 12 −1.8 7.6

MM 7 −2.4 3.6

PAUT 9 1.7 12.5

All 28 −0.8 8.9

Table 5.17 Length Sizing Results for Procedures Applied to SBDMW Test Blocks with 

O.D. Access

NOBS Bias (mm) RMSE (mm)

HHUT.27.1 9 −14.9 20.7

PAUT.114 19 2.1 13.0

PAUT.131.2 18 0.7 6.4

PAUT.131.4 8 2.2 3.4

PAUT.20 4 −5.0 7.6

SAFT.17 13 3.5 14.3

SHPA.6.1 4 1.8 4.9

SHPA.6.2 4 −14.8 15.6

UT.104 4 1.2 2.4

All 84 −0.9 11.9

Table 5.18 Length Sizing Results for Procedures Applied to SBDMW Test Blocks with 

I.D. Access

NOBS Bias (mm) RMSE (mm)

AECT.33 12 2.4 3.3

ECT.16 20 0.4 11.1

All 32 1.2 9.0

Table 5.19 Length Sizing Results for Procedures Applied to LBDMW Test Blocks with 

O.D. Access

NOBS Bias (mm) RMSE (mm)

PAUT.150 4 10.8 20.8

SAFT.17 9 9.0 15.2

All 13 9.5 17.1
5-21

Table 5.20 Length Sizing Results for Procedures Applied to LBDMW Test Blocks with 

I.D. Access

NOBS Bias (mm) RMSE (mm)

AECT.33 8 −1.2 7.4

CEECT.5.2 2 −10.0 10.4

ECT.16 2 4.5 4.5

MM.28.1 7 −2.4 3.6

PAUT.7 9 1.7 12.5

All 28 −0.8 8.9

5.2.1 Length Sizing Regression Plots for ADVPAUT Procedure Types

Plots of regression curves fit to length sizing data for ADVPAUT procedure types are provided in

Figures 5.22 and 5.23. Figure 5.22 provides the curve for ADVPAUT procedure types applied to 

SBDMW test blocks with O.D. access, while Figure 5.23 provides the curve for ADVPAUT 

procedure types applied to LBDMW test blocks with O.D. access. A compilation of all length

sizing regression plots for individual ADVPAUT procedures and for ADVPAUT procedure types 

applied to SBDMW and LBDMW test blocks with I.D. and O.D. access is provided in

Appendix G. 

Figure 5.22 Length Sizing Regression for ADVPAUT Procedures on SBDMW Test 

Blocks in PARENT Open Testing (O.D. access)
5-22

Figure 5.23 Length Sizing Regression for ADVPAUT Procedures on LBDMW Test 

Blocks in PARENT Open Testing (O.D. access)

5.2.2 Length Sizing Regression Plots for NLUT Procedure Types

A plot of a regression curve fit to length sizing data for NLUT procedure types is provided in 

Figure 5.24 for SBDMW test blocks with O.D. access. A compilation of all length sizing 

regression plots for individual NLUT procedures and for NLUT procedure types applied to 

SBDMW and LBDMW test blocks with I.D. and O.D. access is provided in Appendix G. 
5-23

Figure 5.24 Length Sizing Regression for NLUT Procedures on SBDMW Test Blocks in 

PARENT Open Testing (O.D. access)

5.2.3 Length Sizing Regression Plots for PAUT Procedure Types

Plots of regression curves fit to length sizing data for PAUT procedure types are provided in 

Figures 5.25 and 5.27. Figure 5.25 provides the curve for PAUT procedure types applied to 

SBDMW test blocks with O.D. access, while Figure 5.26 provides the curve for PAUT procedure 

types applied to LBDMW test blocks with O.D. access. Figure 5.27 provides the curve for PAUT 

procedure types applied to LBDMW test blocks with I.D. access. A compilation of all length

sizing regression plots for individual PAUT procedures and for PAUT procedure types applied to 

SBDMW and LBDMW test blocks with I.D. and O.D. access is provided in Appendix G. 
5-24

Figure 5.25 Length Sizing Regression for PAUT Procedures on SBDMW Test Blocks in 

PARENT Open Testing (O.D. access)

Figure 5.26 Length Sizing Regression for PAUT Procedures on LBDMW Test Blocks in 

PARENT Open Testing (O.D. access)
5-25

Figure 5.27 Length Sizing Regression for PAUT Procedures on LBDMW Test Blocks in 

PARENT Open Testing (I.D. access)

5.2.4 Length Sizing Regression Plots for Conventional UT Procedure Types

A plot of a regression curve fit to length sizing data for conventional UT procedure types is provided in 

Figure 5.28 for SBDMW test blocks with O.D. access. A compilation of all length sizing regression 

plots for individual conventional UT procedures and for conventional UT procedure types applied to 

SBDMW and LBDMW test blocks with I.D. and O.D. access is provided in Appendix G. 

Figure 5.28 Length Sizing Regression for Conventional UT Procedures on SBDMW Test 

Blocks in PARENT Open Testing (O.D. access)
5-26

5.2.5 Length Sizing Regression Plots for ECT Procedure Types

Plots of regression curves fit to length sizing data for ECT procedure types are provided in 

Figures 5.29 and 5.30. Figure 5.29 provides the curve for ECT procedure types applied to 

SBDMW test blocks with I.D. access, while Figure 5.30 provides the curve for ECT procedure 

types applied to LBDMW test blocks with I.D. access. A compilation of all length sizing 

regression plots for individual ECT procedures and for ECT procedure types applied to SBDMW 

and LBDMW test blocks with I.D. and O.D. access is provided in Appendix G. 

Figure 5.29 Length Sizing Regression for ECT Procedures on SBDMW Test Blocks in 

PARENT Open Testing (I.D. access)
5-27

Figure 5.30 Length Sizing Regression for ECT Procedures on LBDMW Test Blocks in 

PARENT Open Testing (I.D. access)

5.2.6 Length Sizing Regression Plots for MM Procedure Types

A plot of a regression curve fit to length sizing data for MM procedure types is provided in 

Figure 5.31 for LBDMW test blocks with I.D. access. A compilation of all length sizing regression 

plots for individual MM procedures and for MM procedure types applied to SBDMW and 

LBDMW test blocks with I.D. and O.D. access is provided in Appendix G. 

Figure 5.31 Length Sizing Regression for MM Procedures on LBDMW Test Blocks in 

PARENT Open Testing (I.D. access)
5-28

5.3 BMI Data Analysis Results

The length sizing analysis results for BMI test blocks is provided in Table 5.21 for individual 

procedure types. All data was collected by accessing the J-groove weld surface. Due to the limited 

amount of data collected on BMI test blocks, no attempt has been made to group results by 

procedure types. Plots of regression curves fit to length sizing data can be found in Appendix G.9. 

Table 5.21 Length Sizing Results for Procedures Applied to BMI Test Blocks with 

J-Groove Weld Surface Access

NOBS Bias (mm) RMSE (mm)

AECT.33 4 −5.2 5.3

ECT.16 3 4.0 5.0

ECT.7 14 3.4 4.9

LUV.170 5 −0.2 1.0

MM.28.1 1 −7.0 7.0

5.4 Indication Plots

Indication plots for individual inspections are compiled in Appendix H. 
6-1

6 ANALYSIS OF RESULTS

This section provides some additional discussion and analysis of the results presented in 

Section 5. In particular, PAUT and ADVPAUT procedure type performances are compared 

based on sizing RMSEs in Section 6.1 and NLUT procedure type performances are compared 

with PAUT and ADVPAUT procedure type performances in Section 6.2. Depth sizing results for 

FB test blocks are presented in Section 6.3 to observe the impact of complex stress corrosion 

crack morphology on sizing results and data for test block P38 are also considered to determine 

if the weld asymmetry in this test block has an observable impact on performance. The results 

for linear and sectorial PAUT examinations by team 122 are compared in Section 6.4. Results 

obtained by UIR examinations are discussed in Section 6.5; and the results from RT, 

conventional UT, and ECT examinations are briefly discussed in Section 6.6. Section 6.7

includes a brief analysis of data response images obtained from FB test blocks to illustrate the 

difficulty in distinguishing crack tip responses of SCC flaws from noise. Sparsely populated 

datasheets are highlighted in Section 6.8 to illustrate that some techniques had difficulty with 

identifying flaws under the open test conditions. Section 6.9 includes a brief discussion of test 

block appropriateness and how limitations of the test blocks available for open testing inhibited 

an effective evaluation of some techniques. Finally, Section 6.10 provides a summary of open 

techniques that exhibited sufficient capability in open testing such that further blind testing to 

obtain more detailed assessments of performance is justified. 

6.1 Comparison of ADVPAUT and PAUT Procedure Types

A comparison of ADVPAUT and PAUT procedure types is provided in Table 6.1 based on depth 

sizing RMSE results. In this table, comparisons are made considering data from SBDMW and 

FB test blocks, considering data from only SBDMW test blocks, considering data from only FB 

test blocks, and considering data from LBDMW test blocks. The RMSE data indicate that PAUT 

procedures generally outperformed the ADVPAUT procedures in open testing. The generally 

better performance observed for PAUT procedures may reflect increased familiarity of teams 

with PAUT procedures in comparison to ADVPAUT procedures. This would also indicate that 

the performance of ADVPAUT procedures could improve with additional experience. However, 

a review of depth sizing regression plots for ADVPAUT and PAUT procedure types on SBDMW 

test blocks with O.D. access in Figures 6.1 and 6.2 show that while ADVPAUT procedure types 

may not have depth sized flaws as accurately as PAUT procedure types, depth sizing results for 

ADVPAUT procedure types are more conservative than PAUT procedure types, showing an 

oversizing trend over the entire flaw depth range considered. In the depth sizing regression 

plots for ADVPAUT and PAUT procedure types applied to FB test blocks with O.D. access in 

Figures 6.3 and 6.4, both procedure types show a similar sizing trend of oversizing shallower 

flaws and undersizing the deep flaws.
6-2

Table 6.1 Summary of Depth Sizing RMSEs for ADVPAUT and PAUT Techniques 

Applied to SBDMW and LBDMW Test Blocks with O.D. and I.D. Access

ADVPAUT PAUT

NOBS RMSE (mm) NOBS RMSE (mm)

SBDMW and FB Test Blocks with O.D. Access 57 5.3 79 3.4

SBDMW Test Blocks with O.D. Access 36 5.5 47 2.4

FB Test Blocks with O.D. Access 21 5.0 32 4.5

FB Test Blocks with I.D. Access 14 3.1 2 1.2

LBDMW Test Blocks with O.D. Access 36 9.1 3 5.1

LBDMW Test Blocks with I.D. Access 8 6.7 8 5.2

Figure 6.1 Depth Sizing Regression for ADVPAUT Procedures on SBDMW Test Blocks 

in PARENT Open Testing (O.D. access – w/o FB test blocks)
6-3

Figure 6.2 Depth Sizing Regression for PAUT Procedures on SBDMW Test Blocks in 

PARENT Open Testing (O.D. access – w/o FB test blocks)

Figure 6.3 Depth Sizing Regression for ADVPAUT Procedures on FB Test Blocks in 

PARENT Open Testing (O.D. access)
6-4

Figure 6.4 Depth Sizing Regression for PAUT Procedures on FB Test Blocks in PARENT 

Open Testing (O.D. access)

A summary of depth sizing RMSEs for ADVPAUT and PAUT procedures is provided in 

Tables 6.2 through 6.5 for SBDMW and FB test blocks. These tables indicate that several 

ADVPAUT and PAUT procedures exhibited variation in performance for SBDMW test blocks 

(solidification cracks) versus FB test blocks (mostly laboratory-grown SCC). For instance, 

procedures LASH.18 and PAUT.20 exhibit better performance on SBDMW test blocks versus 

FB test blocks and procedures SAFT.17 and PAUT.114 exhibit better performance on FB test 

blocks versus SBDMW test blocks.

Length sizing RMSEs are summarized in Table 6.6 for ADVPAUT and PAUT procedure types 

applied to SBDMW and LBDMW test blocks with O.D. access. In this case, PAUT procedure 

types exhibit better length sizing performance on SBDMW test blocks. ADVPAUT procedure types 

exhibit better length sizing performance than PAUT procedure types on LBDMW test blocks; 

however, the sample sizes are relatively small. Length sizing performances of individual 

ADVPAUT and PAUT procedures applied to SBDMW test blocks are summarized in Tables 6.7

and 6.8, respectively. A review of length sizing regression plots for PAUT and ADVPAUT 

procedure types in Figures 6.5 and 6.6, respectively, for SBDMW test blocks with O.D. access 

show that ADVPAUT procedure types exhibit a trend of oversizing short flaws and undersizing 

long flaws while PAUT procedure types oversize longer flaws and slightly undersize shorter flaws. 
6-5

Table 6.2 Summary of Depth Sizing Performances for ADVPAUT Procedure Types 

Applied to SBDMW Test Blocks with O.D. Access w/o FB Test Blocks

NOBS Bias (mm) RMSE (mm)

LASH.18 4 0.0 1.0

PAATOFD.29.0 13 0.8 4.6

PATP.29 9 2.4 6.6

SAFT.17 14 4.0 5.4

SHPA.6.1 4 1.8 2.1

SHPA.6.2 4 −5.2 5.4

Table 6.3 Summary of Depth Sizing Performances for ADVPAUT Procedure Types 

Applied to FB Test Blocks with O.D. Access

NOBS Bias (mm) RMSE (mm)

LASH.18 5 −3.0 4.3

PAATOFD.29.1 7 3.6 5.5

PAATOFD.29.2 7 3.9 5.8

SAFT.17 7 2.0 3.5

SHPA.6.1 1 1.0 1.0

SHPA.6.3 4 1.0 1.4

Table 6.4 Summary of Depth Sizing Performances for PAUT Procedure Types Applied to 

SBDMW Test Blocks with O.D. Access w/o FB Test Blocks

NOBS Bias (mm) RMSE (mm)

PAUT.114 19 0.2 3.3

PAUT.131.2 16 0.3 0.6

PAUT.131.4 8 −0.1 0.4

PAUT.20 4 −3.1 3.7

Table 6.5 Summary of Depth Sizing Performances for PAUT Procedure Types Applied to 

FB Test Blocks with O.D. Access

NOBS Bias (mm) RMSE (mm)

PAUT.114 7 0.1 0.8

PAUT.122.1 7 0.4 0.9

PAUT.122.2 7 −0.0 1.1

PAUT.131.1 5 4.1 8.8

PAUT.20 6 1.0 6.2
6-6

Table 6.6 Summary of Length Sizing RMSEs for ADVPAUT and PAUT Techniques 

Applied to SBDMW and LBDMW Test Blocks with O.D. Access

ADVPAUT PAUT

NOBS RMSE (mm) NOBS RMSE (mm)

SBDMW Test Blocks with O.D. Access 14 14.0 49 9.3

LBDMW Test Blocks with O.D. Access 9 15.2 4 20.8

Table 6.7 Summary of Length Sizing Performances for ADVPAUT Procedure Types 

Applied to SBDMW Test Blocks with O.D. Access w/o FB Test Blocks

NOBS Bias (mm) RMSE (mm)

SAFT.17 14 3.9 14.0

SHPA.6.1 4 1.8 4.9

SHPA.6.2 4 −14.8 15.6

Table 6.8 Summary of Length Sizing Performances for PAUT Procedure Types Applied

to SBDMW Test Blocks with O.D. Access w/o FB Test Blocks

NOBS Bias (mm) RMSE (mm)

PAUT.114 19 2.1 13.0

PAUT.131.2 18 0.7 6.4

PAUT.131.4 8 2.2 3.4

PAUT.20 4 −5.0 7.6

Figure 6.5 Length Sizing Regression for PAUT Procedures on SBDMW Test Blocks in 

PARENT Open Testing (O.D. access)
6-7

Figure 6.6 Length Sizing Regression for ADVPAUT Procedures on SBDMW Test Blocks 

in PARENT Open Testing (O.D. access)

6.2 Comparison of NLUT with PAUT and ADVPAUT Procedure Types

The performance of NLUT procedure types can be compared with the performance of PAUT and 

ADVPAUT procedure types by reviewing depth sizing results in Tables 5.1 through 5.3 for 

SBDMW and FB test blocks with O.D. access, Table 5.4 for FB test blocks with I.D. access, and 

Table 5.5 for LBDMW test blocks with O.D. access. Tables 5.1 through 5.3 indicate that NLUT 

procedure types are less accurate at depth sizing than PAUT and ADVPAUT procedure types 

based on RMSE, though the depth sizing accuracies are comparable. Similarly, these tables 

indicate that the bias for NLUT procedure types is also comparable to the bias observed for PAUT 

and ADVPAUT procedure types. Table 5.4 indicates that the RMSE for NLUT procedure types is 

less than for ADVPAUT procedure types but greater than for PAUT procedure types for FB test 

blocks by I.D. access and, Table 5.5 indicates that the RMSE for NLUT procedure types is less 

than for PAUT and ADVPAUT procedure types for LBDMW test blocks with O.D. access, but the 

sample size is limited in these cases. A review of depth sizing regression plots in Figures 5.7

through 5.9 show that NLUT procedure types exhibit a trend of oversizing shallow flaws and 

undersizing deep flaws in testing performed on SBDMW and FB test blocks with O.D. access. 

The length sizing performance of NLUT procedure types may be compared with PAUT and 

ADVPAUT procedure types in Table 5.13, which shows that NLUT procedure types exhibit a 

much higher RMSE than ADVPAUT and PAUT procedure types for SBDMW test blocks with O.D. 

access and that NLUT procedure types exhibit a strong negative bias. A review of the length 

sizing regression curve for NLUT procedure types applied to SBDMW test blocks with O.D. 

access in Figure 5.24 shows a strong tendency to undersize flaws over most of the flaw length 

range. However, a review of individual NLUT procedure depth sizing regression plots in

Figures 6.7 through 6.12 indicates, that overall, NLUT procedures based on higher harmonic 

techniques do not perform as well as NLUT procedures based on sub-harmonic techniques.

Figures 6.7 and 6.10 show a weak correlation between measured depth and true depth based on 
6-8

HHUT.27.1 and HHUT.27.2 procedures. Figures 6.8 and 6.11 for procedures SHPA.6.1 and 

SHPA.6.3 indicate a more consistent measurement error over the entire depth ranges considered 

with slight conservative (oversizing) bias over the full flaw depth range. Finally, Figure 6.9

indicates that procedure LASH.18 for SBDMWs exhibits a slight undersizing of shallower flaws 

and a slight oversizing of deep flaws, and Figure 6.12 indicates that procedure LASH.18 for FB 

test block exhibits an oversizing of shallower flaws and a undersizing of deep flaws.

Figure 6.7 Depth Sizing Regression Plot for HHUT.27.1 Applied to SBDMW Test Blocks

(w/o FB test blocks) with O.D. Access
6-9

Figure 6.8 Depth Sizing Regression Plot for SHPA.6.1 Applied to SBDMW Test Blocks 

(w/o FB test blocks) with O.D. Access

Figure 6.9 Depth Sizing Regression Plot for LASH.18 Applied to SBDMW Test Blocks

(w/o FB test blocks) with O.D. Access
6-10

Figure 6.10 Depth Sizing Regression Plot for HHUT.27.2 Applied to FB Test Blocks with 

O.D. Access

Figure 6.11 Depth Sizing Regression Plot for SHPA.6.3 Applied to FB Test Blocks with 

O.D. Access
6-11

Figure 6.12 Depth Sizing Regression Plot for LASH.18 Applied to FB Test Blocks with 

O.D. Access

6.3 Analysis of FB Test Block Results

A summary of I.D. and O.D. access depth sizing performances for all FB test blocks is provided 

in Table 6.9 in terms of RMSE. This table indicates that the RMSE for I.D. access examinations 

of P32 is much greater than for other FB test blocks. In addition, the RMSE for O.D. access 

examinations of P31, P32, and P38 is greater than for other FB test blocks. All of the FB test 

blocks contain laboratory-grown SCC flaws with the exception of P30, which contains an MFC, 

and P42, which contains an EDM notch. Specimen P38 is the only specimen to exhibit 

geometric asymmetry in the weld.

Summaries of depth sizing performances for procedure types applied by I.D. access to FB test 

blocks are provided in Tables 6.10 through 6.16. These summaries show that the ADVPAUT 

procedure type is the only procedure type applied for I.D. access examination of all FB test 

blocks. Summaries of depth sizing performances for procedure types applied by O.D. access to 

FB test blocks are provided in Tables 6.17 through 6.23. The RMSE for ADVPAUT procedures 

applied by I.D. and O.D. access is greater for P32 than for other FB test blocks. For test block 

P38, the PAUT and UIR procedure types applied by O.D. access exhibit greater RMSE than for 

other FB test blocks. However, the sizing data for UIR is only based on one sample in each of 

Tables 6.17 through 6.23. 
6-12

Table 6.9 Comparison of Depth Sizing Performances for FB Test Blocks

I.D. Access O.D. Access

NOBS RMSE (mm) NOBS RMSE (mm)

P28 3 0.9 14 2.5

P29 3 1.7 15 2.1

P30 3 1.9 15 2.4

P31 3 2.2 13 7.0

P32 3 6.0 13 4.3

P38 2 1.3 12 7.0

P42 2 1.0 9 0.9

Table 6.10 Depth Sizing Results for P28 by Procedure Type for I.D. Access

NOBS Bias (mm) RMSE (mm)

ADVPAUT 2 0.7 0.7

NLUT 1 1.3 1.3

All 3 0.9 0.9

Table 6.11 Depth Sizing Results for P29 by Procedure Type for I.D. Access

NOBS Bias (mm) RMSE (mm)

ADVPAUT 2 1.7 2.0

NLUT 1 −0.7 0.7

All 3 0.9 1.7

Table 6.12 Depth Sizing Results for P30 by Procedure Type for I.D. Access

NOBS Bias (mm) RMSE (mm)

ADVPAUT 2 −0.2 0.2

NLUT 1 −3.2 3.2

All 3 −1.2 1.9

Table 6.13 Depth Sizing Results for P31 by Procedure Type for I.D. Access

NOBS Bias (mm) RMSE (mm)

ADVPAUT 2 2.2 2.7

NLUT 1 0.6 0.6

All 3 1.7 2.2
6-13

Table 6.14 Depth Sizing Results for P32 by Procedure Type for I.D. Access

NOBS Bias (mm) RMSE (mm)

ADVPAUT 2 7.3 7.3

NLUT 1 −1.6 1.6

All 3 4.3 6.0

Table 6.15 Depth Sizing Results for P38 by Procedure Type for I.D. Access

NOBS Bias (mm) RMSE (mm)

ADVPAUT 2 1.2 1.3

All 2 1.2 1.3

Table 6.16 Depth Sizing Results for P42 by Procedure Type for I.D. Access

NOBS Bias (mm) RMSE (mm)

ADVPAUT 2 0.9 1.0

All 2 0.9 1.0

Table 6.17 Depth Sizing Results for P28 by Procedure Type for O.D. Access

NOBS Bias (mm) RMSE (mm)

ADVPAUT 3 3.2 3.4

NLUT 3 2.1 3.1

PAUT 5 −0.8 1.9

RT 1 −1.4 1.4

UIR 1 0.3 0.3

UT 1 1.2 1.2

All 14 0.9 2.5

Table 6.18 Depth Sizing Results for P29 by Procedure Type for O.D. Access

NOBS Bias (mm) RMSE (mm)

ADVPAUT 3 2.8 3.3

NLUT 3 1.8 2.2

PAUT 5 −0.3 0.9

RT 2 1.5 2.1

UIR 1 −2.1 2.1

UT 1 −0.7 0.7

All 15 0.8 2.1
6-14

Table 6.19 Depth Sizing Results for P30 by Procedure Type for O.D. Access

NOBS Bias (mm) RMSE (mm)

ADVPAUT 3 −0.7 2.7

NLUT 3 −2.6 3.9

PAUT 5 −1.1 1.7

RT 2 −0.7 0.9

UIR 1 2.2 2.2

UT 1 −0.2 0.2

All 15 −1.0 2.4

Table 6.20 Depth Sizing Results for P31 by Procedure Type for O.D. Access

NOBS Bias (mm) RMSE (mm)

ADVPAUT 3 6.5 6.9

NLUT 3 5.4 10.0

PAUT 4 4.2 7.0

RT 1 −0.1 0.1

UIR 1 1.2 1.2

UT 1 −0.1 0.1

All 13 4.1 7.0

Table 6.21 Depth Sizing Results for P32 by Procedure Type for O.D. Access

NOBS Bias (mm) RMSE (mm)

ADVPAUT 3 3.8 7.2

NLUT 3 −1.6 4.0

PAUT 4 1.0 1.7

RT 1 −3.7 3.7

UIR 1 −2.8 2.8

UT 1 −1.1 1.1

All 13 0.2 4.3
6-15

Table 6.22 Depth Sizing Results for P38 by Procedure Type for O.D. Access

NOBS Bias (mm) RMSE (mm)

ADVPAUT 3 6.2 6.7

NLUT 1 −3.7 3.7

PAUT 5 4.0 8.9

RT 1 −0.6 0.6

UIR 1 7.2 7.2

UT 1 0.7 0.7

All 12 3.5 7.0

Table 6.23 Depth Sizing Results for P42 by Procedure Type for O.D. Access

NOBS Bias (mm) RMSE (mm)

ADVPAUT 3 0.5 1.2

NLUT 1 0.0 0.0

PAUT 4 −0.1 0.5

UT 1 1.5 1.5

All 9 0.3 0.9

6.4 Comparison of Linear and Sectorial PAUT by Team 122

The depth sizing performances of procedures PAUT.122.1 and PAUT.122.2 are summarized in 

Table 6.24 and in Figures 6.13 and 6.14. Descriptions of the PAUT.122.1 and PAUT.122.2 

procedures are provided in Appendix C.3.3. PAUT.122.1 employs a linear PAUT technique and 

PAUT.122.2 employs a sectorial PAUT technique. The data provided in Table 6.24 and in 

Figures 6.13 and 6.14 indicate that both procedures exhibit similar performances.

Table 6.24 Summary of Depth Sizing Performances for Procedures PAUT.122.1 and 

PAUT.122.2

NOBS Bias (mm) RMSE (mm)

PAUT.122.1 (Linear) 7 0.4 0.9

PAUT.122.2 (Sectorial) 7 0.0 1.1
6-16

Figure 6.13 Depth Sizing Regression for Procedure PAUT.122.1 (Linear) for FB Test 

Blocks by O.D. Access

Figure 6.14 Depth Sizing Regression for Procedure PAUT.122.2 (Sectorial) FB Test 

Blocks by O.D. Access
6-17

6.5 UIR Results

Depth sizing results are reported for UIR procedures applied to FB test blocks with O.D. access 

in Table 5.3. However, these depth sizing results are obtained from viewing the sides of the FB 

test blocks as depicted in Figures 6.15 and 6.16. This type of access is not practical in a field 

environment, and in this context, the results provide a better representation of length sizing 

performance. A view of the test block surface that the crack initiates from is provided in 

Figure 6.17. Together, Figures 6.15 through 6.17 demonstrate the capability of UIR to detect 

cracks in these specimens under laboratory conditions.

Figure 6.15 UIR Image of FB Test Block P29 (view from side surface)

Figure 6.16 UIR Image of FB Test Block P29 (view from side surface)

Figure 6.17 UIR Image of FB Test Block P29 (view of surface from which crack initiates)
6-18

6.6 RT, Conventional UT, and ECT Results

The RT and conventional UT procedure types generated the most accurate depth sizing data 

based on FB test blocks as indicated in Table 5.3. Figure 5.16 and Figure 5.21 indicate that that 

RT and conventional UT procedure types have a tendency to oversize the shallow flaws and to 

undersize for deeper flaws. Table 5.13 indicates that conventional UT has superior length sizing 

accuracy for SBDMW test blocks with O.D. access; however, the sample size is limited. 

ECT length sizing results can be reviewed for SBDMW test blocks and LBDMW test blocks with 

I.D. access in Tables 5.14 and 5.16, respectively. Figure 5.29 and Figure 5.30 indicate a

tendency to oversize shorter flaws and undersize longer flaws for both types of test blocks.

Table 5.18 indicates that “advanced” ECT procedures (i.e., AECT.33) perform better than

conventional ECT procedures (i.e., ECT.16) for SBDMW test blocks.
6-19

Table 5.20 indicates that the opposite is true for LBDMW test blocks; however, the sample sizes 

are limited in this case. Length sizing regression plots for specific ECT procedures can be 

reviewed in Figures 6.18, 6.19, and 6.20. Figure 6.18 indicates that AECT.33 may have a 

tendency to oversize shorter flaws and undersize longer flaws for SBDMW test blocks.

Figure 6.19 shows that ECT.16 provides a response that correlates well with the true length 

over the full range of lengths considered for SBDMW test blocks. Finally, Figure 6.20 shows that 

AECT.33 has a tendency to oversize shorter flaws and undersize longer flaws for LBDMW test 

blocks although linear sizing performance is within the 95% confidence bounds. 

Figure 6.18 Length Sizing Regression Plot for Procedure AECT.33 Applied to SBDMW 

Test Blocks with I.D. Access
6-20

Figure 6.19 Length Sizing Regression Plot for Procedure ECT.16 Applied to SBDMW 

Test Blocks with I.D. Access

Figure 6.20 Length Sizing Regression Plot for Procedure AECT.33 Applied to LBDMW 

Test Blocks with I.D. Access
6-21

6.7 Analysis of Data Response Images from FB Test Blocks

This section provides a brief discussion and analysis of data image responses obtained from FB 

test blocks with EDM notch, MFC, and SCC type flaws and a blank test block to illustrate the 

difficulty of detecting crack tip responses from SCC flaws and how it can be difficult to 

distinguish the crack tip response of SCC flaws from noise. 

6.7.1 Comparison of PAATOFD.29.2 Responses from P42, P30, and P32

Some responses of technique PAATOFD.29.2 are reviewed in this section to compare 

responses obtained from EDM, MFC, and SCC flaws and to compare responses from I.D. 

access with responses from O.D. access. A summary of PAATOFD.29.2 is included in the table 

of Appendix B.1 and a description of the Phased Array Asymmetric TOFD technique is provided 

in Section 3 and in Appendix C. The responses are obtained from FB test blocks; specifically, 

test block P42 that contains an EDM notch, P30 that contains the MFC flaw, and P32 that 

contains a laboratory-grown SCC flaw. Figures 6.21 and 6.22 display responses for O.D. and 

I.D. access, respectively, on P42 while Figures 6.23 and 6.24 display the responses for O.D. 

and I.D. access, respectively, on P30. Finally, Figures 6.25 and 6.26 display O.D. and I.D. 

responses, respectively, from P32. In each figure, a red cursor appears over a region in the data 

image that identifies the response from the flaw tip. In addition, the depth position at 0 mm 

indicates the inspection surface, which is specified in the figure captions as I.D. or O.D and the 

opposite surface is located at 30 mm. In this case, it appears that the clearest tip signals are 

obtained from the EDM notch in P42, followed by the MFC flaw in P30, and the SCC flaw in P32 

produces the weakest response. In comparing O.D. access response versus I.D. access 

response, it appears that both O.D. and I.D. access results in strong responses from the EDM 

notch in P42. Conversely, a clear response cannot be observed for the SCC block in P32 

regardless of O.D. or I.D. access. It is unlikely that crack tip response is correctly identified by 

the red cursor in Figure 6.25 based on the location of the red cursor. The potential influence of 

O.D. versus I.D. access on signal response is most clearly demonstrated for the MFC flaw in 

P30. In this case, a stronger response from the tip of the MFC flaw is observed for I.D. access in 

Figure 6.24 in comparison to O.D. access in Figure 6.23. 

Figure 6.21 PAATOFD.29.2 Inspection of P42 (EDM) from O.D.
6-22

Figure 6.22 PAATOFD.29.2 Inspection of P42 (EDM) from I.D.

Figure 6.23 PAATOFD.29.2 Inspection of P30 (MFC) from O.D.
6-23

Figure 6.24 PAATOFD.29.2 Inspection of P30 (MFC) from I.D.

Figure 6.25 PAATOFD.29.2 Inspection of P32 (SCC) from O.D.
6-24

Figure 6.26 PAATOFD.29.2 Inspection of P32 (SCC) from I.D.

6.7.2 Comparison of SAFT.17 Responses from P42, P30, and P32

For comparison of SAFT.17 responses, data images from an EDM notch (P42), MFC flaw 

(P30), and SCC flaw (P32) are provided in Figures 6.27 through 6.29, respectively, and the 

indication depth profiles along x for P42, P30, and P32 are provided in Figures 6.30 through 

6.32, respectively. Although the SCC flaw in P32 appears to give a crack tip response that is 

comparable to the tip response obtained from the MFC flaw in P30, a review of the indication 

depth profiles indicates that the depth profile for the SCC flaw in P32 (Figure 6.32) is very 

uneven in contrast to the depth profiles for P42 and P30. Finally, the indication plots provided in 

Figures 6.33, 6.34, and 6.35 reveal how accurately SAFT.17 depth sized flaws in P42, P30, and 

P32, respectively. While depth measurements of the EDM notch in P42 and the MFC flaw in 

P30 are pretty accurate, the depth of the SCC flaw in P32 is significantly undersized.
6-25

Figure 6.27 Data Images of Responses Obtained by SAFT-17 on Test Block P42 with 

EDM Notch
6-26

Figure 6.28 Data Images of Responses Obtained by SAFT-17 on Test Block P30 with 

MFC Flaw
6-27

Figure 6.29 Data Images of Responses Obtained by SAFT-17 on Test Block P32 with 

SCC Flaw
6-28

Figure 6.30 Indication Depth Profile Obtained by SAFT-17 on Test Block P42 with EDM 

Notch
6-29

Figure 6.31 Indication Depth Profile Obtained by SAFT-17 on Test Block P30 with MFC 

Flaw
6-30

Figure 6.32 Indication Depth Profile Obtained by SAFT-17 on Test Block P32 with SCC 

Flaw

Figure 6.33 Indication Plot for Procedure SAFT.17 Applied to Test Block P42 in 

PARENT Open Testing (X – Z view)
6-31

Figure 6.34 Indication Plot for Procedure SAFT.17 Applied to Test Block P30 in 

PARENT Open Testing (X – Z view)

Figure 6.35 Indication Plot for Procedure SAFT.17 Applied to Test Block P32 in 

PARENT Open Testing (X – Z view)

6.7.3 PAUT.122.1 Responses from SCC Flaws 

Data image responses from PAUT.122.1 are provided in this section from inspections of SCC 

flaws in P28 and P32 and inspections of MFC and EDM notch flaws in P30 and P42, 

respectively. PAUT.122.1 is a linear scan PAUT method applied with multiple refraction angles. 

Data images obtained for 60° and 50° angles applied to P28 from the right side of the weld are 

provided in Figure 6.36 and Figure 6.37, respectively. Figure 6.36 includes two arrows to 

highlight two weak signals that are considered possible crack tip responses. In Figure 6.37, a 

much stronger crack tip response is identified and used as the depth sizing basis for the 

inspection of P28.
6-32

Data images obtained from P32 are also included in Figure 6.38, Figure 6.39, and Figure 6.40. 

Figure 6.38 was obtained from the right side of the crack at a refraction angle of 50°. In this 

image, it is difficult to identify the response from the crack tip because of noise. Figure 6.39 and 

Figure 6.40 show data responses obtained from the left side of the weld in P32 at angles of 50° 

and 55°, respectively. In these figures, postulated crack tip responses are highlighted. Finally, 

Figure 6.41 and Figure 6.42 show data responses obtained from an MFC flaw in P30 and an 

EDM notch in P42, respectively.

Figure 6.36 Data Image Response for PAUT.122.1 Inspection of SCC Flaw in P28 

Viewed from the Right Side of Weld. The Inspection was performed by 

linear scanning with longitudinal wave modes from TRL probe at 60°. Two 

possible crack tip signals are highlighted by arrows in the image. 
6-33

Figure 6.37 Data Image Response for PAUT.122.1 Inspection of SCC Flaw in P28 

Viewed from the Right Side of Weld. The Inspection was performed by 

linear scanning with longitudinal wave modes from TRL probe at 50°. The 

likely crack tip signal is identified with the white circle.
6-34

Figure 6.38 Data Image Response for PAUT.122.1 Inspection of SCC Flaw in P32 

Viewed from the Right Side of Weld. The inspection was performed by 

linear scanning with longitudinal wave modes from TRL probe at 50°. The 

white circle indicates that it is difficult to separate the tip response from 

noise. 
6-35

Figure 6.39 Data Image Response for PAUT.122.1 Inspection of SCC Flaw in P32

Viewed from the Left Side of Weld. The inspection was performed by linear 

scanning with longitudinal wave modes from TRL probe at 55°. The white 

arrow highlights a weak signal considered to be the crack tip response. 
6-36

Figure 6.40 Data Image Response for PAUT.122.1 Inspection of SCC Flaw in P32 

Viewed from the Left Side of Weld. The inspection was performed by linear 

scanning with longitudinal wave modes from TRL probe at 45°. The white 

circle highlights the signal considered to be the crack tip response. 
6-37

Figure 6.41 Data Image Response for PAUT.122.1 Inspection of MFC Flaw in P30 

Viewed from the Left Side of Weld. The inspection was performed by linear 

scanning with longitudinal wave modes from TRL Probe at 50°. The white 

circle highlights the signal considered to be the tip response. 
6-38

Figure 6.42 Data Image Response for PAUT.122.1 Inspection of EDM Notch in P42 

Viewed from the Right Side of Weld. The inspection was performed by 

linear scanning with longitudinal wave modes from TRL probe at 50°. The 

white circle highlights the signal considered to be the tip response. 

6.7.4 Team 22 SAFT and PATRT Responses from P29

Images of team 22 responses obtained on FB test block P29 are included in Figures 6.43

through 6.46. The flaw in FB test block is a laboratory-grown SCC flaw. The responses are 

obtained for a synthetic aperture focusing technique (SAFT) and phased array time reversal 

technique (PATRT) using longitudinal (L-mode) and shear (S-mode) waves. The A-scan in the 

left of Figure 6.43 indicates a sharp response at the potential location of the crack tip; however, 

the back-wall signal is not observable. Figures 6.44 and 6.46, which represent responses for Smode waves using SAFT and PATRT, respectively, illustrate that although the crack tip signal 

may be discernable, the SNR does not appear to be large. Finally, the image in Figure 6.45 for 

L-mode waves using PATRT appears to provide the clearest crack tip and back-wall signals.
6-39

Figure 6.43 Image of Response for Team 22 SAFT Response with L-waves

Figure 6.44 Image of Response for Team 22 SAFT Response with S-waves

Figure 6.45 Image of Response for Team 22 PATRT Response with L-waves
6-40

Figure 6.46 Image of Response for Team 22 PATRT Response with S-waves

6.7.5 SAFT.17 Depth Measurement on P46

Test data collected by SAFT.17 on FB test block P46 is interesting because P46 is blank and a 

depth measurement was reported. An illustration of P46 geometry and dimensions are provided 

in Figure 6.47. In this case, measurements were made on both sides of the center of P46 where 

a flaw would be expected (at y = 110) and access was from the O.D. surface. Data images of 

the response from SAFT.17 obtained at y = 103.6 mm are provided in Figure 6.48 and a profile 

of the measured indication depth along x is provided in Figure 6.49. Similarly, data images of 

the response from SAFT.17 obtained at y = 120 mm are provided in Figure 6.50 and a profile of 

the measured indication depth along x is provided in Figure 6.51. These measurements indicate 

that the level of noise in blank test block P46 is sufficient to be mistaken for an actual defect. 

Figure 6.47 Coordinate System Definition, Dimensions, and Illustrations of FB Test 

Block P46
6-41

Figure 6.48 Data Images of Responses Obtained by SAFT-17 on Test Block P46 from 

y-position 103.6 mm
6-42

Figure 6.49 Indication Depth Profile Obtained by SAFT-17 on Test Block P46 from 

y-position 103.6 mm
6-43

Figure 6.50 Data Images of Responses Obtained by SAFT-17 on Test Block P46 from 

y-position 120 mm
6-44

Figure 6.51 Indication Depth Profile Obtained by SAFT-17 on Test Block P46 from 

y-position 120 mm

6.8 Procedures with Sparsely Populated Datasheets

Datasheets for several procedures were submitted with most of the X, Y, and Z coordinate fields 

for indications populated with non-numerical entries. This indicates that X, Y, and Z coordinate 

information for flaws could not be identified with the applied procedure, despite having 

knowledge of the true state. This situation applied to procedures MM.28.1, MM.28.2, GUW.21, 

NRUS.11, and PECT.11. An example of a sparsely populated sheet submitted for MM.28.1 and 

MM.28.2 is provided in Figure 6.52. Similar examples are provided for GUW.21, PECT.11, and 

NRUS.11 in Figures 6.53, 6.54, and6.55, respectively. In the case of MM.28.1, MM.28.2, and 

GUW.21, some datasheets were submitted with numerical data in some of the X, Y, and Z 

coordinate fields, indicating that flaw detection was possible in some instances. All of the 

datasheets for PECT.11 and NRUS.11 were submitted with non-numerical data in the X, Y, and 

Z coordinate fields. This data indicates that the techniques applied in these procedures are 

relatively insensitive to detect flaws or that more development is required for applying the 

techniques for this application.
6-45

Figure 6.52 Example of Datasheet Submission for Procedures MM.28.1 and MM.28.2 

with Non-Numerical Data in X, Y, and Z Fields for Indications
6-46

Figure 6.53 Example of Datasheet Submission for Procedure GUW.21 with Blank X, Y, 

and Z Fields for Indications
6-47

Figure 6.54 Example of Datasheet Submission for Procedures PECT.11 with NonNumerical Data in X, Y, and Z Fields for Indications
6-48

Figure 6.55 Example of Datasheet Submission for Procedures NRUS.11 with NonNumerical Data in X, Y, and Z Fields for Indications

6.9 Discussion of Test Block Appropriateness

As discussed in Section 6.8, datasheets for several procedures were sparsely populating, 

indicating difficulty in obtaining detectable signals from flaws in the inspected test blocks or 

difficulty in interpreting the responses. This may indicate that more development of the 

techniques employed in these procedures is required before practical applications are 

considered. For some techniques, however, the test blocks provided in PARENT were not 

adequate for performing a fair evaluation. For instance, testing by guided wave ultrasound 

(GUW) results in signals that travel significant distances in component materials. Boundaries 

and discontinuities cause reflections to appear in the signal, which greatly complicates signal 

analysis and interpretation. The test blocks in PARENT represent sectioned or cut-out portions 

of reactor components. As a result, the test blocks have boundaries that do not represent actual 

field conditions, but have an adverse influence on testing by GUW techniques. Team 21 makes 

note of this difficulty in comments entered into the example datasheet in Figure 6.53 for 

procedure GUW.21. 

The test blocks used in PARENT open testing were also not ideal for evaluating testing by nonlinear ultrasound techniques (NLUT). NLUT techniques such as NRUS and HHUT are being 

researched by the community primarily for detecting degradation in metals at early stages, or 
6-49

before macro-discontinuities form. All of the flaws intentionally inserted into PARENT test blocks 

are macro-discontinuities including various forms of cracks that are described in Section 2.6. 

Future efforts to evaluate NLUT techniques should include test blocks with flaws intentionally 

inserted to represent earlier stages of degradation, prior to the formation of macrodiscontinuities.

6.10 Techniques to Consider for Blind Testing

The results of open testing indicate that several techniques demonstrate a capability of 

detecting simulated PWSCC/IDSCC flaws. However, a reliable measure of detection 

performance cannot be obtained under open conditions. To obtain a measure of detection 

performance, a blind test could be performed on techniques that exhibit sufficient capability 

under the open test. Further criteria should be applied in choosing open techniques for blind test 

evaluation such as the ability to deploy the technique for a measurement in the field. Further, 

although several conventional UT and PAUT techniques were included in the open test study, 

these techniques were also evaluated in the PARENT blind test, and thus, additional blind 

testing is not deemed useful. Applying these criteria, the list of open techniques for which further 

blind testing is recommended include:

• ADVPAUT

− PAATOFD.29.0

− PAATOFD.29.1

− PAATOFD.29.2

− PAATOFD.29.3

− PATP.29

− PATRT.22

− SAFT.17

• NLUT

− SHPA.6.1

− SHPA.6.2

− SHPA.6.3

− LASH.18

− HHUT.27.1

− HHUT.27.2

− HHUT.30

• ECT

− ECT.7

− AECT.33

− ECT.16 

It is noted that while certain techniques such as UIR.20 and LUV.170 demonstrated a capability 

for detection of flaws, both techniques required access to the surface that the cracks intersect 

with. It is not clear that these techniques could be useful for detection of I.D.-connected flaws 

with access to the O.D. surface or if I.D. access in the field is feasible for the two techniques.

7-1

7 CONCLUSIONS AND FUTURE WORK

This report documents the results of the Open RRT portion of PARENT. Data were collected for 

procedures incorporating novel NDE techniques on SBDMW, FB, LBDMW, and BMI test blocks. 

This analysis has been restricted to depth sizing and length sizing analysis because of the open 

nature of the test. The objective of open testing is in establishing basic capability of techniques 

to justify further development and more detailed assessments of performance. Thus, only 

approximate measures of depth and length sizing performance were sought in open testing. To 

obtain a more complete picture of performance, some data response images provided by test 

participants were qualitatively analyzed to supplement the sizing analysis. Relative comparisons 

within open testing are emphasized over absolute values obtained by sizing analyses. Data was 

collected using established PAUT techniques to provide a benchmark for comparison. Readers 

are cautioned against directly comparing the sizing results from open testing with sizing results 

from blind testing because of the different conditions associated with each test.

Some significant conclusions drawn for the results documented in this report include:

• A general trend is observed for oversizing shallow flaws and undersizing deep flaws with the 

exception of ADVPAUT procedure types and NLUT procedures based on sub-harmonic 

techniques, which exhibit a more consistent error over the range of flaw depths considered. 

• NLUT procedures based on sub-harmonic techniques exhibit better depth sizing 

performance than NLUT procedures based on higher harmonic techniques based on overall 

RMSE and regression fits.

• ADVPAUT procedure types do not exhibit better overall depth sizing accuracy than PAUT 

procedure types in this study based on RMSE.

• Overall, NLUT procedure types do not exhibit better overall depth sizing accuracy in 

comparison to ADVPAUT and PAUT procedure types based on RMSE.

• PAUT procedures exhibit a more consistent length sizing error over the range of flaw 

lengths considered for SBDMW test blocks in comparison to ADVPAUT, which tend to 

oversize short flaws and undersize long flaws.

• Better depth sizing performance is observed on FB test blocks (most with laboratory-grown 

SCC flaws) for ADVPAUT, NLUT, and UT procedure types in comparison to SBDMW test 

blocks (with SC flaws). PAUT procedure types exhibit better depth sizing performance on 

SBDMW test blocks in comparison to FB test blocks.

• ECT.16 exhibits a more consistent length sizing error over the range of flaw lengths 

considered for SBDMW test blocks in comparison to “Advanced” ECT procedures 

(AECT.33), which tend to oversize short flaws and undersize long flaws.

• Depth sizing data for UIR.20 was obtained in a way that would not be practical in a field 

environment. However, the results indicate a capability for flaw detection and flaw length sizing.

• Data response images for PAATOFD.29.2 and SAFT.17 in Sections 6.7.1 and 6.7.2

illustrate that SCC flaws result in weaker crack tip responses in comparison to MFC and 

EDM notch flaws.
7-2

• Data response images for PAUT technique PAUT.122.1 in Section 6.7.3 illustrate that 

identifying crack tip signals with established PAUT can be difficult and that crack tip signal 

identification by image pattern analysis is, in part, a subjective determination.

• Data response images for SAFT.17 obtained from blank test block P46 in Section 6.7.5 and 

PAUT.122.1 in Section 6.7.3 illustrate difficulty in distinguishing noise from crack tip 

responses.

• Tip diffraction signals with low SNR are easier to detect under open testing conditions with 

flaw information provided to test participants. Detecting tip diffraction signals with low SNR 

under blind test conditions will be more challenging. 

Based on the results documented in this report and the conclusions outlined above, the 

following recommendations can be made:

• Blind testing of some of the open test procedures described in this report could be 

conducted based on the open testing results to obtain an estimate of detection performance 

and more realistic estimates of sizing performance. The specific techniques for which blind 

testing is recommended are summarized in Section 6.8 and included here for convenience:

− ADVPAUT

○ PAATOFD.29.0

○ PAATOFD.29.1

○ PAATOFD.29.2

○ PAATOFD.29.3

○ PATP.29

○ PATRT.22

○ SAFT.17

− NLUT

○ SHPA.6.1

○ SHPA.6.2

○ SHPA.6.3

○ LASH.18

○ HHUT.27.1

○ HHUT.27.2

○ HHUT.30

− ECT

○ ECT.7

○ AECT.33

○ ECT.16 

• Procedures UIR.20 and LUV.170 incorporate stand-off inspection techniques that have the 

potential for deployment during reactor operation. Evaluation of these procedures should be 

based on test pieces subject to relevant field conditions. 
7-3

• NLUT procedure types, which incorporate techniques that are sensitive to degradation in 

early stages, should be evaluated using test blocks with simulated early degradation to 

better evaluate their potential.

• Procedure GUW.21 had difficulty detecting flaws due to the geometrical limitations of the 

test blocks used in PARENT. Future efforts to evaluate GUW testing should ensure the 

dimensions of the test blocks are sufficient so that boundaries do not significantly influence 

the response.

8-1

8 REFERENCES

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Abidin IZ, C Mandache, GY Tian and M Morozov. 2009. "Pulsed Eddy Current Testing with 

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Cumblidge SE, SR Doctor, PG Heasler and TT Taylor. 2010. Results of the Program for the 

Inspection of Nickel Alloy Components. NUREG/CR-7019; PNNL-18713, Rev. 1, U.S. Nuclear 

Regulatory Commission, Washington, D.C.

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Goebbels, H Hanselka, J Nuffer and W Daum. 2007. "Performance Control and Condition 

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Hirsekorn S, M Hirsekorn and PP Delsanto. 2006. "Nonlinear Ultrasonic Transmission Through 

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Nonclassical Nonlinearity, Ch. 15, pp. 231-250. ed: P Delsanto. Springer, New York.

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the Depth of SCCs in Dissimilar Metal Weld." In 9th International Conference on NDE in 

Relation to Structural Integrity for Nuclear and Pressurized Components, pp. 754-762. May 22-

24, 2012, Seattle, Washington. NDT.net, Rheintalstr, Germany.

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IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control 47(3):540-548.

Karasawa H, T Ikeda, S Matsumoto, T Hamajima and H Isobe. 2009. "3D-SAFT Ultrasonic 

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683. May 12-14, 2009, Yokohama, Japan. European Commission Joint Research Centre, 

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Centre, Luxembourg.

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Lee KH, MK Baek and IH Park. 2012. "Estimation of Deep Defect in Ferromagnetic Material by 

Low Frequency Eddy Current Method." IEEE Transactions on Magnetics 48:3965-3968.

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Ultrasonics 36(1–5):147-154.

Maldague X. 2001. Theory and Practice of Infrared Technology for Nondestructive Testing. 

John Wiley and Sons, New York.

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Meyer RM and PG Heasler. 2017. Results of Blind Testing for the Program to Assess the 

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Ohara Y, K Kawashima, M Murase and N Hirose. 2003. "Identification of Sintered Irons with 

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Melville, New York.

Ohara Y, S Yamamoto, T Mihara and K Yamanaka. 2008. "Ultrasonic Evaluation of Closed 

Cracks Using Subharmonic Phased Array." Japanese Journal of Applied Physics 47(5):3908-

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Prada C, S Manneville, D Spoliansky and M Fink. 1996. "Decomposition of the Time Reversal 

Operator: Detection and Selective Focusing on Two Scatterers." The Journal of the Acoustical 

Society of America 99(4):2067-2076.

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the Acoustical Society of America 75(3):723-732. 

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Complete Nonclassical Spectra." In Universality of Nonclassical Nonlinearity, Ch. 29, pp. 467-

486. ed: P Delsanto. Springer, New York.

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Wave Spectroscopy (TR NEWS) Techniques." International Journal of Non-Linear Mechanics

43(2):209-216.

Yusa N, Y Sakai and H Hashizume. 2011. "An Eddy Current Probe Suitable to Gain 

Information about the Depth of Near-side Flaws Much Deeper than the Depth of Penetration." 

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Detection." Fatigue & Fracture of Engineering Materials & Structures 31:695-713.

APPENDIX A

–

11TH ICNDE PAPERS 

A-1 

APPENDIX A

11TH ICNDE PAPERS

A.1 Simulation of Inspection for Dissimilar Metal Welds by Phased Array UT with 

Focusing Techniques................................................................................................. A-2

A.2 Challenge for the Detection of Crack in Dissimilar Weld Region Using PECT 

(Pulsed Eddy Current Technology) ...........................................................................A-7

A.3 Manufacturing of a New Type of NDE Test Samples with Laboratory-Grown 

Intergranular SCC Cracks in a Nickel-Base Weld – Comparison of Various 

NDE-Techniques Applied to a Challenging Crack Morphology.............................A-15

A.4 Integrity Evaluation Case Subject to Replacement & Preventive Maintenance 

for NPP Ni-alloy Components ..................................................................................A-29
A-2 

A.1 Simulation of Inspection for Dissimilar Metal Welds by Phased Array UT 

with Focusing Techniques
A-3 
A-4 
A-5 
A-6 
A-7 

A.2 Challenge for the Detection of Crack in Dissimilar Weld Region Using PECT 

(Pulsed Eddy Current Technology)
A-8 
A-9 
A-10
A-11
A-12
A-13
A-14
A-15

A.3 Manufacturing of a New Type of NDE Test Samples with Laboratory-Grown 

Intergranular SCC Cracks in a Nickel-Base Weld – Comparison of Various 

NDE-Techniques Applied to a Challenging Crack Morphology
A-16
A-17
A-18
A-19
A-20
A-21
A-22
A-23
A-24
A-25
A-26
A-27
A-28
A-29

A.4 Integrity Evaluation Case Subject to Replacement & Preventive Maintenance 

for NPP Ni-alloy Components
A-30
A-31
A-32
A-33
A-34
A-35
A-36
A-37
A-38
A-39
A-40
APPENDIX B

–

SUMMARY TABLE OF OPEN NDE TECHNIQUES 

B-1 

APPENDIX B

SUMMARY TABLE OF OPEN NDE TECHNIQUES

B.1 Summary of Techniques Applied to Flat Bar Test Blocks .......................................B-2

B.2 Summary of Techniques Applied to SBDMW Test Blocks.......................................B-7

B.3 Summary of Techniques Applied to LBDMW Test Blocks.....................................B-15

B.4 Summary of Techniques Applied to BMI Test Blocks............................................B-21
B

-2

B.1 Summary of Techniques Applied to Flat Bar Test Blocks

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface Comment Function

11 Nonlinear 

Resonant Ultrasound Spectroscopy

11.1 NRUS.11 11-NRUT0 P28, P29, 

P30 

Manual N O.D. Wide-band piezo-electric 

element. Resonance frequencies and vibration modes are specified from prior vibration mode analysis for the specimen.

Detection

Pulsed Eddy Current

11.2 PECT.11 11-PECT0 P28, P29, 

P30 

Manual N O.D. 10 ms (pulse width), 0.5 (duty 

ratio)

Detection

20 Phased Array 

UT

20.1 PAUT.20 20-PA1 P31, P32, 

P38 

Manual N O.D. Shear wave Location, 

Length, Depth Sizing

20-PA2 P28, P29, 

P30 

Manual N O.D. Longitudinal wave

Ultrasound Infrared Thermography

20.2 UIR.20 20-UIR0 P28, P29, 

P30, P31, P32, P38

Manual N Side Excitor Frequency 20 

(kHz)/Inspection Angle 90 (Deg.)/Detector 20 mk (NETD)Access ID: label side, opposite label side, bottomAccess O.D.: Top

Location, Length, Depth Sizing

22 Phased Array 

UT

22.1 PATRT.22 22-PASAFT1 P29 Manual N O.D. 5 MHz/45° SAFT. P-Wave

OLYMPUS 5L64-A2 

Location, Length, Depth Sizing

22-PASAFT2 P29 Manual N O.D. 5 MHz/55° SAFT, S-Wave

OLYMPUS 5L64-A2 
B

-3

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface Comment Function

22-PATRT1 P29 Manual N O.D. 5 MHz/45° Time Reversal Technique

P-WaveOLYMPUS 5L64-A2 

22-PATRT2 P29 Manual N O.D. 5 MHz/55° Time Reversal Technique

S-WaveOLYMPUS 5L64-A2 

30 Higher 

Harmonic UT

30.1 HHUT.30 30-HHUT0 P28, P29, 

P30 

AutomatedManual

N I.D.

O.D.

3 MHz vertical beamT: 2 MHz, R: 4 MHz 45° Access: Auto: PE(Z-axis), 

Manual: PE(X-axis) and VS

Olympus V126Krautkramer MWB45-2, MWB45-4

Location/Depth Sizing

30-HHUT1 P28, P29, 

P30 

AutomatedManual

N I.D.

O.D.

3 MHz vertical beamT: 2 MHz, R: 4 MHz 45° Access: Auto: PE(Z-axis), 

Manual: PE(X-axis) and VS

Olympus V126Krautkramer MWB45-2, MWB45-4

27 Higher 

Harmonic UT

27.1 HHUT.27.2 27-HHUT3 P28, P29, 

P30, P31, P32, P38, P42, P46

Automated Y O.D. 5 MHz/Immersion/2°Angular

Focal depth: 76 mm/3.5 MHz excitation

Detection, Depth Sizing, Characterization, Length Sizing and Positioning

6 Subharmonic 

Phased Array for Crack Evaluation (SPACE) 

6.1 SHPA.6.1 6-SHPA1 P28 Manual N O.D. 5 MHz-Bulk-Space Detection, 

Characterization, Depth Sizing

6-SHPA4 P28 Manual N I.D. 3.5 MHz-SAW-Space Detection, 

Characterization, 
B

-4

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface Comment Function

Length Sizing, Positioning

6.3 SHPA.6.3 6-SHPA2 P29, P30, 

P31, P32

Manual N O.D. 2 MHz-Bulk-Space Detection, 

Characterization, Depth Sizing

6-SHPA4 P29, P30, 

P31, P32

Manual N I.D. 3.5 MHz-SAW-Space Detection, 

Characterization, Length Sizing, Positioning

17 3 Dimensional 

Synthetic Aperture Focusing Technique

17.1 SAFT.17 17-SAFT1 P28, P29, 

P30, P31, P32, P38, P42, P46

Manual N O.D. 2 MHz, 16×16ch, 45°

16×16ch Matrix array SAFT

Detection, Characterization, Depth Sizing, Positioning

18 Large 

Amplitude Excitation Subharmonic UT

18.1 LASH.18 18-LASH1 P28, P29, 

P30, P31, P32 

O.D. B-scan image by aperture 

synthesis5 MHz ultrasound

Detection, Depth Sizing, Characterization

18-LASH2 P28, P29,

P30, P31, P32 

O.D. Large Amp. Excitation SPACE 

Input 5 MHz (ω) burst1. Amplitude of subharmonic echo at crack2. Imaging of high voltage3. Imaging by ω and ω/24. Detectability of crack tip diffraction echo
B

-5

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface Comment Function

29 Phased Array 

Asymmetrical Beam TOFD

29.3 PAATOFD.29.1 29-

PAATOFD1 

P28, P29, P30, P31, P32, P38, P42, P46 

Automated Y I.D. Phased array asymmetrical 

beam TOFD method with 2×16 probeFrequency: 2.25 MHzInspection angle: −32 ~ +32 at 1°1. Detection of tip echo on B, C, D-scan images2. Determine the X position of the tip echo for the MA method3. MA synthesis of scanning data4. Depth sizing of the tip echo on the MA B-scan image

Depth Sizing

29.4 PAATOFD.29.2 29-

PAATOFD2 

P28, P29, P30, P31, P32, P38, P42, P46

Automated Y I.D. Phased array asymmetrical 

beam TOFD method with 4×8 probeFrequency: 2.25 MHzInspection angle: −28 ~ +28 at 1°1. Detection of tip echo on B, C, D-scan images2. Determine the X position of the tip echo for the MA method3. MA synthesis of scanning data4. Depth sizing of the tip echo on the MA B-scan image

Depth Sizing

33 Advanced 

ECT

33.1 AECT.33 33-AECT1 P28, P29, 

P30, P31, P32, P38, P42, P46

Automated Y I.D. 100 kHz/Pancale-4ch-TR probe 

Pancake-4ch-TR-probe, 100 

kHz

Detection, Characterization, Length Sizing, Positioning
B

-6

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface Comment Function

16 Eddy Current 16.1 ECT.16 16-ECT1 P28, P29, 

P30, P31, P32, P38, P42, P46

Automated Y I.D.: 

DMWO.D.: BMI

20 k–1 MHz/3 mm-12×2ch CrossColi-Array-24ch-200 kHz

Detection, Characterization, Length Sizing, Positioning

28 Microwave 

Near-field Microscope

28.2 MM.28.2 28-MM12 P28, P29, 

P30, P31, P32 

Automated Y I.D. Open-ended coaxial line 

sensor, 110 GHzOpen-ended coaxial line sensor, 110 GHz

Detection, Characterization, Length Sizing, Depth Sizing, Positioning

104 Mechanized 

UT Through Transmission Pitch-Catch

104.1 UT.104 104-UTP/C0 P28, P29, P30, P31, 

P32, P38, P42, P46

Automated Y O.D. 1 MHz (10 mm aperture) 

2.25 MHz (6 mm aperture)Through transmission, sound beam perpendicular to weld

Detection, Characterization, Length, Depth, Positioning

131 Manual Linear 

TR UT-PA; 

131.1 PAUT.131.1 131-PA0 P28, P29, 

P30, P31, P32, P38, P42 

Manual N O.D. 2.33 MHz/24 Elements; 

TRL40–70UT PA Long 40–70; MultiX Contact Pulse Echo

Detection, Characterization, Length, Depth, Positioning

122 TRL Linear 

UT-PA Encoded 

122.1 PAUT.122.1 122-PA1 P28, P29, 

P30, P31, P32, P38, P42 

Automated Y O.D. 1.5 MHz, beam steering with 

fixed refraction angles

Detection, Characterization, Length, Depth, Positioning

TRL Sectorial Phased Array

122.2 PAUT.122.2 122-PA2 P28, P29, 

P30, P31, P32, P38, P42 

Automated Y O.D. 1.5 MHz, sectorial scan 40–70

CIRCU-TRL-270/40-70LW 

CIRCD-TRL-90/40-70LW

Detection, Characterization, Length, Depth, Positioning

114 Encoded 

Linear TR UTPA 

114.1 PAUT.114 114-PA1 P28, P29, 

P30, P31, P32, P38, P42 

Automated Y O.D. 1.5 MHz, beam steering with 

fixed refraction angles

Detection, Characterization, Length, Depth, Positioning
B

-7

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface Comment Function

109 X-Ray 

Computed Tomography

109.1 RT.109 109-X-Ray 

CT

P29, P30, P31, P32, P38, P42

Automated Not 

Specified

O.D. Source: 450 kV /3.3 mA /1.0 

mm focal spot; Detector: Single collimated (W) line detector (CdWO4) with 125 detector channels

Detection, Depth Sizing

112 X-Ray Digital 

Radiography

112.1 RT.112 112-X-Ray 

CT

P28, P29, P30 

Automated Not 

Specified

O.D. Source: 300 to 450 kV; 1.5 to 

2.25 mA; 0.4 mm focus; detector: CCD with scintillating faceplate with fiber optic lens; the projection angle is from −10° to +10°, with increments of 2°. 

Detection, Depth Sizing

TRL = transmit-receive longitudinal

B.2 Summary of Techniques Applied to SBDMW Test Blocks

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface 

Probe Frequency (MHz)/ 

Inspection Angle (Deg.)/ 

Skew (Deg.) Function

6 Subharmonic 

Phased Array for Crack Evaluation (SPACE) 

6.1 SHPA.6.1 6-SHPA1 P1 Manual N O.D. 5 MHz-Bulk-Space Detection, 

Characterization, Depth Sizing

6-SHPA4 P1 Manual N I.D. 3.5 MHz-SAW-Space Detection, 

Characterization, Length Sizing, Positioning
B

-8

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface 

Probe Frequency (MHz)/ 

Inspection Angle (Deg.)/ 

Skew (Deg.) Function

6.2 SHPA.6.2 6-SHPA1 P4 Manual N O.D. 5 MHz-Bulk-Space Detection, 

Characterization, Depth Sizing

6-SHPA3 P4 Manual N O.D. 7 MHz-Bulk-Space Detection, 

Characterization, Length Sizing, Positioning

6-SHPA4 P4 Manual N I.D. 3.5 MHz-SAW-Space Detection, 

Characterization, Length Sizing, Positioning

17 3 Dimensional 

Synthetic Aperture Focusing Technique

17.1 SAFT.17 17-SAFT1 P1, P41 Manual N O.D. 2 MHz, 16×16ch, 45°

16×16ch Matrix array SAFT

Detection, Characterization, Length Sizing, Depth Sizing, Positioning

18 Large 

Amplitude Excitation 

18.1 LASH.18 18-LASH1 P1 O.D. B-scan image by aperture 

synthesis5 MHz ultrasound

Detection, Depth Sizing, Characterization
B

-9

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface 

Probe Frequency (MHz)/ 

Inspection Angle (Deg.)/ 

Skew (Deg.) Function

Subharmonic UT

18-LASH2 P1 O.D. Large Amp. Excitation SPACE 

Input 5 MHz (ω) burst1. Amplitude of subharmonic echo at crack2. Imaging of high voltage3. Imaging by ω and ω/24. Detectability of crack tip diffraction echo

Detection, Depth Sizing, Characterization

20 Phased Array 

UT

20.1 PAUT.20 20-PA1 P1 Manual N O.D. PAUT (Shear wave) Location, 

Length, Depth Sizing

33 Advanced 

ECT

33.1 AECT.33 33-AECT1 P41 Automated Y I.D. 100 kHz/Pancake-4ch-TR-probe 

Pancake-4ch-TR probe, 100 kHz

Detection, Characterization, Length Sizing, Positioning

16 Eddy Current 16.1 ECT.16 16-ECT1 P1, P4, 

P41 

Automated Y I.D.: 

DMWO.D.: BMI

20 k–1 MHz/3 mm-12x2ch CrossColi-Array-24ch-200 kHz

Detection, Characterization, Length Sizing, Positioning

104 Mechanized 

UT Through Transmission Pitch-Catch

104.1 UT.104 104-UTP/C0 P41 Automated Y O.D. 1 MHz (10 mm aperture) 2.25 MHz (6 mm aperture)

Through transmission, sound beam perpendicular to weld

Detection, Characterization, Length, Depth, Positioning

114 Encoded 

Linear TR UT-PA 

114.1 PAUT.114 114-PA1 P1, P4, 

P41 

Automated Y O.D. 1.5 MHz, beam steering with 

fixed refraction angles

Detection, Characterization, Length, Depth, Positioning
B

-10

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface 

Probe Frequency (MHz)/ 

Inspection Angle (Deg.)/ 

Skew (Deg.) Function

112 X-Ray Digital 

Radiography

112.1 RT.112 112-X-Ray 

CT

P41 Automated Not 

Specified

O.D. Source: 300 to 450 kV; 1.5 to 

2.25 mA; 0.4 mm focus; Detector: CCD with scintillating faceplate with fiber optic lens; The projection angle is from −10° to +10°, with increments of 2°.

Detection, Depth Sizing

21 Guided Wave 

UT

21.1 GUW.21 21-GUW1 P4 Manual N O.D. 0.5/42/Yes

GUW (L-wave mode)

Location

27 Higher 

Harmonic UT

27.1 HHUT.27.1 27-HHUT1 P1, P41 Automated Y O.D. 5 MHz/Immersion/Normal/Focal 

depth: 76 mm/4 MHz excitation Immersion-Normal-Incidence

Detection, Depth Sizing, Characterization, Length Sizing, and Positioning

HHUT.27.2 27-HHUT2 P1, P41 Automated Y O.D. 5 MHz/Immersion/5°Angular/

Focal depth: 76 mm/4 MHz excitation Immersion-5°AngularIncidence

Detection, Depth Sizing, Characterization, Length Sizing, and Positioning
B

-11

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface 

Probe Frequency (MHz)/ 

Inspection Angle (Deg.)/ 

Skew (Deg.) Function

5 Controlled 

Excitation ECT

5.1 CEECT.5.1 5-CEECT1 P1, P4 Manual I.D. Eddy current inspection using a 

probe that enables to evaluate the depth of deep flaws more quantitatively than conventional eddy current testing. The distance between the exciters was 12 mm so that the probe could approach the inner surface of the specimen.The probe was positioned at Y=−7.57 mm, and scanned the inner surface of the specimen in the circumferential direction (i.e., parallel to the flaws). The scanning was conducted manually, and the length of a scanning line to measure each flaw is approximately 200 mm. No scanning in axial direction was conducted because of the difficulty in positioning the probe. The probe was positioned so that the axes of the exciters were parallel to the flaws.

Detection, Length Sizing, Depth Sizing, Characterization and Positioning

28 Microwave 

Near-field Microscope

28.1 MM.28.1 28-MM1 P1, P4, 

P41 

Manual N I.D. Open-ended coaxial line sensor, 

67 GHz

Detection, Characterization, Length Sizing, Depth Sizing, Positioning
B

-12

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface 

Probe Frequency (MHz)/ 

Inspection Angle (Deg.)/ 

Skew (Deg.) Function

29 Phased Array 

Twin Probe

29.2 PATP.29 29-PATP0 P1, P41 Manual N O.D. Phased Array Twin Probe 

Method with 10×25 probe

Frequency: 1.5 MHz

Inspection angle: −45 ~ +45 at 1°1. Detection of tip echo on B, C, D-scan images2. Determine the X position of the tip echo for the MA method3. MA synthesis of scanning data4. Depth sizing of the tip echo on the MA B-scan image

Depth Sizing
B

-13

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface 

Probe Frequency (MHz)/ 

Inspection Angle (Deg.)/ 

Skew (Deg.) Function

29 Phased Array 

Asymmetrical Beam TOFD

29.1 PAATOFD.29.0 29-

PAATOFD0

P1, P41 Manual N O.D. Phased array asymmetrical 

beam TOFD method with 10×25probeFrequency: 1.5 MHzInspection angle: −35 ~ +35 at 1°1. Detection of tip echo on B, C, D-scan images2. Determine the X position of the tip echo for the MA method3. MA synthesis of scanning data4. Depth sizing of the tip echo on the MA B-scan image

Depth Sizing
B

-14

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface 

Probe Frequency (MHz)/ 

Inspection Angle (Deg.)/ 

Skew (Deg.) Function

131 Manual Linear 

TR UT-PA; Manual UTPA; Probe: GEIT; Equipment MultiX

131.2 PAUT.131.2 131-PA1 P1, P41 Manual N O.D. 2 MHz/2×16 Elements; TRL25–

65UT PA Long: Probe GEIT 16×2:Equip.: MultiX

Detection, Characterization, Length, Depth, Positioning

Manual Encoded Linear UT-PA; Probe: Sonaxis; Equipment: MultiX

131.2 PAUT.131.2 131-PA2 P4 Manual N O.D. 2 MHz/2x16 Elements; TRL45–

75UT PA Long 45–75L PE Probe: Sonaxis: MultiX

Detection, Characterization, Length, Depth, Positioning

Manual Matrix Unisequential UT-PA; Probe: GEIT; Equipment Phasor XS

131.4 PAUT.131.4 131-PA3 P41 Manual N O.D. 1,5 MHz/2x(5x3) Element; 

TRL40-70UT PA Long/Probe: GEIT 16×2/Equipment Phasor XS

Detection, Characterization, Length, Depth, Positioning

170 Laser 

Ultrasound Visualization

170.1 LUV.170 170-LUV P1 Automated Not 

Specified

O.D. PZT excitation w/laser detection Detection, 

Length Sizing
B

-15

B.3 Summary of Techniques Applied to LBDMW Test Blocks

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface

Probe Frequency (MHz)/ 

Inspection Angle (Deg.)/ 

Skew (Deg.) Function

17 3 Dimensional 

Synthetic Aperture Focusing Technique

17.1 SAFT.17 17-SAFT1 P12, P23, 

P24, P37

Manual N O.D. 2 MHz, 16×16ch, 45°

16×16ch Matrix array SAFT

Detection, Characterization, Length Sizing, Depth Sizing, Positioning

18 Large 

Amplitude Excitation Subharmonic UT

18.1 LASH.18 18-LASH1 P12 O.D. B-scan image by aperture 

synthesis5 MHz ultrasound

Detection, Depth Sizing, Characterization

18-LASH2 P12 O.D. Large Amp. Excitation SPACE 

Input 5 MHz (ω) burst1. Amplitude of subharmonic echo at crack2. Imaging of high voltage3. Imaging by ω and ω/24. Detectability of crack tip diffraction echo

Detection, Depth Sizing, Characterization
B

-16

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface

Probe Frequency (MHz)/ 

Inspection Angle (Deg.)/ 

Skew (Deg.) Function

29 Phased Array 

Twin Probe

29.2 PATP.29 29-PATP0 P12, P23, 

P24, P37

Manual N O.D. Phased Array Twin Probe 

Method with 10×25 probe

Frequency: 1.5 MHz

Inspection angle: −45 ~ +45 at 1°1. Detection of tip echo on B, C, D-scan images2. Determine the X position of the tip echo for the MA method3. MA synthesis of scanning data4. Depth sizing of the tip echo on the MA B-scan image

Depth Sizing
B

-17

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface

Probe Frequency (MHz)/ 

Inspection Angle (Deg.)/ 

Skew (Deg.) Function

29 Phased Array 

Asymmetrical Beam TOFD

29.1 PAATOFD.29.0 29-

PAATOFD0 

P12, P23, P24, P37

Manual N O.D. Phased array asymmetrical 

beam TOFD method with 10×25probeFrequency: 1.5 MHzInspection angle: −35 ~ +35 at 1°1. Detection of tip echo on B, C, D-scan images2. Determine the X position of the tip echo for the MA method3. MA synthesis of scanning data4. Depth sizing of the tip echo on the MA B-scan image

Depth Sizing
B

-18

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface

Probe Frequency (MHz)/ 

Inspection Angle (Deg.)/ 

Skew (Deg.) Function

29 Phased Array 

Asymmetrical Beam TOFD

29.3 PAATOFD.29.1 29-

PAATOFD1 

P12, P23, P24, P37 

Automated Y I.D. Phased array asymmetrical 

beam TOFD method with 2×16probeFrequency: 2.25 MHzInspection angle: −32 ~ +32 at 1°1. Detection of tip echo on B, C, D-scan images2. Determine the X position of the tip echo for the MA method3. MA synthesis of scanning data4. Depth sizing of the tip echo on the MA B-scan image

Depth Sizing

29.4 PAATOFD.29.2 29-

PAATOFD2 

P12 Automated Y I.D. Phased array asymmetrical 

beam TOFD method with 4×8probeFrequency: 2.25 MHzInspection angle: −28 ~ +28 at 1°1. Detection of tip echo on B, C, D-scan images2. Determine the X position of the tip echo for the MA method3. MA synthesis of scanning data4. Depth sizing of the tip echo on the MA B-scan image

Depth Sizing
B

-19

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface

Probe Frequency (MHz)/ 

Inspection Angle (Deg.)/ 

Skew (Deg.) Function

33 Advanced 

ECT

33.1 AECT.33 33-AECT1 P12, P37 Automated Y I.D. 100 kHz/Pancake 4ch-TRprobe Pancake 4ch-TR probe, 

100 kHz

Detection, Characterization, Length Sizing, Positioning

16 Eddy Current 16.1 ECT.16 16-ECT1 P12 Automated Y I.D.: 

DMWO.D.: BMI

20 k–1 MHz/3 mm-12×2ch CrossColi-Array-24ch-200 kHz

Detection, Characterization, Length Sizing, Positioning
B

-20

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface

Probe Frequency (MHz)/ 

Inspection Angle (Deg.)/ 

Skew (Deg.) Function

28 Microwave 

Near-field Microscope

28.1 MM.28.1 28-MM1 P12, P23, 

P24 

Manual N I.D. Open-ended coaxial line 

sensor, 67 GHz

Detection, Characterization, Length Sizing, Depth Sizing, Positioning

150 Phased Array 

UT

150.1 PAUT.150 150-PA1 P12, P37 Automated Encoded O.D. MHz 2x(10×5) element matrix 

array Azimuthal PA angle sweeps from 20–80; 0,±10 degree skew angles1.0 MHz Imasonic TRL array probe

Detection, Characterization, Length Sizing, Depth Sizing, Positioning

7 Phased Array 

UT

7.2 PAUT.7 7-PA1 P12, P37 Automated Encoded I.D. 1.5 MHz electronic sweeping of 

the examination angle from 60° to 88° at 2° incrementsA Zetec Tomoscan-III PA 32/128 UT instrument was used for data acquisition 

Detection, Characterization, Length Sizing, Depth Sizing, Positioning
B

-21

B.4 Summary of Techniques Applied to BMI Test Blocks

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface 

Probe Frequency (MHz)/ 

Inspection Angle (Deg.)/ 

Skew (Deg.) Function

16 Eddy Current 16.1 ECT.16 16-ECT1 P5, P7 Automated Y I.D.: 

DMWO.D.: BMI

20 k–1 MHz/3 mm-12×2ch CrossColi-Array-24ch-200 kHz

Detection, Characterization, Length Sizing, Positioning

33 Advanced 

ECT

33.1 AECT.33 33-AECT1 P5, P7 Automated Y I.D. 100 kHz/Pancake-4ch-TRprobe Pancake-4ch-TR probe, 

100 kHz

Detection, Characterization, Length Sizing, Positioning

5 Controlled 

Excitation ECT

5.1 CEECT.5.1 5-CEECT1 P7 Manual I.D. Eddy current inspection using a 

probe that enables to evaluate the depth of deep flaws more quantitatively than conventional eddy current testing. The distance between the exciters was 12 mm so that the probe could approach the inner surface of the specimen.The probe was positioned at Y=−7.57 mm, and scanned the inner surface of the specimen in the circumferential direction (i.e., parallel to the flaws). The scanning was conducted manually, and the length of a scanning line to measure each flaw is approximately 200 mm. No scanning in axial direction was conducted because of the difficulty in positioning the probe. The probe was positioned so that the axes of the exciters were parallel to the flaws.

Detection, Length Sizing, Depth Sizing, Characterization and Positioning
B

-22

Team 

# 

NDE 

Technique 

Description 

(from Test 

Block Master)

Form 

Procedure 

ID

Procedure ID 

Used in Formal 

Documentation

Technique 

ID

Test Blocks 

Technique 

Applied To

Manual or 

Automated

Encoded 

(Y/N)

Exam 

Surface 

Probe Frequency (MHz)/ 

Inspection Angle (Deg.)/ 

Skew (Deg.) Function

170 Laser 

Ultrasound Visualization

170.1 LUV.170 170-LUV P5, P7 Automated Not 

Specified

O.D. PZT excitation w/laser detection Detection, 

Length Sizing

7 Eddy Current 7.1 ECT.7 7-ECT1 P5, P7, 

P21, P22

Manual Not 

Specified

O.D. 50 kHz flexible eddy current 

array probe 3×3 

Detection, Length Sizing

28 Microwave 

Near-field Microscope

28.1 MM.28.1 28-MM1 P21 Manual N I.D. Open-ended coaxial line 

sensor, 67 GHz

Detection, Characterization, Length Sizing, Depth Sizing, Positioning

21 Guided Wave 

UT

GUW 21.1 21-GUW2 P5 Manual N O.D. 2/65/Yes

GUW (Surface wave)

Location
APPENDIX C

–

SUMMARIES OF OPEN NDE TECHNIQUES

C-1

APPENDIX C

SUMMARIES OF OPEN NDE TECHNIQUES 

C.1 Technique Summaries................................................................................................C-1

C.2 Europe Detailed Technique Descriptions................................................................C-60

C.3 Korea Detailed Technique Descriptions................................................................C-215

C.4 USA Detailed Technique Descriptions ..................................................................C-271

C.5 Japanese Detailed Technique Descriptions..........................................................C-291

C.1 Technique Summaries

C.1.1 Korean Techniques
C-2
C-3
C-4
C-5
C-6
C-7
C-8
C-9
C-10
C-11
C-12
C-13
C-14
C-15
C-16

C.1.2 Japanese Techniques
C-17
C-18
C-19
C-20
C-21
C-22
C-23
C-24
C-25
C-26
C-27
C-28
C-29
C-30
C-31
C-32
C-33
C-34
C-35
C-36

C.1.3 European Techniques
C-37
C-38
C-39
C-40
C-41
C-42
C-43
C-44
C-45
C-46
C-47

C.1.4 USA Technique 7-ECT1
C-48
C-49
C-50
C-51
C-52

C.1.5 USA Technique 7-PA1
C-53
C-54

C.1.6 ISA Technique 150-PA0
C-55
C-56

C.1.7 USA Technique 170-LUV0
C-57
C-58
C-59
C-60

C.2 Europe Detailed Technique Descriptions

C.2.1 Through Transmission of Longitudinal Waves, Technique ID 104-UT-P/C0

C.2.1.1 Overview

Trough transmition of ultrasonic longitudinal waves is amongst others used for detection of 

delaminations in composites with difficult accoustic properties. Normally the delaminations are 

expected to be parallel to the inspection surface and sender and receiver probe are on oposite 

sides of the part to be inspected. In case of a delamiation the sound will be blocked and 

therefore the receiving probe will detect a reduced amplitude.

For this application there are mainly two things different:

1. The orientation of the crack is more or less perpendicular to the surface.

2. There is only access from one side

To get an interaction between crack and sound beam and to be able to measure the depth 

extension of the crack, through transmission with angle beam is necessary. 

To overcome the problem with the not accessible back wall, the receiving probe will be placed 

on the same surface as the sending probe and one reflection on the back wall will be used.

With the set-up shown in Figure C.1, it is possible to detect and measure cracks perpendicular 

to the surface:

Figure C.1 Illustration of Inspection Set-up and Calculation of Depth Extension of Crack
C-61

Sound is sent from S1 via back wall to R1, from S2 to R2 etc. As long as there is no discontinuity on the sound path the 

receiver will detect high amplitude (green). In case sound is blocked by a discontinuity (red) the receiver will detect much 

lower amplitude. The received amplitude can then be displayed on a C-Scan representation and calculation described in 

Figure C.1 can be done using this C-Scan. Figure C.4 shows such a C-Scan.

Figure C.2 Inspection Principle

Figure C.3 Probe Holder with Defined Distance between Sender and Receiver

To allow offline evaluation of the data the full A-scan information needs to be stored together 

with position information (X and Y coordinates).
C-62

The lower C-Scan shows the received amplitude color coded (0% FSH [white] to 100% FSH [red]). The upper C-Scan shows 

the C-Scan after using a 6 dB drop filter (0% to 50 % FSH [white] and 50% to 100% FSH [red]). On the left side of the CScans the influence of the cladding is visible. The attenuation caused by the cladding is a limiting factor and if it’s too high 

it can make inspection impossible.

Figure C.4 Example of C-Scan Representation Used for Evaluation (circumferential flaw, 

open to inner surface)
C-63

C.2.1.2 NDE Equipment

A ZScan PA 64 (ZPA5022) from ZETEC together with Ultravision software was used for data 

aquisition. To facilitate coupling the part to be inspected was immersed in water. An XYZscanner was used to move the probe holder over the surface of the part. Encoder information 

from the scanner was provided to the ZScan to be stored together with A-scan data.

Two Panametrics probes were used:

• C548-SM with a diameter of 10 mm and a frequency of 1.0 MHz (sender)

• A548-SM with a diameter of 10 mm and a frequency of 1.5 MHz (receiver)

Rexolite wedges were used and their angle was machined to get an incident angle of 45° 

longitudinal wave in the test piece.

Distance between the probe indices is set to two times the wall thickness of the part to be 

inspected.

C.2.1.3 Data Acquisition Process (for defects with circumferential orientation)

The probe holder was placed on the outer surface of the part to be inspected in a way that the 

direction from sender to receiver was parallel to the axial direction of the tube. This set-up is 

only valid for circumferential crack orientation.

After start of data acquisition in Ultravision the scanner was started as well. Scanning direction 

was in axial direction and the scanning length was set in a way that both probes were passing 

weld, buttering and HAZ. After one scan line the probe holder was shifted in circumferential 

direction (index) and a scan in opposite direction to the first one was performed.

Like this a certain circumferential rage was tested. This range was limited due to the fact that it 

was not possible to rotate the part while scanning and the probe holder was only able to 

compensate a limited change of the surface orientation.

C.2.1.4 Data Analysis

C-scan of 45° LL reflection of back wall was evaluated:

Where no (perpendicular) crack is present the back wall will be detected with high amplitude. At 

positions where the sound path from sender to receiver is affected by the crack the amplitude 

will drop. 6 dB drop compared to sound material will be used to define the extensions of the 

flaw. Additionally pattern recognition will be used.

A crack connected to the inner surface will result in a C-scan where the area with amplitude 

drop will be continuous whereas an inclusion or lack of fusion will result in two individual 

(mirrored) areas with amplitude drop). 

Length of the crack corresponds to the scanning index distance where the crack will be 

detected.
C-64

Crack depth is calculated from the scanning distance where a drop of amplitude is detected. For 

calculation of crack depth compare sketch and formula in Figure C.1. 

Sizing technique will be used for defect positioning. Centerline (perpendicular to scanning 

direction) of the area with amplitude drop will be used as defect position whereas the

mechanical reference of the C-scan will be the center of the probe assembly.

C.2.1.5 Self Assessment

Advantages of this UT inspection technique are: 

• No influence of flaw surface roughness

• Orientation of flaw doesn’t influence detectability

• Very low noise from scattered sound (grain boundaries...), therefore higher frequencies can 

be used

Disadvantage of this approach are: 

• Cladding of the surface influences the amplitude of transmitted sound and therefore alters 

the inspection results

• A parallel inner surface is necessary. Otherwise Scanning becomes difficult (position 

dependent distance and/or inspection angle of sender and receiver probe).

• Altered microstructure influences the inspection result. This is mainly the problem when 

artificial flaws are produced by local heating or welding / brazing of a defective volume into 

the reference block.

C.2.2 Phased Ultrasonic Array, Technique ID 131-PA0

C.2.2.1 Overview

The techniques described in this report were utilized for the examination of the -specimens P28, 

P29, P30, P31, P32, P42 and P46. 

Method Phased Array Ultrasonic Testing

Array / Technique Single / Linear / Pulse Echo

Wave Mode Longitudinal

Angle Range 40° – 70°

Frequency 2.33 MHz

UT Instrument M2M MultiX 64

Scan Plan Encoded in +Y and – Y direction

Scanning Surface W & X
C-65

Figure C.5 Technique Overview Illustrations

C.2.2.2 NDE Equipment / UT Settings

Search Unit

For the measurement a sonaxis probe and wedge was used. The essential variables of the 

search unit are described below.
C-66

Crystal Shape

Figure C.6 

Focusing

Figure C.7 
C-67

Wedge

Figure C.8 
C-68

Signal

Figure C.9 
C-69

Phased Array Settings – Focal Law

Initialization

Figure C.10

Sequencing

The number and position of used elements was chosen to get good beam properties in the 

range of the expected flaw depth. The values are specified in the Cal and DAC Files of each 

specimen. The figure below shows an active aperture of 24 Elements (17 to 41).

Figure C.11

Transmission 

The sector range goes for all measurements from 40° to 70° (Step 1°) Longwaves. The focal 

depth was chosen to get good beam properties in the range of the expected flaw depth. The 

values are specified in the Cal and DAC Files of each specimen. The figure below shows an 

example of the calculated focal points at 13 mm depth. 
C-70

Figure C.12
C-71

UT Equipment Settings - M2M MultiX 64

For the measurements a M2M MultiX UT System was used. MultiX system is a fully parallel 

architecture with 64 channels. In the following chapters the essential equipment settings are 

listed.

General Settings

Figure C.13

Gates

Figure C.14

DAC

Figure C.15
C-72

Coders

Figure C.16

Trajectories

Figure C.17

Filters

Figure C.18
C-73

Units

Figure C.19

Calibration

The calibration of the measurement system were conducted direct before data acquisition. In 

the following sections the calibration process is described.

Probe Element Check (PEC)

• Load File: C:\Users\Multi2000\Desktop\PARENT_L40-70 Contact\02 Default Cal Files\ 

PEC_Sonaxis_64.m2K

• Perform PEC (configuration see figure below)

• Pass criterions: continuous slope - correct wiring, delta dB < 9dB

• Document PEC in Cal Sheet

Figure C.20
C-74

Wedge Calibration

• M2M > Parameters > Wedge Calibration

• Drag and Drop Bscan

• Set and adjust the gate on the wedge shoe echo

• Start wedge calibration

• Write values for Computed Angle and Computed Height on Cal Sheet

Define Inspection Configuration

• Load Cal File: Cal*_**Ele_FD**_**_Notch.m2k

• M2M > Configuration > Probe > Wedge > Insert correct values for Computed Angle and 

Computede Heigth (see Cal Sheet)

• Array settings > Input Patter > Safe

• Array settings > Transmission > Input Focal Depth, and compute Focal Laws

• Change to Parameters by clicking Apply

Probe Exit Point

• Choose shot in Sscan with angle nearest to 50°

• Find Ascan maximum at 100mm radius of ferritic K1, mark the position with green ink on 

wedge (see picture below), document Reference Sensitivity (FSH) and Probe Index Point on 

Cal Sheet
C-75

Figure C.21

Refracted Angle

• Measure Refracted Angle 50° on ferritic K1, document the value in Cal Sheet (see picture

below) 

Figure C.22
C-76

Depth Calibration

• Bring Cal Block KKM_24_18_12_6 (see figure below) 18mm notch tip to 80% screen height 

using the 50° angle, document

− gain/echo height

− path length (PL) and TWS (Depth)

− S/N

in Cal Sheet (in case of OD notch start with 6mm notch)

Figure C.23

• bring Cal Block KKM_24_18_12_6 12mm notch tip to maximum using the 50° angle, 

document echo height, path length/TWS and S/N in Cal Sheet

• bring Cal Block KKM_24_18_12_6 12mm notch tip to maximum using the 50° angle,

document echo height, path length/TWS and S/N in Cal Sheet

• Save the Cal file

• Save the measurement file

PARENT_OT_ENSI_L40-70_AAE_FDBB_C_PCC_D_+E.m2k

AA > Number of Elements

BB > Focal Depth

CC > Specimen Number
C-77

D > Scan surface according to figure coordinate system (W or X)

E > Beam Direction (+Y or -Y)

C.2.2.3 Data Acquisition

The figure below shows a picture of the measurement setup. A simple string encoder was used 

for encoded data acquisition.

Figure C.24

The figures below show the scan plan. Data were just taken along one 120 mm long scan line in 

the center of the specimen with 0.5mm step width (240 steps).
C-78

Figure C.25

The figure below shows the scan coordinate system and a example how it is defined in the data 

aquisition file name

PARENT_OT_ENSI_L40-70_24E_FD13_C_P28_W_+Y

Figure C.26

C.2.2.4 Data Analysis

Depth Sizing Technique

For flaw depth sizing the Absolut Arrival Time Technique (AATT) is used. The technique relies 

upon obtaining a direct signal response from the flaw tip using a material depth calibration. 
C-79

From the flaw tip response the amount of unflawed material or remaining ligament can be read 

directly from the Sscan. Flaw depth is calculated by subtracting the remaining ligament from the 

actual material thickness.

The figure below illustrates the technique. 

Figure C.27

UT Depth Sizing Images

The figure below shows a typical depth sizing print out used in the measurement report 

(2012_Par_OT_ENSI Spec_MeasReport_L40-70C_PE). The figure includes remarks for 

explanation of the UT images.
C-80

Figure C.28

C.2.2.5 Results Specimens P28, P29, P30, P31, P32, P42 and P46

Specimen Information and Coordinate System

PARENT Sp. Designation P28 P29 P30 P31 P32 P42 P46 P38

PSI Sp. Designation 6* 10* *7 *1 *5 *12 *13 *3

Type of Crack SCC SCC MF SCC SCC EDM SCC

* MN 220 AD U, MF... Mech. Fatigue, SSC ... Stress Corrosion Crack

merged (mean) view of all Sscans

Sscan used for depth sizing

Ascan used for depth sizing

flaw depth value

Flaw Tip 

Flaw Tip 

DAQ file name
C-81

Coordinate System P28, P29, P30, P31, P32, P42 and P46

Figure C.29

Coordinate System P38

Figure C.30
C-82

Flaw Depth Summary Table Specimen Scanning Surface Beam Direction

DAQFile NameNb. of Elem.Focal DepthFlaw Depth*

UT Analysis / Images Chap.

Cal Sheet No:.

P28

W +Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P28_W_+Y 24 13 13.2 3.1 1

W -Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P28_W_-Y 24 13 12.7 3.1 1

P29

W +Y PARENT_OT_ENSI_L40-70_24E_FD18_C_P29_W_+Y 24 18 10.7 3.2 6

W -Y PARENT_OT_ENSI_L40-70_24E_FD18_C_P29_W_-Y 24 18 8.9 3.2 6

P30

W +Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P30_W_+Y 24 13 16.6 3.3 1

W -Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P30_W_-Y 24 13 17.8 3.3 1

P31

W +Y PARENT_OT_ENSI_L40-70_32E_FD25_C_P31_W_+Y 32 25 2.7 3.4 3

W -Y PARENT_OT_ENSI_L40-70_32E_FD25_C_P31_W_-Y 32 25 2.8 3.4 3

X +Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P31_X_+Y 24 13 4.3 3.4 4

X +Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P31_X_-Y 24 13 4.6 3.4 4

P32

W +Y PARENT_OT_ENSI_L40-70_24E_FD18_C_P32_W_+Y 24 18 9.5 3.5 6

W -Y PARENT_OT_ENSI_L40-70_24E_FD18_C_P32_W_-Y 24 18 7.5 3.5 6

X +Y PARENT_OT_ENSI_L40-70_32E_FD20_C_P32_X_+Y 32 20 12.4 3.5 5

X -Y PARENT_OT_ENSI_L40-70_32E_FD20_C_P32_X_-Y 32 20 13.4 3.5 5

P42

W +Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P42_W_+Y 24 13 9.3 3.6 1

W -Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P42_W_-Y 24 13 9.7 3.6 1

P38

W +Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P38_W_+Y 24 13 6.6 3.7 1

W -Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P38_W_-Y 24 13 6.4 3.7 1

X +Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P38_X_+Y 24 13 5 3.7 4

X -Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P38_X_-Y 24 13 5.7 3.7 4

* bolt values are final flaw depth calls
C-83

UT Analysis Images

Specimen 28 Specimen Scanning Surface Beam

DirectionDAQFile NameNb. of Elem.Focal DepthFlaw Depth (mmm)EVal. Angle (°) S/N. (dB)

P28 W +Y PARENT_OT_ENSI_L40-70_24E_FD17_C_P28_W_+Y 24 13 13.2 44 7.5

Figure C.31 Specimen Scanning

SurfaceBeamDirectionDAQFile NameNb. of Elem.

Focal DepthFlaw Depth (mmm)EVal. Angle (°)S/N. (dB)
C-84

P28 W -Y PARENT_OT_ENSI_L40-70_24E_FD17_C_P28_W_-Y 24 13 12.7 59 10

Figure C.32

Specimen P29 Specimen Scanning Surface Beam

DirectionDAQFile NameNb. of Elem.Focal DepthFlaw Depth (mmm)EVal. Angle (°)S/N. (dB)

P29 W +Y PARENT_OT_ENSI_L40-70_24E_FD18_C_P29_W_+Y 24 18 10.7 57 9
C-85

Figure C.33 Specimen Scanning

SurfaceBeamDirectionDAQFile NameNb. of Elem.Focal DepthFlaw Depth (mmm)EVal. Angle (°)S/N. (dB)

P29 W -Y PARENT_OT_ENSI_L40-70_24E_FD18_C_P29_W_+Y 24 18 8.9 61 3
C-86

Figure C.34

Specimen P30 Specimen Scanning Surface Beam

DirectionDAQFile NameNb. of Elem.Focal DepthFlaw Depth (mmm)EVal. Angle (°)S/N. (dB)

P30 W +Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P30_W_+Y 24 13 16.6 50 10
C-87

Figure C.35 Specimen Scanning

SurfaceBeamDirectionDAQFile NameNb. of Elem.Focal DepthFlaw Depth (mmm)EVal. Angle(°)S/N. (dB)

P30 W -Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P30_W_-Y 24 13 17.8 59 8
C-88

Figure C.36

Specimen P31 Specimen Scanning Surface Beam

DirectionDAQFile NameNb. of Elem.Focal DepthFlaw Depth (mmm)EVal. Angle (°)S/N. (dB)

P31 W +Y PARENT_OT_ENSI_L40-70_32E_FD25_C_P31_W_+Y 32 25 2.7* 49 6

* no mode converted TLL - shallow crack, tip weak, bad SN, only RATT
C-89

Figure C.37 Specimen Scanning

SurfaceBeamDirectionDAQFile NameNb. of Elem.

Focal Depth

Flaw Depth (mmm)EVal. Angle (°)S/N. (dB)

P31 W +Y PARENT_OT_ENSI_L40-70_32E_FD25_C_P31_W_-Y 32 25 2.8* 45 3

* no mode converted TLL - shallow crack, tip weak, bad SN, only RATT
C-90

Figure C.38 Specimen Scanning

SurfaceBeamDirectionDAQFile NameNb. of Elem.

Focal Depth

Flaw Depth (mmm)EVal. Angle (°)S/N. (dB)

P31 W +Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P31_X_+Y 24 13 4.3 63 10

* Remark. Weld drawing not correct.
C-91

Figure C.39 Specimen Scanning

SurfaceBeamDirectionDAQFile NameNb. of Elem.

Focal Depth

Flaw Depth (mmm)EVal. Angle (°)S/N. (dB)

P31 W -Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P31_X_-Y 24 13 4.6 50 5

* Remark. Weld drawing not correct.
C-92

Figure C.40

Specimen P32 Specimen Scanning Surface Beam

DirectionDAQFile NameNb. of Elem.

Focal Depth

Flaw Depth (mmm)EVal. Angle (°)S/N. (dB)

P32 W +Y PARENT_OT_ENSI_L40-70_24E_FD18_C_P32_W_+Y 24 18 9.5 63 6
C-93

Figure C.41 Specimen Scanning

SurfaceBeamDirectionDAQFile NameNb. of Elem.Focal DepthFlaw Depth (mmm)EVal. Angle (°)S/N. (dB)

P32 W +Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P32_W_-Y 24 13 7.5 57 10
C-94

Figure C.42. Specimen Scanning Surface

BeamDirectionDAQFile NameNb. of Elem.Focal DepthFlaw Depth (mmm)EVal. Angle (°)S/N. (dB)

P31 X +Y PARENT_OT_ENSI_L40-70_32E_FD20_C_P32_X_+Y 32 20 12.4 61 13
C-95

Figure C.43. Specimen Scanning Surface

BeamDirectionDAQFile NameNb. of Elem.Focal DepthFlaw Depth (mmm)EVal. Angle (°)S/N. (dB)

P32 X -Y PARENT_OT_ENSI_L40-70_32E_FD20_C_P32_X_-Y 32 20 13.4 52 8
C-96

Figure C.44. 

Specimen P42 Specimen Scanning Surface Beam

DirectionDAQFile NameNb. of Elem.Focal DepthFlaw Depth (mmm)EVal. Angle (°)S/N. (dB)

P42 W +Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P42_W_+Y 24 13 9.3 46 11
C-97

Figure C.45. Specimen Scanning Surface

BeamDirectionDAQFile NameNb. of Elem.Focal DepthFlaw Depth (mmm)EVal. Angle (°)S/N. (dB)

P31 W -Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P42_W_-Y 24 13 9.7 48 8
C-98

Figure C.46. 

Specimen P38 Specimen Scanning Surface Beam

DirectionDAQFile NameNb. of Elem.Focal DepthFlaw Depth (mmm)EVal. Angle (°)S/N. (dB)

P38 W +Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P38_W_+Y 24 13 6.6 59 4

*weak mode converted TLL - shallow crack, tip very weak, bad SN
C-99

Figure C.47. Specimen Scanning Surface

BeamDirectionDAQFile NameNb. of Elem.Focal DepthFlaw Depth (mmm)EVal. Angle (°)S/N. (dB)

P38 W -Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P38_W_-Y 24 13 6.4 59 5.3

*weak mode converted TLL - shallow crack, tip very weak, bad SN
C-100

Figure C.48. Specimen Scanning Surface

BeamDirectionDAQFile NameNb. of Elem.Focal DepthFlaw Depth (mmm)EVal. Angle (°)S/N. (dB)

P38 X +Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P38_X_+Y 24 13 5 50 11
C-101

Figure C.49. Specimen Scanning Surface

BeamDirectionDAQFile NameNb. of Elem.Focal DepthFlaw Depth (mmm)EVal. Angle (°)S/N. (dB)

P38 X -Y PARENT_OT_ENSI_L40-70_24E_FD13_C_P38_X_-Y 24 13 5.7 51 7
C-102

Figure C.50. 

C.2.2.6 Self Assessment

• Good TWS of EDM notch and mechanical fatigue crack, clear tip diffraction echo’s from all 

examination directions visible

• TWS of stress corrosion cracks challenging, tip diffraction echo’s not seen from all 

examination directions (Remark: TWS of specimen SCC under field conditions (surface 

conditions, access) very hard and sometimes not possible)
C-103

C.2.3 Phased Ultrasonic Array, Technique ID 131-PA1

C.2.3.1 Overview

The techniques described in this report were utilized for the examination of the PARENT 

specimens P1 and P41.

Method Phased Array Ultrasonic Testing

Array / Technique Dual / Linear / Transmit - Receive

Wave Mode Longitudinal 

Angle Range 25° – 65°

Frequency 2 MHz

UT Instrument M2M MultiX 64

Scan Plan Manual scanning parallel and perpendicular to weld from both directions

Scanning Surface OD

Figure C.51. 
C-104

C.2.3.2 NDE Equipment / UT Settings

Search Unit

For the measurement a GEIT probe and wedge was used. The essential variable of the search 

unit are described in the next chapters.

Crystal Shape

Figure C.52
C-105

Focusing

Figure C.53
C-106

Wedge for Axial Scanning (Circ Flaws)

Wedge material: Rexolite cl=2237 m/s

Figure C.54
C-107

Wedge for Circumferential Scanning (Axial Flaws)

Figure C.55
C-108

Signal

Figure C.56
C-109

Phased Array Settings – Focal Laws

Initialization

Figure C.57

Sequencing

Transmission Element 1 (lower wedge end) to Element 14

Figure C.58
C-110

Receiving Element 1 (lower wedge end) to Element 14

Figure C.59

Transmission 

The focusing type is sectorial scanning. The sector range goes from 25° to 65° (Step 1°) 

longitudinal waves. 

Figure C.60
C-111

Figure C.61

UT Eqipment Settings - M2M MultiX 64

For the measurements a M2M MultiX UT System was used. MultiX system is a fully parallel 

architecture with 64 channels. In the following chapters the essential equipment settings are 

listed.
C-112

General Settings

Figure C.62

Gates

Figure C.63

DAC

Figure C.64
C-113

Coders

Figure C.65

Trajectories

Figure C.66

Units

Figure C.67
C-114

C.2.3.3 Data Acquisition (Scan Plan for Manual Examination)

Scanning for Circumferential Flaws

• Beam shall be directed essentially perpendicular to the weld axis from both directions

Figure C.68

Scanning for Axial Flaws

• Beam shall be directed essentially parallel to the weld in two opposing directions

Figure C.69
C-115

C.2.3.4 Analysis

Detection

The detection of surface breaking ID flaws relies upon the corner response being observed.

Characterization

The characterization is based on the identification of flaw like indications which cannot be 

attributed to the component geometry based on the supplied as built drawings, manufacturing 

defects (reported during previous inspections) or indications due to reflection’s or scattering on 

the anisotropic und heterogeneous weld structure.

Flaw discrimination criterions: 

• Good signal to noise ratio (variations along the length)

• Plots to susceptible crack location

• Substantial echo dynamic travel

• Areas of unique amplitude

• Inconsistent time base positions

• Tip signals

• Conformation from the opposite direction

• Seen with many angles

• Mode converted shear signal (only circ flaws with substantial depth)

• Non relevant indications criterions:

• Near WCL or weld geometry

• Seen continuously

• Consistent time & amplitude

• Weak echo dynamic travel

Length Sizing

• Length of a flaw is determined by moving the probe along the flaw.

• on the same side of the weld as the indication
C-116

• optimize the signal from the flaw indication

• adjust the system gain until the response is ~ 80 % FSH

• scan along the length of the flaw in each direction until the signal response has been 

reduced to:

− background noise for far side indication

− 20% FSH (12 dB drop) for near side indication

• The length on outside diameter is longer than the actual inside diameter length. Calculate 

correct ID flaw length according to: (ID/OD) x OD flaw length = ID flaw length.

Depth Sizing

For flaw depth sizing the Absolut Arrival Time Technique (AATT) is used. The technique relies 

upon obtaining a direct signal response from the flaw tip using a material depth calibration. 

From the flaw tip response the amount of unflawed material or remaining ligament can be read 

directly from the Sscan. Flaw depth is calculated by subtracting the remaining ligament from the 

actual material thickness. 

The figure below illustrates the technique. 
C-117

Figure C.70

Defect Positioning

Due to uncertainties associated with sound propagation in anisotropic, heterogeneous austenitic 

weld material indication positioning require detailed evaluation. The information provided below

may assist indication positioning. 
C-118

• Perform thickness and surface contour recordings at the indication position. 

• Evaluate the flaw signal amplitude responses from each side of the weld. Observe if the 

signal response appears reduced due to weld volume sound attenuation from one side or 

another. 

• Identify standard benchmark responses (weld root, weld noise, acoustic interfaces) and flaw 

indication responses.

• Coordinate and plot the information on a cross sectional drawing of the weld.

C.2.3.5 Self Assessment

The manual Phased Array Technique using a dual linear search unit and longitudinal waves in 

the range from 25° to 65° demonstrated good detection, length sizing and TWS performance of 

ID flaws with depth greater than 10% of the wall thickness. 

C.2.4 Phased Ultrasonic Array, Technique ID 131-PA2

C.2.4.1 Overview

The techniques described in this report were utilized for the examination of the PARENT 

specimens P4. In case of P4 different techniques were used for examination in +Y and –Y 

direction.

Figure C.71
C-119

Scanning for Circumferential Flaws in +Y Direction

Method Phased Array Ultrasonic Testing

Array / Technique Dual / Linear / Transmit - Receive

Wave Mode Longitudinal 

Angle Range 25° – 65°

Frequency 2 MHz

UT Instrument M2M MultiX 64

Scan Plan Manual scanning perpendicular to weld in +Y direction

Scanning Surface OD

Scanning for Circumferential Flaws in -Y Direction

Method Phased Array Ultrasonic Testing

Array / Technique Single / Linear / Puls Echo

Wave Mode Longitudinal

Angle Range 40° – 75°

Frequency 2.33 MHz

UT Instrument M2M MultiX 64

Scan Plan Manual scanning perpendicular to weld in -Y direction

Scanning Surface OD

C.2.4.2 NDE Equipment / UT Settings / +Y Technique

Search Unit

For the measurement a GEIT probe and wedge was used. The essential variable of the search

unit are described in the next chapters.
C-120

Crystal Shape

Figure C.72

Focusing

Figure C.73
C-121

Wedge for Axial Scanning (Circ Flaws)

Wedge material: Rexolite cl=2237 m/s

Figure C.74
C-122

Signal

Figure C.75
C-123

Phased Array Settings – Focal Laws

Initialization

Figure C.76

Sequencing

Transmission Element 1 (lower wedge end) to Element 14

Figure C.77
C-124

Receiving Element 1 (lower wedge end) to Element 14

Figure C.78

Transmission 

The focusing type is sectorial scanning. The sector range goes from 25° to 65° (Step 1°) 

longitudinal waves. 

Figure C.79
C-125

Figure C.80

UT Equipment Settings – M2M MultiX 64

For the measurements a M2M MultiX UT System was used. MultiX system is a fully parallel 

architecture with 64 channels. In the following chapters the essential equipment settings are 

listed.
C-126

General Settings

Figure C.81

Gates

Figure C.82

DAC

Figure C.83
C-127

Coders

Figure C.84

Trajectories

Figure C.85

Units

Figure C.86

C.2.4.3 NDE Equipment / UT Settings / -Y Technique

Search Unit

For the measurement a Sonaxis probe and wedge was used. The essential variable of the 

search unit are described in the next chapters.
C-128

Crystal Shape

Figure C.87

Focusing

Figure C.88
C-129

Wedge for Axial Scanning (Circ Flaws)

Figure C.89 Wedge Material: Rexolite cl=2237 m/s
C-130

Signal

Figure C.90
C-131

Phased Array Settings – Focal Laws

Initialization

Figure C.91

Sequencing

Figure C.92

Transmission 

The focusing type is sectorial scanning with constant focal depth at 35mm. The sector range 

goes from 45° to 75° (Step 1°) longitudinal waves. 
C-132

Figure C.93

Sound Field Simulations for 65° Angle

Figure C.94 65° Beam, Black Line: ID Position ≈ 38 mm
C-133

UT Equipment Settings - M2M MultiX 64

For the measurements a M2M MultiX UT System was used. MultiX system is a fully parallel 

architecture with 64 channels. In the following chapters the essential equipment settings are 

listed.

General Settings

Figure C.95

Gates

Figure C.96

DAC

Figure C.97
C-134

Coders

Figure C.98

Trajectories

Figure C.99

Filters

Figure C.100
C-135

Units

Figure C.101

C.2.4.4 Data Acquisition (Scan Plan for Manual Examination)

Scanning for Circumferential Flaws

• Beam shall be directed essentially perpendicular to the weld axis from both directions.

C.2.4.5 Analysis

Detection

The detection of surface breaking ID flaws relies upon the corner response being observed.

Characterization

The characterization is based on the identification of flaw like indications which cannot be 

attributed to the component geometry based on the supplied as built drawings, manufacturing 

defects (reported during previous inspections) or indications due to reflection’s or scattering on 

the anisotropic und heterogeneous weld structure.

Flaw discrimination criterions: 

• Good signal to noise ratio (variations along the length)

• Plots to susceptible crack location

• Substantial echo dynamic travel

• Areas of unique amplitude

• Inconsistent time base positions

• Tip signals

• Conformation from the opposite direction

• Seen with many angles
C-136

• Mode converted shear signal (only circ flaws with substantial depth)

Non relevant indications criterions:

• Near WCL or weld geometry

• Seen continuously

• Consistent time & amplitude

• Weak echo dynamic travel

Length Sizing

• Length of a flaw is determined by moving the probe along the flaw.

• on the same side of the weld as the indication

• optimize the signal from the flaw indication

• adjust the system gain until the response is ~ 80 % FSH

• scan along the length of the flaw in each direction until the signal response has been 

reduced to:

− background noise for far side indication

− 20% FSH (12 dB drop) for near side indication

• The length on outside diameter is longer than the actual inside diameter length. Calculate 

correct ID flaw length according to: (ID/OD) x OD flaw length = ID flaw length.

Depth Sizing

For flaw depth sizing the Absolut Arrival Time Technique (AATT) is used. The technique relies 

upon obtaining a direct signal response from the flaw tip using a material depth calibration. 

From the flaw tip response the amount of unflawed material or remaining ligament can be read 

directly from the Sscan. Flaw depth is calculated by subtracting the remaining ligament from the 

actual material thickness. 

The figure below illustrates the technique. 
C-137

Figure C.102
C-138

Defect Positioning

Due to uncertainties associated with sound propagation in anisotropic, heterogeneous austenitic 

weld material indication positioning require detailed evaluation. The information provided below

may assist indication positioning. 

• Perform thickness and surface contour recordings at the indication position. 

• Evaluate the flaw signal amplitude responses from each side of the weld. Observe if the 

signal response appears reduced due to weld volume sound attenuation from one side or 

another. 

• Identify standard benchmark responses (weld root, weld noise, acoustic interfaces) and flaw 

indication responses.

• Coordinate and plot the information on a cross sectional drawing of the weld.

C.2.4.6 Self Assessment

Scanning for Circumferential Flaws in +Y Direction

The manual Phased Array Technique using a dual linear search unit and longitudinal waves in 

the range from 25° to 65° demonstrated good detection, length sizing and TWS performance of 

ID flaws with depth greater than 10% of the wall thickness.

Scanning for Circumferential Flaws in -Y Direction

Using the +Y direction technique the detection, length sizing and TWS of two flaws in P4 was 

challenging. Therefore a different search unit was for the –Y direction examinations. The 

performance of this search unit was better but TWS was still very challenging. It has to be 

mentioned, that the used linear array probe is due to its size (large footprint) not suitable for field 

inspections.

C.2.5 Phased Ultrasonic Array, Technique ID 131-PA3

C.2.5.1 Overview

The techniques described in this report were utilized for the examination of the PARENT 

specimen P41.

Method Phased Array Ultrasonic Testing

Array / Technique Dual / Matrix / Transmit - Receive

Wave Mode Longitudinal 

Angle Range 40° – 70°

Frequency 1.5 MHz

UT Instrument Phasor XS

Scan Plan Manual scanning perpendicular to weld both directions

Scanning Surface OD
C-139

Figure C.103

C.2.6 NDE Equipment / UT Settings

UT Instrument

For the measurements a GEIT Phasor XS was used. 

Search Unit

For the measurement a GEIT probe and wedge was used. The essential variable of the search 

unit are described in the next chapters. 
C-140

Figure C.104
C-141

Crystal Shape

Figure C.105
C-142

Focusing

Figure C.106
C-143

Wedge for Axial Scanning (Circ Flaws)

Wedge material: Rexolite cl=2237 m/s

Figure C.107
C-144

Wedge for Circumferential Scanning (Axial Flaws)

Figure C.108
C-145

Signal

Figure C.109
C-146

Phased Array Settings – Focal Laws

Initialization

Figure C.110

Sequencing

Figure C.111
C-147

Transmission 

The focusing type is sectorial scanning at a constant focal depth of 25.4 mm. The sector range 

goes from 40° to 70° (Step 1°) longitudinal waves. 

Figure C.112

C.2.6.1 Data Acquisition (Scan Plan for Manual Examination)

Scanning for Circumferential Flaws

• Beam shall be directed essentially perpendicular to the weld axis from both directions

Scanning for Axial Flaws

• Beam shall be directed essentially parallel to the weld in two opposing directions 
C-148

C.2.6.2 Analysis

Detection

The detection of surface breaking ID flaws relies upon the corner response being observed.

Characterization

The characterization is based on the identification of flaw like indications which cannot be 

attributed to the component geometry based on the supplied as built drawings, manufacturing 

defects (reported during previous inspections) or indications due to reflection’s or scattering on 

the anisotropic und heterogeneous weld structure.

Flaw discrimination criterions: 

• Good signal to noise ratio (variations along the length)

• Plots to susceptible crack location

• Substantial echo dynamic travel

• Areas of unique amplitude

• Inconsistent time base positions

• Tip signals

• Conformation from the opposite direction

• Seen with many angles

• Mode converted shear signal (only circ flaws with substantial depth)

Non relevant indications criterions:

• Near WCL or weld geometry

• Seen continuously

• Consistent time & amplitude

• Weak echo dynamic travel

Length Sizing

• Length of a flaw is determined by moving the probe along the flaw.

• on the same side of the weld as the indication
C-149

• optimize the signal from the flaw indication

• adjust the system gain until the response is ~ 80 % FSH

• scan along the length of the flaw in each direction until the signal response has been 

reduced to:

− background noise for far side indication

− 20% FSH (12 dB drop) for near side indication

• The length on outside diameter is longer than the actual inside diameter length. Calculate 

correct ID flaw length according to: (ID/OD) x OD flaw length = ID flaw length

Depth Sizing

For flaw depth sizing the Absolut Arrival Time Technique (AATT) is used. The technique relies 

upon obtaining a direct signal response from the flaw tip using a material depth calibration. 

From the flaw tip response the amount of unflawed material or remaining ligament can be read 

directly from the Sscan. Flaw depth is calculated by subtracting the remaining ligament from the 

actual material thickness. 

The figure below illustrates the technique. 
C-150

Figure C.113

Defect Positioning

Due to uncertainties associated with sound propagation in anisotropic, heterogeneous austenitic 

weld material indication positioning require detailed evaluation. The information provided below

may assist indication positioning. 

• Perform thickness and surface contour recordings at the indication position. 

• Evaluate the flaw signal amplitude responses from each side of the weld. Observe if the 

signal response appears reduced due to weld volume sound attenuation from one side or 

another. 

• Identify standard benchmark responses (weld root, weld noise, acoustic interfaces) and flaw 

indication responses.
C-151

• Coordinate and plot the information on a cross sectional drawing of the weld.

C.2.6.3 Results PARENT Specimen P41

Specimen Information and Coordinate System

Geometry

Figure C.114
C-152

Flaw Information

Figure C.115
C-153

Coordinate System

The figure shows the PARENT Coordinate System. The X direction is opposite to the SQC 

drawing coordinate system. To allow direct comparison of the SQC drawing flaw positions to the 

measurements in this report the X direction were therefore defined in the opposite direction (see 

figure).

Figure C.116
C-154

Corrected Flaw Positions (PARENT coordinate system) 

Figure C.117
C-155

Flaw Indication Summary Tables

Circumferential Flaws

Probe Position: Carbon Steel Side / Beam Direction: +Y

Figure C.118 Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X Position OD Flaw 

Depth

Flaw

Y 

Pos.

Flaw X Position OD Flaw 

Depth

Flaw

Y 

Pos. Start Length End Start Length End

mm mm mm mm mm mm mm mm

1 0.0 12.9 12.9 2 CS*

B** 895 15 8 3.2 -Y 1) 4.1 1 

2 69.9 7.7 77.6 3 CS*

B** 72 85 13 3.2 -Y 2) 4.2 1 

5 252.1 64.4 316.5 26 CS*

B** 250 72 322 26.1 -Y 3) 4.3 2 

7 431.8 25.8 457.5 6 CS*

B** 432 33 465 5.55 -Y 4) 4.4 3 

9 574.0 64.4 638.5 17 CS*

B** 578 67 645 14.7 -Y 5) 4.5 4 

12 811.1 25.8 836.9 6 CS*

B** 813 32 845 5.55 -Y 6) 4.6 3 

*Flaw on Carbon Steel (CS) / Buttering (B) Side in respect to weld center line

See next page for Remarks!
C-156

Remarks:

1) No separation of tip diffraction from corner trap echo, no TLL echo indicates shallow flaw, 

flaw depth estimation procedure: if no separation of tip diffraction from corner trap and flaw 

seems to be shallow the flaw depth is defined per default to 10% pipe thickness at flaw 

position → 3.2 mm

2) No separation of tip diffraction from corner trap echo, no TLL echo indicates shallow flaw, 

flaw depth estimation procedure: if no separation of tip diffraction from corner trap and flaw 

seems to be shallow the flaw depth is defined per default to 10% pipe thickness at flaw 

position → 3.2 mm

3) For quantitative flaw depth sizing calibration at 24 mm deep notch of calibration block 

KKM_24_18_12_6 (RL = 6 mm)

4) For quantitative flaw depth sizing calibration at 6 mm deep notch of calibration block 

KKM_24_18_12_6 (RL = 24 mm)

5) For quantitative flaw depth sizing calibration at 12 mm deep notch of calibration block 

KKM_24_18_12_6 (RL = 18 mm)

6) For quantitative flaw depth sizing calibration at 6 mm deep notch of calibration block 

KKM_24_18_12_6 (RL = 24 mm)

Probe Position: Stainless Steel Side / Beam Direction: -Y 

Figure C.119
C-157

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X Position OD 

Flaw 

Depth

Flaw

Y 

Pos.

Flaw X Position OD

Flaw 

Depth

Flaw

Y 

Pos. Start Length End Start Length End

mm mm mm mm mm mm mm mm

1 0.0 12.9 12.9 2 CS*

B** no detection from fare side -Y - - 1 

2 69.9 7.7 77.6 3 CS*

B** no detection from fare side -Y - - 1 

5 252.1 64.4 316.5 26 CS*

B** 252 60 312 25.89 -Y 1) 4.7 2 

7 431.8 25.8 457.5 6 CS*

B** 432 29 461 7.78 -Y 2) 4.8 3 

9 574.0 64.4 638.5 17 CS*

B** 578 67 645 14.7 -Y 3) 4.9 4 

12 811.1 25.8 836.9 6 CS*

B** 817 25 842 3.2 -Y 4) 4.10 1 

*Flaw on Carbon Steel (CS) / Buttering (B) Side in respect to weld center line

See below for remarks!

1) For quantitative flaw depth sizing calibration at 24 mm deep notch of calibration block 

KKM_24_18_12_6 (RL = 6 mm)

2) Very hard to find the tip for depth sizing, only possible if inspector knows in witch depth 

region he has to look for tips; flaw depth estimation procedure: if flaw is seen with high 

angles of the S-scan and there is a quiet strong TLL reflection it indicates that flaw has at 

least some true wall extension (20-40%); delta to as built depth may result from beam 

redirection in heterogeneous anisotropic weld material

3) For quantitative flaw depth sizing calibration at 12 mm deep notch of calibration block 

KKM_24_18_12_6 (RL = 18 mm), delta to as built depth may result from beam redirection in 

heterogeneous anisotropic weld material

4) No separation of tip diffraction from corner trap echo, no TLL echo indicates shallow flaw, 

flaw depth estimation procedure: if no separation of tip diffraction from corner trap and flaw 

seems to be shallow the flaw depth is defined per default to 10% pipe thickness at flaw 

position → 3.2 mm
C-158

Axial Flaws

Scan Direction: + X

Figure C.120 Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

mm mm mm mm mm mm

3 135 10 2 CS*

B** 135 ≈ 10 3.2 -Y 1) 4.11 6 

4 193 6 3 CS*

B** 195 ≈ 6 3.2 -Y 2) 4.12 6 

6 374 20 26 CS*

B** 370 ≈ 30 26 -Y 3) 4.13 7 

8 515 20 6 CS*

B** 515 ≈ 25 6.07 -Y 4) 4.14 8 

10 696 20 17 CS*

B** 698 20 16.74 -Y 5) 4.15 9 

11 754 20 6 CS*

B** 750 20 6.67 -Y 6) 4.16 8 

*Flaw on Carbon Steel (CS) / Buttering (B) Side in respect to weld center line

See next page for remarks!
C-159

Remarks

1) Very hard to detect with manual inspection; length sizing hard lots of noise from buttering; 

no separation of tip diffraction from corner trap echo, no TLL echo indicates shallow flaw, 

flaw depth estimation procedure: if no separation of tip diffraction from corner trap and flaw 

seems to be shallow the flaw depth is defined per default to 10% pipe thickness at flaw 

position → 3.2 mm

2) Hard to detect with manual inspection; length sizing hard lots of noise from buttering; no 

separation of tip diffraction from corner trap echo, no TLL echo indicates shallow flaw, flaw 

depth estimation procedure: if no separation of tip diffraction from corner trap and flaw 

seems to be shallow the flaw depth is defined per default to 10% pipe thickness at flaw 

position → 3.2 mm

3) Length sizing hard lots of noise from buttering; for quantitative flaw depth sizing calibration 

with 9 mm deep SDH (Ø 1,5 mm) of calibration block “SVTI AS_D270_T30”

4) Length sizing hard lots of noise from buttering; depth sizing only possible when probe is 

skewed (flaw skew angle 10°); for quantitative flaw depth sizing calibration with 26 mm deep 

SDH (Ø 1,5 mm) of calibration block “SVTI AS_D270_T30”

5) Quantitative flaw depth sizing calibration with 15 mm deep SDH (Ø 1,5 mm) of calibration 

block “SVTI AS_D270_T30”

6) Flaw depth sizing hard, very week tip signal; quantitative flaw depth sizing calibration with 

26 mm deep SDH (Ø 1,5 mm) of calibration block “SVTI AS_D270_T30”

Scan Direction: - X 

Figure C.121
C-160

Flaw No.: 

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

mm mm mm mm mm mm

3 135 10 2 CS*

B** 135 ≈ 10 3.2 -Y 1) 4.17 6 

4 193 6 3 CS*

B** 195 ≈ 6 3.2 -Y 2) 4.18 6 

6 374 20 26 CS*

B** 370 ≈ 20 26.48 -Y 3) 4.19 7 

8 515 20 6 CS*

B** 515 ≈ 25 6.81 -Y 4) 4.20 8 

10 696 20 17 CS*

B** 698 ≈ 25 16.74 -Y 5) 4.21 9 

11 754 20 6 CS*

B** 750 20 6.37 -Y 6) 4.22 8 

*Flaw on Carbon Steel (CS) / Buttering (B) Side in respect to weld center line

See below for remarks!

1) Very hard to detect with manual inspection; length sizing hard lots of noise from buttering; 

no separation of tip diffraction from corner trap echo, no TLL echo indicates shallow flaw, 

flaw depth estimation procedure: if no separation of tip diffraction from corner trap and flaw 

seems to be shallow the flaw depth is defined per default to 10% pipe thickness at flaw 

position → 3.2 mm

2) Hard to detect with manual inspection; length sizing hard lots of noise from buttering; no 

separation of tip diffraction from corner trap echo, no TLL echo indicates shallow flaw, flaw 

depth estimation procedure: if no separation of tip diffraction from corner trap and flaw 

seems to be shallow the flaw depth is defined per default to 10% pipe thickness at flaw 

position → 3.2 mm

3) Length sizing hard lots of noise from buttering; for quantitative flaw depth sizing calibration 

with 9 mm deep SDH (Ø 1,5 mm) of calibration block “SVTI AS_D270_T30”

4) Length sizing hard lots of noise from buttering; depth sizing hard only possible when probe 

is skewed (flaw skew angle 10°); for quantitative flaw depth sizing calibration with 26 mm 

deep SDH (Ø 1,5 mm) of calibration block “SVTI AS_D270_T30”

5) Quantitative flaw depth sizing calibration with 15 mm deep SDH (Ø 1,5 mm) of calibration 

block “SVTI AS_D270_T30”

6) Flaw depth sizing good, good tip signal; quantitative flaw depth sizing calibration with 26 mm 

deep SDH (Ø 1,5 mm) of calibration block “SVTI AS_D270_T30”
C-161

UT Analysis Images

Flaw 1 / Probe Position: Carbon Steel Side / Beam Direction: -Y 

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X Position OD 

Flaw 

Depth

Flaw

Y 

Pos.

Flaw X Position OD

Flaw 

Depth

Flaw

Y 

Pos. Start Length End Start Length End

mm mm mm mm mm mm mm mm

1 0.0 12.9 12.9 2 CS*

B** 895 15 8 3.2 -Y 1) 3.1 1 

No separation of tip diffraction from corner trap echo, no TLL echo indicates shallow flaw, 

flaw depth estimation procedure: if no separation of tip diffraction from corner trap and flaw 

seems to be shallow the flaw depth is defined per default to 10% pipe thickness at flaw 

position → 3.2 mm

Remarks: File name in picture not correct (coordinate system problem), file name has been 

renamed correctly during analysis

Figure C.122
C-162

Flaw 2 / Probe Position: Carbon Steel Side / Beam Direction: -Y 

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X Position OD 

Flaw 

Depth

Flaw

Y 

Pos.

Flaw X Position OD

Flaw 

Depth

Flaw

Y 

Pos.

Start Length End Start Length End

mm mm mm mm mm mm mm mm

2 69.9 7.7 77.6 3 CS*

B** 72 85 13 3.2 -Y 2) 1 

Hard to detect; no separation of tip diffraction from corner trap echo; no TLL echo indicates 

shallow flaw; flaw depth estimation procedure: if no separation of tip diffraction from corner 

trap and flaw seems to be shallow the flaw depth is defined per default to 10% pipe 

thickness at flaw position → 3.2 mm

Remarks: File name in picture not correct (coordinate system problem), file name has been 

renamed correctly during analysis

Figure C.123
C-163

Flaw 5 / Probe Position: Carbon Steel Side / Beam Direction: -Y 

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X Position OD Flaw 

Depth Flaw

Y 

Pos.

Flaw X Position OD Flaw 

Depth Flaw

Y 

Pos.

Start Length End Start Length End

mm mm mm mm mm mm mm mm

5 252.1 64.4 316.5 26 CS*

B** 250 72 322 26.11 -Y 3) 2 

For quantitative flaw depth sizing calibration at 24 mm deep notch of calibration block 

KKM_24_18_12_6 (RL = 6 mm)

Remarks: File name in picture not correct (coordinate system problem), file name has been 

renamed correctly during analysis

Figure C.124
C-164

Flaw 7 / Probe Position: Carbon Steel Side / Beam Direction: -Y 

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X Position OD 

Flaw 

Depth Flaw

Y 

Pos.

Flaw X Position OD

Flaw 

Depth Flaw

Y 

Pos.

Start Length End Start Length End

mm mm mm mm mm mm mm mm

7 431.8 25.8 457.5 6 CS*

B** 432 33 465 5.55 -Y 4) 3 

For quantitative flaw depth sizing calibration at 6 mm deep notch of calibration block 

KKM_24_18_12_6 (RL = 24 mm)

Figure C.125
C-165

Flaw 9 / Probe Position: Carbon Steel Side / Beam Direction: -Y 

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X Position OD 

Flaw 

Depth Flaw

Y 

Pos.

Flaw X Position OD

Flaw 

Depth Flaw

Y 

Pos.

Start Length End Start Length End

mm mm mm mm mm mm mm mm

9 574.0 64.4 638.5 17 CS*

B** 578 67 645 14.7 -Y 5) 4 

For quantitative flaw depth sizing calibration at 12 mm deep notch of calibration block 

KKM_24_18_12_6 (RL = 18 mm)

Remarks: File name in picture not correct (coordinate system problem), file name has been 

renamed correctly during analysis

Figure C.126
C-166

Flaw 12 / Probe Position: Carbon Steel Side / Beam Direction: -Y 

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X Position OD 

Flaw 

Depth

Flaw

Y 

Pos.

Flaw X Position OD

Flaw 

Depth

Flaw

Y 

Pos.

Start Length End Start Length End

mm mm mm mm mm mm mm mm

12 811.1 25.8 836.9 6 CS*

B** 813 32 845 5.55 -Y 6) 3 

For quantitative flaw depth sizing calibration at 6 mm deep notch of calibration block 

KKM_24_18_12_6 (RL = 24 mm)

Remarks: File name in picture not correct (coordinate system problem), file name has been 

renamed correctly during analysis

Figure C.127
C-167

Flaw 5 / Probe Position: Stainless Side / Beam Direction: +Y

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X Position OD 

Flaw 

Depth Flaw

Y 

Pos.

Flaw X Position OD

Flaw 

Depth Flaw

Y 

Pos.

Start Length End Start Length End

mm mm mm mm mm mm mm mm

5 252.1 64.4 316.5 26 CS*

B** 252 60 312 25.89 -Y 1) 4.7 2 

For quantitative flaw depth sizing calibration at 24 mm deep notch of calibration block 

KKM_24_18_12_6 (RL = 6 mm)

Remarks: File name in picture not correct (coordinate system problem), file name has been 

renamed correctly during analysis

Figure C.128
C-168

Flaw 7 / Probe Position: Stainless Side / Beam Direction: +Y

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X Position OD 

Flaw 

Depth

Flaw

Y 

Pos.

Flaw X Position OD

Flaw 

Depth

Flaw

Y 

Pos.

Start Length End Start Length End

mm mm mm mm mm mm mm mm

7 431.8 25.8 457.5 6 CS*

B** 432 29 461 7.78 -Y 2) 4.8 3 

Very hard to find the tip for depth sizing, only possible if inspector knows in witch depth 

region he has to look for tips; flaw depth estimation procedure: if flaw is seen with high

angles in the S-scan and there is a quiet strong TLL reflection it indicates that flaw has at 

least some true wall extension (20-40%); delta to as built depth may result from beam 

redirection in heterogeneous anisotropic weld material.

Figure C.129
C-169

Flaw 9 / Probe Position: Stainless Side / Beam Direction: +Y

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X Position OD Flaw 

Depth Flaw

Y 

Pos.

Flaw X Position OD Flaw 

Depth Flaw

Y 

Pos.

Start Length End Start Length End

mm mm mm mm mm mm mm mm

9 574.0 64.4 638.5 17 CS*

B** 578 67 645 14.7 -Y 3) 4.9 4 

For quantitative flaw depth sizing calibration at 12 mm deep notch of calibration block 

KKM_24_18_12_6 (RL = 18 mm), delta to as built depth may result from beam redirection in 

heterogeneous anisotropic weld material

Remarks: File name in picture not correct (coordinate system problem), file name has been 

renamed correctly during analysis

Figure C.130
C-170

Flaw 12 / Probe Position: Stainless Side / Beam Direction: +Y

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X Position OD Flaw 

Depth

Flaw

Y 

Pos.

Flaw X Position OD Flaw 

Depth

Flaw

Y 

Pos.

Start Length End Start Length End

mm mm mm mm mm mm mm mm

12 811.1 25.8 836.9 6 CS*

B** 817 25 842 3.2 -Y 4) 4.10 3 

No separation of tip diffraction from corner trap echo, no TLL echo indicates shallow flaw, 

flaw depth estimation procedure: if no separation of tip diffraction from corner trap and flaw 

seems to be shallow the flaw depth is defined per default to 10% pipe thickness at flaw 

position → 3.2 mm

Remarks: File name in picture not correct (coordinate system problem), file name has been 

renamed correctly during analysis

Figure C.131
C-171

Flaw 3 / Scan Direction: + X Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

mm mm mm mm mm mm

3 135 10 2 CS*

B** 135 ≈ 10 3.2 -Y 1) 4.9

Very hard to detect with manual inspection; length sizing hard lots of noise from buttering; 

no separation of tip diffraction from corner trap echo, no TLL echo indicates shallow flaw, 

flaw depth estimation procedure: if no separation of tip diffraction from corner trap and flaw 

seems to be shallow the flaw depth is defined per default to 10% pipe thickness at flaw 

position → 3.2 mm.

Figure C.132
C-172

Flaw 4 / Scan Direction: + X

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

mm mm mm mm mm mm

4 193 6 3 CS*

B** 195 ≈ 6 -Y 2)

Hard to detect with manual inspection; length sizing hard lots of noise from buttering; no 

separation of tip diffraction from corner trap echo, no TLL echo indicates shallow flaw, flaw 

depth estimation procedure: if no separation of tip diffraction from corner trap and flaw 

seems to be shallow the flaw depth is defined per default to 10% pipe thickness at flaw 

position → 3.2 mm.

Figure C.133
C-173

Flaw 6 / Scan Direction: + X

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

mm mm mm mm mm mm

6 374 20 26 CS*

B** 370 ≈ 30 26.02 -Y 3) 4.13 4 

Length sizing hard lots of noise from buttering; for quantitative flaw depth sizing calibration 

with 9 mm deep SDH (Ø 1,5 mm) of calibration block “SVTI AS_D270_T30”

Figure C.134
C-174

Flaw 8 / Scan Direction: + X

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

mm mm mm mm mm mm 

8 515 20 6 CS*

B** 515 ≈ 25 6.07 -Y 4) 4.14 5 

Length sizing hard lots of noise from buttering; depth sizing only possible when probe is 

skewed (flaw skew angle 10°); for quantitative flaw depth sizing calibration with 26 mm deep 

SDH (Ø 1,5 mm) of calibration block “SVTI AS_D270_T30”

Figure C.135
C-175

Flaw 10 / Scan Direction: + X

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

mm mm mm mm mm mm

10 696 20 17 CS*

B** 698 20 16.74 -Y 5) 4.15 6 

Quantitative flaw depth sizing calibration with 15 mm deep SDH (Ø 1,5 mm) of calibration 

block “SVTI AS_D270_T30”

Figure C.136
C-176

Flaw 11 / Scan Direction: + X

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

mm mm mm mm mm mm

11 754 20 6 CS*

B** 750 20 6.67 -Y 6) 4.16 5 

Flaw depth sizing hard, very week tip signal; quantitative flaw depth sizing calibration with

26 mm deep SDH (Ø 1,5 mm) of calibration block “SVTI AS_D270_T30”

Figure C.137
C-177

Flaw 3 / Scan Direction: - X 

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

mm mm mm mm mm mm

3 135 10 2 CS*

B** 135 ≈ 10 3.2 -Y 1)

Very hard to detect with manual inspection; length sizing hard lots of noise from buttering; 

no separation of tip diffraction from corner trap echo, no TLL echo indicates shallow flaw, 

flaw depth estimation procedure: if no separation of tip diffraction from corner trap and flaw 

seems to be shallow the flaw depth is defined per default to 10% pipe thickness at flaw 

position → 3.2 mm

Figure C.138
C-178

Flaw 4 / Scan Direction: - X 

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

mm mm mm mm mm mm

4 193 6 3 CS*

B** 195 ≈ 6 -Y 2)

Hard to detect with manual inspection; length sizing hard lots of noise from buttering; no 

separation of tip diffraction from corner trap echo, no TLL echo indicates shallow flaw, flaw 

depth estimation procedure: if no separation of tip diffraction from corner trap and flaw 

seems to be shallow the flaw depth is defined per default to 10% pipe thickness at flaw 

position → 3.2 mm

Figure C.139
C-179

Flaw 6 / Scan Direction: - X 

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

mm mm mm mm mm mm

6 374 20 26 CS*

B** 370 ≈ 20 26.48 -Y 3) 4 

Length sizing hard lots of noise from buttering; for quantitative flaw depth sizing calibration 

with 9 mm deep SDH (Ø 1,5 mm) of calibration block “SVTI AS_D270_T30”

Figure C.140
C-180

Flaw 8 / Scan Direction: - X 

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

mm mm mm mm mm mm

8 515 20 6 CS*

B** 515 ≈ 25 6.81 -Y 4) 5 

Length sizing hard lots of noise from buttering; depth sizing hard only possible when probe 

is skewed (flaw skew angle 10°); for quantitative flaw depth sizing calibration with 26 mm 

deep SDH (Ø 1,5 mm) of calibration block “SVTI AS_D270_T30”

Figure C.141
C-181

Flaw 10 / Scan Direction: - X 

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

mm mm mm mm mm mm

10 696 20 17 CS*

B** 698 ≈ 25 16.74 -Y 5)

Quantitative flaw depth sizing calibration with 15 mm deep SDH (Ø 1,5 mm) of calibration 

block “SVTI AS_D270_T30”

Figure C.142
C-182

Flaw 11 / Scan Direction: - X 

Flaw No.:

As Built Information (SQC Drawing) Measurement Results

RemarksUT Analysis SectionCal Sheet No:

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

Flaw X 

Position 

OD

Length Flaw 

Depth

Flaw

Y 

Pos.

mm mm mm mm mm mm

11 754 20 6 CS*

B** 750 20 6.37 -Y 6)

Flaw depth sizing good, good tip signal; quantitative flaw depth sizing calibration with 26 mm 

deep SDH (Ø 1,5 mm) of calibration block “SVTI AS_D270_T30”

Figure C.143

C.2.6.4 Self Assessment

The manual Phased Array Technique using a dual matrix search unit and longitudinal waves in 

the range from 40° to 70° demonstrated good detection, length sizing and TWS performance of 

ID flaws with depth greater than 10% of the wall thickness.
C-183

C.2.7 Computer Tomography, Technique ID 109-CT0

C.2.7.1 Assignment of Task

Analysis of crack depth in weld of PARENT Test Blocks by means of X-ray computed

tomography according procedure elaborated for Sample P32.

C.2.7.2 Test Objects

Test object PARENT Test Block

Material Base metal: 22 NiMoCr 3 7 (SA 508 Class 2)

Weld: Alloy 182

Dimensions [mm] ca. 35 x 30.3 x 220

Weight [kg] 1.84 kg

Fixation on CT-scanner double sided adhesive tape

Photo of test object on CT-scanner:

Figure C.144 Test Block ID: P32 (N 220 AD U TS 5), view from X-ray source towards the 

line detector. The sample is oriented such that the crack opening is located

on the side of the X-ray source.
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C.2.7.3 Parameters for Data Acquisition

CT-Scanner CITA 101 B+ (Cita Systems)

Beam geometry Fan beam

X-ray source X-ray system MG452 (YTU450-D09)

Parameters of X-ray source 450 kV / 3.3 mA / 1.0 mm focal spot

External X-ray filtration 1.5 mm Brass

Detector Single collimated (W) line detector (CdWO4) with 125

detector channels

Detector aperture [mm] 0.35 x 0.15

Manipulator position 16

Pixel size of CT-slice [mm] 0.12 x 0.12

Slice distance [mm] 0.12

Object diameter [mm] 60

Ray Spacing [mm] 0.18

Integration time [ms] 100

Beam hardening correction 1.5

Specific Parameters

Test Block ID P28 P29 P30 P31 P32 P38

Number of slices 39 32 25 30 41 40

Z position of 1st slice [mm] 109.68 110.64 106.80 106.80 108.36 106.80

Vertical scanning range [mm] 4.56 3.72 2.88 3.48 4.80 4.68

C.2.7.4 Analysis of Crack Depth

Test Block ID P28 P29 P30 P31 P32 P38

Slice # of max. crack depth 31 26 06 17 34 29

Z position of max. crack depth [mm] 113.28 113.64 107.40 108.72 112.32 110.16

Crack depth [mm] 14.0 13.0 17.8 3.9 11.3 4.4

Weld thickness [mm] 30.3 30.3 30.3 30.3 30.3 30.3

Crack depth in % of weld thickness 46.2 42.9 58.7 12.9 37.3 14.5

C.2.7.5 CT Images

Figure C.145 shows the CT-slices of the six test blocks in which the maximum crack depth is

assumed. The crack depth is measured from the sample surface and is indicated in the CTimages. Figure C.146 shows a stack of 15 CT-slices per test block. Figure C.147 shows the 3DCT visualization of the six test blocks with VGStudioMax.

All CT-slices are available on the FTP server of EMPA as individual TIFF or 16 bit raw image

files and as 3D-CT volumes in VGStudioMax format.
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Figure C.145a CT-slice #31 (z=113.28 mm) of test block P28 (N 220 AD U 6), crack

depth: 14.0 mm (+/- 2 pixel = 0.24 mm), 46.2% of weld thickness

Figure C.145b CT-slice #26 (z=113.64 mm) of test block P29 (N 220 AD U 10), crack

depth: 13.0 mm (+/- 2 pixel = 0.24 mm), 42.9% of weld thickness
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Figure C.145c CT-slice #06 (z=107.40 mm) of test block P30 (N 220 AD U 7), crack 

depth: 17.8 mm (+/- 2 pixel = 0.24 mm), 58.7% of weld thickness

Figure C.145d CT-slice #17 (z=108.72 mm) of test block P31 (MN 220 AD U 1), crack 

depth: 3.9 mm (+/- 2 pixel = 0.24 mm), 12.9% of weld thickness
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Figure C.145e CT-slice #34 (z=112.32 mm) of test block P32 (N 220 AD U TS 5), 

crack depth: 11.3 mm (+/- 2 pixel = 0.24 mm), 37.3% of weld thickness

Figure C.145f CT-slice #29 (z=110.16 mm) of test block P38 (N 220 AD U TS 3), crack 

depth: 4.4 mm (+/- 2 pixel = 0.24 mm), 14.5% of weld thickness
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Test Block P28 (N 220 AD U 6)

Figure C.146a 15 CT-slices in stack of 39, starting with slice #20 and ending with #34
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Test Block ID P29 (N 220 AD U 10)

Figure C.146b 15 CT-slices in stack of 32, starting with slice #13 and ending with #27
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Test Block ID P30 (N 220 AD U 7)

Figure C.146c 15 CT-slices in stack of 25, starting with slice #3 and ending with #17
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Test Block ID P31 (MN 220 AD U 1)

Figure C.146d 15 CT-slices in stack of 30, starting with slice #10 and ending with #24
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Test Block ID P32 (N 220 AD U TS 5)

Figure C.146e 15 CT-slices in stack of 41, starting with slice #26 and ending with #40
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Test Block ID P38 (N 220 AD U TS 3)

Figure C.146f 15 CT-slices in stack of 40, starting with slice #20 and ending with #34
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Test Block ID P28 (N 220 AD U 6)

Figure C.147a Visualization of 3D-CT volume of test block P28 with VGStudioMax
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Test Block ID P29 (N 220 AD U 10)

Figure C.147b Visualization of 3D-CT volume of test block P29 with VGStudioMax
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Test Block ID P30 (N 220 AD U 7)

Figure C.147c Visualization of 3D-CT volume of test block P30 with VGStudioMax
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Test Block ID P31 (MN 220 AD U 1)

Figure C.147d Visualization of 3D-CT volume of test block P31 with VGStudioMax
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Test Block ID P32 (N 220 AD U TS 5)

Figure C.147e Visualization of 3D-CT volume of test block P32 with VGStudioMax
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Test Block ID P38 (N 220 AD U TS 3)

Figure C.147f Visualization of 3D-CT volume of test block P38 with VGStudioMax
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C.2.8 High Resolution X-ray, Technique ID 112-HRT0

C.2.8.1 Introduction

This report describes an x-ray technique that has been developed for detection and 

characterization of service induced defects, e.g., intergranular stress corrosion cracking 

(IGSCC). The x-ray source is a 450 kV x-ray machine and the detector is CCD-based with fiber 

optic lens and glass fiber optic scintillation screen. The objects are positioned and rotated by a 

rotation unit which is stepper motor driven. 

Figure C.148 Set Up

C.2.8.2 X-ray Machine

The X-ray machine is a GE Titan 450 kV constant potential with ISOVOLT 450 M2/0.4-1.0HP 

tube. This is a high power tube with a small focus, f, of only 0,4 mm (25 % modulation). 

Figure C.149 X-ray Tube
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The source to object distance (SOD) has been 650 mm and object to detector distance (ODD) 

was 50 mm. In this case the crack opening is defined as the object. The geometrical 

unsharpness is less than 0,04 mm.

[mm] g

f ODD U

SOD

⋅ = (C.1) 

C.2.8.3 Digital Detector

The x-ray camera is an imaging detector with a scintillating screen of glass fiber optics. It is a 

new design of a proven concept where the design issue was to minimize the amount radiation 

induced noise. This was done by bending the fiber optic lens (image conduit) which moved 

CCD-chip out of the primary beam. The spatial resolution is increased by using a new type of 

scintillating face plate. The new scintillating faceplate has unique properties which have 

eliminated the internal light spread and increased the spatial resolution. 

Figure C.150 Fiber Optic Lenses and Scintillating Faceplate

The new detector is based on a front illuminated full frame CCD camera (EEV CCD42-40) (2K x 

2K) with pixel size of 13,5x13,5 μm. It is Peltier cold down to -30°C and is equipped with fiber 

optic input window. The input window is a fiber optic lens with fiber diameter of 4,5 μm with a

length of 50 mm (see Figure C.150). In the front of the camera, the bended fiber optic lens with 

the scintillating screen is mounted. 

The imaging area is only 27 x 27 mm (see Figure C.151) but the spatial resolution is very high. 

The detector unsharpness is measured to be less than 0,08 mm. Better than 50% modulation of 

the 13:th wire pair with the EN462-5 double wire IQI.
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Figure C.151 The X-ray Detector with a Cu-filter in Front

C.2.8.4 Exposure Data

For the test blocks P28-P30 the following data was applied:

• U= 300 kV; I= 2,25 mA; 30 mm Iconel

• Exposure time: 8 x 60 s (18 mAmin)

For the test block P41 is following data used:

• U= 450 kV; I= 1,5 mA, 64 mm Inconel

• Exposure time: 8 x 120 s (24 mAmin)

The reason to use such a long exposure time is that it corresponds to an optical density 

between 3,0-3,5 with Agfa D5 industrial x-ray film. We are using the cooled CCD to be able to 

integrate for long exposure times. In other word we have similar exposure time as film but much 

better image quality.

C.2.8.5 Test Procedure

The object coordinate system is placed so the crack opening is coincident to the axis of rotation 

in the object manipulator. The defects in test block P41 are orientated in two directions, axial 

and circumferential and P41 test block is thus in two different positions. 

• The test block P28-P30 (square bars) is placed in such a way that its X-axis is parallel to the 

axis of rotation of the object manipulator in the coordinates Y=0 and Z=30,3 [mm] (see 

Figure C.152). 

• In the position for testing axial defects in test block P41, the Y-axis of the test object 

coincident to the axis of rotation of the object manipulator in coordinate Z=0 [mm] and the 

polar coordinate X [degrees]of the defect (see Figure C.153). 

• In the position for testing circumferential defects the tangent of the defects polar Xcoordinate coincident with the axis of rotation of the object manipulator. The Y-coordinate is 

the value for the actual defect and Z=0 [mm].
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X-ray radiography is a volumetric method and to be able to detect cracks or parts of cracks the 

orientation has to be reasonably parallel with the x-ray beams. Therefore each defect is 

radiographed in series of projections. The projection angle is from -10° to +10°, with increments 

of 2°.

Figure C.152 Test Block P28–P30

Figure C.153 Test Block P41. Position for axial defects.
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C.2.8.6 Image Processing

Each x-ray image is divided in eight exposures. They are then integrated to improve the signalto-noise (SNR) ratio. As each image also can contain radiation induced noise they are 

compared statistically and the noise (white dots) are removed. Conventional background and 

flat field correction to remove the structural noise is done in the next step. Finally a “lifting”-

operation is done by multiplying the corrected raw image with an interpolated surface based on 

curve fitting in the perpendicular direction of the cracks. The Fourier-series of third grade is used 

as function for curve fitting as it can adapt nearly any shape in a “smooth” way. 

The images are presented in an animation (link below each image). By using animations the 

crack can be seen clearly and it is easy to characterize them. 

C.2.8.7 Size

To determine the size or the depth (z-coordinate) an expression (see Figure C.154) is 

developed which describes the depth, d, as function of the movement of the observed crack tip 

between the end positions in the series of exposures.

Figure C.154 Crack Depth Calculation

Where Θ, is the projection angle of the crack tip in the center position of the projection 

series. The angle, α, is half the angle between the end positions. The distance, nopx, is 

measured between the end positions of the crack tip. The pixel size is pxsize=0,0135 

[mm]. The geometrical enlargements is M=1,045. And finally, d, is the depth of the defect 

(Zmax-coordinate).

[mm] 2 cos tan

nopx pxsize d

M θ α

⋅ = ⋅⋅ ⋅ (C.2) 

The measured width (nopx) can be seen in Figure C.155. 
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Figure C.155 Measurement of the Distance, nopx

Sizing of each defect is presented in a table with:

• X X-coordinate of the defect [mm or degrees].

• X1, X2 Coordinates of the line profile.

• nopx No. of pixels (projected width).

• Zmax(1) Maximum Z-coordinate (=d, maximum depth of the defect).

• Length Real length in the image plane.

All images are of same size, 26,45 x 26,45 mm2

, which is the real size in the image plane. The 

size in the detector plane is compensated by the geometrical enlargement, M.

 

(

1

) The Zmax is systematically under estimated in the case of “real” defects such as SCC and 

fatigue in P28-P30. This is because the volume in the crack close to the crack tip goes to 

zero. Experience from earlier work with SCC gave an under estimation of about 1–2 mm. 

In the test block P41 where the defects are artificially produced the Zmax estimation is more 

correct.
C-206

U6 (SCC)

α=10°and Θ=8°; From -10° to +10°; 2°/pos; 11 positions

X [mm] X1 X2 nopx Zmax [mm]

27,8 85 341 256 9,5

22,7 71 323 252 9,3

17,5 93 329 236 8,7

12,3 93 381 288 10,6

7,2 97 358 261 9,7

Figure C.156 U6, 6th position (Image size 26,45 x26,45 mm2

) 

P28 MN 220 AD U6 spline 8 bit 512 inv.avi
C-207

U7 (Fatigue)

α=6° and Θ=5°; From +1° to -11°; 1°/pos; 13 positions

X [mm] X1 X2 nopx Zmax [mm]

27,8 82 289 207 12,8

22,7 94 366 272 16,8

17,5 60 295 235 14,5

12,3 94 311 217 13,4

7,2 96 271 175 10,8

Figure C.157 U7, 7th position (Image size 26,45 x26,45 mm2

) 
C-208

U10 (SCC)

α=10°and Θ=6°; From -10° to +10°; 2°/pos; 11 positions

X [mm] X1 X2 nopx Zmax [mm]

27,8 90 260 170 6,2

22,7 81 309 228 8,4

17,5 186 462 276 10,1

12,3 136 386 250 9,2

7,2 149 411 262 9,6

Figure C.158 U10, 6th position (Image size 26,45 x26,45 mm2

) 

P29 MN 220 AD U10 spline 8bit 512 inv.avi
C-209

Defect nr1 (P41)

α=8°and Θ=8°; From -8° to +8°; 2°/pos; 9 positions

X [mm] X1 X2 nopx Zmax [mm] Length [mm]

0 86 118 32 1,5 10,7

Figure C.159 Defect nr1, (P41) 3rd position (Image size 26,45 x26,45 mm2

) 
C-210

Defect nr2 (P41)

α=8°and Θ=4°; From -8° to +8°; 2°/pos; 9 positions

X [mm] X1 X2 nopx Zmax [mm] Length [mm]

0 69 112 43 2,0 7,4

Figure C.160 Defect nr2, (P41) 2nd position (Image size 26,45 x26,45 mm2

) 

P41 nr2 28 deg spline 8 bit 512 inv.avi
C-211

Defect nr3 (P41)

α=8°and Θ=4°; From -8° to +8°; 2°/pos; 9 positions

X [mm] X1 X2 nopx Zmax [mm] Length [mm]

0 73 116 43 2,0 11,4

Figure C.161 Defect nr3, (P41) 6th position (Image size 26,45 x26,45 mm2

) 
C-212

Defect nr4 (P41)

α=8°and Θ=4°; From -8° to +8°; 2°/pos; 9 positions

X [mm] X1 X2 nopx Zmax [mm] Length [mm]

0 97 124 27 1,5* 7,2

Figure C.162 Defect nr4, (P41) 2nd position (Image size 26,45 x26,45 mm2

) 

P41 nr4 77 deg spline 8 bit 512 inv.avi
C-213

Defect nr7 (P41)

α=8°and Θ=8°; From -8° to +8°; 2°/pos; 9 positions

X [mm] X1 X2 nopx Zmax [mm] Length [mm]

0 34 237 237 11,0 22,6

Figure C.163 Defect nr7, (P41) 8th position (Image size 26,45 x26,45 mm2

) 
C-214

Defect nr8 (P41)

α=8°and Θ=2°; From -8° to +8°; 2°/pos; 9 positions

X [mm] X1 X2 nopx Zmax [mm] Length [mm]

0 116 236 120 5,5 22,7

Figure C.164 Defect nr8, (P41) 6th position (Image size 26,45 x26,45 mm2

) 

P41 nr8 206 deg spline 8 bit 512 inv.avi
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C.3 Korea Detailed Technique Descriptions

C.3.1 Nonlinear Resonant Ultrasound Spectroscopy, Technique ID 11-NRUT0

C.3.1.1 Overview

Principles of Nonlinear Resonant Ultrasound Spectroscopy

The studies on nonlinear acoustic effects have focused on identifying structural material 

characteristics and damage features. Different nonlinear effects include second harmonic 

generation, modulation of sound by low-frequency vibrations, amplitude-dependent internal 

friction, and amplitude-dependent resonance frequency shifts. The first applications of the 

nonlinear acoustic technique for material characterization used measurements of the second 

harmonic generated by the nonlinear distortion of a primarily sinusoidal acoustic wave 

propagating in a medium with defects. Later it was realized that harmonic generation analysis is 

not the only, and not always the best way to implement the effective nonlinear acoustic NDE. 

Other nonlinear techniques include the cross-modulation (frequency mixing) of low and highfrequency sound and studies of the amplitude dependence of the mode resonance peak in a 

specimen conducted at Los Alamos National Laboratory. All these techniques are based on 

nonlinear wave interactions and nonlinear resonances. Due to the use of resonant modes, these 

methods need much less acoustic power than the travelling-wave methods used before. In 

particular, acoustic effects due to material hysteresis what is often associated with the crack 

presence have been observed in these experiments. It was also found that the nonlinear 

methods turn out to be more sensitive to damage-related structural alterations than any known 

method based on the measurements of linear parameters such as wave speed and attenuation. 

It was also confirmed that the macroscopic nonlinear response of a material is largely 

determined by its microstructure, which is understood as structural inhomogeneities with the 

scales small as compared to the sample sizes and the acoustic wavelength. 

Nonlinear Resonance Frequency Shift

Resonance frequency shift, together with wave damping in resonance, is analysed as a function 

of the peak acceleration amplitude. A detailed discussion of the corresponding experimental 

apparatus can be found in papers published by the Nonlinear Elasticity group of Los Alamos 

National Laboratory in collaboration with several European laboratories and universities. One 

example is an experiment with a thin, rectangular beam (400mm × 26mm × 4mm) made of fibrecemented artificial slate used in roofing constructions. The synthetic fibres (4 mm thick) used in 

the production process have a principal orientation perpendicular to the length-wise direction of 

the beam. The beam is excited at its lowest-order flexural (bending) resonance mode by a lowdistortion speaker, positioned at 2 cm from the beam middle, parallel to its surface. The sample 

is suspended with nylon wires at the nodal points of the considered mode. The coupling medium 

between the specimen and the speaker is air (non-contact excitation). The speaker is driven in 

discrete frequency steps by a function generator through a high-power amplifier. In order to take 

the amplitude-frequency response near resonance, 4 to 10 sweeps over the same frequency 

interval, encompassing the first flexural mode resonance, were made at successively increasing 

voltages.

Materials Characterization Using Nonlinear Acoustic Parameters

To characterize the properties of the media, the conventional acoustic NDT technique utilizes 

linear acoustic parameters, such as sound speed and attenuation coefficient. Similarly, the non-
C-216

linear technique employs the non-linear parameter (parameters) for the material 

characterization. The classical approach to describe the nonlinearity of a homogeneous elastic 

media is based on Taylor expansion of the dependence between the stress and strain tensors in 

the material and considers the coefficients of this expansion as the parameters of nonlinearity. 

In a simple example of one-dimensional longitudinal deformations in an isotropic solid, this 

expansion can be taken in a scalar form: 

( ) 2 23

o 1 σ = ρ ε + βε + γε + c ,  (C.3) 

where ρ0 and c1 are the density and the longitudinal sound speed in the medium, 

respectively, σ is the stress, ε is the strain, β, γ, ... are the non-linear parameters, which 

characterize, respectively, the quadratic and cubic non-linearity of the medium. 

Typical values of the non-linear parameter β do not exceed 10 for homogeneous media without 

defects (where nonlinearity is due to the inter-atomic forces acting in the crystal lattice), so that 

the contribution of the non-linear quadratic term into the relationship (1) is very small for 

practically all non-destructive strains, and the medium exhibits a linear behavior. The same is 

even more applicable for the cubic term with the coefficient γ. However, the presence of 

structural inhomogeneities such as grains, pores, cracks, and other defects is able to increase 

the nonlinear response of a material by orders of magnitude. This is true for a large variety of 

natural and constructive material such as rock and many metals. 

The practical importance of using the parameters of acoustic nonlinearity as a possible tool for 

non-destructive testing, including that of the material defects caused by fatigue of external 

damage has been fully recognized during the last decade. Still, the crucial steps to transition the 

use of nonlinear acoustic techniques from the laboratory to practical applications is yet to be 

accomplished. Indeed, the nonlinear properties of many materials are more complicated than 

described by simple models. An important aspect of “structural nonlinearity” is that stress-strain 

dependence is hysteretic. In other words, the material behaves differently at the compression 

and dilatation phases of the loading cycle. This feature, known before in strong static loading, is 

now known to be present in very low dynamic strains, in the order of 10-7–10-8. The 

corresponding stress-strain dependence has a singularity and in a simplest case, it reads

( ) 2 22

o l c 0 , σ=ρ ε±η ε −ε     (C.4) 

where η is the coefficient of hysteretic nonlinearity and the “+” and “–” signs are taken for 

stress increase and decrease phases, respectively. As a result, the observed nonlinear 

behavior is quite specific; for instance, the resonance frequency shift is proportional to 

the amplitude of the basic signal rather than to the square of it as could be expected 

from the “normal” behavior corresponding to the expansion (C.3). To obtain quantitative 

relationships between the state of the measured characteristics and the state of the 

material, a reliable theoretical basis must be created. 

Recent research has demonstrated that nonlinear acoustic parameters of the material are 

closely related to the crack size distribution and elastic properties of the defects and, therefore, 

high acoustical nonlinearity due to cracks can be used for the damage assessment.

In summary;
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- As the driving voltage increases, a shifting of resonance frequency is observed.

 This resonance peak shifting indicates a nonlinearity of the specimen. 

 Resonance peak shift and peak width is related to Moduli E and Q-value of the 

materials.

- Normalized resonance pattern also reflects the nonlinearity.

 If the resonance pattern is identical as the driving voltage increases, the 

specimen shows no nonlinearity (linear elastic response)

 Otherwise (if the peak amplitude decreases as the driving voltage increases), the 

specimen reveals a nonlinear elasticity.

C.3.1.2 Equipment Apparatus and Setup the Transducer to the Specimen

All active acoustic methods of NDE are based on radiation of the required acoustic signals, 

reception and signal processing. The different regimes of operations require different kinds of 

radiation signals and different types of processing. The NRUS is a fully digital system that 

radiates and processes any acoustic signal.

The Nonlinear Resonant Ultrasound Spectroscopy (NRUS) methods are based on excitation of 

sweep frequency signals in the tested material and measurements of the dependence of the 

recorded signal amplitude on frequency. In this regime the sweep frequency signal is formed 

within the PC and is transformed to the transmitter channel of the NRUS system. The developed 

NRUS software provides radiation of sweep frequency signal in defined frequency band and 

sweep time. The Amplitude Frequency Responses (AFR) between transmitting and receiving 

are recorded for various output voltages. The results are presented in the normalized form 

where the received signal is divided to the system output. In the linear case the measured 

Normalized Amplitude Frequency Response (NAFR) does not depend on the applied signal 

amplitude and difference in the Normalized Amplitude Frequency Responses shows the 

presence of the tested part nonlinearity (Resonance frequency shift and amplitude dependable 

losses). 

Figure C.165 shows a photo for the measurement system of nonlinear resonant ultrasound 

spectroscopy (NRUS). An arbitrary waveform generator and high power amplifier supply a 

sinusoidal wave with swept frequency. The piezoelectric elements are bonded on a side of the 

specimen for generation of the ultrasonic waves and reception of the waves (Figure C.166). In 

addition, a laser doppler vibrometer (Polytec LDV) was used for an acquisition of the ultrasonic 

waves (Figure C.167). A PC program controls all the equipment in the system and data 

acquisition.

In order to get an accurate ultrasonic resonance signals, following equipment are assembled as; 

• An arbitrary waveform generator to generate the sinusoidal signals with specific frequency

• An high frequency amplifier to amplify the sinusoidal signal to 1~100 Vpp. The frequency 

response of the amplifier ranges up to 300 kHz. The output or the amplifier applied to a 

wide-band piezoelectric transducer to vibrate the specimen with frequency sweep.

• A digital oscilloscope for monitoring the waveform in time domain.
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• A PC with software program to sweep the desired frequency range and store and display 

the spectrum in frequency domain.

• A laser Doppler vibrometer to measure the high frequency vibration or displacement the 

specimen.

An actual NRUS system is assembled for the Open RRT, shown in Figure C.168. 

Figure C.165 Photo of Nonlinear Resonant Ultrasound Spectroscopy (NRUS) with a Laser 

Doppler Vibrometer

Figure C.166 Schematic Drawing of the Configuration No. 1 of the Piezoelctric Transducer and 

the PARENT Specimen for Nonlinear Resonant Ultrasound Spectrocopy
C-219

Figure C.167 Schematic Drawing of the Configuration No. 2 of the Piezoelctric Transducer and 

the PARENT Specimen for Nonlinear Resonant Ultrasound Spectrocopy

Figure C.168 Photo Shows a PARENT Specimen (P28) at the NRUS Experiment. The 

resonance spectrum was acquired by both a piezoelctric transducer and a laser 

Doppler vibrometer.

C.3.1.3 Preliminary Estimation of Resonance Frequencies of the Specimens (P28, P29, 

and P30)

Resonance frequencies and vibration modes are estimated by the LANL RPR code1

(rectangular parallelepiped model). The specimen (SA 508 cl. 2) was assumed as a low carbon 

steel with an elastically isotropic material. The input parameters for the estimation are the 

dimension of the specimen (d1 = 22 cm, d2 = 3.03 cm, d3 = 3.5 cm), density = 7.8 gm/cc and 

initial guess of ε11 = 277.0 GPa, ε44 = 79.14 GPa (Cheong et al. 2000). 

Table C.1 shows the estimated resonance frequencies and vibration modes for the specimen. 

Table C.1 lists the first 50 resonance frequencies with the vibration modes and orders. The 

abbreviations of the vibration modes, "k" are summarized as, 

 

1 RUSpec software by Magnaflux Quasar Inc.
C-220

k=1 uniform translation along x-direction

k=2 rotation about y-axis

k=3 rotation about z-axis

k=4 rotation about x-axis

k=5 volume oscillation

k=6 uniform translation along z-direction

k=7 uniform translation along y-direction

k=8 complex motion.

The number of vibration orders are also listed in the column 'i'.
C-221

Table C.1 Estimated Resonance Frequencies and Vibration Modes for the Specimen 

P28, P29, and P30
C-222

C.3.1.4 Data Analysis of NRUS Data

Examples of NRUS Applications

It is seen that variations of NRUS spectrum for the cracked ring are much higher than for the 

intact ring. We used steel bearing ring (#1, left specimen of Figure C.169) and two bearing rings 

made from sintered metal (middle and right specimens of Figure C.169). It was not completely 

sintered (“green” part) and specimen #2 (middle specimen of Figure C.169) has several cracks 

that provided high acoustic nonlinearity. Nonlinear amplitude frequency response of intact 

specimen (#1) is shown Figure C.170 and cracked specimen (#2) shown in Figure C.171. 

Figure C.169 Reference Tested Specimens

Figure C.170 Measured Nonlinear Amplitude Frequency Response (NAFR) for Intact “Green” 

Ring (Sample #1) in the Frequency Band 180–220 kHz
C-223

Figure C.171 Measured Nonlinear Amplitude Frequency Response (NAFR) for Cracked 

“Green” Ring (Sample #2) in the Frequency Band 180–220 kHz 

Another example of resonance frequency shift in a CT (Compact Tension) specimen with a 

stage of crack initiation and a specimen with a long crack, such as crack length of 7 mm are 

shown in Figure C.172. Resonance pattern from an intact CT specimen shows a little shift of 

resonance frequency even the driving amplitude varies. It means a little nonlinearity and almost 

no non-uniformity in the specimen. However, significant amount of the resonance frequency 

shifts downward is observed in the cracked specimen, as the driving voltage increases. As the 

crack length is in the range of mm, resonance frequency shifts downward and the normalized 

amplitude decreases as the driving voltage increases. 

 

Figure C.172 Resonance Frequency Frequency Shift in (a) CT Specimen in the Early Stage of 

Crack Initiation (left) and (b) CT Specimen with Crack Length of 7.0 mm (right) 

C.3.2 Pulsed Eddy Current, Technique ID 11-PECT0 

PEC testing has been demonstrated to be one of the most effective methods, and is capable of 

tackling different inspection tasks, such as sub-surface defect detection in complex structures. 

Among the available conventional NDT methods, eddy current testing (ECT) is the most 

promising technique to detect flaws in conductive materials. The conventional ECT uses singlefrequency sinusoidal excitation for the detection of defects or flaws as a function of changes in 

voltage, impedance, or phase, because of limited depths of penetration and complexity in a 

signal analysis ECT was confined to limited applications. Unlike a conventional ECT, PEC uses 

multiple frequency sinusoidal excitation pulse of the electric current through the excitation coil. 
C-224

PEC is more economical than other NDT methods. Because of many advantages of PEC over a 

conventional eddy current method, such as low power consumption owing to a short pulse 

excitation and the broad band nature of a pulse, PEC has the capability to penetrate different 

depths in a conductive material and provides the depth information of the defects. Even though 

the use of PEC has long been considered for the testing of materials, in recent decades, PEC 

testing has become the subject of wide spread interests in NDT because of its advancement in 

technologies such as computer data acquisition and digital signal processing. Furthermore, PEC 

has the capability to measure the thickness, conductivity, and in particular, sub-surface crack 

measurements, crack reconstruction, and depth estimation. 

C.3.2.1 Overview

The PEC testing is the new promising technological approach to NDT, and it has been 

principally developed for surface, subsurface flaws measurements and corrosion in the 

multilayered structures. Among the available conventional NDT methods, one of the most used 

is eddy current testing (ECT) to detect the flaws in conductive materials. Unlike conventional 

ECT the PEC uses pulse of electric current through the excitation coil. In contrast to the 

conventional ECT (operates with single sinusoidal frequency), the pulse ECT employ repetitive 

pulses having short duration in time (having broad band), which yields a signal having frequency 

contents from DC to several KHz or higher. Skin depth is a function of the resistivity and 

permeability of the test material, and test frequency. Because the eddy current diffusion depth 

depends on the excitation frequency the PEC technique has the potential for bringing up deeper 

information about the tested sample. In order to detect deep crack from the surface, the 

magnetic field has to penetrate the sample and arrive up to the crack. Therefore, high current 

and reasonable frequency range are essential for the detection of defects using PEC. In PEC, a 

response pulse always comes after an excitation pulse is over, so this method is less 

susceptible to interference, moreover the pulse excitation can minimize the power consumption, 

which is more capable in the development of portable instruments. Because of the potential 

advantages of the PEC, prevalent investigations on this technique have been made, such as for 

detection of subsurface crack and corrosion in aircraft multi-layer structure. 

C.3.2.2 PEC Equipment

The block diagram of the PEC system design is shown in Figure C.173. The system consists of 

a rectangular waveform generator, a probe integrated with an excitation coil and a Hall-sensor, 

an amplifier to amplify the signal from Hall-sensor, a data acquisition card and a PC with signal 

processing software. The system works as follows; the waveform generator produces a 

rectangular waveform with variable frequency and duty cycle. The waveform is fed to a coil 

driver circuit, which excites the induction coil in the probe with pulsed current. When the probe is 

mounted on the metal structure, the pick-up sensor will measure the vertical resultant magnetic 

field, which is the vector sum of the one generated by the excitation coil and the opposing one 

generated by the induced eddy current in the sample (Primary flux Φ1 created by driving coil 

induces EC in the conducting medium, induced EC produces counter flux Φ2. Now pick-up 

sensor measures total flux Φ = Φ1 + Φ2.). A voltage amplifier with variable gain amplifies the 

signal from the pick-up sensor. The A/D card will convert the input signal into digital data ready 

to be processed by written software in the PC. The software performs communication with the 

data acquisition card. Signal pre-processing, feature extraction, defect categorization, and the 

presentation of the results are on the PC monitor.
C-225

Figure C.173 Block Diagram of the PEC System

The amplifier supplies the high current uni-polar (+Ve) pulse to the Driving Coil or exciting coil 

which is in the PEC probe. With this amplifier we can control the pulse width considering the 

skin depth of sample (from 1 ms–10 ms) in case of nonmagnetic materials, pulse frequency 

(500 MHz–50 Hz), and pulse amplitude (max- 100 A). The excitation coil is a copper wire which 

has square cross section with 1×3 mm having total resistance 0.92 Ω, wound 132 turns on the 

cylindrical ferrite core. The probe has a 60mm height and 9mm inner diameter, and the Hallsensor was positioned in the center of probe to detect the induced signal from defects. The 

cylindrical type ferrite core not only reduces the magnetic leakage but also improves the 

detection sensitivity by sustaining adequate excitation intensity. The Hall-sensor gives the 

frequency independent sensitivity from DC to 100 kHz, high spatial resolution having less power 

consumption with increased sensitivity and simple readout circuitry. When we bring the probe 

proximity to conducting plate, the steep exciting pulse induces eddy currents and its associated 

magnetic field dissipates exponentially to approach its steady state. The induced eddy currents 

flow in the opposite direction to the currents which are flowing in the exciting coil, hence when 

the probe is placed on the conducting plate, the detected field rises slowly to the maximum peak 

value.

C.3.2.3 Tested Sample and Detection of Crack

The three kinds of test blocks with ID 28, 29, and 30 provided by ALSTOM, and the flaw types 

of these test blocks are BWR/NWC SCC Crack, Fatigue Crack, and PWR SCC crack, 

respectively. The sample was composed by the welding of two base metals, and the 

composition of base metal is 22NiMoCr37, and the welding metal is alloy 182. A 10 mSec pulse 

width and 15A excitation current is applied to exciting coil of the probe to test the sample. The 

PEC probe is fixed to the X-Y scanner to perform the manual scanning on the defect free side of 

the tested sample. A LabVIEW-based data acquisition program was developed to continuously 

monitor the variation in the thickness of the sample and is observed on the computer screen. 

The time domain feature which is the peak value of detected pulse is used for the scanning test 

to detect the sub-surface cracks in the tested sample. 
C-226

Figure C.174 (a) Configuration of PEC System; (b) LabVIEW Data Acquisition Front Panel

Figure C.175 Pulsed Eddy Current System and Experimental Setup (Probe on Sample)

C.3.2.4 Configuration of PARENT Test Specimen (P28, P29, P30)

Figure C.176 Schematic of PARENT Test Specimen. PECT probe is located on the opposite 

side of crack surface.
C-227

C.3.2.5 Experimental Results and Feature Extraction

If the probe placed on the test sample in such a position, then the typical response signal shown

in Figure C.177, is the induced signal detected by the Hall-sensor from test block.

Figure C.177 Typical PEC Signal Induced in the Hall-sensor from the Test Block

Calibration of PEC signal with standard specimen is essential to obtain a reliable experimental

result. Because of no calibration sample is prepared, the validity of experiment was verified 

using the difference of the PEC peak amplitude obtained in the crack and opposite side 

(Figure C.178). The base metal of sample block 22NiMoCr37 is ferromagnetic and welding 

material alloy 182 is nonmagnetic material. Therefore, the PEC amplitude measured in the 

ferromagnetic part is higher than that of the nonmagnetic part. The y coordinate 10 and 12 cm 

neighborhood is the interface region between ferromagnetic and nonmagnetic material. The 

crack is positioned in the neighborhood of y coordinate 11 cm, which shows the minimum PEC 

signal amplitude.

The important characteristic of detected signal to interpret the results is the peak value of the 

pulse. The measuring points were selected as a x-y coordinate, the x points were fixed at the 

center of transverse direction and y points were selected along the longitudinal direction. 

Figure C.179 show the change of PEC peak amplitude along the coordinate. 
C-228

Figure C.178 The Difference of the PEC Peak Amplitude Obtained in the Crack and Opposite 

Side for P28, P29 and P30
C-229

Figure C.179 The Difference of the PEC Peak Amplitude Obtained in the Crack and Opposite 

Side for P28, P29 and P30
C-230

C.3.2.6 Summary

The nondestructive evaluation (NDE) using PEC to detect the sub surface crack under the thick 

plate has been performed on the PARENT round robin sample. The PEC amplitude measured 

in the ferromagnetic part is higher than that of the nonmagnetic part; therefore, it is not certain 

that the decrements of amplitude are attributed to the defects or nonmagnetic part. The y 

coordinate 10 and 12 cm neighborhood is the interface region between ferromagnetic and 

nonmagnetic material. The crack is positioned in the neighborhood of y coordinate 11 cm, which 

shows the minimum PEC signal amplitude.

C.3.3 Phased Ultrasonic Array, Technique ID 20-PA1, 20-PA2

C.3.3.1 Scope

• This procedure is applicable to ultrasonic examination of dissimilar metal weds and adjacent 

material utilizing phased array technique (PAUT). 

• The objective of examination performed in accordance with this procedure is to accurately 

detect, length sizing and depth sizing within the specified examination volume.

C.3.3.2 Personnel Requirement

• Personnel performing exams has an experience for equipment setup, calibration, 

examination and data evaluation.

C.3.3.3 Equipment

• Olympus-Omniscan MXU (16:128) instrument with 8 channels

• Software (TomoView-2.R3) capable of collecting and storing full waveform signals

C.3.3.4 Transducer and Wedge

• Total element: 32 or 64

• Focal range: 40–60 mm

• Frequency: 2.25 or 5 MHz

• Wedge: Angle/Length/Width

• Element size: Length/Width/Pitch

C.3.3.5 Calibration

• Velocity calibration for angle beam probe using IIW radius block

• Instrument linearity check (Screen height/Amplitude control/Transducer values)
C-231

• Examination range and signal amplitude calibration

• Sensitivity calibration using calibration block

− A detailed drawings for calibration block with dimension shall be provided

C.3.3.6 Inspection Technique

• Examination volume

Figure C.180 P1 Specimen

Figure C.181 P28, P29, P30, P31, P32
C-232

• Axial examination

− For examination reflectors oriented parallel with the weld, scanning shall be directed 

essentially perpendicular to the weld axis from two directions (Up/Down)

• Circumferential examination

− For examination of reflectors oriented perpendicular with weld, scanning shall be 

performed along the weld axis in both clockwise and counter-clockwise directions 

(CW/CCW)

• Scan speed

− Scan speed shall be not excited 2.0 inches per second for examination

• Overlap

− Scan pattern shall provide min of 50 % overlap the transmitting element in the indexing 

direction

• Examination sensitivity

− Scan image shall be established on the component to be examined and adjust the gain 

level until the signal response from the inside diameter (ID roll) is between 5 % and 20 % 

FSH

• All suspected flaw indications, regardless of amplitude, shall be investigated to the extent 

necessary to provide accurate characterization, identify, and location

C.3.3.7 Inspection Classification

• Flaw indications

− All images produced by reflectors within the volume to be examined, regardless of 

amplitude that cannot be clearly attributed to the geometrical or metallurgical properties 

of the well configuration shall be considered as flaw indications.

• Non-relevant indication (Geometric/Metallurgical)

− All image produced by reflectors within the volume to be examined that can be attributed 

to the geometry of the weld configuration shall be considered as non-relevant indicators.

C.3.3.8 Indication Discrimination

• Indication has a good image along the length of the component

• Indication provides substantial and unique flaw image
C-233

C.3.3.9 Indication Sizing

Figure C.182 PAUT Image from Flaw

C.3.3.10 Recording of Reflectors

• The datum “0” reference points used for recording indications shall be in accordance with 

the system shown in following figure.

• Flaw indications

− For flaw indications (images) the following information shall be recorded regardless of 

amplitude

− Record the flaw location (Y1 and Y2) from weld center line zone

− The length dimension (X1 and X2) from “0” reference points

− The dimension Z1 (upper) and Z2 (lower) through wall
C-234

C.3.3.11 Examination Reporting

• Examination data shall be recorded on a data sheet

− calibration data sheet

− examination personnel and examination data

− examination procedure number/revision number

− equipment serial number, manufacturer, model=

− search unit angle, manufacturer, serial number, model=

− search unit frequency, size, mode, shape, beam focus, wedge

− cable type, length, couplant type

− signal response amplitude and sweep position obtained from reflectors

− examination sensitivity and location of reflectors
C-235

C.3.3.12 Calibration Data Sheet for Phased Array Ultrasonic Examination

C.3.3.13 PARENT RRT Data Sheet
C-236

C.3.3.14 DAG Technique Summary

• Inspection company: KRISS

• Team code : KRISS TEAM 20 

• Inspection Procedure: KRISS-PAUT-01

• Specimen: P1, P7, P28, P29, P30, P31, P32

• Inspection type: Manual Phased Array Ultrasonic Examination from OD

• Scan type: Scanning for circumferential flaw (oriented parallel to the weld) and scanning for 

axial flaw (oriented transverse to the weld)

• Detection

Technique detection Evaluation methodology detection

PAUT with curved wedge based on reflection 

from flaw

- Pulse echo PAUT probe with 32 elements, 

2.25 MHz, reflection (Longitudinal-wave)

Based on PAUT image from echo 

dynamic pattern and/or signal amplitude

- Evaluation of images by PAUT Tx-Rx 

dynamic focusing algorithm

• Characterization

Technique characterization Evaluation methodology characterization

PAUT with curved wedge contact technique 

based on reflection of flaw. 

- Image by PAUT pulse echo method Difference between flaw image and nonrelevant indication (geometric/metallurgical)

- Whether the images can be clearly 

attributed to the geometric/metallurgical 

properties of weld configuration or not

- Characterized as embedded flaws if the 

image doesn’t show evidence of flaw from 

the inside back wall

• Length and width sizing and flaw positioning

Length sizing and positioning Evaluation methodology sizing and 

positioning
C-237

PAUT with curved wedge contact technique 

based on reflection of flaw. 

- Image by PAUT pulse echo method 

PAUT equipment provides the size of flaw 

and position from the sector scan image

C.3.4 Ultrasound Infrared Thermography, Technique ID 20-UIR0

C.3.4.1 Outline

• Inspection procedures include record of mandatory variable used to determine the defect 

detection, characterization and defect size 

• Procedures written in English (MS Word) (Design/Review/Approved, Procedures/Revision 

number, Date)

• Before the start of the RRT, documents submit to the supervisor/ supervisor Review

• DAG (Data Analysis Group) Technique Summary writing / submit to the supervisor

− Brief summary of technique for defect detection, characterization and defect size to ease 

data evaluation /review

C.3.4.2 Mandatory Variable to be Included in Inspection Procedures (IP)

• Weld shape

• Inspection technique

• Used equipment 

• Surface emissivity

• Horn type, Frequency, Output

• Thermal imaging equipment calibration

• Defect sizing

• Data acquisition

UIR Techniques Essential Variable

• Equipment

• Horn type

• Horn displacement • Horn contact force
C-238

• Ultrasound output • Ultrasound duration

• The contact direction and location of horn

• Defect sizing method

• Lock-in thermography

C.3.4.3 TD Document that must be Included in the Essential Variables

Scope

• This procedure is applied to non-destructive examination of dissimilar metal welds and

adjacent materials utilizing ultrasound infrared thermography or vibration infrared 

thermography. 

• The objective of examination performed in accordance with this procedure is to accurately

detect length sizing and width sizing of defect within the specified examination volume

Personnel Requirement

• Personnel performing exams has an experience for equipment setup, calibration, 

examination and data evaluation.

Equipment (ultrasound generator, infrared thermography)

• Ultrasound generator by UlTec–SEE2 Sonic 

• Infrared thermography by Flir Cedip siver480 

Transducer and Horn

• Frequency (20 kHz) 

• Output (420 W) 

• Horn type (Point) 

• Contact area (mm2

) 

• Horn material (STS304) 

Calibration

• Frequency and displacement check using ultrasound generator and horn

• Performance test of Infrared thermography camera using blackbody
C-239

• Maintenance more than 0.95 of surface emissivity for inspection body using flat black paint

Inspection Technique

• Examination volume

Figure C.183 P28, P29, P30, P31, P32, P38 Specimen

• Examination – After occurring ultrasound in a base metal outside of welds and heat-affected 

zone, examination shall be performed by detecting heat of welds using infrared 

thermography 

• Inspection speed – Inspection speed shall be not exceed 20 minutes after occurring 

ultrasound 

• Examination Sensitivity – After setting the components that can be examined, the contact 

force shall be adjusted so that displacement containing welds can be in the range of 100 

μm. 

• All suspected defect indications, shall be investigated to the extent necessary to provide 

accurate characterization, identify, and location

Inspection Classification

• Defect indications – All indications produced by infrared thermal image and lock-in phase 

image with temperature difference within the volume to be examined shall be considered as 

defect indications, after exciting the basic material near the welds by ultrasonic waves after 

for a certain amount of time

• Non – relevant indication – All indications produced by infrared thermal image and lock-in 

phase image without temperature difference within the volume to be examined shall be 

considered as non-relevant indication, after exciting the basic material near the welds by 

ultrasonic waves after for a certain amount of time
C-240

Indication Discrimination

• Indication has a healthy image to show temperature difference (< 0.15°C) along the position 

of component

• Indication provides substantial and unique temperature and lock in phase travel

Figure C.184

Indication Sizing

• Lock-in phase thermography technique

− Defect size is computed to pixel and measuring image

Figure C.185

Recording of Thermography

• As shown in Figure C.186, the specimen is rotated to 4 directions with 90° interval during 

the test. 

• The “0” reference points used for recording indications shall be in accordance with the 

system shown in Figure C.186
C-241

Figure C.186

• Defect indications 

• For defect indications the following information shall be recorded shown in Figure C.187

− Record the defect location (Y1 and Y2) from weld center line zone

− The length dimension (X1 and X2) from “0” reference points

− The dimension Z1 (Upper) and Z2 (Lower) through wall 

Figure C.187

Examination Reporting

• Examination data shall be recorded on a data sheet

− Examination personnel and examination data

− Examination procedure number/revision number

− Equipment serial number, manufacturer, model
C-242

− Search unit angle, manufacturer, serial number, model

− Search unit frequency, size, mode, shape, displacement, horn

− Calibration data sheet

Calibration Data Sheet for Ultrasound Infrared Thermography

PARENT RRT Data Sheet

DAG Technique Summary

• Inspection company: KRISS

• Team code: 20.2 ( KRISS TEAM 1)
C-243

• Inspection Procedure: 20.2.1 (KRISS-UIR-01)

• Specimen:P28, P29, P30, P31, P32, P38

• Inspection type: Manual Ultrasound Thermography from specimen

• Scan type: The Specimen has been rotated to 4 directions with 90° interval during the test.

• Detection

Technique detection Evaluation methodology detection

Thermal energy is based on a ultrasound forces

• Sine wave : 20 kHz

• Displacement : 100 μm

• Frequency : 30 MHz 

UIR technique is based on image of infrared 

thermography

-Based on temperature, Lock-in phase 

or amplitude image

• Evaluation of lock in phase images 

with temperature distribution through 

the temperature and position 

• Temperature difference to evaluate 

defect is more than 0.15°C

-Hot spot defect images will have 

measured during the ultrasound excite.

• Characterization

Technique characterization Evaluation methodology characterization

UIR technique is based on ultrasound 

forces and infrared thermography

• Characterization is determination 

between health area and defect 

area

-Temperature difference(T) between defect 

indication and health indication

• If T>0.15°C, the area is classified as a defect, 

if not the area is classified as a health °C 

-All indications produced by infrared thermal 

image and lock-in phase image with temperature 

difference within the volume to be examined shall 

be considered as defect indications

DAG Technique Summary

• Inspection company: KRISS

• Team code: 20.2. (KRISS TEAM 1) 

• Inspection Procedure: 20.2.2 (KRISS-UIR-01) 

• Specimen: P28 , P29, P30, P31, P32, P38

• Inspection type: Manual Ultrasound Thermography from specimen

• Scan type: The Specimen has been rotated to 4 directions with 90° interval during the test.
C-244

• Length & width sizing

Technique length sizing Evaluation methodology length sizing

UIR technique is based on ultrasound 

forces and infrared thermography

-If T>0.15°C, the area is classified as a defect, if not 

the area is classified as a health °C

• Evaluation of defect size using spatial 

resolution of pixel image 

• Evaluation of lock in phase images with 

temperature distribution through the 

temperature difference.

-Hot spot image indications produced by infrared 

thermal image and lock-in phase image with 

temperature difference within the volume to be 

examined shall be measurement as defect size

• Defect positioning

Technique defect Positioning

Evaluation methodology Technique defect 

positioning

Based on technique for detection, 

length and width sizing

Based on previous described methodology for 

detection, length and width sizing

• X position, along defect, is taken from length 

sizing

• Y position, across defect, is taken from width 

sizing

• Z position, across defect, is taken from width 

sizing

C.3.5 Guided Ultrasonic Wave, Technique ID 21-GW1, 21-GW2

C.3.5.1 Overview

Introduction of Guided Wave

Guided wave (GW) technique was employed for PARENT Open Test specimen (P4 and P5) to 

investigate defects size.

Traditional Bulk wave ultrasonic inspection method can do thickness measurements, defect 

detection and material property characterization in a local area. This technique has 

disadvantage on large area inspection. Transducer should move point by point to cover a large 

region to scan whole area. Also, it is difficult to inspect inaccessible structure and area by 

traditional bulk wave inspection method.
C-245

Figure C.188 Guided Wave Generation and Propagation

A guided wave inspection technique which is presented on this technical description has 

different feature compared to conventional bulk wave ultrasonic test. Guided waves are 

generated with special frequency and excited angle on certain specimen geometry and 

boundary condition. Once ultrasonic wave is generated as Figure C.188 bulk wave (longitudinal 

and transverse wave) will propagate on the specimen. Those waves will reflect on the boundary 

and wave mode conversion will occur to produce guided wave mode with special condition. A 

guided wave travels along with inspecting material. Guided waves have great advantage on 

large area inspection due to the propagation on long distance without losing wave energy. 

However, guided waves include infinite wave mode with different distribution in the structure. 

This feature makes people hard to analysis and gives more or less sensitivity on different types 

of defects and loading condition. Guided wave mode and loading condition can be chosen by 

structure condition and defect size and location, such as on the surface or sub surface. 

It is physically and scientifically based approach to generate certain guided wave mode. Guided 

wave mode is very much dependent on frequency and geometry of specimen. The main 

characteristic of guided wave is dispersion. Figure C.189 shows guided wave dispersion curve 

on cylindrical coordinate. 

Figure C.189 Guided Wave Dispersion Curves on Cylindrical Coordinate. (a) Phase velocity 

dispersion curve, (b) Group velocity dispersion curve
C-246

Every possible propagation mode can be show on dispersion curve. Through the contribution of 

advanced computational power and analysis, nowadays, it is possible to deal with advanced 

understanding and utilization. Wave structure profiles can be obtained for a given structure due 

to the generation of a dispersion curve. Wave structure profiles can be obtained according to 

the dispersion curve. How many types of energy are distributed along the thickness of the 

structure is shown, looking into the profiles of the wave structure. Guided waves ease Structural 

health monitoring by taking these concepts. Moreover, it is possible to monitor very large areas 

with great accuracy by using tomographic algorithms with Guided waves. In addition, multiple 

phased array exciters can be used to focus guided wave energy within structures.

• Pulse echo (PE)

This technique shown as Figure C.190 is pulse echo method in guided wave inspection 

technique. Guided waves propagate from the fixed position with single transducer. Transducer 

receives reflected signal from discontinuities. Once we tuned guided wave mode, then defect 

distance from transducer position based on wave mode velocity. 

Figure C.190 Pulse Echo Technique

• Pitch Catch (Pc)

This technique shown as Figure C.191 is pitch catch method in guided wave inspection 

technique. Guided waves are generated from one transducer and propagate through the 

specimen. The other receiving transducer detects wave signal at the distance from excitation 

transducer. If there are any discontinuities on the specimen, received signal amplitude will be 

decreased or wave mode will be changed with respect to specimen thickness. 

Figure C.191 Pitch Catch Technique

Personnel Requirement for Guided Wave Inspection

• Personnel performing exams has an experience for equipment setup, calibration, 

examination and data evaluation.

• Guided wave mode analysis and dispersion curve analysis knowledge. 
C-247

Inspection Equipment

• Tone-bust pulser

− Ritec – Ritec RPR 4000 instrument with high power voltage

• Oscilloscope 

− LeCroy Wave Surfer 42Xs, Sampling rate is 2.5GS/s

• Transducer and Wedge

− Frequency (500 kHz, 1 MHz, 1.5 MHz, 2.25 MHz)

− Inspection range (Length with respect to Frequency)

− Wedge (20° ~ 70°)

• Calibration

− Wave mode selection

− Group velocity calibration

− Measure weld and edge signal

C.3.5.2 Inspection Technique

Examination Volume

• P4 specimen

Figure C.192
C-248

Guided wave propagates into the specimen. This inspection method can be applied two 

different ways. First, guided wave is generated from axial direction to the specimen, so reflect 

signal from defect and weld can be detected by transducer. The other way is generate guided 

wave along the circumferential direction. Guided wave propagates through the specimen and 

travel whole specimen volume and receive signal from the other transducer. 

• P5 specimen

Figure C.193

There are two different way to inspect on P5 specimen. One is generating guided wave on the 

bottom block. The other way is that generate guided wave from nozzle to weld part. It can detect 

weld delamination and defect between nozzle and weld.

Data Analysis of Guided Wave Signal

Guided wave can propagate long distance on the inspection specimen. With long propagation

distance, there are several features on wave RF signal. Over the distance, it is shown on 

Figure C.194, over the long distance on the pipe, some key feature information can be found on 

the signal. 
C-249

Figure C.194 Guided Wave Inspection Signal on the Long Distance Pipe

C.3.6 Phased Ultrasonic Array, Technique ID 22-PA-SAFT1, 22-PA-SAFT2, 

22-PA-TRT1, 22-PA-TRT2

C.3.6.1 Introduction

Scope

• This technical description is applicable to ultrasonic examination for dissimilar metal welds 

and adjacent material utilizing phased array ultrasonic techniques and applicable to the 

open RRT specimens.

• The objective of examination performed in accordance with this procedure is to accurately 

detect, length size and depth size for EDM notches, thermal fatigue cracks, fatigue cracks in 

the specified examination volume.

Personnel Requirement

• Personnel performing exams have experience for equipment setup, calibration, examination, 

time delay setup, signal interpretation, and data evaluation.

Specimens

• P29 specimen has one fatigue crack.
C-250

Figure C.195 Schematic Diagram of P29 Specimen

C.3.6.2 Overview of Inspection System

System

• Phased Array Ultrasonic Testing System: Olympus Omniscan

• Scanner: Manual Scanner

• Software: Tomoview (collection and storing full waveforms)

− MATLAB Program is used for determination of time delay using time reversal method.

Transducer and Wedge

• Total Number of Element: 16 and 32 Olympus Phased Array Ultrasonic Probes

• Frequency: 2.25 MHz

• Elements Size (Length/Width/Pitch): 44.8 mm/26 mm/2 mm (for 16 elements)

: 24 mm/24 mm/0.75 mm (for 32 elements)

Calibration of System

• Instrument linearity check

• Sensitivity of each element using calibration block: 

− Scanning on the calibration block with scanning phased array ultrasonic probes

− Checking the received scattering signals from the SDH in the calibration block

− Adjust amplitude of the received signals to uniform by controlling gain value

220 mm 35 mm

30.3 mm

Inspection 

Surface

Inner 

Diameter

110 mm

FLAW % wt

Inspection 

Surface

Outer 

Diameter
C-251

Figure C.196 Calibration Block 

C.3.6.3 Inspection Technique 

Description of Inspection Technique 

x To enhance flaw detectability, focusing of ultrasonic waves on a target in an inhomogeneous 

medium is a key issue. 

x Time Reversal Technique provides a very robust technique to focus ultrasonic waves 

through inhomogeneous media as compared to conventional focusing techniques. 

If we consider the wave equation in a lossless fluid medium without body force, we have the 

wave equation of pressure, p t   x, , as: 

    2

2 2

1 , , 0 p t p t c t

w

 

w

x

x (C.5) 

In Eq. (C.5), the wave equation contains a second-order time-derivative operator. Thus, if 

p t   x, is solution of Eq. (C.5), then p t   x, also is another solution. Time reversal 

techniques rely on this property. So, if we have a received signal scattered from a flaw 

located in complex material, we have another wave theoretically that is time reversed one. 

Thus, using this property, we could precisely focus on a flaw. 

The D.O.R.T. method is a detection technique that is derived from the theoretical analysis of 

TRM. As shown in Figure C.197, the signal received by the l

th element of the array 

transducer, which has N elements, is defined as 

  

1

N

l lm m

m

rt k t e t

 

  ¦ (C.6) 

where em(t) is the input signal applied to the mth element, klm(t) is the impulse response from 

the l

th element to the mth element and  is the convolution in the time domain. 

If we take the Fourier transform of Eq. (C.5) and use matrix notation, we have 

R KE   Z ZZ (C.7) 

where K(Z), the transfer matrix, is an N u N matrix (Prada et al. 1996). Since we consider 

the linear-time-invariant system, the new input signal at the i

th iteration, Ei

(Z), can be defined 

by 

   i i * 1* ZZZ  E KE (C.8) 

6'+
C-252

where * denotes complex conjugation corresponding to a time reversal. Thus, the received 

signal at the i

th iteration, Ri

(ω), can be written as

( ) ( ) ( ) ( ) i i * 1 ω ωω ω     − =         R KKE (C.9) 

where ( ) ( ) * K K ω ω is called the time reversal operator (Prada et al. 1996). 

Based on the assumptions, a linear time-invariant system and lossless medium, the transfer 

matrix is symmetrical. Thus, the time reversal operator is Hermitian positive. Also, the 

number of significant eigenvalues of the time reversal operator is equal to the number of 

well resolved scatterers (Prada et al. 1996). From the eigenvector corresponding to 

significant eigenvalues, we can obtain the time delays required to focus on the scatterer 

using Eq. (C.10). 

i

it φ

ω

∆ ∆ = (C.10) 

where φi is the phase of the eigenvector.

• Procedure of pre-focused time reversal techniques as follow:

(1) Exciting ultrasonic waves with pre-calculated time delay using conventional method

(2) Received signals are measured by each element of the phased array probe

(3) Calculating eigenvalues and eigenvectors using the receive signals

(4) Determined number of flaws in the specimen using number of signification eigenvalues

(5) Calculating time delay using the eigenvalues for focusing ultrasonic waves on the flaws

(6) Re-firing ultrasonic waves using the calculated time delay

Figure C.197 Procedure of Pre-focused TR Technique

Inspection Classification

• Flaw Indications:

Set the pre-calculated time-delay

(Conventional Method)

Performing the Scan

Flaw like signal?

Acquiring the pre-focused 

interelement signal

Calculate the eigenvalues

and eigenvectors

Calculate the time-delay

Obtain the flaw signal

enough S/N Ratio

Save/analysis

of the flaw signal

Yes

No

No

Yes
C-253

− All indications produced by reflectors, except signals that can be clearly attributed to the 

geometrical or metallurgical properties of the weld configuration, shall be considered as 

flaw indication.

− Amplitude of signals and/or image is more than two time bigger than noise could be 

considered as indications.

• Flaw Location:

− Location of flaw determines based on time of flight of the flaw indications and sound 

velocity of the specimen

• Flaw Sizing:

− Size of the flaw calculate from amplitude of reflected signals from cracks including EDM 

notches

− Also, tip echo method (one of Tip Diffraction Methods) will be apply to calculate size of 

the flaws

Examination Reporting

• Examination reporting is following PARENT RRT guideline:

(1) Parent RRT-Procedure Summary Data Sheet

(2) Parent RRT-DMW Technique Data Sheet

(3) Parent RRT-DMW Inspection Summary Data Sheet

(4) Calibration Data Sheet

• Also, provide A-Scan signals and Scan images of detected flaws in the specimens
C-254

C.3.6.4 Appendix

Calibration Data Sheet

PARENT RRT-Procedure Summary Data Sheet

PARENT RRT-DMW Techniques Data Sheet
C-255
C-256
C-257

PARENT RRT-DMW Inspection Summary Data Sheet

C.3.7 Higher Harmonic Ultrasound Technique, Technique ID 30-HHUT0, 30-

HHUT1

C.3.7.1 Overview

Introduction of Nonlinear Ultrasonic Technique

We applied the nonlinear ultrasonic technique (NUT), higher harmonic ultrasonic technique 

(HHUT) for PARENT Open Test specimens (ID 28, 29 and 30) having the crack in DWM to 

detect the existence of the close crack and measure its depth.

In PARENT Open RRT, we investigated the higher-harmonic generation effect at the crack. Its 

basic principle is the contact acoustic nonlinearity (CAN) that generates the harmonic frequency 

components owing to the crack temporarily closed and opened or the nonlinear pressuredisplacement relation at the contact interface when ultrasonic waves encounter the imperfect 

interfaces shown as Figure C.198. As the result, the acoustic wave waveform becomes

distorted and the higher harmonic frequency components are generated in the transmitted wave

or in the reflected wave from the crack. The magnitude of the harmonic frequency component

depends on the crack opening distance (COD) or the contact stiffness of crack interfaces 

(Abeele and Windels 2006; Biwa et al. 2006; Buck et al. 1978; Jhang 2000; Kim et al. 2006; 

Solodov et al. 2006; Ulrich et al. 2008). 

Thus, it would be possible to detect closed cracks by monitoring the magnitude of the higher 

harmonic frequency component generated in the transmitted or the reflected wave. Usually, 

considering up to the second order nonlinearity, the relative nonlinear parameter (β’) defined by 
C-258

the ratio of the second order harmonic frequency magnitude to the power of the fundamental 

frequency magnitude is used as the monitoring parameter, which is convenient for the relative 

evaluation (Jhang 2000). We were expecting that this parameter would much more sensitive to 

closed-cracks than the conventional linear characteristics of ultrasonic waves. Many studies 

have been done for modeling and verifying this phenomenon (Biwa et al. 2006; Buck et al. 

1978; Hirsekorn et al. 2006; Kim et al. 2006; Ohara et al. 2003; Solodov 1998). 

Figure C.198 The Basic Principle of the Contact Acoustic Nonlinearity 

For the test, we designed the measurement system with PZT transducers and the pneumatic 

clamping equipment. By doing so, the experimental conditions could be consistent, which 

assured the reliable measurement of the ȕ¶. In our experiments, two kinds of inspection methods 

were carried out as follows. 

x Pulse echo (PE) 

This technique shown as Figure C.199 is one of common techniques in ultrasonic testing where 

a pulsed wave is transmitted into the sample and then the reflected signal from discontinuities is 

received. When we know the wave velocity in the material, we can locate the defect. As the 

application of this technique for HHUT, we will use the broadband transducer of 5 MHz mainresonance frequency. We generated the longitudinal waves of 3 MHz high power tone burst. 
C-259

Figure C.199 Pulse Echo Technique 

x V-scan (VS) 

In this technique, the ultrasonic beam path follows V-line shown as Figure C.200. The beam 

path looks V-line when two transducers for transmitting and receiving the ultrasonic are put 

oppositely within one skip distance space. If a crack exists on the beam path, the amplitude of 

the received signal will decrease. By doing so, we can identify the existence of a crack. As the 

application of this technique for HHUT, we used two 45° angle beam transducers. The 

transducer of 2 MHz main-resonance frequency was used as a transmitter and one of 4 MHz 

was used as a receiver to measure the harmonic frequency component sensitively. 

Figure C.200 V-scan Technique 

Sensitivity and Resolution of HHUT 

There is no report on the sensitivity and the resolution of HHUT since it is strongly dependent on 

the equipment and the measurement skill at the present stage. Instead, we have tried to show 

the excellence of HHUT in sizing performance by comparing the lengths of defects artificially 

fabricated in the acrylic and the aluminum specimens by using conventional linear ultrasonic 

technique (UT) and HHUT. UT measures only the amplitude of the reflection or the transmission 

signal, whereas HHUT measures nonlinear parameter by measuring the ratio of the 

fundamental and the second harmonic frequency magnitudes in the transmission or the 

reflection signal. The measured result showed HHUT was more accurate than UT. Details are 

shown in below. 

x Acrylic Specimen 

An acrylic specimen was made of two blocks by being contacted together. One of the blocks 

has flat surface and the other has unevenness on the contacting surfaces. Thus only the outside 

of uneven area will be contacted. Unevenness was fabricated by polishing with #220 sand 
C-260

papers. The picture of the specimens is shown as Figure C.201. There are two kinds of 

specimens with different uneven areas. The change of the contact area according to the 

contacting pressure is shown as Figure C.202 , which was taken by ink print. The initial 

noncontact area in No. 1 specimen is bigger than that in No. 2 specimen, and the initial axial 

length of noncontact areas were measured as approximately 40 mm and 30 mm, respectively. 

According to the increase of pressure, the noncontact area became decreased: The decreasing 

rate in No. 1 was faster than in No. 2, which means that the unevenness of No. 1 specimen is 

smaller than No. 2 specimen. 

Figure C.201 Shape of Defects in Acrylic Specimens 

Figure C.202 The Change of the Contact Area According to the Increase of Contacting 

Pressure 

When changing the contacting pressure, the result of ultrasonic test is shown as Figure C.203. 

The left side of the figure shows the result of the linear method, and right side shows the 

nonlinear parameter using the pulse echo method. The result of the linear method shows the 

large amplitude at the noncontact area while the nonlinear parameter showed the large 

amplitude at the boundaries of contact and noncontact interfaces. This means that the 

boundaries act as partially closed interfaces so that the contact acoustic nonlinearity is activated 

in maximum there. 

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uUGX uUGY

W 

XWWW 

YWWW 

ZWWW 

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W 

XWWW 

YWWW 

ZWWW 

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C-261

Figure C.203 $PSOLWXGHRIOHIWíG%0HWKRGDQGULJKW5HODWLYH1RQOLQHDU3DUDPHWHU

Table C.2 shows the results of measuring the axial length of the noncontact area by using the 

6 dB drop method in UT and by measuring the distance between left and right side peaks of 

nonlinear parameter in HHUT. UT evaluated the size smaller than the real size. Moreover, the 

measured size is decreasing by the increase of the contact pressure. On the other hand, HHUT 

evaluated the size in similar to real size regardless of the contact pressure. These results 

support the usefulness of HHUT for the detection of closed interfaces and for the improvement 

of the sizing accuracy. 

Table C.2 Result of Unevenness Size Measurement at Different Loading (dimension in 

mm) 

Load 

No. 1 No. 2 

6 dB drop method &RQVLGHUȕ¶ 6 dB drop method &RQVLGHUȕ¶

0 kg - - - - 

1000 kg 43 43 34.2 38 

2000 kg 35 42 29.6 32 

3000 kg 30.8 42 27.2 30 

4000 kg 28.2 42 25.3 30 

5000 kg 24.5 42 23.7 30 

0 10 20 30 40 50 0

5

10

15

Distance (mm)

Amplitude

0kg

1000kg

2000kg

3000kg

4000kg

5000kg

0 10 20 30 40 50 0

0.005

0.01

0.015

0.02

0.025

0.03

Distance (mm)

Amplitude

0kg

1000kg

2000kg

3000kg

4000kg

5000kg

0 10 20 30 40 50 0

0.5

1

1.5

2

2.5

3

3.5

4

Distance (mm)

Amplitude

0kg

1000kg

2000kg

3000kg

4000kg

5000kg

0 10 20 30 40 50 0

0.005

0.01

0.015

0.02

0.025

Distance (mm)

Amplitude

0kg

1000kg

2000kg

3000kg

4000kg

5000kg

0Q

0Q
C-262

• CT Specimen

The dimension of the specimen used in our investigation is shown as Figure C.204, which is a 

compact tension (CT) specimen of Al6061 material. This specimen was degraded by the fatigue 

test to initiate a micro-crack from the notch. There are opened cracks around V-notch and 

closed cracks around crack tip. The measurement size from notch to crack tip is roughly 10 mm.

Figure C.204 Geometry of Specimen (dimension in mm)

The magnitudes of the fundamental frequency and the second harmonic frequency at different 

measuring positions along the crack direction from notch are shown as Figure C.205. For this, 

the pulse echo technique was used. The maximum magnitude of the fundamental frequency 

appears at 4 mm, and the crack length was measured by 6.5 mm by using 6 dB drop method. 

On the other hand, the second harmonic magnitude shows the maximum value at 5 mm as well

as has large value until 9 mm, which is close to the real size of the crack. 

(a) Magnitude of the fundamental component (b) Magnitude of the second harmonic 

component

Figure C.205 Result of Crack Length Using Pulse Reflection Method and Nonlinear 

Ultrasound

From this result, we will be able to solve the problem of the conventional ultrasonic technique 

that is to underestimate the size of the crack. The conventional ultrasonic techniques was 

sensitive to only the open crack. However, nonlinear ultrasonic technique was sensitive to the 
C-263

closed crack. Therefore, the evaluation method of the length of the crack using the nonlinear 

ultrasonic, it may become an important technique to verify the integrity of the structure.

C.3.7.2 Introduction of the Experimental Equipment and Setup

Experimental Equipment

The broadband transducer (Olympus) of 5 MHz main-resonance frequency is shown as 

Figure C.206(a). The diameter of the transducer is 10 mm. The angle beam transducer

(Krautkramer) is shown as Figure C.206(b). The yellow one and the blue one have 2 MHz and 4 

MHz main-resonance frequencies, respectively. The size of the transducer is 8 X 9 mm.

(a) (b)

Figure C.206 Transducers Used in (a) Pulse Echo Method and (b) V-scan Method

To generate a high power tone-burst signal, a high-power gated amplifier (RAN-5000 SNAP) 

was used.
C-264

Figure C.207 High Power Pulser-Receiver (RAM-5000 SNAP)

In the experiment, the received signal was A/D converted by using NI PCI-5122 board (National 

Instruments). The board has 100 M/s real time sampling and its resolution is 14 bits. 

Figure C.208 A/D Board (NI PCI-5122)

When the received signal level is too low, it should be amplified. For that, the pulser-receiver

5077PR (Olympus) was used.
C-265

Figure C.209 Pulser-Receiver (5077PR)

Universal motion controller / driver ESP300 (Newport) was used to move the transducer in the 

interval of 1 mm. This controller / driver is used with the motorized linear stage M-433 

(Newport).

Figure C.210 Universal Motion Controller / Driver (ESP300)

Figure C.211 The Motorized Linear Stage (M-433)

And pneumatic system (self-production) was employed to keep constant pressure between 

transducers and specimens. The loaded pressure was 0.7 MPa.
C-266

Figure C.212 Pneumatic System 

Experimental Setup (Pulse Echo) 

To apply the pulse-echo method, the experimental system was set shown as Figure C.213. The 

experimental conditions and parameters were controlled as Table C.3. 

Figure C.213 Experimental Setup 

Table C.3 RAM-5000 & 5077PR Setting Condition 

RAM-5000 & 5077PR Setting

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C-267

Frequency 3 

No. of Cycle 11 

GA Output 50 

Gain + 30 dB 

HPF 1 MHz 

LPF FULL BW 

In the pulse-echo method, the specimen was scanned from 23 mm to 7 mm on Z-axis at interval 

of 1 mm. This Z-axis measurement was conducted repeatedly from 7.5 mm to 22.5 on X-axis at 

interval of 5 mm. 

C.3.7.3 Experimental Setup (V scan) 

To apply the V-scan method, the experimental system was set shown as Figure C.214. The 

experimental conditions and parameters were controlled as Table C.4. 

Figure C.214 Experimental Setup 

Table C.4 RAM-5000 & 5077PR Setting Condition 

RAM-5000 & 5077PR Setting

Frequency 2 

No. of Cycle 11 

GA Output 60

Gain + 10 dB 

HPF OUT 

LPF FULL BW 

In the V-scan technique, the specimen was scanned on Y-axis at interval of 1 mm. Likewise, 

with the pulse-echo method, the specimen was scanned on X-axis at interval of 5 mm. 







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C-268

C.3.7.4 The Data Acquisition Process/Parameters 

For acquiring the data by using HHUT method in PARENT specimen, A-scan signal was 

measured in the way of the pulse-echo method shown as Figure C.215. Select a signal from the 

full time echo signal by using a fixed time gate, of which time range covers the echo from the 

welded area only. 

Figure C.215 The Region of Data Acquire (PE) 

On Z-axisWKHVFDQZDVFDUULHGRXWIURPWKHERWWRPWRWKHWRSaPPDWLQWHUYDORIPP

by using motorized linear stage. On X-axis, the data was manually acquired from 7.5 mm to 

22.5 mm at interval of 5 mm. Transducer was placed on the right side of the specimen in order 

to transmit the ultrasonic wave towards the direction perpendicular to the crack propagation 

direction. The other information such as the transmit frequency, the number of cycle and the 

gain of the receiver is tabulated in Table C.3. 

In the V-scan method, A-scan signal was acquired shown as in Figure C.216. Select a signal 

from the full time echo signal by using a fixed time gate, of which time range covers the echo 

from the welded area only. 

Figure C.216 The Region of Data Acquire (VS) 

On Z-axis, the receiver was manually moved from 76 mm to 114 mm and the transmitter was 

manually moved from 136 mm to 174 mm at interval of 1 mm by using motorized linear stage. 

On X-axis, the data was manually acquired from 7.5 mm to 22.5 mm at interval of 5 mm same 

as PE. Transducer was placed on the top side of the specimen. The other information such as 

the transmit frequency, the number of cycle and the gain of the receiver is tabulated in Table 

C.4. 

By converting the scan data from the relevant area same as Figure C.217, the crack size can be 

measured. Here, Z0 is the first scan point and Z30 is the last scan point. 
C-269

Figure C.217 The Converted Axis (VS) 

C.3.7.5 Signal Processing Performed on the Acquired Data 

From the acquired data with each method, the magnitudes of the fundamental frequency (A1) 

and the second harmonic frequency (A2) were obtained by using fast-Fourier transform in the 

WLPHLQWHUYDO3(aV96a2 μs) presumed to be the crack signal. The relative 

nonlinear parameter (Ec

) was calculated from Eq. (C.11). 

2

2

1

A

A Ec (C.11) 

Fast-Fourier transform was processed in MATLAB. Here, zero-padding was 200 times to length 

of the data and any window function was not applied. 

C.3.7.6 Acquired Data Analysis for the Technique 

Through the signal processing, the depth of the crack was estimated from the magnitudes of 

fundamental and the second harmonic frequency components, the relative nonlinear parameter. 

The estimation algorithm was shown as Figure C.218. 

Figure C.218 Flow Chart for Detection and Depth Sizing of Crack 

 \G [G ZG YG X

W

ˎ

ˎ

ˎ

ˎ

ZW
C-270

C.3.8 References

Abeele K and F Windels. 2006. "Characterization and Imaging of Microdamage Using Nonlinear 

Resonance Ultrasound Spectroscopy (NRUS): An Analytical Model." In Universality of 

Nonclassical Nonlinearity, pp. 369-388, Ch. 23. ed: P Delsanto. Springer, New York.

Biwa S, S Hiraiwa and E Matsumoto. 2006. "Experimental and Theoretical Study of Harmonic 

Generation at Contacting Interface." Ultrasonics 44, Supplement:e1319-e1322.

Buck O, WL Morris and JM Richardson. 1978. "Acoustic Harmonic Generation at Unbonded 

Interfaces and Fatigue Cracks." Applied Physics Letters 33(5):371-373.

Cheong YM, JH Kim, JW Hong and HK Jung. 2000. "Measurement of Dynamic Elastic 

Constants of RPV Steel Weld due to Localized Microstructural Variation." Journal of Korean 

Society of Nondestructive Testing 20(5):390-396. In Korean.

Hirsekorn S, M Hirsekorn and PP Delsanto. 2006. "Nonlinear Ultrasonic Transmission Through 

Thin Bonded Interfaces: Theoretical Background and Numerical Simulations." In Universality of 

Nonclassical Nonlinearity, pp. 231-250, Ch. 15. ed: P Delsanto. Springer, New York.

Jhang K-Y. 2000. "Applications of Nonlinear Ultrasonics to the NDE of Material Degradation." 

IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control 47(3):540-548.

Kim J-Y, A Baltazar, JW Hu and SI Rokhlin. 2006. "Hysteretic Linear and Nonlinear Acoustic 

Responses from Pressed Interfaces." International Journal of Solids and Structures

43(21):6436-6452.

Ohara Y, K Kawashima, M Murase and N Hirose. 2003. "Identification of Sintered Irons with 

Ultrasonic Nonlinearity." In Review of Progress in Quantitative Nondestructive Evaluation, Vol. 

22, pp. 1257-1264. July 14-19, 2002, Bellingham, Washington. American Institute of Physics, 

Melville, New York.

Prada C, S Manneville, D Spoliansky and M Fink. 1996. "Decomposition of the Time Reversal 

Operator: Detection and Selective Focusing on Two Scatterers." The Journal of the Acoustical 

Society of America 99(4):2067-2076.

Solodov I, K Pfleiderer and G Busse. 2006. "Nonlinear Acoustic NDE: Inherent Potential of 

Complete Nonclassical Spectra." In Universality of Nonclassical Nonlinearity, pp. 467-486, Ch. 

29. ed: P Delsanto. Springer, New York.

Solodov IY. 1998. "Ultrasonics of Non-linear Contacts: Propagation, Reflection and NDEapplications." Ultrasonics 36(1–5):383-390.

Ulrich TJ, AM Sutin, RA Guyer and PA Johnson. 2008. "Time Reversal and Non-linear Elastic 

Wave Spectroscopy (TR NEWS) Techniques." International Journal of Non-Linear Mechanics

43(2):209-216.
C-271

C.4 USA Detailed Technique Descriptions

C.4.1 Eddy Current Technique, Technique ID 7-ECT1

C.4.1.1 Overview

The data were taken using an eddy current insptection technique. This is a well-established 

technique for finding surface defects in conducting materials. In it, a coil is excited with an AC 

current at one or more frequencies. The magnetic field from the coil induces eddy currents in 

the test specimen. These eddy currents diffuse through the specimen. Defects in the specimen 

cause changes in the amplitude and direction of these eddy currents. These changes can be 

measured as changes in either the impedance of the exciting coil, or as changes in the 

amplitude and phase of the voltage induced in a second receiving coil. In the technique used 

here, we employed the receiving coil. This approach is illustrated in the Figure C.219. 

Figure C.219 Illustration of Eddy Current Testing Flaw Detection Using Separate Exciter and 

Receiver Coils

In the approach used for these tests, a flexible probe consisting of an array of exciter and 

receiver coils shown in Figure C.220 was used. The exciter and receiver coils are physically 

displaced in the test surface plane, as can be seen in the figure; the displacement was chosen 

to reduce signal variations caused by probe liftoff variations. The largest flaw signal is obtained 

when the flaw lies along the axis formed by the centers of the two displaced coils. In operation, 
C-272

the probe is scanned over the surface of the specimen. For these tests, the scanning was 

performed manually.

Figure C.220 Flexible Eddy Current Probe and Rigid Adapter Board

C.4.1.2 NDE Equipment

A CoreStar Omni 200 ET instrument and a Southwest Research Institute (SwRI) flexible eddy 

current probe, shown in the Figure C.220, were used. The probe was SwRI Part Number 

201115836-003. A rigid adapter board (also shown in Figure C.220), Part Number 201115836-

004, was used to connect the flexible array to the eddy current instrument cables. The probe 

includes 9 coils arranged in 3 rows of 3 coils each. The 3 coils in the center are operated as 

exciters; each additional row of 3 coils on either side of the exciter row are used as sensors, 

with the probe operated in driver-pickup mode; that is, one coil is used as an exciter and the 

other as a receiver, for each channel used. The spacing between the exciters and receivers had 

been chosen to minimize the effect of liftoff variations based on tests on different (carbon steel) 

specimens. The probe was operated at a test frequency of 50 kHz. Only a single exciter/

receiver coil set on the probe was used for these tests. The probe phase was adjusted so that 

liftoff variations on the specimens were primarily in the horizontal direction on the instrument. 

The probe was designed for detection of relatively large flaws on rough welded surfaces, and for 

operation at frequencies greater than 50 kHz; it was therefore not surprising that there was no 

siginficant phase difference information that could be used to estimate flaw depth.

C.4.1.3 Data Acquisition Process

For the test performed, the instrument was first set up on a calibration plate. The plate is A36 

steel; it contains 3 EDM notches. The probe was scanned around the plate; the phase of the 

display was rotated to make liftoff variations be primarily in the horizontal direction.

For data acquisition, the probe was scanned manually around the penetration, held against the 

surface by manual pressure. The orientation of the probe was also varied manually; the probe 

was rotated to maximize the response to any observed defect.

C.4.1.4 Data Analysis

No additional signal processing was performed on the data. The technique was developed to 

detect and locate surface-breaking defects. Therefore, analysis consisted primarily of estimating 

the location of the ends of the flaws. 
C-273

Flaw position was estimated using a visual technique in order to eliminate the need for a 

mechanized scanner. Holes were punched in gaps between coils of the probe. Flaw edges were 

estimated by manually scanning the probe and observing the amplitude of coil pairs that had the 

largest signal indication. Locations where the amplitude dropped by 6 dB were designated as 

ends of flaws, and a marker was used to mark the mockup surface through the holes in the 

probe. Generally, 4 marks were made for each observed flaw. The marks can be seen in the 

photographs shown with each flaw. The eddy current instrument impedance plane display was 

recorded at the location of maximum flaw amplitude response.

The position of the marks, and therefore the estimated position of the flaws, was first measured 

using a coordinate measuring machine (CMM) at SwRI. This machine is maintained in 

calibration, with an accuracy much better than 0.1 mm. The machine was set up so that it 

reported X-Y coordinates, with the origin at the plane of the surface of the block and at the 

center of the penetration. The CMM machine was used to generate position values for the 

marks that had been placed on the specimens. Flaw ends were estimated by averaging the 

2 pairs of locations marked for each flaw. Then the X-Y coordinates were converted into R-theta 

values for reporting.

After following this procedure, it was noted that the angular positions were generally accurate, but 

the values of R1 and R2 were too large, especially on blocks P21 and P22. The errors were typically 

5 to 9 mm. Visual examination of the photographs showing the flaws and the marks on these blocks 

clearly showed that the flaw ends were marked much more accurately than reported. Therefore, a 

different method was used for measuring the locations for blocks P21 and P22. For block P21, 

which consists of radially oriented EDM notches, the theta values as determined by the CMM were 

retained. The values of R1 and R2 were determined by measuring the error in pixels in the 

photographs, and determining a scale factor of pixels per mm using the known flaw length. For 

block P22, the location of the flaw ends and the marks were measured in pixels. The 2 marks near 

each flaw end were averaged to provide a positon of each flaw end. Then the error in pixels 

between each actual flaw end and the estimated flaw end was calculated. The error in pixels was 

converted to mm using the reported flaw length. The same scale factor of pixels to mm was used for 

both X and Y axes. Then the estimated flaw end locations were converted to mm, and these X-Y 

coordinates were converted to R-theta coodinates.

C.4.1.5 Self Assessment

The advantages of this type of ET probe are 

• Low cost for the part of the probe that will be subject to wear.

• Possibility of manufacturing with even greater number of coils to ensure 100% coverage 

with a single scan.

• Fabrication technique ensures accurate manufacturing repeatability.

• Probe flexibility greatly simplifies the motions required of a mechanized scanner, especially 

in the case of penetrations that are not normal to the vessel surface.
C-274

The disadvantage of this approach was 

• The use of single layer flexible printed circuit material (used to provide great flexibility) limits 

the number of turns of the coil; hence, the spatial resolution is limited and the operating 

frequency had to be kept at 50 kHz or greater.

PARENT RRT – BMI TECHNIQUE Data Sheet

Procedure ID: 7.1 Tech ID: 7-ECT1

Inspection ID: 7.P21.1 Access: OD

Test Block ID: P21 Date: 2012/11/28

Team ID: 7

Weld Volume Inspected:

Detection: Yes θ1: 0 θ2: 360

Length Sizing: Yes R1: 10 R2: 90

Depth Sizing: No Z1: 0 Z2: 0

Defect

No

θ1 

Deg.

θ2 

Deg.

R1

mm

R2

mm

Z1

mm

Z2

mm

Rmax

mm

Amp

dB

Surface

Breaking Comments

BTE-1 358.5 358.6 27.6 32.1 n/a n/a n/a n/a yes See below

BTE-2 269.7 268.8 27.0 33.7 n/a n/a n/a n/a yes See below

BTE-3 178.5 177.5 26.3 33.3 n/a n/a n/a n/a yes See below

BTE-4 88.9 89.6 22.2 38.2 n/a n/a n/a n/a yes See below

Note: Flaw location end points were determined by using an amplitude drop technique and 

physically marking the probe location at the flaw edges (reference the attached test specimen 

photos showing the marks made on the block to show flaw location). Each mark was then 

measured using the BMI coordinate system. 

PARENT RRT – BMI INSPECTION SUMMARY Data Sheet

Inspection ID: 7.P21.1 Procedure ID: 7.1

Test Block ID: P21 Date: 2012/11/28

Team ID: 7 Access: OD

Weld Volume Inspected:

Detection: yes θ1: 0 θ2: 360

Length Sizing: yes R1: 10 R2: 90

Depth Sizing: no Z1: 0 Z2: 0

Defect

No

θ1 

Deg.

θ2 

Deg.

R1

mm

R2

mm

Z1

mm

Z2

mm

Rmax

mm

Amp

dB

Surface

Breaking Comments

BTE-1 358.5 358.6 27.6 32.1 n/a n/a n/a n/a yes

BTE-2 269.7 268.8 27.0 33.7 n/a n/a n/a n/a yes

BTE-3 178.5 177.5 26.3 33.3 n/a n/a n/a n/a yes

BTE-4 88.9 89.6 22.2 38.2 n/a n/a n/a n/a yes
C-275

PARENT RRT – BMI TECHNIQUE Data Sheet

Procedure ID: 7.1 Tech ID: 7-ECT1

Inspection ID: 7.P22.1 Access: OD

Test Block ID: P22 Date: 2012/11/28

Team ID: 7

Weld Volume Inspected:

Detection: Yes θ1: 0 θ2: 360

Length Sizing: Yes R1: 20 R2: 90

Depth Sizing: No Z1: 0 Z2: 0

Defect

No

θ1 

Deg.

θ2 

Deg.

R1

mm

R2

mm

Z1

mm

Z2

mm

Rmax

mm

Amp

dB

Surface

Breaking Comments

BHE-1

BHE-2

355.7 4.3 29.6 30.0 n/a n/a n/a n/a yes See below

BHE-2 262.0 276.8 27.9 29.5 n/a n/a n/a n/a yes See below

BHE-3 166.8 173.0 27.6 32.0 n/a n/a n/a n/a yes See below

BHE-4 69.1 110.4 25.0 31.1 n/a n/a n/a n/a yes See below

Note: Flaw location end points were determined by using an amplitude drop technique and 

physically marking the probe location at the flaw edges (reference the attached test specimen 

photos showing the marks made on the block to show flaw location). Each mark was then 

measured using the BMI coordinate system. 

PARENT RRT – BMI INSPECTION SUMMARY Data Sheet

Inspection ID: 7.P22.1 Procedure ID: 7.1

Test Block ID: P22 Date: 2012/11/28

Team ID: 7 Access: OD

Weld Volume Inspected:

Detection: yes θ1: 0 θ2: 360

Length Sizing: yes R1: 20 R2: 90

Depth Sizing: no Z1: 0 Z2: 0

Defect

No

θ1 

Deg.

θ2 

Deg.

R1

mm

R2

mm

Z1

mm

Z2

mm

Rmax

mm

Amp

dB

Surface

Breaking Comments

BHE- 355.7 4.3 29.6 30.0 n/a n/a n/a n/a yes

BHE-2 262.0 276.8 27.9 29.5 n/a n/a n/a n/a yes

BHE-3 166.8 173.0 27.6 32.0 n/a n/a n/a n/a yes

BHE-4 69.1 110.4 25.0 31.1 n/a n/a n/a n/a yes
C-276

PARENT RRT – BMI TECHNIQUE Data Sheet

Procedure ID: 7.1 Tech ID: 7-ECT1

Inspection ID: 7.P5.1 Access: OD

Test Block ID: P5 Date: 2012/11/28

Team ID: 7

Weld Volume Inspected:

Detection: Yes θ1: 0 θ2: 360

Length Sizing: Yes R1: 23 R2: 100

Depth Sizing: No Z1: 0 Z2: 0

Defect

No

θ1 

Deg.

θ2 

Deg.

R1

mm

R2

mm

Z1

mm

Z2

mm

Rmax

mm

Amp

dB

Surface

Breaking Comments

12 11.2 31.5 30.8 31.2 n/a n/a n/a n/a yes See below

2 154.0 166.7 42.6 40.6 n/a n/a n/a n/a yes See below

3 284.9 286.1 25.7 39.3 n/a n/a n/a n/a yes See below

Note: Flaw location end points were determined by using an amplitude drop technique and 

physically marking the probe location at the flaw edges (reference the attached test specimen 

photos showing the marks made on the block to show flaw location). Each mark was then 

measured using the BMI coordinate system. 

PARENT RRT – BMI INSPECTION SUMMARY Data Sheet

Inspection ID: 7.P5.1 Procedure ID: 7.1

Test Block ID: P5 Date: 2012/11/28

Team ID: 7 Access: OD

Weld Volume Inspected:

Detection: yes θ1: 0 θ2: 360

Length Sizing: yes R1: 23 R2: 100

Depth Sizing: no Z1: 0 Z2: 0

Defect

No

θ1 

Deg.

θ2 

Deg.

R1

mm

R2

mm

Z1

mm

Z2

mm

Rmax

mm

Amp

dB

Surface

Breaking Comments

1 11.2 31.5 30.8 31.2 n/a n/a n/a n/a yes

2 154.0 166.7 42.6 40.6 n/a n/a n/a n/a yes

3 284.9 286.1 25.7 39.3 n/a n/a n/a n/a yes
C-277

PARENT RRT – BMI TECHNIQUE Data Sheet

Procedure ID: 7.1 Tech ID: 7-ECT1

Inspection ID: 7.P7.1 Access: OD

Test Block ID: P7 Date: 2012/11/28

Team ID: 7

Weld Volume Inspected:

Detection: Yes θ1: 0 θ2: 360

Length Sizing: Yes R1: 23 R2: 100

Depth Sizing: No Z1: 0 Z2: 0

Defect

No

θ1 

Deg.

θ2 

Deg.

R1

mm

R2

mm

Z1

mm

Z2

mm

Rmax

mm

Amp

dB

Surface

Breaking Comments

1 57.7 57.3 55.3 45.6 n/a n/a n/a n/a yes See below

2 109.0 111.5 47.8 55.9 n/a n/a n/a n/a yes See below

3 162.5 165.0 27.7 36.4 n/a n/a n/a n/a yes See below

4 293.3 298.8 36.7 54.0 n/a n/a n/a n/a yes See below

Note: Flaw location end points were determined by using an amplitude drop technique and 

physically marking the probe location at the flaw edges (reference the attached test specimen 

photos showing the marks made on the block to show flaw location). Each mark was then 

measured using the BMI coordinate system. 

PARENT RRT – BMI INSPECTION SUMMARY Data Sheet

Inspection ID: 7.P7.1 Procedure ID: 7.1

Test Block ID: P7 Date: 2012/11/28

Team ID: 7 Access: OD

Weld Volume Inspected:

Detection: yes θ1: 0 θ2: 360

Length Sizing: yes R1: 23 R2: 100

Depth Sizing: no Z1: 0 Z2: 0

Defect

No

θ1 

Deg.

θ2 

Deg.

R1

mm

R2

mm

Z1

mm

Z2

mm

Rmax

mm

Amp

dB

Surface

Breaking Comments

1 57.7 57.3 55.3 45.6 n/a n/a n/a n/a yes

2 109.0 111.5 47.8 55.9 n/a n/a n/a n/a yes

3 162.5 165.0 27.7 36.4 n/a n/a n/a n/a yes

4 293.3 298.8 36.7 54.0 n/a n/a n/a n/a yes
C-278

C.4.2 Phased Ultrasonic Array, Technique ID 7-PA1, 7-PA2

C.4.2.1 Overview

The data was taken using an automated ultrasonic phased array contact examination technique 

that was conducted from the inside surface of each test specimen. The phased array technique 

allows the use of multiple examination angles generated by a single search unit to improve both 

detection capability and examination efficiency. The examinations were performed with the UT 

search unit looking in four directions (toward, away, clockwise, counter clockwise) for detection

and sizing of flaws both parallel and transverse to the weld. Flaws are detected and chacterized 

by evaluating fully merged data from all four directions. Detection is based on multi-directional 

confirmation, signal and spatial characteristics of the flaw. All suspect indications, regardless of 

amplitude, are investigated to the extent necessary to determine accurate characterization of 

the nature of the indication. A separate depth sizing examination was conducted after the 

detection examination to attain the through-wall dimension of each flaw.

Figure C.221 Graphical Illustration of Phased Array Examination on Test Block

C.4.2.2 NDE Equipment

A Zetec Tomoscan-III PA 32/128 UT instrument was used for data acquisition. This system is 

capable of handling up to 128 phased array channels. The system utilizes Ultravision acquisition 

and analysis software, which is Windows-based and uses standard PC hardware for acquisition 

and analysis. Once the system is set up and calibrated, all of the UT parameter and scan 

parameter settings can be saved and then recalled for future use. A-scan, B-scan, end-, side-, 

and C-scan views are available as well as composite views and other options that allow the 

analyst a broad selection of software analysis tools.
C-279

The UT phased array search units for detection and sizing were designed to produce the 

desired beam angles and waveforms in the DM weld materials, yet be small enough to maintain 

satisfactory contact when wavy or rough surfaces are encountered on the inside surface of the 

weld. The 1.5 MHz search unit contains two linear arrays in a pitch-ctach configuration mounted 

on an integral wedge, which incorporates a roof angle to provide geometric focusing of the two 

arrays in the near 1/3 of the weld thickness for the examination of the standard ASME Section 

XI examination volume. The search unit design allows electronic sweeping of the examination 

angle from 60° to 88° at 2° increments. Calibration of the search units and instrument is attained 

by using a standard IIW reference block of the same or similar material containing a 1-inch and 

4-inch radius that are used for measuring angles, exit points, establishing system delay and 

reference sensitivity. The 4-inch radius was used to establish system delay and reference 

sensitivity.

An encoded scanner capable of providing accurate position information was utlized. The 

scanner was capable of performing scan and indexing movements as required and provided 

adequate force to keep the search unit coupled to the component surface. 

Figure C.222 22-Element Phased Array Search Unit

Data Acquisition Process: The data acquisition was performed in instrument Log mode with a 

focal law gain of 14 dB for the detection and length sizing examination and 20 dB for the depth 

sizing examinations. The Log mode allows the T-III acquisition system to utilize the dynamic 

gain range of the amplifier. Data acquisition was performed with the scanner moving 

circumferentially and indexing axaially for both axial and circumferential flaws. Beam direction 

was parallel to the weld for axial flaws and perpendicular to the weld for circumferential flaws. 

The search unit movement rate did not exceed 2-inches per second for circumferential flaw 

detection and depth sizing, 1.5-inches per second for transverse flaw detection, and 0.75-inches 

per second for transverse flaw depth sizing. The maximum increment resolution for detection of 
C-280

circumferential flaws was 0.15-inches while the maximum increment for detection of axial flaws 

was 0.05-inches. The maximum increment resolution for depth sizing was 0.10-inches.

C.4.2.3 Data Analysis

Detection

Prior to analyzing data, the Data Analyst ensures the quality of the data by verifying a number of 

items (20-point checklist is used to verify data quality) and areas not meeting the quality 

acceptance criteria are re-exmained. After the data quality is verified, the appropriate data file is 

loaded, ensuring that each data file has been fully merged. In all of the volume corrected 

displays, the cursors are adjusted to envelop the entire scan area. The color palette range is 

adjusted to provide resolution of the various reflectors throughout the scan and to provide 

optimum image contrast and to ensure that indications are not masked with the background 

noise. The volumetric images for each channel are analyzed to identify areas that exhibit 

deviation from the component geometrical or metallurgical interface responses. Patterns from 

the VC Top (C) pane that exhibit echo-dynamics in the VC (B) pane are considered flaws. All 

suspect indications, regardless of amplitude, are investigated to the extent necessary to 

determine accurate characterization of the nature of the indication. Profilimetry data, thickness 

measurements, contours, and previous data are also utilized in analyzing the detection data. 

Flaw descrimination is procedurialized and conditions are provided and used by the analyst to 

determine if a flaw is present and to determine the flaw location including the determination if a 

flaw is surface breaking. Surface breaking characterization is based on signal and spatial 

characteristics. The flaw signal will drive to 0 inches on the a-scan when the flaw is surface 

breaking. 

Depth Sizing 

A data quality assessment is made similar to the detection analysis as previously stated prior to 

determining the flaw depth. After data quality is determined to be acceptable, the depth sizing 

evaluation is made as described below for axial and circumferential flaws:

Circumferential Flaws: Circumferential depth sizing data is taken using two dual 1.5 MHz 1D 

linear array probes phasing at a 30°–70° azimuthal scans with 1-degree resolution. Data from 

two beam directions (Twd & Awy) is considered and an evaluation of the unmerged data is 

made for several discrete beam angles to establish the flaw depth range and to identify the 

channel providing the greatest flaw depth. Depth sizing data is then evaluated using full and 

discrete merges and Z1 and Z2 are identified. Correction values are considered and applied as 

well as an evaluation of search unit contact that may be affected due to complex inside surface 

geometry. Search units can tilt when indexing over changing elevations so profilometry data is 

considered when evaluating sizing data.

Axial Flaws: Axial depth sizing data is taken using dual 1.5 MHz 1D linear arrays phasing at a 

60°–82° and 40°–46° azimuthal scans with 2-degree resolution. Data from two beam directions 

(Cw & CCw) is considered. Depth sizing unmerged data from two opposing channels is 

evaluated to identify Z1 and Z2. Depth measurements are read directly and corrected for 

cylinder geometry using the software tooling.
C-281

C.4.2.5 Self Assessment

The advantages of this type of technique include:

• Allows the use of multiple elements within a single search unit for multiple inspection angles 

that can be steered and focused to the examination area of interest.

• The use of multiple inspection angles increases the probability of detection.

• Allows for sectorial scanning and simplification of DMW’s with complex geometry.

• A separate detection procedure allows larger indexing for a quicker detection examination. 

The disadvantages of this type of technique include:

• A more complex examination technique which requires personnel with proper training and 

/or experience to implement it.

• A separate depth sizing examination at smaller indexing is required after flaw detection is 

completed. 

C.4.3 Phased Ultrasonic Array, Technique ID 150-PA0

C.4.3.1 Overview

The mockup components (P12 & P37) were evaluated using an encoded outside diameter (OD) 

transmit-receive longitudinal (TRL) ultrasonic phased array technique with continuous flow water 

coupling. Given that the specimen is composed of carbon and stainless steels (dissimilar metal 

weld) and is considered large-bore (thickness between 77–79 mm), a phased array probe was 

chosen with a center frequency of 1.0 MHz for inspection. A frequency of 1.0 MHz will provide 

excellent penetration into the inner diameter (ID) regions of these components while maintaining 

good overall flaw characterization resolution as the nominal wavelength in stainless steel is 

approximately 5 mm. The phased array technique was applied as it is a very versatile and 

adaptable inspection technique. It can be applied to a multitude of different components due to 

the ability to apply a variety of focal styles, a range of focal depths and refracted and skewed 

angles in order to insonify the region or regions of interest with a well-focused beam. This 

volumetric assessment technique can be used to characterize the length, depth, and location of 

flaws present in the inspected volume. 
C-282

Figure C.223 Graphic Showing Electronic Focusing Used in Phased Array Technique 

C.4.3.2 Phased Array Equipment 

Phased array data acquisition hardware 

Data acquisition was accomplished using the DYNARAY® system for all PA probes evaluated in 

this study. This commercially available system is equipped to accommodate a maximum of 256 

channels from PA probes and requires the use of Ultravision® 3 software. Its frequency pulsing 

electronics will drive probes in the 0.2–20 MHz range. The laboratory workstation and 

DYNARAY® data acquisition system are shown in Figure C.224.

Figure C.224 Data Acquisition System and Laboratory Workstation. Left: DYNARAY®

phased array data acquisition system (courtesy of ZETEC®). Right: 

Laboratory workstation for both data acquisition and data analysis, with 

the DYNARAY® system on the lower shelf. 
C-283

C.4.3.3 Necessary Equipment and Function (Figure C.225)

• Dynaray Acquisition System (Zetec Inc.)

− Dynaray Lite will also work – Need minimum of 50 P/R channels

○ Pulse/Receive phased array probe and collect Phased array data

• Ultravision 3 software (Zetec Inc.)

− Setup focal laws and execute scanning

• Ultrasonic phased array probe (Imasonic Inc.)

− Inspection array

• Desktop or Laptop computer with Ethernet connection

− Run the software for data collection and analysis

• Motion control drive unit (MCDU) (Zetec Inc.)

− Provide power and control for scanner. Relay positional information

• GPS 1000 Scanner unit (ATCO Inc.)

− Provide scan and index motion and special encoding information
C-284

Figure C.225 Phased Array Data Acquisition Connection Schematic 

Phased Array Probe 

The 1.0 MHz Imasonic TRL array (Figure C.226) was originally designed for evaluating 

inspection effectiveness of PA methods on components with inlays, onlays, and overlays. It 

consists of two 10-element by 5-element matrix arrays. Each element of the array is 3.5 mm u

3.5 mm with separation of 0.5 mm on each side, thus primary and secondary axis pitch is 4.0 

mm. One array is used for transmitting, the other for receiving ultrasonic signals. This probe has 

DEDQGZLGWK%:DWíG%DQGDQDSSUR[LPDWHO\-mm2

 (1.97-in.2) footprint with a 

customized wedge for data collection in tight geometrical configurations. The 1.0 MHz probe 

was used with a removable outside diameter (OD) contoured Rexolite wedge assembly with a 

wedge angle of 15 degrees. The probe’s nominal wavelength in stainless steel is 5.31 mm 

(0.21 in.) at its average center frequency of 1.1 MHz. Skew angles of r20 degrees were 

possible with this array. 
C-285

Figure C.226 1.0 MHz Transmit-Receive Phased Array Probe

C.4.3.4 Data Acquisition Process and Parameters

Focal Law Development

Before a phased-array probe can be used to perform an examination, a set of focal laws must 

be produced to control the firing of individual elements. The focal laws are inputs to the 

Ultravision® control software, which determines specific elements to excite at specific times to 

allow for proper beam-forming in the material to be examined. The focal laws also contain 

details about the angles being generated, the focal point of the sound field, the delays 

associated with the wedge and electronics, and the orientation of the probe. The inspection 

team uses a software package contained in the Ultravision® 3 software program for producing 

focal laws known as the “ZETEC® Advanced Focal Law Calculator.” The software package 

performs two functions: 1) focal law generation and 2) simulation of the ultrasonic field produced 

by the probe when using the generated laws. The user enters the physical information about the 

PA probe, such as the number of elements and the sizes of the elements, and the wedge 

information, such as the wedge angle and the wedge size, into the program. The desired angles 

and focal distances are then entered, and the software generates the needed delays for each 

element to produce the desired beam steering and focusing in the material. The software beam 

simulation produces a simple image of the probe on the wedge, ray-tracing to show the focal 

depth and steering desired, and density mapping to enable the viewer to see how well the 

sound field responds for a particular angle and whether grating lobes exist that may be 

detrimental to the examination. Figure C.227 shows an example of the ray tracing for a probe on 

the left with the sound field density mapping on the right. It should be noted that this simulation 

is performed in isotropic material; that is, the velocity of sound is maintained throughout any 

angle for a particular wave mode, which is not really the true state for CASS, but enables the 

user to estimate sound field parameters and transducer performance for optimal array design 

and focal law development. 
C-286

Figure C.227 The ZETEC® Advanced Phased Array Calculator is Useful for Generating 

Focal Laws (left) and Simulating the Sound Field for the Focal Law (right) to 

Determine Beam Characteristics

Data Acquisition Parameters

• 1.0 MHz 2×(10×5) element matrix array 

− Transmit-Receive Longitudinal

− Each element pulsed with 500 ns negative 200V square wave excitation (Dynaray)

− True Depth and Half Path focusing techniques (Figure C.228) 

− 20–60 degree azimuthal angle sweep, 3 degree increment

− 0,±10 degree skew angles

• Outside Diameter (OD) inspection

− Raster scan resolution: 1.0 mm scan, 1.0 mm index

− Automated and encoded

• OD contoured Rexolite wedge

− 15 degree wedge angle

• 0 pt., coordinates and scan conventions followed from test block information sheet

• Continuous water loop used for ultrasonic coupling between the wedge and the component

• Circumferential scans (looking for axially oriented flaws)

− Collect data in clockwise and counter clockwise directions

Focal Law 

Generation

Sound Field

Simulation
C-287

• Axial scans (looking for circumferentially oriented flaws)

− Collect data from up-stream and down-stream locations

• Target Focus: Inner Diameter Regions

− ID connected flaws (cracks)

1. Projection – focusing in a specific vertical plane. Parameters: distance from probe reference point, 

sweep angles (start, stop, interval), skew angle(s).

2. True depth – focusing at specific constant depth with all angles focused at this depth. Parameters: 

focusing depth, sweep angles (start, stop, interval), skew angle(s).

3. Half-path – sound path held constant as beam is swept. Parameters: sound path length, sweep 

angles (start, stop, interval), skew angle(s).

4. Focal plane – arbitrary user-defined plane of focus. Low angle path length, high angle path length, 

sweep angles (start, stop, interval), skew angle(s).

Figure C.228 Beam Focusing Options for Phased Array Probes

C.4.3.5 Signal Processing of the Phased Array Data

• Ultravision 3 software was used to reconstruct the phased array data into images. No 

additional filtering or manipulations of the data were conducted. 

C.4.3.6 Analysis of the Phased Array Data

• Phased array image analysis was conducted using Ultravision 3 software to display a variety 

of images including: (Figure C.229) 

− A-Scan (time-amplitude) along selected angles

− C-Scan (Top View) scan vs. index axes – location and length of flaw

− B-Scan (Side View) scan vs. ultrasound axes – depth of flaw
C-288

− D-Scan (End View) index vs. ultrasound axes – length and depth of flaw

• Detection

− Strong response signal(s) present in the ID region of component

○ Signal strength above background noise levels to be considered (greater than 6 dB 

above background)

• Characterization

− Detected signals will be length sized using a −6 dB and loss of signal (LOS) method in 

the D-Scan view

− Depth sizing will be assessed by measuring maximum flaw extent in the B- and/or DScan view(s)

− Overall flaw circumferential and axial location assessed with C-Scan view

Figure C.229 Example of Phased Array Image Data

C.4.4 Laser Ultrasound Visualization Method, Technique ID LUV0, LUV-ASW0, 

LUV-BSW0

Figure C.230 illustrates the laser ultrasound visualization system for material nondestructive 

evaluation/testing. The proposed laser ultrasound visualization system is a fully standalone, 
C-289

self-contained and battery-powered sensor unit. It consists of four major components: laser 

pulse energy delivery system, a miniature piezoelectric transducer (PZT), control and data 

acquisition electronics, and a laptop computer for signal processing and visualization. The 

processes for defect/flaw inspections are as follows: The sensor unit will be placed at a standoff 

distance from the object under testing with the galvanometer scanner facing the surface of the 

testing areas. The end user will push a button, which will generate a trigger signal to start the 

inspection process. Control signals will be generated by the sensor electronics and sent to the 

pulsed laser and the galvanometer scanner. Consequently, the laser pulses are precisely 

delivered onto different locations of the testing object, and swept in a raster scan pattern. As the 

laser pulses are delivered onto each spot, they generate local heating, which induces minute 

surface motions. Such a surface motion propagates through other area of the object, thus 

leading to the generation of ultrasound pulses. It should be emphasized that the laser pulse 

energy used for the ultrasound generation is several orders of magnitude lower than the laser 

material damage threshold, thus causing no damages to testing object. A PZT transducer will be 

placed at a convenient location by the end user on the outer surface of the testing object to 

detect the ultrasound pulses. The PZT sensor signals will be recorded and stored in a laptop 

computer. After a complete scan in the testing area, the stored ultrasound propagation data will 

be processed and displayed. The ultrasound signal propagation characteristics in the testing 

area can be mapped with laser ultrasound generations at different spots. Those signals will be 

in the form of a movie clip for the end users to visualize the ultrasound signal propagation 

characteristics. Consequently, defects including mechanical cracks, stress corrosion cracks,

voids, welding flaws etc., can all be easily visualized without any complicated pattern 

recognition algorithm, ultrasound modeling tools or a well-trained technician. Any maintenance 

personnel should be able to operate the proposed sensor without any difficulty because the 

detections of those defects are straightforward. For example, small mechanical cracks inside 

the testing structure will act as ultrasound wave scatterers, which lead to the formation of ring 

patterns around those cracks in the ultrasound propagation images. 

Figure C.230 A Schematic of the Envisioned Laser Ultrasound Visualization System 

Used for Inline Pipeline Integrity Assessment

It should be noted that the underlying principle of proposed laser ultrasound visualization 

technique is similar to the traditional ultrasound testing in that the ultrasound propagation 
C-290

characteristics in the specimens are monitored, based on which various defects and the state of 

the specimen can be detected and identified. One distinct difference between the proposed 

laser ultrasound and the traditional ultrasound testing is that the proposed method allows the 

defect detection and identification based on two dimensional images instead of only an onedimensional waveform. This is because the ultrasound wave propagations in real-world 

structures are very complicated, as a lot of propagation modes and features could arise due to 

multiple wave bouncing from various boundaries, weld seams, walls and interfaces. 

Consequently, those one-dimensional waveforms are heavily convoluted, and the detections of 

specific features are very challenging. Often, very complicated modeling works are required, 

making it difficult to interpret the ultrasound data. The proposed laser ultrasound technique, 

however, can form the two dimensional images to reveal the ultrasound wave propagations in 

structures. The defects present in structures with complicated shapes and configurations can be 

directly visualized.

The merits of the proposed laser ultrasound visualization sensor system and its advantages 

over other techniques are listed below: 

1. Compact, lightweight, and portable: Using a compact, lightweight and low power 

consumption fiber laser, the whole laser ultrasound sensor system will have a size 

~12"×12"×8", weigh around 20 lbs, and can be powered by a 24V battery. The 

compactness, lightweight and portability of the proposed laser ultrasound visualization 

system makes it practical to be used in the field.

2. Capable of detecting a wide variety of defects: Defects including cracks (partial or full 

cracks), delamination/debonding, voids, porosity, foreign particle inclusions, moisture 

ingression, and material fatigue and work hardening can all be detected using the proposed 

sensor.

3. Compatible with complex shapes and configurations: With the proposed laser 

ultrasound system, there is no need to control the laser incidence angle and laser focus, 

thus making it possible to inspect objects with any arbitrary shapes and configurations.

4. High sensitivity and good spatial resolution: The combination of using short ns- laser 

pulse for ultrasound generation and miniature PZT transducers for ultrasound detection 

enables very high signal to noise ratio, thus leading to very high sensitivity in defect 

detection. Additionally, the laser ultrasound system should allow very good spatial resolution 

(i.e., hundreds of micrometer to ~1 mm) in detecting defected area.

5. High measurement throughput: The high measurement throughput is a direct result of the 

high speed enabled by the laser galvanometer scanner, which can scan in both x and y 

direction with a maximum speed of 2 m/s. 

6. Easy and safe to the operators: In the traditional ultrasound technique, the defect 

detection is based on one-dimensional waveforms. The data interpretations are not 

straightforward and typically involve complicated modeling. The proposed laser ultrasound 

system, however, allows defect detection and identification based on visual images of the 

ultrasound propagation characteristics in the testing object. Additionally, compared to the Xray tomography technique, the laser ultrasound visualization system is much safer to the 

operators, as it does not involve any harmful radiations. 
C-291

C.5 Japanese Detailed Technique Descriptions

C.5.1 Phased Array Asymmetrical Beam TOFD and Phased Array Twin Probe, 

Technique ID 29-PA-ATOFD0, 29-PA-ATOFD1, 29-PA-ATOFD2, 29-PA-TP0

The TOFD method can precisely measure crack depth, but is not suitable for materials with high 

ultrasonic attenuation, such as stainless steel cast piping, austenitic stainless steel piping welds 

and dissimilar welds in vessel nozzles in nuclear power plant equipment.

Two kinds of scanning methods have been developed with a phased array system along with a 

method for analysis of the data (Ishida and Kitasaka 2013). 

One of these scanning methods is a TOFD method with asymmetrical ultrasonic beams of a 

transmitter and a receiver (hereafter PA-ATOFD method; phased array asymmetrical beam 

TOFD method”).

The other is a phased array twin probe method with a transmitter and a receiver (hereafter PATP method).

An analysis method synthesizes plural scanning data with different refraction angles and path 

lengths (hereafter “MA method; multi-angle synthesis method”) acquired by the PA-ATOFD or 

the PA-TP method.

C.5.1.1 Principle of Scanning and Synthesis Methods

Phased Array Asymmetrical Beam TOFD Method (PA-ATOFD Method)

Figure C.231 illustrates a schematic diagram of the conventional TOFD method. Two probes 

with a single element are used for the transmitter and receiver. To change the refraction angle 

with a reflection source it is necessary to change the probes with another incident angle or the

distance between the transmitter and receiver. 

Figure C.232 illustrates a schematic diagram of the phased array TOFD method. We can set the

focus and convergence point of the ultrasonic beams of the transmitter and receiver at arbitrary 

different positions in a material. However, to change the refraction angle with a reflection source 

it is necessary to change the distance between the transmitter and receiver. 

Figure C.233 illustrates a schematic diagram of the phased array asymmetrical beam TOFD 

method. Ultrasonic beams with different refraction angles and path lengths of the transmitter and 

receiver are set at an arbitrary focal and convergence point in the material in order to acquire the 

tip echo of the SCC with different refraction angles. Furthermore, the scanning data are 

synthesized with different refraction angles and different depths of focus point. This synthesis is 

expected to enable us to distinguish easily the echo from reflected sources and noise.
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Figure C.231 Conventional TOFD Method 

Figure C.232 Phased Array TOFD Method 

Figure C.233 Phased Array Asymmetrical Beam TOFD Method (PA-ATOFD Method) 

Transmitter Receiver

Scan

Surface

Surface

Ultrasonic path

Transmitter Receiver

<Side view>

<Top view> <End view>

Scan

Scan

Focal point

(Convergence point)

Focal point

Focal point

(Convergence point)

Surface

Ultrasonic path

Transmitter Receiver

<Side view>

<Top view> <End view>

D䠖Scan angle

D

Scan

Scan

Focal point

-D
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Phased Array Twin Probe Method (PA-TP Method)

Figure C.234 shows a schematic drawing of a phased array twin probe method. In the 

longitudinal (back/forth) direction to the incidence of ultrasound waves, the element 

arrangement in this direction can focus the ultrasonic beam on different refracting angles and 

different focus point depths. The elements were arranged in right/left directions to focus the 

ultrasonic beam at different depths in this direction as well. 

Figure C.234 Phased Array Twin Probe Method 

Multi-angle Synthesis Method (MA Method) 

Figure C.235 illustrates the multi-angle synthesis method. The scanning data are synthesized 

with different scan or refraction angles and different depths of focal point. This synthesis is 

expected to enable us to distinguish easily the echo from reflected sources and noise. 

The scanning data are synthesized by an original calculation program on a PC. 

Surface

Transmitter

Receiver

<Side view>

<Top view> <End view>

D䠖Refraction angle

D

Scan

Scan

Ultrasonic path

Focal point

(Convergence point)

Focal point

-D
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(1) Synthesis of PA-ATOFD method data 

Figure C.235 Multi-angle Synthesis Method (MA Method) (1/2) 

1mm

1mm

Flaw A Flaw B

Noise source A

Noise source B

Transmitter Receiver

Scan angle D1

Scan angle E1

Scan angle = 0

Noise source C

Focal depth d1

Synthesis (averaging) of 

the different scan angle data in focal depth d1

Scan angle = 0

Focal depth d2

Scan angle D1

Scan angle E1

Synthesis (averaging) of 

the different scan angle data in focal depth d2

Synthesis (choosing maximum) of 

the different scan angle data in focal depth d1, d2,
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(2) Synthesis of PA-TP method data 

Figure C.235 Multi-angle Synthesis Method (MA Method) (2/2) 

C.5.1.2 Inspection Procedure 

PA-ATOFD Method 

(A) Procedure 

1. Scan and acquire data by PA-ATOFD method 

2. Determine an analysis section for B-scan analysis by MA method analysis 

3. Analyze and draw a B-scope image by MA method analysis 

1mm

1mm

Flaw A Flaw B

Noise source A

Noise source B

Probe

Scan angle D1

Noise source C

Focal depth d1

Synthesis (averaging) of 

the different scan angle data in focal depth d1

Focal depth d2

Synthesis (averaging) of 

the different scan angle data in focal depth d2

Synthesis (choosing maximum) of 

the different scan angle data in focal depth d1, d2,

Scan angle D2

Scan angle D3

Scan angle D1

Scan angle D2

Scan angle D3
C-296

(B) Equipment

• Transducer (Figure C.236, Table C.5) 

− 2×16 matrix array (Inner surface (near crack side))

− 4×8 matrix array (Inner surface (near crack side))

− 10×25 matrix array (Outer surface (far crack side)

− Transducers are fit with a wedge on the surface of the specimen.

• Pulser/Receiver (Figure C.237) 

− Zetec Dynaray (256ch P/R)

• Delay setting / Imaging software (Figure C.237) 

− Zetec Ultravision(1)

• Scanner (Figure C.237) 

− X-Y 

(C) Calibration

• Use reference block with side drilled hole to calibrate echo height and path length 

− (φ3mm, 4, 8, 12 ~ 36, 40 mm depth)

(D) Scan

• Scan direction Perpendicular to the crack surface

• Scan pitch 1 mm

• Index pitch 2 mm

• Scan angle +40 ~ −40 deg. (maximum)

• Images B, C, D-scope (Ultravision)

 B-scope (MA method)

(E) MA Method Analysis

• PC

 

(1) The delay time of the array probe was originally set be the inspection team..
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• Synthesis calculation program on the MATLAB

• Imaging B-scope

• Synthesis pitch 1 mm

PA-TP Method

(A) Procedure

1. Scan and acquire data by PA-TP method

2. Determine an analysis section for B-scan analysis by MA method analysis

3. Analyze and draw a B-scan image by MA method analysis

(B) Equipment

• Transducer (Figure C.236, Table C.5) 

− 10×25 matrix array (Outer surface (far crack side))

− Transducers are fit with a wedge on the surface of the specimen.

• Pulser/Receiver (Figure C.237) 

− Zetec Dynaray (256ch P/R)

• Delay setting / Imaging software (Figure C.237) 

− Zetec Ultravision

• Scanner (Figure C.237) 

− X-Y 

(C) Scan

• Scan direction Perpendicular to the crack surface

• Scan pitch 1 mm

• Index pitch 2 mm

• Scan angle +45 ~ −45 deg. (maximum)

• Images B, C, D-scope (Ultravision)

 B-scope (MA method)
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(D) MA Method Analysis

• PC

• Synthesis calculation program on the MATLAB

• Imaging B-scope

• Synthesis pitch 1 mm

Table C.5 Array Transducers

Type 2×16 Matrix Array 4×8 Matrix Array 10×25 Matrix Array

Frequency (MHz) 2.25 2.25 2

Elements 32 32 250

Array of elements

(width × length) 2×16 4×8 10×25

Size (mm)

(width × length)

Element

Aperture

7.4×1.8

14.9× 31.8

3.8×1.8

15.8×15.8

3.8×3.0

39.8×79.8

(1) 2×16 matrix array (2) 4×8 matrix array

(3) 10×25 matrix array (4) Example of probe with the wedge

Figure C.236 Transducer
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Figure C.237 Measurement Set-up (Example for the Specimen P37)

C.5.1.3 Team’s Assessment of the Technique Based on the Round-Robin Test Results

Met Our Expectation

• Better result by PA-TP method with MA method for the outer surface scan.

− PA-TP method gives us a defect position by the corner echo. But PA-ATOFD method 

gives us a tip echo only. It is difficult to discriminate a tip eco directly by PA-ATOFD. 

− But for the inner surface scan, PA-ATOFD method gives us a defect position by lack of 

the signal.

To be Improved

• Develop a coupling supply system for the large aperture transducer.

− We frequently met lack of coupling (glycerin paste) on the scanning surface.

• Determine the best transducer specification of the PA-ATOFD method for the inner surface.

− We could not detect the tip echo of the deep defect (20mm~) on the inner surface by our 

PA-ATOFD probe. This result tells us necessity of the larger aperture probe.
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Further detailed assessment should be evaluated with defect destructive information.

C.5.2 Three-Dimensional Synthetic Aperture Focusing, Technique ID 17-SAFT1

C.5.2.1 Principle

Synthetic Aperture Focusing Technique (SAFT) is used to construct an ultrasonic image from 

ultrasonic signals obtained with several transmitter-receiver combinations. When an array 

transducer is used for the acquisition of these ultrasonic signals, ultrasonic waves transmitted 

by one selected transducer element are received by all the transducer elements. By shifting the 

element used for the transmitter, the ultrasonic signals for every transmitter-receiver 

combination are collected.

Let xi be the position of the transmitter, xj be the position of the receiver and x be the position of 

a defect. Here we suppose that an ultrasonic wave transmitted from xi is reflected at x and

received at xj (Figure C.238). The distance between xi and x is denoted by i i r = − x x , and the 

distance between xj and x is denoted by j j r = − x x . If the wave velocity is given by v, the 

propagation time from xi to xj via x is calculated by t r r /v ij i j = + ( ) . 

Conversely, the sum of the distances i j r r + can be calculated with the wave velocity v and the 

propagation time tij, which can be derived from the ultrasonic signals obtained with the receiver. 

If the total travel distance i j r r + is known, the defect position x can be narrowed down. The 

defect position x should be on the circumference of the ellipse determined by the conditions that 

its focal points are xi and xj and the sum of the distances from any point on this ellipse to these 

focal points is i j r r + . A different transmitter-receiver combination provides a different ellipse on 

the circumference of which the defect position x is located. Then, multiple transmitter-receiver 

combinations specify the defect position x. 

Figure C.238 One Combination of Transmitter and Receiver

Let us denote the ultrasonic signals obtained with the combination of the transmitter at xi and 

the receiver at xj by uij(t), which is a function of time. Because the signal amplitude becomes 

large at the time when the ultrasonic wave reflected by the defect arrives at the receiver, uij(tij) is 

expected to have a large amplitude. By using the definitions shown above, uij(tij) can be 

expressed as
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( ) . i j i j

ij ij ij ij

r r

ut u u

v v

  +   −+ − = =        

xxxx

This expression implies that, for an arbitrary position x, uij(tij) has a large amplitude when a 

defect exists at x. To construct an ultrasonic image by SAFT, a data array is prepared to store 

the accumulation of uij(tij) for each discrete point x in the target area of a test object. After the 

ultrasonic signals uij(t) are acquired by measurement for each i and j, the accumulation S(x) is 

calculated by

1 1

( ) for each 

N N i j

ij

i j

S u

v = =

  −+ − =  

 

∑∑ xxxx

x x , 

where N is the number of the elements of the array transducer. Then, S(x) itself provides an 

ultrasonic image that shows high intensity at the place where a defect may exist.

In the above example, the transducer elements are linearly aligned, but the idea of SAFT can be 

expanded for an array transducer that has a two-dimensional array of transducer elements to 

deal with three-dimensional ultrasonic images. That is called three-dimensional SAFT (3D 

SAFT).

The feature and advantages of 3D SAFT UT technique is shown in Figure C.239 as compared 

with the principle of usually used UT technique such as conventional angle beam technique and 

phased array technique (Komura and Furukawa 2010). 

Figure C.239 The Difference of Principle between Phased Array Technique and 3D SAFT UT 

Technique

In the case of conventional angle beam technique and phased array technique shown in

Figure C.239(a), the ultrasonic beam is transmitted to the particular direction, and returned 

beam from the same direction as to the transmitted direction caused by the reflection and/or 

diffraction of defects, geometrical and metallurgical discontinuities. The imaging results of 

inspection show the image which is observed from particular direction of beam transmitted. 

Then the noise echoes, such as geometrical and metallurgical echo, are displayed in the same 
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way as the defect indication. Therefore it is difficult to discriminate the defect indications from 

noise echoes. Furthermore it required the probe scanning in order to transmit the UT beam to 

the exact position of SCC opening and SCC tip, and to acquire the inspection data under the 

suitable conditions. 

In the case of 3D-SAFT UT, on the other hand, UT beam is transmitted by one element of 

matrix array probe, and reflected or diffracted UT wave from the opening of SCC, face of SCC, 

and tip of SCC is detected by transmitted element and other all elements of matrix array probe. 

This action is repeated for transmitting by all matrix array elements. Then the data of (the 

number of line elements × the number of column elements) are stored in the memory of 

equipment. These all data are used to the calculation of SAFT processing as shown in 

Figure C.238, and 3D image within the inspected volume are displayed. By this 3D image data, 

three 2D images, C-scan/B-scan/D-scan image, are drawn.

In this 3D-SAFT technique, the waveform data which have different beam path by the 

combination of transmitted element and received element are used for the image calculation. 

Therefore obtained defect image is the image which is constructed by the data of different view 

directions. Then, random signals such as metallurgical noises are eliminated each other and SN 

ratio of true defect is increased. Furthermore this performance of 3D-SAFT is achieved by the 

inspection without probe scanning. It means the possibility of monitoring the SCC growth at the 

fixed position.

C.5.2.2 Equipment

Figure C.240 shows the inspection system used for this measurement. The inspection 

instrument is MatrixeyeTM 256ch manufactured by Toshiba corporation (Karasawa et al. 2009). 

The ultrasonic transducer consists of 16×16 transducer elements and its nominal frequency is 2 

MHz. The wedge combined with the transducer is an angle beam wedge made of polystyrene, 

and its nominal refraction angle is 45° for longitudinal waves in stainless steel. Table C.6

provides more detailed information.

(a) MatrixeyeTM 256ch (b) Ultrasonic transducer

Figure C.240 Inspection System

Table C.6 Detailed Information about Inspection System

Item Description

Testing method Direct coupling
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Couplant Sonicoat

Frequency 2 MHz

Transducer elements 16×16 (3 mm-pitch)

A/D sampling 30 MHz

Wedge Polystyrene (2,360 m/s)

Sound velocity of test object 5,750 m/s

Refraction angle (calculated) 45.1°

Gain 30 dB

Averaging 8

T/R pattern Ttidori-Rall

C.5.2.3 Data Acquisition

Defects are open on the inner surface of the pipe specimens. The inspections are carried out 

from the outer surface of the specimens. The transducer is placed in such a way that the 

incident direction is perpendicular to the longer direction of the defect. The inspection is 

performed toward both sides of the defect (Figure C.241). Figure C.242 shows how the 

transducer is actually placed. The contact surface of the wedge is flat for the ENSI blocks, and it 

is respectively contoured for the pipe specimens to be matched to the specimen surface where 

the transducer is placed for each case that the incident direction is the axial or circumferential 

direction.

Figure C.241 Inspection Direction

Circumferential flaw

Axial flaw

Flaws are inspected 

from both sides.

weld

weld
C-304

Figure C.242 Probe Placement

Figure C.243 shows the inspection conditions. The x, y and z coordinates are defined as shown 

in Figure C.243 (this definition does not always correspond with the coordinates of a specimen). 

Because the locations and sizes of the defects are disclosed, the transducer is placed as the

“central beam axis” bumps on the defect plane (the plane that includes a defect surface such as 

a crack face) at the distance l from the incident point. Here the “central beam axis” means the 

central beam axis when all the transducer elements are regarded as one transducer element. 

After the ultrasonic signals for every transmitter-receiver combination are recorded, threedimensional SAFT data is generated based on the principle explained in Section C.5.2.1. The 

center point of the area where the data is generated is the point at the distance l from the 

incident point along the center beam axis. The size of the y-z cross-section of the area is 

determined by the length a in the direction parallel to the central beam axis and the length b in 

the direction perpendicular to the central beam axis. Table C.7 shows the values l, a and b

determined for each specimen. The length of the area in the x direction is fixed to 40 mm.

ENSI block Small bore Large bore
C-305

Figure C.243 Inspection Conditions

Table C.7 Parameters for Imaging Range

l (mm) a (mm) b (mm)

ENSI Block 42.5 45 50

Large bore pipe specimen 80 100 120

Small bore pipe specimen 43 80 70

From the three-dimensional SAFT data, two-dimensional SAFT images are constructed on 

several cross-sections to examine the inside of the specimen. At one position of the transducer, 

SAFT images are constructed on 40 y-z cross-sections (20 cross-sections on either side of the 

center section) at 1-mm pitch in the x direction. If the SAFT images obtained at one transducer 

position are insufficient for evaluating a whole defect, the transducer is moved along the longer 

direction of the defect with a 20-mm pitch, and the SAFT images are obtained at each position. 

Also, when the images are not clear enough to evaluate a defect, the transducer is moved 

forward toward the defect to obtain better images.

When an axial defect on a pipe specimen is evaluated, a specimen surface has a curvature in 

the incident direction as shown in Figure C.244. The transducer is placed with this curvature 

taken into consideration. However, the x, y and z coordinates of the data acquisition software for 
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this measurement are the same relative to the transducer as the transducer is placed on a flat 

plate. Because the PARENT protocol prescribes, for the pipe specimens, the x and y

coordinates go along the outer surface of the specimen and the z coordinate is perpendicular to 

the outer surface of the specimen, the prescribed coordinates become inclined with increasing 

distance from the transducer in the circumferential direction, which causes an error between 

these two coordinate systems. As a result, although the true z direction is perpendicular to the 

outer surface of a pipe specimen, a defect perpendicular to the outer surface of the pipe 

specimen is considered to be inclined with respect to the z direction of the coordinate system of 

the data acquisition software when the specimen surface has a curvature in the incident 

direction. In this case, the z component of the defect size is shortened.

Figure C.244 Inspection Conditions for Axial Defect of Pipe Specimens

Let us consider the error due to the above-mentioned problem. The central angle of the arc 

between the incident point and the defect plane is given by

OD

arctan

2r

θ

  =   −  



 , 

where l is the distance between the incident point and the defect plane along the center 

beam axis, and rOD is the outer radius of the pipe specimen. If the true z component of 

the defect size is d, the z component shown by the data acquisition software is d cosθ, 

and then the difference between them is d (1-cosθ), which is the percentage of the true z

component. This percentage is 1% for the large bore pipe specimens and 3.5% for the 

small bore pipe specimens. In this inspection, this error is less than 1 mm. Therefore, 

any correction is not made for this error in this inspection.

If bottom echoes are not obtained in the measurement, the bottom surface is assumed to be the 

level at the depth equal to the pipe wall thickness below the incident point. However, when the 

inner surface of the specimen has a curvature in the incident direction, the z coordinate of the 

inner surface is not constant along the incident direction in the coordinate system of the data 

acquisition software. Then, this causes an error if bottom echoes are not obtained in the 

measurement because the z component of the defect size is obtained by the difference of the z

coordinates between the tip of the defect and the assumed bottom surface. Let rID be the inner 

radius of the pipe specimen. The z coordinate of the inner surface where the defect is located is 

lower than that of the assumed bottom surface by the distance rID (1-cosθ). Therefore, the z
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component of the defect size is shortened due to this gap. In this inspection, any correction is 

not made for this gap either.

C.5.2.4 Data Analysis

After the acquisition of the three-dimensional SAFT data, the defect profile is derived from SAFT 

images. Figure C.245 shows the accumulated images on x-y (C-scan), y-z (B-scan) and z-x 

(D-scan) planes that are obtained by adding up values of the SAFT data along the direction 

perpendicular to each plane. In these images, the z-x plane corresponds to the defect plane 

(this coordinate system corresponds to that of a specimen only when the defect extends in the 

circumferential direction). In the image on the z-x plane, the strong indications a little below the 

center are induced by the corner echoes, and the weak indications that shape the elliptical 

outline above the center are formed by the defect tip echoes.

Figure C.245 Accumulated Images Obtained by Merging SAFT Images (when the defect 

extends in the circumferential direction)

Figure C.246 shows the derivation of defect profile. The left image of Figure C.246 is obtained 

by binarizing the accumulated image on the z-x plane with the noise level used as the threshold. 

The noise level is determined from a set of the SAFT images. This binarized image represents 

the defect shape. The SAFT images on the y-z plane are closely examined one by one to locate 

the tip and corner echo positions as coordinate values, which results in the right graph in 

Figure C.246. In this process, a significant indication is distinguished from a strong noise by 

considering the positional relation between the corner indications and the tip indications, the 

continuity of indications, and the tendency for indications to follow the movement of the 

transducer. The defect depth and length are determined from these results. In this data 

analysis, an indication that cannot be characterized as a noise on systematic criteria is 

evaluated as a significant indication even if that indication obviously seems to be a noise 

because its positional relation is unlikely for a defect.
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Figure C.246 Derivation of Defect Profile

If strong indications are found around the bottom surface just below defect tip indications, that 

defect is considered as a surface-breaking defect. The point of the peak value in the indications 

around the bottom surface is taken as the representative point of the bottom surface. A point in 

the tip indications is selected as the defect apex in such a way that the distance in the z

direction between this point and the representative point of the bottom surface is maximized. 

The depth of a defect is defined by this distance in the z direction. When indications are not 

obtained around the bottom surface and only tip indications are obtained, the bottom surface is 

determined as the level at the depth equal to the pipe wall thickness below the incident point.

To obtain the defect length, each end of a defect is determined as the point where the amplitude 

of an indication around the bottom surface becomes less than the noise level. When indications 

spread over a wide range around the bottom surface and it is difficult to determine the ends of 

the indications, the point where the distance from the bottom surface first becomes less than 1 

mm is taken as an end of the defect. When no indication is found around the bottom surface, it 

is decided that the defect length cannot be obtained.

On a data sheet of the round robin test, the position and the dimensions of a defect is reported 

as the x, y and z coordinates that describe a defect area, which is the smallest cuboid that can 

contain the defect. When a defect area is set up from a measurement result, a defect area is 

considered as a two-dimensional rectangular area perpendicular to the x-y plane, parallel to the 

longer direction of the defect and including the defect apex. The edges of the defect area are 

determined by the defect apex and both ends of the defect.

As mentioned in Section C.5.2.3, a defect is inspected from both sides of the defect. To report 

the x, y and z coordinates of a defect area, the measurement results for both sides of the defect 

should be combined. From the two measurement results, two defect areas are obtained for 

each defect. If the perpendicular distance between the two defect areas is less than or equal to 

10 mm, the conclusive defect area is reported as the smallest cuboid that contains the two 

defect areas. If the perpendicular distance is greater than 10 mm but the tip indications of these 

measurement results intersect with each other, the two defect areas are treated as one 

conclusive defect area and its range in the direction perpendicular to the two defect areas is 

made ±5 mm from the middle point of the two defect areas. Besides, if the above-mentioned 

conditions are not satisfied but any special reason is found such as profile symmetry of both 

sides and correlation of the distributions of indications, the conclusive defect area is reported in 

Binarized image

Z

X

outline

corner echo

Z (mm)*

X (mm)

*In this graph, Z is 0 

on the inner surface.

outline Outline of the flaw depth

length

tip echo

corner echo
C-309

the same manner as the above second case. In the other cases, the two defect areas are 

considered to be caused by independent defects and each area is individually reported as a 

conclusive defect area.

C.5.2.5 Team’s Assessment of the Technique Based on the Round Robin Test Results

Whereas phased array ultrasonic testing has a low accuracy for crack depth sizing at a steep 

slope of the crack profile, 3D SAFT can obtain the overall profile of the crack and an accurate 

depth estimate even at such a steep part.

Although the specimens P1 and P37 include internal cracks, it is difficult to catch an indication 

of the lower end of an internal crack because strong indications around the bottom surface 

obscure weak indications due to the lower end of an internal crack. Therefore, it had to be 

considered that the lower end of an internal crack reaches the bottom surface.

In this round robin test, since the defects exists in the nickel-based alloy welds and several 

specimens have about 80 mm-thick walls, ultrasonic testing results are subject to strong 

attenuation. 3D SAFT has difficulty generating high-amplitude ultrasonic waves and sometimes 

cannot even detect a defect because 3D SAFT uses a transducer that consists of many small 

transducer elements. Therefore, the results show low detectability of the defects especially for 

measuring the axial defects, which require ultrasonic waves to travel a long distance inside weld 

metal. Meanwhile, 3D SAFT obtained the approximate profiles of the detected defects and can 

be expected to estimate the profile of a defect in a nickel-based alloy weld unless ultrasonic 

attenuation causes a significant problem. Although the results of the defect profile estimation 

cannot be evaluated for lack of the information of the true profiles, most of the sizing errors are 

acceptable and it is considered that 3D SAFT provided reliable defect profile estimation. 

C.5.3 Subharmonic Phased Array for Crack Evaluation, Technique ID 6-SHPA1, 

6-SHPA2, 6-SHPA3, 6-SHPA4

C.5.3.1 Overview

Crack can be detected by ultrasound if cracks are open, since ultrasound is strongly scattered 

by the crack. However, if cracks are closed because of compressive residual stress and/or the 

oxide films generated between crack faces, ultrasonic inspection can cause the underestimation 

or nondetection of cracks since ultrasound penetrates through the closed crack. To detect and 

measure defects, a crack imaging method, subharmonic phased array for crack evaluation 

(SPACE) was used. SPACE is on the basis of the subharmonic generation by short-burst waves 

and the phased array algorithm with frequency filtering. There are two types of SPACE. One is 

SAW SPACE which uses surface acoustic wave (SAW), where the array transducer is 

positioned on the crack opening side through a wedge designed to generate SAW. SAW 

SPACE is used to detect defects and measure their lengths. The other one is Bulk SPACE 

which uses bulk longitudinal wave, where the array transducer is positioned on the opposite of 

crack opening side. Bulk SPACE is used to measure the depths of defects.

C.5.3.2 Principle

The schematic of SAW SPACE is shown in Figure C.247. SAW SPACE uses a surface acoustic

wave (SAW). A PZT array transducer with a wedge was used to generate intense ultrasound by 

focusing. The phased array equipment is MultiX LF (produced by M2M). Each element of the 

PZT array transducer was excited by a three-cycle burst of a frequency of 3.5 MHz with 150 V 
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following a delay law for transmission focusing. The scatterings of fundamental and 

subharmonic waves occur at the open and closed parts of defects, respectively. The scattered 

waves received by the PZT array transducer are analog-to-digital converted. Subsequently, they 

are digitally filtered at fundamental and subharmonic frequencies, where the sampling frequency 

was 50 MS/s. After their phased shift following the delay law for reception focusing, they are 

summed. Finally, the root-mean-square (RMS) value is calculated as the intensity at a focal 

point. This process is repeated over a scan area with a step to create images. The image is 

created in sequence for each transmission focal point. The images for all transmission focal 

points can be merged. The fundamental array (FA) and subharmonic array (SA) images 

obtained can indicate the open and closed parts of cracks, respectively.

The schematic of Bulk SPACE is shown in Figure C.248. A PZT array transducer was used to 

generate and receive ultrasound by focusing. The phased array equipment are MultiX LF 

(produced by M2M) and PAL (produced by KrautKramer). Each element of the PZT array 

transducer was excited by a three-cycle burst with 150 V following a delay law for transmission 

focusing. We selected the input frequency of 2 MHz, 5 MHz, and 7 MHz, depending on 

specimens. The scattering of fundamental and subharmonic waves occur at the open and 

closed parts of defects, respectively. The scattered waves received by the PZT array transducer 

are analog-to-digital converted. Subsequently, they are digitally filtered at fundamental and 

subharmonic frequencies. After their phased shift following the delay law for reception focusing, 

they are summed. Finally, the root-mean-square (RMS) value is calculated as the intensity at a 

focal point. This process is repeated over a scan area with a step to create images. The image 

is created in sequence for each transmission focal point. The images for all transmission focal 

points can be merged. The FA and SA images obtained can indicate the open and closed parts 

of cracks, respectively.

Figure C.247 Schematic of SAW SPACE

Transmission focal points

Wedge

r θ

Merged FA image

Closed 

crack

Open 

crack

FA images

SA images

Closed 

crack

Open 

Open crack

crack

Closed 

crack Closed 

crack Closed 

crack

Phased array 

with digital filter

SAW SPACE

Array 

transducer

SAW

(Rayleigh wave)

Wedge

Crack

Merged SA image

Crack
C-311

Figure C.248 Schematic of Bulk SPACE

C.5.3.3 Procedure and Technique

We selected four techniques, which are SHPA01, SHPA02, SHPA03, and SHPA04 as follows:

• [SHPA0]

− FA image (5 MHz) of Bulk SPACE

− Phased array apparatus: PAL produced by KrautKramer

− Probe: PZT array transducer (5 MHz, 32 el, 0.5 mm pitch, 10 mm width) produced by 

Imasonic

− Input frequency: 5 MHz

− Input voltage: 100 V

− Scanning condition: 

○ Focus on transmission: depth=15 mm–45 mm (3.5-mm step), θ=10° ~60° (1° step)

○ Focus on reception: depth=15 mm–45 mm (3.5-mm step), θ=10° ~60° (1° step)

• [SHPA1]

− FA image (2 MHz) of Bulk SPACE

− Phased array hardware: PAL (produced by KrautKramer)

Transmission focal points

Crack

Array 

transducer

FA image

SA image

Open 

Crack

Closed 

Crack

Merged FA image

Merged SA image

Phased array with 

digital filter

Open 

Crack

Closed 

Crack
C-312

− Probe: PZT array transducer (2 MHz, 32 el, 0.5 mm pitch, 10 mm width) produced by 

JapanProbe

− Input frequency: 2 MHz

− Input voltage: 100 V

− Scanning condition: 

○ Focus on transmission: depth=15 mm–45 mm (3.5-mm step), θ=10° ~60° (1° step)

○ Focus on reception: depth=15 mm–45 mm (3.5-mm step), θ=10° ~60° (1° step)

• [SHPA2]

− SA image (3.5 MHz) of Bulk SPACE (f/2)

− Phased Array Hardware: MultiX-LF produced by M2M

− Probe: PZT array transducer (5 MHz, 32 el, 0.5 mm pitch, 10 mm width) produced by 

Imasonic

− Input frequency: 7 MHz

− Input voltage: 150 V

− Scanning condition:

○ Focus on transmission: r=14 mm–42 mm (7-mm step), θ=6°–65° (1° step)

○ Focus on reception: 0.5-mm step

• [SHPA3]

− FA image (3.5 MHz) of SAW SPACE

− Phased array hardware: MultiX-LF produced by M2M

− Probe: PZT Array transducer (5 MHz, 32 el, 0.5 mm pitch, 10 mm width) produced by 

Imasonic

− Input frequency: 3.5 MHz

− Input voltage: 100 V

− Scanning condition:

○ Focus on transmission: r=39.5 mm, θ=−14°~15° (1° step)
C-313

○ Focus on reception: r=39.5 mm, θ=−14°~15° (1° step)

C.5.3.4 Self Assessment of the Technique Based on the Round Robin Test Results

In this measurement, we used flat PZT array transducer because the curvature of the specimen 

is not so large. On the other hand, our techniques can be applied to specimens with a large 

curvature by using flexible array transducer or a shoe conformable to the curvature with a delay 

law under the consideration of curvature. 

Specimens P1, P4, P28-P32 were measured by subharmonic phased array for crack evaluation 

(SPACE). As a result, most cracks were visualized in FA images, suggesting that they were 

open. On the other hand, hipped EDM (P4, Nos. 1 and 2) were visualized in SA images, 

suggesting that they were closed. Thus, it was proved that SPACE was capable to detect all the 

cracks of each specimen, and to measure their lengths and depths. In addition, the importance 

of the subharmonic waves with lower frequency than the incident wave was verified to detect 

and measure closed defects in highly attenuating objects with coarse grains or textures.

C.5.4 Large Amplitude Excitation Subharmonic UT, Technique ID 18-LASH1, 

18-LASH2

C.5.4.1 Overview of LASH Technique

LASH (Large Amplitude Subharmonic) technique develops to combine with a SPACE 

measurement system as shown in Figure C.249. When larger amplitude ultrasound is incident 

to the crack subharmonic wave sometime generate at the crack. For the imaging of these 

subharmonic images, commercial phased array system is applied using aperture synthesis 

processing and additional digital filter. However amplitude of transmitted ultrasound is limited 

because larger voltage burst wave of SPACE will be damage to the usual transducers. Thus, 

LASH technique is expected to break this limitation of SPACE in industrial inspection.

Figure C.249 Schematic Diagram of Basic SPACE System

The schematic diagram of LASH (Lager amplitude SPACE) system is shown in Figure C.250. 

Only the ultrasonic transmission components were improved from usual SPACE. We must be 

focus whether the LASH system has an advantage in crack tip echo identification of low S/N 

ratio for conventional SPACE system or not.

Digital filter

受信探触子

(フェーズドアレイ)

aperture synthesis

Fundamental image ω

transmitter

receiver

(phased array)

High voltage 

pulser

ω,ω/2 ω

Subharmonic image ω/2

PAL-3 GA-5000

Digital filter

受信探触子

(フェーズドアレイ)

aperture synthesis

Fundamental image ω

transmitter

receiver

(phased array)

High voltage 

pulser

ω,ω/2 ω

Subharmonic image ω/2

PAL-3 GA-5000
C-314

Figure C.250 Schematic Diagram of Improved LASH System

For the high voltage excitation of SPACE without any damage in transducer, the structure of 

transducer must improve to proof up to 2000 V excitation as shown in Figure C.251. Since the 

fabricated temperature of process is 600 °C which is higher than the Curie point of the PZT, repolarization process with the DC voltage of 1000 V/mm during 30 minutes at 200 °C in silicon oil 

bath is applied after the fabrication of the transducer. We have developed two techniques of 

high voltage pulser (include the transformer coil system) and laminated transducer system as 

the LASH techniques. In this study high voltage pulser up to 1000V excitation was used for the 

large amplitude ultrasound transmission. We call tech ID 18-0 for 400 V excitation LASH 

measurement system which is as same excitation voltage as conventional SPACE 

measurement, and tech ID 18-1 for high voltage excitation LASH measurement system.

Figure C.251 Improvement for High Voltage Transducer

In comparison of the spatial resolution with conventional inspection imaging and the SPACE, 

our SPACE system applied here is a laboratory system which used 32 element phased array 

and 8 bit RF signals for subharmonic imaging by aperture synthesis improving the old 

commercial phased array system. Therefore, obtained images may be inferior to the one by 

modern phased array systems (e.g., 128 element and 10 bit) in measurement sensitivity or in 

spatial resolution. However the most important point here is whether the SPACE technique has 

an advantage in crack tip echo identification or not in case that the estimated crack tip show 

lower S/N ratio in conventional inspections. If the advantage of SPACE can be found for even 

some of the cracks, higher resolution and sensitivity can be improved by replacing the old 

phased array system of present SPACE to the modern commercial phased array system in 

future.

C.5.4.2 Inspection Procedures for Open Specimens

Since all the positions of cracks in each our measurement specimens were open, we positioned 

the transducers to given crack positions and only the detectability of crack tips were investigated 

using LASH. In these measurements, single B-scope was measured by aperture synthesis 

procedures with LASH system.

ω,ω/2 ω

○ SHPA (SPACE)

Phased Array

Imaging

Pulser

ω,ω/2 ω

○ SHPA (SPACE)

Phased Array

Imaging

Pulser

ω,ω/2 ω

High Voltage proof

Transmitter Phased Array

Imaging

○ LASH (Large amplitude SPACE)

High Voltage

Pulser

ω,ω/2 ω

High Voltage proof

Transmitter Phased Array

Imaging

○ LASH (Large amplitude SPACE)

High Voltage

Pulser

Cable

Ag paste

Ag paste

(at 600 °C)

Cu 

plate

element

electrode

Insulation resin
C-315

Furthermore only for the cracks in which crack tips can be clearly observed in subharmonic 

B-scope images, three dimensional B-scope images were measured using the encoder system 

with 1.3 mm pitch as shown in Figure C.252 to estimate of the three dimensional crack shape. 

Reconstruction of the three dimensional B-Scope images was made at the parallel positions 

along the weld line. Since this scanning equipment with encoder also fabricated for laboratory 

use, fairly good image can be obtained for flat surface specimen of P-28 㹼 P-32, however 

significant measurement can’t be made for large curved surface specimens of P-1 and P-12. 

Thus, B-scan image at the center position of each given crack position was measured as a 

standard inspection data and a three dimension image with encoder system obtained as an 

optional one in this report. 

Figure C.252 Three Dimensional Inspection with Encoder 

C.5.4.3 Experimental Results 

Small Flat Specimen 

Representative B-scan images at the center of given crack position of P28 specimen were 

shown in Figure C.253. Left image was a fundamental 5 MHz image (correspond to 

conventional inspection of linear ultrasound) and right one was a subharmonic 2.5MHz image. 

Red line shows a position of a back surface and black dot line shows a crack tip from the given 

crack position. 

B-scan images for specimen P30, P31 and P32 were shown in Figures C.254–C.256. All the 

images were obtained by 1000 V excitation which expected to obtained the highest S/N ratio of 

crack tip echo comparing to the one by standard 400 V excitation of conventional SPACE. 

Figure C.253 B-Scope Image of P28 Specimen 

Scanning

Encoder RF data store

3D Inspection 

image

BPF4-6 32db BPF2-3 54db

P28 1000V

X=12
C-316

Figure C.254 B-Scope Image of P30 Specimen

Figure C.255 B-Scope Image of P31 Specimen

Figure C.256 B-Scope Image of P32 Specimen

Measurement condition of amplitude and applied band path filter for each imaging were 

described in top of each figure. All the obtained images of specimen P28, P30, P31 and P32 

show low S/N ratio in crack tip echo detection due to the large backscattering from 

microstructure around the welding area. Only in P28 image in Figure C.253, crack tip could be 

detected especially in right subharmonic image. However in all the specimens crack tip cannot 

be clearly detected both by linear and nonlinear ultrasound measurement.

B-scan images for specimen of P29 for the excited voltage of 400V, 700V and 1000V were 

shown in Figure C.257(a), (b), (c). 

P30

BPF4-6 38db BPF2-3 54db

1000V

X=13

P31

BPF4-6 32db BPF2-3 54db

1000V

X=13

P32

BPF4-6 38db BPF2-3 54db

X=9mm 1000V
C-317

(a) 400V Excitation

(b) 700V Excitation

(c) 1000V Excitation

Figure C.257 B-Scope Image of P29 Specimen

Comparing with the fundamental left images, crack tip echo could be obtained clearly in 

subharmonic right images for all excitation voltage and S/N ratio and the detectability of crack 

tip echo were increasing according to the excitation voltage. In fundamental linear images of left 

one, any crack tip echoes could not be detected due to large backscattering noise. For the 

detection of the crack tip in P29 specimen, thus, especially LASH technique was extremely 

effective. Since we can clearly detect the crack tip echo for P28 and P29 specimens, three 

dimensional imaging procedures using encoder were applied. Sample of the results were shown 

in Figure C.258. Upper one was 3D view and lower one was cross-section view. Left one was 

fundamental images and right one was subharmoinic images.

P29

BPF4-6 37db BPF2-3 54db

X=11mm 400V

P29

BPF4-6 37db BPF2-3 54db

X=11mm 700V

P29

BPF4-6 37db BPF2-3 54db

X=11mm 1000V
C-318

Figure C.258 Three-D View and Cross-section View of P29 Specimen with 1000V 

Excitation

Hatchings in 3D images were the given positions of crack tip and back surface. Though we 

show the 3D images only for the specimens P28 andP-29 in this report, significant crack tip 

could not be obtained because of large scattering noise in other 3D images for other specimens.

Large Specimens

Though we tried to detect the cracks of BMI specimens, the curved specimen surface and large 

thickness of the specimen did not match our measurement setup because our system had been 

developed in laboratory use for a flat and small specimen. 

Representative B-scan images at the center of the given position of SCC in P12 specimen with 

1000V excitation were shown in Figure C.259. 

Figure C.259 B-Scope Image of SCC in P12 Specimen

Both in left fundamental image and right subharmonic image, crack tip cannot be detected due 

to the extremely large scattering noise. This might be caused by the bad couplant condition due 

cross-section view

3D view

Back

surface

Crack tip

Back

surface

Crack tip

cross-section view

3D view

Back

surface

Crack tip

Back

surface

Crack tip

P12-SCC Y=-7mm

BPF4-6 40db BPF2-3 54db

1000V
C-319

to the curved surface and to the large thickness of the specimen P12. For the comparison, 

B-scan images of EDM notch in specimen P12 with 1000V excitation with no filter were shown 

in Figure C.260. 

Figure C.260 B-Scope Image of EDM Notch in P12 Specimen

Though EDM notch tip could be recognized at the given position of dotted line due to the large 

amplitude of tip echo, extremely large scattering echoes were also observed. B-scan images of 

flaws 1, 3, 4 in specimen P1 are shown in Figure C.261(a), (b), (c). All the images were 

obtained by 1000 V excitation which expected as higher S/N ratio of flaw tip echo.

Since the thickness of the specimen P1 was thinner than specimen P12, scattering noises from 

microstructures were lower than one of P12 specimen. However, both in left fundamental image 

and right subharmonic image, crack tip echo cannot be detected for the flaw-1, 3, 4. B-scan 

images of flaw 2 in specimen P1 with the excited voltage of 400V, 700V and 1000V are shown 

in Figure C.262(a), (b), (c).

Since Flaw-2 show lower scattering noise than one of other flaws, crack tip echo might be 

detected extremely in higher voltage subharmonic images using LASH technique. However S/N 

ratio of flaw tip echo was not enough and further improvement of the measurement setup 

especially for curved surface specimen will be expected. 

P12-EDM

No Filter 40db

1000V

Y=10
C-320

(a) Flaw 1

(b) Flaw 3

(c) Flaw 4

Figure C.261 B-Scope Images of Flaws in P1 Specimen

P1-FLAW1

BPF4-6 36db BPF2-3 54db

1000V X=108.36mm

ω ω/2

P1-FLAW3

BPF4-6 32db BPF2-3 52db

1000V X=655.05mm

P1-FLAW4

BPF4-6 32db BPF2-3 50db

1000V X=979.16mm
C-321

(a) 400V Excitation

(b) 700V Excitation

(c) 1000V Excitation

Figure C.262 B-Scope Images of Flaw 2 in P1 Specimen

C.5.4.4 Assessment of LASH Technique for the Round Robin Test

We applied LASH techniques with high voltage SPACE of nonlinear imaging inspection system 

up to 1000 V excitation to the five small and two large DMW specimens and obtained following 

conclusions.

P1-FLAW2

BPF4-6 32db BPF2-3 52db

400V X=450.38mm

P1-FLAW2

BPF4-6 32db BPF2-3 52db

700V X=450.38mm

P1-FLAW2

BPF4-6 32db BPF2-3 52db

1000V X=450.38mm
C-322

1. About the crack in small specimen P-28, 29 and the Flaw-2 in large specimen, LASH 

technique up to 1000V was effective for the detection of the flaw tip echo comparing with the 

conventional linear ultrasound technique and conventional SPACE technique. 

2. However an improvement of the measurement setup especially for couplant to curved 

surface specimen will be required. Larger amplitude ultrasonic incident and the improvement 

of the S/N ratio in subharmonic inspection image will also be required.

C.5.5 Higher Harmonic UT, Technique ID 27-HHUT1, 27-HHUT2, 27-HHUT3

C.5.5.1 Overview

Higher harmonic ultrasonic testing (HHUT) detects waveform distortion of the ultrasonic waves 

scattered at cracks or SCC in comparison with the incident sinusoidal tone-burst wave as higher 

harmonic amplitudes. Different from the conventional UT based on the acoustic impedance 

difference, HHUT is free from the grain boundary scattering noise, therefore it can detect closed 

cracks and SCC with high S/N ratio.

We apply an immersion higher harmonic imaging technique (HHIT) for detecting cracks and 

SCC.

C.5.5.2 Principle of Higher Harmonic UT and Higher Harmonic Imaging

Waveform Distortion and Harmonic Generation

Ultrasonic propagation across cracks and SCC in metals could be modeled as shown in 

Figure C.263. The cracked face has high stiffness for compressive stress, however, it has far 

lower stiffness in tensile stress. When a sine burst wave is sent for a cracked face, the 

transmitted wave across the face is severely deformed. The fast Fourier transformation (FFT) of 

the transmitted wave has many higher harmonics in frequency domain as shown in 

Figure C.264. By using an analog high pass filter with appropriate cut-off frequency, we could 

extract desired higher harmonics.
C-323

Figure C.263 Waveform Distortion of the Incident Sine Wave at Crack Face

Figure C.264 Extraction of Higher Harmonics Using Analog High Pass Filter

Immersion Higher Harmonic Imaging of Cracks and SCCs

The higher harmonic imaging system is composed of a sine burst wave pulser, a focused 

transducer, an in-plane scanning unit, analog high pass filters, an A/D wave memory and 

imaging software. The burst wave pulser, RITEC RPR-4000, transmits high power sinusoidal 

wave with low noise of harmonics. The higher harmonic waveforms scattered at cracks or SCC 

are extracted by using the analog high pass filter and stored in the wave memory and the 

harmonic amplitude is mapped on X-Y plane. 

The main units of the imaging system are shown in Figures C.265–C.267. For angular

incidence, the transducer is mounted on the attachment shown in C.267. 
C-324

Figure C.265 Higher Harmonic Imaging System

Figure C.266 Measurement Setup for Normal Incidence
C-325

Figure C.267 Measurement Setup for Angular Incidence

Examples images of crack or SCC are shown in Figures C.268 and C.269. These images are 

constructed by using imaging software of InsightScan and InsightAnalysis. The C-scan images 

in Figures C.268 and C.269 are the best images of crack or SCC corresponding to the slice

gates shown in Figure C.270. 
C-326

Figure C.268 Example of C-, B-, and D-scan Images, Waveforms and FFT of Normal 

Incidence
C-327

Figure C.269 Example of C-, B-, and D-scan Images and Waveforms of Angular Incidence
C-328

Figure C.270 Slice of Gates for C-scan

The B- and D-scan images show the horizontal and vertical cross-section along the horizontal 

and vertical red line in the C-scan image. The waveform at the cross point of the horizontal and 

vertical red lines is shown.

In this in-plane X-Y scanning, as shown in Figure C.271, the ultrasonic beam is deflected away 

from the focus depending on the incident point. Thus the length of circumferential crack or SCC 

is underestimated.

Figure C.271 Beam Deflection by In-plane Scanning
C-329

C.5.5.3 Inspection Technique by Normal Incidence

Setting

• Transducer: Frequency 5 MHz, Focal length 76 mm, element diameter 9.6 mm

• Transmission: 4 MHz, 3 cycle, 240V

• High-pass filter: 8 MHz

• Receiver gain: around 54 dB with 8 MHz high-pass filter

• Angle of incidence: 0 (normal) 

Imaging

• Scan pitch 0.25 mm (X, Y)

• Slice gate for C-scan (20 division)

• Scanning velocity : 20-30 mm/s

• Display: C, B & D

• Imaging higher harmonic: 3rd harmonic (12 MHz)

Calibration

• No calibration because of no suitable calibration blocks for HHUT.

C.5.5.4 Inspection Technique by 5-degree Angular Incidence

Setting

• Transducer: Frequency 5 MHz, Focal length 76 mm, element diameter 9.6 mm

• Transmission: 4 MHz, 3 cycle, 240V

• High-pass filter: 8 MHz

• Receiver gain: around 54 dB with 8 MHz high-pass filter

• Angle of incidence: 5 degree for cylinders.

Imaging

• Scan pitch 0.25 mm (X, Y)

• Slice gate for C-scan (20 division)
C-330

• Scanning velocity : 20-30 mm/s

• Display: C, B & D

• Imaging higher harmonic: 3rd harmonic (12 MHz)

Calibration

• No calibration because of no suitable calibration blocks for HHUT.

C.5.5.5 Inspection Technique by 2-degree Angular Incidence for Rectangular Blocks

Setting

• Transducer: Frequency 5 MHz, Focal length 76 mm, element diameter 9.6 mm

• Transmission: 3.5 MHz, 2 cycle, 240V

• High-pass filter: 10 MHz

• Receiver gain: around 58 dB with 10 MHz high-pass filter

• Angle of incidence: 2 degree 

Imaging

• Scan pitch 0.25 mm (X, Y)

• Slice gate for C-scan (20 division)

• Scanning velocity: 20-30 mm/s

• Display: C, B & D

• Imaging higher harmonic: 3rd harmonic (10.5 MHz)

Calibration

• No calibration because of no suitable calibration blocks for HHUT.

Pipe Square Block

Frequency of burst waves 4 3.5

Cycles of burst waves 3 2

Frequency of high-pass filter 8 MHz 10 MHz

Angle of incidence 0 or 5 degree 2 degree
C-331

C.5.6 Orthogonal Coil Array Eddy Current, Technique 16-ECT1

C.5.6.1 Overview

Eddy Current Testing (ECT) is one of nondestructive testing methods using electromagnetic 

interaction and has high detectability for surface breaking cracks. A test object should be made 

of a conductive material. ECT is performed with a probe that consists of a single or multiple

coils. When a probe is placed on the surface of a test object and an alternating current is 

applied to a coil of the probe, a magnetic field is induced around the coil (this process is called 

excitation). This magnetic field penetrates into the surface of the test object and generates a 

circulating current, which is called eddy current, in the test object. If a defect exists in the test 

object, the defect interferes with this current flow. Then, a coil of the probe can detect a change 

of the magnetic field caused by this current flow and show where the defect exists (this process 

is called detection).

An ECT array probe has several coils so as to inspect a wider area at once.

C.5.6.2 Equipment

The equipment used in this inspection is a commercial ECT system that consists of an 

inspection instrument R/D Tech MS5800 and a ZETEC ECT array probe (E342024D). 

Figure C.272 shows the appearance of this ECT array probe. This ECT array probe has 24 coil 

elements aligned in two rows. Each of 24 output channels of the system outputs ECT signals 

obtained with the corresponding coil element. Figure C.273 shows the coil layout of this ECT 

array probe. Each coil element is 3 mm-wide orthogonal coils that are formed by two coils 

vertically standing on the contact surface and orthogonal to each other. According to the 

specification, the center-to-center distance of the two coil rows is 6.65 mm, and the intervals of 

coils in a row are 4.89 mm. The system employs the impedance (IMP) mode in which both coils 

of a coil element are used for both excitation and detection, and the transmit-receive (TR) mode 

in which one coil is used for excitation and the other is used for detection. Because preliminary 

experiments showed the IMP mode provided better results than the TR mode, only the IMP 

mode is used in this inspection. The excitation frequency is set to 200 kHz.

Figure C.272 ECT Array Probe
C-332

Figure C.273 Coil Layout of ECT Array Probe 

C.5.6.3 Data Acquisition 

The ECT array probe is placed on the inner surface of a test block in such a way that the coil 

rows are perpendicular to the weld line of the test block. The probe is moved along the weld line 

to inspect the surface of an area around the weld line (Figure C.274). In this round-robin test, 

the length of the coil rows can cover the whole areas where the defects exist with one line or 

one circle of movement. 

Figure C.274 Scanning Procedure 

For the pipe test blocks, while the probe is fixed to have contact with the inner surface of a test 

block, the test block is rotated on a rotating rack to make the probe scan an area around the 

weld line (Figure C.275). The wire end of a wire encoder is attached to the outer surface of a 

pipe test block so as to acquire the probe position (Figure C.276). 

6.65 mm

4.89 mm

Width of scan

58.8 mm

weld

defects probe
C-333

Figure C.275 Probe Placement on Pipe Test Blocks

Figure C.276 Wire Encoder Attached to Pipe Test Blocks

For the BMI test blocks, a test block is placed on a turntable, and the probe is fixed on an 

inspected surface of a test block in such a way that the front edge of the probe touches the tube 

in the center of the test block. Then, the test block is rotated on the turntable to make the probe 

scan an area around the weld line (Figure C.277). The wire end of a wire encoder is attached to 

the outer edge of the turntable to acquire the moving distance of the outer edge of the turntable. 

Since the diameter of the turntable is 400 mm, the rotation angle is obtained by dividing this 

moving distance by 200 mm.

For the rectangular test blocks, since the inspected surface is flat, an electric scanner is used to 

make the probe scan the inspected surface (Figure C.278). Only for these test blocks, the probe 

is placed on a test block in such a way that the coil rows are parallel to the weld line and moved 

across the weld line because the rectangular test blocks are elongated in the direction 

perpendicular to the weld line. Figure C.278 shows two blocks are placed together. The right 

block is placed for positioning the probe.

wire

encoder

The wire end is attached 

to the outer surface.
C-334

Figure C.277 Probe Placement on BMI Test Block

Figure C.278 Probe Placement on Rectangular Test Blocks

C.5.6.4 Signal Processing

Since the pipe and BMI test blocks are rotated manually, the intervals of the points to sample 

ECT signals are not constant. To analyze ECT signals smoothly, ECT signals at regular 

intervals are calculated from the measured ECT signals by using linear interpolation. In this 

inspection, these intervals are set to 0.1 mm.

Figure C.279 shows distributions of signal amplitude obtained by inspecting a reference block 

with the equipment explained above. The reference block has four narrow slits that are made by 

wire electrical discharge machining (EDM) across the full width of the block. The depths of these 

EDM slits are 1 mm, 2 mm, 3 mm and 4 mm from the left. As shown in Figure C.279(a), raw 

signals often include noises mainly due to the contact condition between the probe and the 

inspected surface. The differences in the contact conditions among the coil elements give rise to 
C-335

noises that make stripes in a signal distribution. To reduce noises, the following noise reduction 

methods are applied. Note that ECT signals are alternating current (AC) signals and have two 

components (Vx, Vy) that can provide signal amplitudes and signal phases.

Average Noise Reduction

A signal is regarded as a noise according to the following criteria. 

1. The beginning of a signal sequence

The signals at Nav points from the beginning of a signal sequence of each channel are 

always regarded as noises.

2. Small signals

A signal the amplitude of which is less than Vth is regarded as a noise.

3. Signals similar to the average of recent noises

A signal is regarded as a noise when the magnitude of the difference between this signal 

and the average of the noises at the previous Nav points is less than Vth. 

When this average of the noises is calculated, the noise at a point where the signal is 

not regarded as a noise is defined as the average of the noises at the previous Nav

points at that point.

4. Signals similar to the interim average of noises

A signal is regarded as a noise when the magnitude of the difference between this signal 

and the interim average of the noises at the points preceding that point is less than Vth. 

When this average of the noises is calculated, the noise at a point where the signal is 

not regarded as a noise is defined as the average of the noises at the previous Nav

points at that point.

Then, the average of the noises at the previous Nav points is subtracted from an ECT signal at 

each point. At the Nav points from the beginning of a signal sequence, the interim average of the 

noises at the preceding points is subtracted from an ECT signal at each point.

The difference of the material properties between base metal and weld metal causes a 

significant change of an ECT signal when the probe is moved across the border between them. 

Because the rectangular test blocks P28, P29, P30, P31, P32, P38 and P42 have a defect in 

the welded part, only a small part around the defect is analyzed for these test blocks to focus on 

the welded part and avoid picking up indications due to a material difference. However, in the 

case of P38, the defect exists on the border of base metal and weld metal, and the area 

preceding the defect is base metal. Therefore, the average noise reduction is applied backward 

to a sequence of ECT signals for P38.
C-336

(a) Raw signals.

(b) Signals after average noise reduction is applied.

(c) Signals after phase filter is applied.

Figure C.279 Distributions of Signal Amplitude
C-337

Phase Filter

If noises cannot be eliminated enough by the average noise reduction, a phase filter is applied. 

When the excitation frequency is 200 kHz, the signal phase of an indication of a crack parallel to 

the coil rows tends to have a value around 130°, and the signal phase of an indication of a crack 

perpendicular to the coil rows tends to have a value around −50°. Then, to detect a crack 

parallel to the coil rows, the ECT signals are removed at the points where the signal phases are 

out of the range [100°, 160°]. Also, to detect a crack perpendicular to the coil rows, the ECT 

signals are removed at the points where the signal phases are out of the range [−80°, −20°].

The above-mentioned noise reduction methods are applied and the parameters are set as 

follows.

Test Block

Average Noise 

Reduction Phase Filter

P1 Nav=50, Vth=0.2 V Not applied

P4 Nav=50, Vth=0.1 V Not applied

P5, P7, P41 Nav=25, Vth=0.3 V Not applied

P12 Nav=25, Vth=0.3 V Applied

P28, P29, P30, P31,

P32, P38, P42 Nav=25, Vth=0.3 V Applied

C.5.6.5 Data Analysis

A defect indication is defined as a continuous region where the signal amplitude is more than or 

equal to 0.1 V and the maximum signal amplitude of the region is more than or equal to 0.5 V. If 

the minimum gap of two defect indications is less than or equal to 5 mm, these two defect 

indications are treated as one defect indication.

If the aspect ratio of a defect indication is more than or equal to 1.5, the defect is considered as 

an axial or circumferential defect. An axial or circumferential defect is defined as a defect that 

goes through the point of the maximum amplitude of the indication, has a length in the axial or 

circumferential direction and does not have a width. The length of an axial or circumferential 

defect is set to the length of the defect indication in the axial or circumferential direction, 

respectively. If the aspect ratio is less than 1.5, the size of a defect is answered as the minimum 

rectangle that can include the defect indication. In any case, the defect depth is not evaluated.

Furthermore, the length of two adjacent axial or circumferential defects is determined according 

to ASME Boiler & Pressure Vessel Code Section XI IWA-3400.

A preliminary experiment shows the maximum signal amplitude of an indication of a subsurface 

EDM slit is about 0.2 V although the distance between the inspected surface and the top of the 
C-338

slit is less than 0.5 mm. Then, all detected indications are considered as surface-breaking 

defects.

C.5.6.6 Team’s Assessment of the Technique Based on the Round Robin Test Results

Except the defects of the BMI test block P7, all the defects of the inspected test blocks were 

detected. From this result, it can be said that these defects can be sufficiently detected with a 

commercial ECT system. For the defect of P7, more detailed analysis is required to clarify the 

exact cause of the detection failure and verify whether these weld solidification cracks are 

appropriate to simulate PWSCC.

Although most of the defect indications are sufficiently clear, reducing more noises in the signals 

provides more accurate information to discriminate and evaluate defects. More study is 

expected to find a more appropriate way to place the probe and an effective signal processing 

method.

C.5.7 Advanced Eddy Current, Technique ID 33-AECT1

C.5.7.1 Overview

Eddy current testing (ECT) is an analysis using electromagnetic induction whereby flaws in 

conductive materials can be detected. A pancake coil carrying current is placed near the test 

specimen. When an alternating current is supplied to the coil, the magnetic field is changed 

through interaction between the specimen and the eddy current generated near the surface of 

the specimen. Variations in the phase and amplitude of the eddy current can be detected using 

a receiver coil. 

A differential probe is used that easily distinguishes signals from a flaw and background noise, 

because the flaw detection signal features a characteristic loop. However, the drawback is that 

this signal is hard to detect by simple scanning and placement of the detection coils. The signal 

is only significant when the pair of coils scans in a direction perpendicular to the longitudinal 

direction of the flaw. In contrast, if the scan is parallel, the flaw signal is weaker.

The probe used in the present method has four detection coils which are arranged inside one 

exciting coil. Hence, both perpendicular and parallel defect signals can be obtained irrespective 

of scanning direction of the probe over the flaw. Moreover, the technique is robust against lift-off 

noise. 

In this study, the detection performance and sizing performance of the length are evaluated 

using the multi-probe.

C.5.7.2 Principle of Advanced ECT Method (Multi-probe)

Overview and Operating Principle of the Multi-probe for ECT

Figure C.280 shows a schematic of the coil arrangement of the multi-probe. The multi-probe has 

four detection coils which are arranged inside a circular exciting coil. The detection coils are 

labeled 1−4 in a clockwise sense; coils 1 and 3 are aligned perpendicular to the scanning 

direction, whereas coils 2 and 4 are aligned parallel. Irrespective of scan direction, it is possible 

to obtain flaw signals parallel, perpendicular, and at 45° to the scanning direction by taking 

differences in the detection signals of pairs of coils.
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Figure C.280 Overview of the Coil Arrangement and Scanning Procedure of the Multiprobe

An example of a measurement of thermal fatigue specimen is presented. Figure C.281 shows 

the dye-test results of a crack resulting from thermal fatigue. Figure C.282 shows the detection 

signal obtained from each of the detection coils. Additionally, Figure C.283 shows the amplitude 

of the differential signal of coil pairings 1-2, 1-3, 1-4, and 2-4. The flaw can be evaluated in 

detail based on these defect signals. Branching cracks are seen in Figure C.281 and can also 

be inspected.

Figure C.281 Results of a Dye Test of a Crack Produced by Thermal Fatigue
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Figure C.282 ECT Signals from Detection Coils 1–4 
C-341

Figure C.283 Differential Signals from the Various Coil Pairings
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ECT System with the Multi-probe

Figure C.284 shows a schematic diagram of the ECT system. The ECT was conducted with an 

ECT multi-channel flaw detector (48CH flaw detector, Aswan Electronics Co., Ltd., Osaka, 

Japan), multi probe, motorized XY stage or rotation stage, stage controller, and a DAQ pad or 

data logger. The multi-probe is of differential-type consisting of five pancake coils, one excitation 

coil and four detection coils. The excitation coil with 100 turns has an outer diameter of 5 mm,

an inner diameter of 4.2 mm, and a height of 5 mm. The detection coils, each with 300 turns,

have an outer diameter of 1.5 mm, an inner diameter of 0.7 mm, and a height of 1.3 mm. The 

test frequency in this study is 100 kHz.

Figure C.284 Results of a Dye Test of a Crack Produced by Thermal Fatigue

Scanning Method and Data Collection Method

The motorized XY stage or the rotation stage is used in conducting probe scans. The motorized 

XY stage is used in taking measurements of various specimens labeled Test Blocks P28, P29, 

P30, P31, P32, P38, P42, P46, and P12. The rotation stage is used in taking measurements of 

Test Blocks P37, P41, P5, and P7. When using the motorized XY stage, analog signals from the 

flaw detector are converted into digital signals by the DAQ pad to be stored as data on the PC. 

When using the rotation stage, the detection signals are recorded on the PC using a data 

logger.
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Calibration of ECT Signal

Calibrations were conducted so that the EC signals from a 2-dimensional slit with depth of 1 mm 

and width of 0.33 mm have an amplitude of 1 V and a phase of 90°. The four detector coils are 

calibrated in the same way. The specimen material is Inconel 600; its dimensions are 20 mm in 

thickness, 200 mm in length, and 75 mm in width.

Figure C.285 shows the calibrated signal of the four detection coils. Figure C.286 shows the 

differential signal of coil pairs 1-3 and 2-4. These differential signals feature a characteristic 

figure-of-eight shape with an angle of inclination of nearly 90°.

Figure C.285 Calibrated Signals from the Four Detection Coils
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Figure C.286 Differential Signals from the Multi-coil

For this study we prepared type-316 stainless-steel plate specimens each etched with a 2-

dimensional slit of width 0.2 mm but various depths of 1.0, 2.0, 3.0 or 5.0 mm, as illustrated in 

Figure C.287. Figure C.288 shows the results of measurements of these slits using the multiprobe. These results show that the amplitude varies with slit depth, but the phase does not 

change significantly.

Figure C.287 Dimensions of the Type-316 Stainless Steel Plate Specimen
C-345

Figure C.288 ECT Signals from Slits of Various Depths

Signal Processing Method

Figure C.290 shows the Vy and Vx signals of Test Block P28 obtained by scanning from +22.5 

to −22.5 mm along the X-axis direction about the center (Y=0). The signal change in position at 

10 mm and −10mm on the the X-axis are influences from the boundary of the weld and the base 

metal. The defect signal is the signal change about X=0 mm. Figure C.291 shows a typical

Lissajous waveform. In particular, Figure C.291(a) is a Lissajous waveform of the detection 

signal along the X-axis from −22.5 mm to 25 mm. The large amplitude signal that is inclined at 

30° is a signal change resulting from influences from the weld. Figure C.291(b) shows an 

enlargement of the Lissajous waveform corresponding to the flaw. This signal is characteristic of

a flaw signal with its angle of inclination at nearly 90°. The amplitude at the center of the 

Lissajous waveform will not necessarily be 0 V because of influences of lift-off and the weld. 

Hence, the phase is calculated as the inclination of the changing signal between steps of the 

scan. The phase θ is calculated from the inclination between the (Vx,Vy) signal of the nth and 

(n+1)th turning points,

( ( 1) ( ) )

( 1) ( )

, ( )

n n

n n

Vy Vy ATAN Vx Vx θ +

+

  − =   −  

where Vx(n) and Vy(n) are the values of (Vx,Vy) of the nth turning point. Figure C.292

shows the phase results calculated using the amplitude and a threshold of 80−110°. The 

phase of 80−110° near X=1 mm confirms the presence of a flaw at this position.
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Figure C.289 Composition and Dimensions of Test Block P28

Figure C.290 ECT Signals Vx, Vy of Test Block P28 on Y=0
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(a) On X-axis from −22.5 to +22.5 (b) On X-axis from −5 to +5

Figure C.291 Lissajous Waveform of Test Block P28 on Y=0

Figure C.292 Amplitude and Phase of Test Block P28 on Y=0

Figure C.293 shows a C-scan display of Test Block P28. Specifically, Figure C.293(a) gives the 

amplitude of the flaw signal which is smaller than the noise signal from the boundary of the base 

material and welds, Figure C.293(b) gives the phase of the signal, and Figure C.293(c) displays 

the results from the analysis. The threshold for the amplitude is set so that the absolute value of 

the difference between Vy(n+1) and Vy(n) is more than 0.1V, whereas that of the phase is set at 

80−110°. The threshold of amplitude is 25% or more of amplitude which is determined from the 

calibration signal and the scan pitch. Additionally, if the significant value does not appear 

continuously three times or more, the phase is 0°. The flaw, colored orange in Figure C.293(c),

has a length determined from the result of the analysis.

The length of the flaw is evaluated based on the signal disappearance instructions length from 

the analysis result. If the plural defects are adjacent and intermittent, the length is determined by 

ASME XI IWA-3400 “Linear flaws detected by surface or volumetric examinations.”
C-348

Figure C.293 C-scan Display of Test Block P28

C.5.7.3 Inspection Method for the Test Blocks of P28, P29, P30, P31, P32, P38, P42,

P46, and P12

Figure C.294 shows experimental setup for ENSI-Blocks. The motorized XY stage is used in 

scanning the probe over Test Blocks P28−P32, P38, P42, P46, and P12. At each measurement 

point, the probe measures the ECT signal recorded along with the scanning position information 

and stored on the PC. The scan is taken at intervals of 0.25 mm in both X and Y directions. 
C-349

Figure C.294 Experimental Setup for ENSI-Blocks 

C.5.7.4 Inspection Method for the Test Blocks of P37, and P41

Figure C.295 shows experimental setup for Small DMW P41 using rotation stage. The rotation 

stage is used to scan the probe for Test Blocks P37 and P41. The probe is scanned over the 

inner surface of the pipe in conducting the flaw detection test, as shown in Figure C.296. The

measuring angle and rotational speed of the rotation stage are controlled by the stage 

controller. The Y-axis positioning of the probe is performed manually using a feed screw. The 

ECT signal and time measurements are collected using the data logger. The measurement

position (measurement angle) is calculated from the angular speed of the rotation stage and the 

elapsed time. Finally, the angular measurement is converted to a distance from an origin 0 on 

the outer peripheral.

Figure C.295 Experimental Setup for Small DMW P41 Using Rotation Stage
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Figure C.296 Photo of Multi-probe Inside the Pipe

C.5.7.5 Inspection Method for the Test Blocks of P5, and P7

Figure C.297 shows experimental setup for Small DMW P41 using rotation stage. The rotation 

stage is used to scan the probe over Test Blocks P5 and P7 (BMI; Bottom Mounted 

Instrumentation) to perform flaw detection around the pipe, as shown in Figure C.298. The

measuring procedure is the same as in Procedure-2. The ECT signal and elapsed time 

measurements are recorded using the data logger. The measurement position (measurement 

angle) is calculated from the angular speed of the rotation stage and elapsed time 

measurements.

Figure C.297 Experimental Setup for BMI Using Rotation Stage
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Figure C.298 Status of Multi-probe

C.5.7.6 Team’s Assessment of the Technique, Based on the Round Robin Test Results

1. What is the purpose and advantage of the emerging technique (what problem was it 

developed to solve?)?

• The present probe consists of differential receivers and an exciter surrounding receivers, 

and this configuration allows high detectability to small cracks according to the experience 

obtained by the team. In addition, the receiving unit of the probe has two pairs of differential 

coils which are aligned perpendicular to each other. Using two sets of differential signals, 

the probe can detect and evaluate flaws having various directions without rotating the probe. 

Moreover, the technique is robust against lift-off noise.

2. Provide a brief assessment of the results of your testing, specifically regarding the ability of 

the technique to detect and size (length/depth) flaws? 

• Small Test Blocks (P28, P29, P30, P31, P32, P38, P42, P46), DMW Test Blocks (P12, P37, 

P41) and BMI Test Blocks (P5, P7) were evaluated using the multi-probe for eddy current 

testing.

• The flaws located in the weld could be detected, and the length values were evaluated with 

relatively good accuracy.

• However, the signals of flaws lying on the bond of welds include the large amount of noise

and length sizing for these flaws did not work well. In the cased of closed flaws, the 

detectability is low. 

3. Were there any problems/issues that limited application of the technique to the test blocks?

• How often was the technique usable to its full extent (for example, could the technique only 

be applied to the flat ENSI test blocks, but not to curved surfaces?)?
C-352

− In the case of manual inspection of BMI, due to the curvature of welds of penetrating 

pipes, it is difficult to keep constant inclinations, which lead large noises of 

measurements. 

• If there were limitations of the technique, please provide your ideas about how these 

limitations may be overcome in the future. 

− It is necessary to apply a scanner which automatically positions the probe keeping the 

inclination with respect to the weld lines.

C.5.8 Controlled Excitation Eddy Current, Technique ID 5-CEECT1

C.5.8.1 Overview

The technique applied is based on eddy current inspection. The uniqueness of the technique is 

that it would enable to evaluate the depth of deep flaws more quantitatively than conventional 

eddy current testing. 

The physics in action of the technique, which is illustrated in Figure C.299, is basically identical 

that of conventional eddy current testing. That is, the technique emits an alternating magnetic 

field to conductive media to induce eddy currents, and senses the magnetic fields that the 

induced eddy currents generate in order to detect and evaluate a flaw. Measurements are 

carried out on the surface where a flaw opens, and signals are obtained as a function of the 

position of a probe. The amplitude and the phase of the signals are used to estimate the 

position, surface length, and the depth of a flaw. The uniqueness stems from the use of a probe 

consisting of vertical exciters and a horizontal detector situated away from the exciters. The 

physical background of the technique is explained in Yusa et al. (2011) together with several 

experimental validations. 

Figure C.299 Physics in Action

Signals obtained through the technique are maximized above the edges of a flaw, which can be 

used to estimate the position and the surface length of the flaw. The depth of a flaw is evaluated 

on the basis of the relation between the phase of a signal and the depth of a flaw obtained 

through experiments or numerical simulations conducted to gather signals due to artificial slits 

with known depths. Whereas these approaches are basically same with those used in 

conventional eddy current testing, the technique has such advantage that the phase of signals 

changes clearly with the depth of a flaw even though the flaw is several times deeper than the 

depth of penetration as depicted in Figure C.300. 
C-353

Figure C.300 The Advantage of the Technique

One of the largest problems about the technique is that the effect of flaw parameters on 

measured signals is not fully revealed. Whereas earlier studies have confirmed the depth of a 

flaw affects signals significantly, they have also revealed that the length of a flaw has a large 

effect on signals. This implies that the technique is sensitive to the cross-sectional profile of a 

flaw much more than conventional eddy current testing, and it is likely that sophisticated 

inversion is needed to quantitatively evaluate the depth of a flaw. The studies revealed that the 

technique cannot show advantage over conventional eddy current testing if the surface length of 

a flaw is shorter than approximately 20 mm, whose physical background has not been fully 

revealed yet. An exciting frequency of 50 kHz has been used in earlier studies; no quantitative 

evaluation on the effect of frequency has been conducted so far. Consequently, the limitation of 

the technique in flaw evaluation has not been clarified. Another practical drawback is that the 

probe used for the technique is much larger those used for the conventional eddy current 

testing. This makes it difficult to scan non-flat surfaces. 

C.5.8.2 NDE Equipment Used to Implement the Technique

The schematic diagram of the equipment is illustrated in Figure C.301. An AC current is 

supplied to the exciter to induce eddy currents inside the target, and signals are measured by a 

lock-in amplifier. The signals are gathered by a PC through an A/D converter. Important pieces 

of equipment are listed below.

• Function synthesizer (WF1974, NF Corporation)

− The function synthesizer generates sinusoidal voltage to excite the exciter. The 

frequency and the amplitude of the voltage in this experiment were 50 kHz and 15Vpp, 

respectively. 

• Bipoler amplifier (HSA4051, NF Corporation)

− The bipolar amplifier was used to amplify the voltage generated by the function 

synthesizer and to feed sufficiently large exciting current to the exciters. The 

amplification in this experiment was set to 40 times. 
C-354

• Oscilloscope (1001B, Tektronix, Inc.)

− The oscilloscope monitored the exciting current by measuring the voltage of the shunt 

resistance to measure the amplitude of exciting current and to confirm that the current 

exhibits no obvious distortion. 

• Lock-in amplifier (LI5640, NF Corporation)

− The lock-in amplifier was used to measure detector signals. The voltage of the shunt 

resistance, which was measured by the oscilloscope, was used as reference signals. 

The lock-in amplifier displayed both in-phase and quadrature components of the signals, 

and output them as DC signals ranging ±10V.

• A/D converter (NR-500, Keyence Japan)

− The A/D converter was used to convert the output of the lock-in amplifier, which is in 

analog, into digital signals that can be recorded by the PC connected with the A/D 

converter with USB.

• PC

− The PC, which is an ordinary PC with Windows 7, recorded the data using dedicated 

data logger software, Wave Logger (Keyence Japan). 

Figure C.301 Connection Diagram

Probe utilized is shown in Figure C.302. The probe had two vertical exciters and one horizontal 

detector. The two vertical exciters generate magnetic fields with the same polarity, which 

induces a directional eddy current directly below the detector. The distance between the 

exciters was set to either 54 or 12 mm. Note that the technique requires situating the detector 

away from the exciters in order that measured signals changes clearly with the depth of a flaw. 

Therefore, when the distance is 12 mm, the measurements become basically same with 

conventional eddy current testing, and signals measured are used only to detect flaws.
C-355

Figure C.302 Probe

C.5.8.3 Data Acquisition Process/Parameters

• Automated or manual: manual

• Encoded or not: no

• Access surface on test blocks: surfaces where the flaw opens

• Data acquisition speed: 10 kHz

Details are given in the reports.

C.5.8.4 Signal Processing Performed on the Acquired Data

There is no signal processing performed on the data.

C.5.8.5 Acquired Data Analysis Process for the Technique

Signals due to a flaw are distinguished from noise on the basis of the fact that a flaw should 

provide two signal maximums whose phases are opposite to each other as illustrated in 

Figure C.303. It should be noted however, this assumes that a flaw has a symmetric boundary 

profile. It is likely that this approach does not work well if a flaw has an extremely complicated 

boundary profile.
C-356

Figure C.303 Distinguishing Flaw/Non-flaw Signals

The depth of a flaw is evaluated on the basis of the phase of measured signals, as mentioned 

above. More specifically, the trajectory of the measured signals is displayed on two-dimensional 

plane to evaluate the phase of the signals, θ, as shown in Figure C.304. Then, the depth of a 

flaw is estimated using a calibration curve obtained through experiments or numerical 

simulations conducted to gather signals due to artificial slits with known depths.

Figure C.304 Evaluating the Depth of a Flaw

C.5.8.6 Team’s Assessment of the Technique, based on the Round Robin Test Results

The technique was developed to overcome that conventional eddy current does not provide 

clear information about the depth of flaws due to the skin effect. Whereas studies conducted so 

far in laboratories using flat plate specimens have demonstrated the effectiveness of the 

technique, it was not possible to size the flaws used in the round robin test. Furthermore, not all 

the flaws were clearly detected using the technique. Problems that limited the application of the 

technique to the test blocks are as follows. 

1. Low signal-to-noise ratio due to the welds

• The welds caused relatively large noise, which made it difficult to evaluate signals to size 

the flaws. More quantitative information about the position of probe, which would be 

obtained using stages, would enable signal processing to enhance signal-to-noise ratio by 

taking consideration of the spatial distribution of measured signals.

2. Difficulty in inspecting curved surfaces
C-357

• Since the probe needs to be large, inspecting surface with a curvature led to a large lift-off 

and small signal amplitude.

C.5.9 Microwave Near-field Microscope, Technique ID 28-MM1, 28-MM2

C.5.9.1 Overview

Microwave is an electromagnetic wave having a frequency from 300 MHz to 300 GHz. It has an 

advantage of propagating well in air. Therefore, a coupling medium is not necessary when 

nondestructive inspection is carried out. Microwave induces a current on the crack surface, 

when microwave irradiates a metal surface where a crack is present. Therefore, a conductor 

loss is created due to the current flowing on the crack surface. This feature enables us to detect 

cracks on the metal surface. 

An open-ended coaxial line sensor which supports transverse electromagnetic (TEM) waves 

without cutoff frequency for the fundamental TEM mode was used because the operating 

frequency band can be broad, and it is possible to decrease the size of aperture for increasing 

the spatial resolution. A network analyzer was used to generate a continuous wave signal which 

was fed to the open-ended coaxial line sensor and to measure the amplitude of the reflection 

coefficient. The amplitude of the reflection coefficient was used to evaluate the depth of a crack.

C.5.9.2 Principle of Microwave Near-field Microscope Technique

Open-ended Coaxial Line Sensor

Figure C.305 shows the distribution of the electric field at the sensor aperture. For the 

fundamental TEM mode, the electric field is only in the radial direction between inner and outer 

conductors.

Figure C.305 Distribution of the Electric Field at the Sensor Aperture

The microwave is irradiated from sensor to sample. We detect the crack from the reflection of 

wave. Figure C.306 shows the amplitude of the reflected wave measured by scanning a crack in 

a sample at the frequency of 110 GHz. The shape of graph indicates the result of the interaction 

of the microwave with the crack. When the crack is located between the inner and outer 

conductors under the sensor, the sum of the components of the electric field that is 

perpendicular to the crack takes its maximum value, thereby the conductor loss reaches the 

maximum value. Therefore, the value of amplitude shows the largest decrease. However, when 

the crack is located under the center of the sensor, no conductor loss will be generated, since 
C-358

the elected field is parallel to the crack. Moreover, two decreased peaks of the value of 

amplitude can be obtained as shown in Figure C.306, since the crack passes twice between the 

inner and outer conductors under the sensor. Consequently, a W-shaped characteristic signal 

was obtained. 

Hence, the average of the two peaks, P1 and P2 shown in Figure C.306, was used to calculate 

the amplitude difference ∆A. 

1 2

2

P P A + ∆ = (C.12) 

 

Figure C.306 Amplitude of Reflected Wave Measured by Scanning a Crack

Evaluation of Crack Depth

The depth of a crack is evaluated based on microwave propagation theory. Crack is modeled as 

a parallel plate waveguide. Equation for evaluating the depth of the crack is obtained by 

considering the relationship between the crack depth and reflection coefficient as

40(log ) 10 M

A d

e α

∆ = (C.13) 

where, αM is a constant depending on the crack shape and sensor dimension.

C.5.9.3 Experimental Procedure for P1, P4, P12, P21, P23, P24, and P41

Data Acquisition

The photograph of a vector network analyzer is shown in Figure C.307. The frequency band of 

the vector network analyzer used for manual measurement is possible to propagate microwave

from 10 MHz to 67 GHz. In this experiment, the test was performed with the frequency of 67 

GHz. The sensor used for manual measurement in which an open-ended coaxial line was fixed

by encasing in epoxy resin was shown in Figure C.308. The amplitude difference was obtained 

by scanning a crack perpendicular to the crack length direction. The measurement was carried 

out in manual raster scanning. Direction of scanning was perpendicular to the crack direction. A 

crack was measured with the scan pitch of 33 points/sec.
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Figure C.307 Photograph of Vector Network Analyzer and Sensor 

Figure C.308 Photograph of Open-ended Coaxial Line Sensor

Signal Processing and Evaluation

The graph like Figure C.306 can be drawn from the data obtained by scanning the crack. Based 

on the graph, the average value of the two peaks was determined and the crack depth was 

evaluated by substituting the value in Equation (C.13).

C.5.9.4 Experimental Procedure for P28, P29, P30, P31 and P32

Data Acquisition

Experimental method and principle are based on the above measurement. The photograph of 

the microwave microscope is shown in Figure C.309. A network analyzer, which is designed to 

process the amplitude and phase of the transmitted and reflected waves from the network, was 

used to generate a continuous wave signal which is fed to an open-ended coaxial line sensor. 

The photograph of open-ended coaxial line sensor is shown in Figure C.310. The operating 

frequency was 110 GHz, the standoff distance between the sensor and the sample was 60 μm. 

The measurements were carried out in automated raster scanning and scan direction pitch is 

0.04 mm and step direction pitch is 1 mm.
C-360

Figure C.309 Photograph of Microwave Microscope

Figure C.310 Photograph of Open-ended Coaxial Line Sensor

Signal Processing and Evaluation

The measured amplitude of reflected wave was imaged as C-scan, and the crack length on the 

sample surface was measured. In addition, at the position of maximum amplitude difference, the 

crack depth was evaluated by substituting it in Equation (C.13).

C.5.9.5 Team’s Assessment of the Technique, Based on the Round Robin Test Results

The Purpose and Advantage of the Emerging Technique

Microwave has an advantage of propagating well in air. Therefore, a coupling medium is not 

necessary when nondestructive inspection is carried out. In addition, open-ended coaxial line 

sensor supports transverse electromagnetic (TEM) waves without cutoff frequency for the 

fundamental TEM mode. Therefore, the operating frequency band can be broad, and it is 

possible to decrease the size of aperture for increasing the spatial resolution.

A Brief Assessment of the Results of the Testing

EDM slits on the curved surface can be detected, and the cracks length can be evaluated 

correctly. However, fatigue cracks could not be detected. The evaluation of the depth is
C-361

impossible in both. Some cracks in flat ENSI test blocks can be detected, and the cracks length

can be evaluated, but the others could not be detected.

Limitation of the Technique to the Test Block

On the curved surface, the technique only could be applied to EDM slits. And, it is difficult to 

scan rough surface. So, it cannot be applied to cracks on welding part. Since microwave has 

high sensitivity, it is susceptible to surface roughness, i.e., standoff distance between a sensor 

and a sample surface. Therefore, in advance, it should be considered to remove the noise by

measuring the surface shape with a laser displacement meter.

C.5.10 References

Ishida H and J Kitasaka. 2013. "Development of a Phased Array TOFD UT Method to Measure 

the Depth of SCCs in Dissimilar Metal Weld." In 9th International Conference on NDE in

Relation to Structural Integrity for Nuclear and Pressurized Components, pp. 754-762. May 22-

24, 2012, Seattle, Washington. NDT.net, Rheintalstr, Germany. http://www.ndt.net/article/jrcnde2012/papers/120.pdf. 

Karasawa H, T Ikeda, S Matsumoto, T Hamajima and H Isobe. 2009. "3D-SAFT Ultrasonic 

Inspection Equipment "MatrixeyeTM"." In Proceedings of the Seventh International Conference 

on NDE in Relation to Structural Integrity for Nuclear and Pressurised Components, pp. 669-

683. May 12-14, 2009, Yokohama, Japan. European Commission Joint Research Centre, 

Luxembourg. http://www.ndt.net/article/jrc-nde2009/papers/97.pdf. 

Komura I and T Furukawa. 2010. "Improvement of SCC Depth Sizing Capability by 3D-SAFT 

UT Method in Ni Alloy Weld." In Proceedings of the Eighth International Conference on NDE in 

Relation to Structural Integrity for Nuclear and Pressurised Components, pp. 831-837. 

September 29-October 1, 2010, Berlin, Germany. European Commission Joint Research 

Centre, Luxembourg.

Yusa N, Y Sakai and H Hashizume. 2011. "An Eddy Current Probe Suitable to Gain Information 

about the Depth of Near-side Flaws Much Deeper than the Depth of Penetration." NDT & E 

International 44:121-130.



Results of Open Testing for the Program to Assess the Reliability of 

Emerging Nondestructive Techniques August 2017 

R. M. Meyer, A. E. Holmes, and P. G. Heasler

NUREG/CR-7236, Vol. 1

Pacific Northwest National Laboratory

P.O. Box 999 

Richland, WA 99352

Division of Engineering

Office of Nuclear Regulatory Research

U.S. Nuclear Regulatory Commission

Washington, DC 20555-0001

The U.S. Nuclear Regulatory Commission (NRC) conducted agreements with organizations in Finland, 

Japan, South Korea, Sweden and Switzerland to establish the Program to Assess the Reliability of 

Emerging Nondestructive Techniques (PARENT) whose goal was to investigate the performance of current 

and emerging nondestructive examination (NDE) procedures and techniques to find flaws in nickel-alloy 

welds and base materials. This was performed by conducting a series of open and blind international 

round-robin tests on a set of nickel alloy piping components that included large-bore dissimilar metal welds 

(LBDMW), small-bore dissimilar metal welds (SBDMW), and bottom-mounted instrumentation (BMI) 

penetration welds. The project was divided into open and blind testing to separate the evaluation of novel 

techniques implemented by nonqualified teams (open testing) from the evaluation of more established 

techniques implemented by commercial inspection service providers (blind testing). This report is focused 

on documenting the open testing activity and results. The open testing portion of PARENT was performed 

with knowledge of true-state information in the open test blocks provided to teams conducting tests. As a 

result, no detection performance analyses were performed on open test data. Thus, the evaluation of open 

test data is based on statistical analyses of sizing data and qualitative review of data response images.

Nondestructive Examination, Stress Corrosion Cracking, Dissimilar Metal Welds, 

Ultrasonic Testing, Probability of Detection

Technical

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NUREG/CR-7236, Vol. 1 Results of Open Testing for the Program to Assess the Reliability of Emerging 

Nondestructive Techniques

August 2017