Pipeline & Hazardous Materials 

Safety Administration 

 

Pipeline Inspection Technologies 

Demonstration Report 

Pipeline Safety Research & Development 

Program 

Final 
2 

EXECUTIVE SUMMARY 

The pipeline infrastructure is a critical element in the energy delivery system across the United 

States. Its failure can affect both public health and safety directly and indirectly through impacts 

on the energy supply. The pipeline infrastructure is aging, while at the same time Research & 

Development (R&D) funding from the pipeline industry to develop technologies to assure its 

integrity is experiencing budgetary constraints. Total R&D funding is being further reduced 

through the elimination of programs resulting from restructuring within the government and 

energy industry. 

The Pipeline & Hazardous Materials Safety Administration (PHMSA), Pipeline Safety R&D 

Program mission is to ensure the safe, reliable & environmentally sound operation of the nation’s 

pipeline transportation system. With passage of the Pipeline Safety Improvement Act (PSIA) in 

2002, industry is now required to invest significantly more capital to inspect and maintain their 

systems. The PSIA requires enhanced maintenance programs and continuing integrity inspection 

of all pipelines located within “high consequence areas” where a pipeline failure could threaten 

public safety, property and the environment. According to the Interstate Natural Gas Association 

of America (INGAA) the cost to industry to implement the PSIA in the first ten years will 

exceed $2 billion. 

The focus of the PHMSA Pipeline Safety R&D 

Program is to sponsor research and development 

projects intended on providing near-term solutions 

that will improve the safety, reduce environmental 

impact, and enhance the reliability of the nation’s 

pipeline transportation system. Conducting infield technology demonstration test to facilitate 

technology transfer from government funded 

R&D programs strengthens communication and 

coordination with industry stakeholders 

The PHMSA Pipeline Safety R&D Program role in technology development and innovation has 

increased with the passage of the Pipeline Safety Improvement Act of 20021

. The 

implementation of the Integrity Management Program for natural gas and hazardous liquids has 

focused efforts on proactively finding and fixing safety-related problems. 

For several years the PHMSA Pipeline Safety R&D Program along with the DOE/NETL, Gas 

Delivery Reliability Program have funded the development of advanced in-line inspection (ILI) 

technologies to detect mechanical damage, corrosion and other threats to pipeline integrity. 

Several projects have matured to a stage where demonstrations of their detection capability are 

now warranted. During the week of January 9th, 2006, the PHMSA Pipeline Safety R&D 

Program and the DOE/NETL, Gas Delivery Reliability Program co-sponsored a demonstration 

of six innovative technologies. 

 

1

http://www.eia.doe.gov/oil_gas/natural_gas/analysis_publications/ngmajorleg/pubsafety.html 

The keys to enhanced pipeline 

safety are understanding the 

risks, focusing on the problems, 

imagining solutions, and applying 

our ingenuity— 

Ted Willke. 
3 

The demonstrations were conducted at Battelle West Jefferson’s Pipeline Simulation Facility 

(PSF) near Columbus, Ohio. The pipes used in the demonstration were prepared by Battelle at 

the PSF and each was pre-calibrated to establish baseline defect measurements. Each technology 

performed a series of pipeline inspection runs to determine their capability to detect and size 

mechanical damage, corrosion, stress corrosion cracking or plastic pipe defects. Overall, each 

technology performed well in their assessment category. 

BACKGROUND

Information regarding inspection technology advances needs to be disseminated and understood 

by many stakeholders in the pipeline industry. While research reports, review meetings and 

conference presentations are commonly used to disseminate information, live demonstrations can 

provide additional information on the current state and future potential of each development. 

Demonstrations are challenging to technology developers because newly developed technologies 

must be sufficiently reliable to obtain results in a fixed time frame. There is not the opportunity 

to return to the laboratory to confirm results or change parameters. While the pressure to 

demonstrate the best capability of their technology advances is enormous, the developers 

understand these events are needed to bolster support for continued development. The results of 

demonstrations can be difficult to directly compare since each implementation can be at a 

different stage of development. No direct comparisons were made in this report. At this 

demonstration, representatives from the pipeline industry, industry trade associations, and 

pipeline service providers were able to witness the performance of six new technologies and 

interact with technology developers to clarify the current and potential capability of these new 

developments. The participation of these groups was an essential element of the demonstration. 

This is the second benchmark of emerging pipeline inspection technologies performed by 

Battelle for DOT PHMSA Pipeline Safety R&D Program and DOE NETL. Information on the 

pipe defect sets, pipe preparation, demonstration facility layout, and demonstration procedures 

from the first test can be can be found in the final report, Benchmarking Emerging Pipeline 

Inspection Technologies2

, prepared by Battelle. The results from the first benchmarking can be 

found in the Pipeline Inspection Technologies - Demonstration Report3

, prepared by NETL.

Purpose 

This report provides a brief summary assessment of the demonstration benchmark results. The 

purpose of this assessment is to help identify promising inspection technologies best suited for 

further development as part of an integrated teaming effort between robotic platform and sensor 

developers. This report is not intended to provide a detailed analysis of each technology’s 

performance or to rate their performance relative to one another. 

 

2 http://primis.rspa.dot.gov/matrix/FilGet.rdm?fil=718 3

 http://www.netl.doe.gov/technologies/oilgas/publications/td/Battelle%20Inspection%20Demo%20Final%20Report_111804.pdf 
4 

The Technologies 

Six innovative sensor technologies were demonstrated at Battelle’s Pipeline Simulation Facility 

(PSF) the week of January 9, 2006. The different technologies demonstrated their ability to 

detect pipeline corrosion, mechanical defects, stress corrosion cracking, or plastic pipe defects. 

Additional information on each technology may be found in both Appendix B and Appendix C. 

The technologies were: 

ORNL Shear Horizontal Electromagnetic Acoustic Transducer (EMAT) – Oak Ridge National 

Laboratory (ORNL) has developed an EMAT system that uses shear horizontal waves to detect 

flaws on natural gas pipelines. A wavelet-based analysis of ultrasonic sensor signals is used for 

detecting physical flaws (e.g., SCC, circumferential and axial flaws, and corrosion) in the walls 

of gas pipelines. Using an in-line non-contact EMAT transmitter-receiver pair, flaws can be 

detected on the walls of the pipe that the current magnetic flux leakage (MFL) technology has 

problems detecting. One EMAT is used as a transmitter, exciting an ultrasonic impulse into the 

pipe wall while the second EMAT located a few inches away from the first is used as a receiving 

transducer. ORNL’s technology is depicted in Figure 1. 

Figure 1. ORNL Shear Horizontal EMAT 

GTI Remote Field Eddy Current (RFEC) – The Gas Technology Institute (GTI) has developed a 

RFEC inspection technique to inspect pipelines with multiple diameters, valve and bore 

restrictions, and tight or miter bends. This electromagnetic technique uses a simple exciter coil 

that can be less than on third of the pipe diameter and is driven by a low-frequency sinusoidal 

current to generate an oscillating electromagnetic field that small sensor coils can detect. The 

oscillating field propagates along two paths; a direct axial path and an indirect or remote path. 
5 

The direct field attenuates rapidly because the pipe acts as a waveguide that will only allow 

frequencies in the gigahertz range and above to propagate. It becomes negligible after 2 to 3 pipe 

diameters. Thus after 2 to 3 pipe diameters, the only signal left is that from the remote field, 

which propagates out through the pipe wall, along its exterior and then re-enters the pipe 2 to 3 

pipe diameters from the exciter coil. This is exactly what is needed for defect detection since the 

electromagnetic waves must now pass directly through metal loss defect regions and other flaws. 

Changes from nominal values of the amplitude and phase of the remote field detect defects in the 

pipe wall and measure their severity. GTI’s technology is depicted in Figure 2. 

Figure 2. GTI Remote Field Eddy Current 

SwRI Remote Field Eddy Current (RFEC) – Through funding support from PHMSA/OPS, 

Southwest Research Institute® has developed a remote-field eddy current (RFEC) technology to 

be used in unpiggable lines. The SwRI RFEC tool is capable of detecting corrosion on the inside 

or outside pipe surface. Since a large percentage of pipelines cannot be inspected using “smart 

pig” techniques because of diameter restrictions, pipe bends, and valves, a concept for a 

collapsible excitation coil was developed but found unnecessary for the pipe sizes and materials 

of interest in this demonstration. A breadboard system that meets the size, power, and 

communication requirements for integration into the Carnegie Mellon Explorer II robot was 

developed and used in the demonstration tests. This system is shown in Figure 3. The 

demonstration system incorporates eight detectors, and data from all eight channels are acquired 

and processed simultaneously as the system is scanned along the pipe at speeds up to 4 inch/sec. 

All of the instrumentation, except for a DC power supply and a laptop computer (used for 

storage of the processed data), is located on the tool. The RFEC system can expand to inspect 6- 

or 8-inch-diameter pipe and can retract to 4 inches to pass through obstructions. 

Sensor 

Coils

MUX 

Board 

Mock Explorer 

Module 

Drive 

Coil

Support
6 

Laptop Computer with CAN Bus Interface

Encoder Wheel

Electronics Sensors Excitation Coil

DC Power Supply

Figure 3. SwRI Remote Field Eddy Current 

PNNL Ultrasonic Strain Measurement – Pacific Northwest National Laboratory (PNNL) has 

developed an ultrasonic sensor system capable of detecting pipeline stress and strain caused by 

mechanical damage i.e., dents and gouges. PNNL has established the relationship between 

residual strain and the change in ultrasonic response (shear wave birefringence) under a uniaxial 

load. Initial measurements on samples in both axial and biaxial states have shown excellent 

correlation between shear birefringence measurements. The demonstration focused on refining 

the methodology, particularly under circumstances when the damage is more complex than a 

simple uniaxial deformation. PNNL’s technology is depicted in Figure 4. 
7 

EMAT Sensor

Motor for 

sensor 

rotation

Springs for 

smooth 

motion past 

dents

Figure 4. PNNL Ultrasonic Strain Measurement 

Rotating Permanent Magnet – Battelle is developing a rotating permanent magnet inspection 

system where pairs of permanent magnets are rotated around the central axis. This alternative to 

the more common concentric coil method can be used to induce high current densities in the 

pipe. Along the pipe away from the magnets in either direction, the currents flow in the 

circumferential direction. Anomalies and wall thickness variations are detected with an array of 

sensors that measure local changes in the magnetic field produced by the current flowing in the 

pipe. The inspection methodology can be configured to pass tight restrictions and narrow 

openings such as plug valves. The separation between the magnets and the pipe wall is on the 

order of an inch (2.5cm). The strength of circumferential current produces signals on the order 

of a few gauss, which can be detected by hall effect sensors positioned between 8 and 40 inches 

(10 and 100 cm) away from the rotating magnets. This evolving inspection methodology was 

first demonstrated in summer of 2004. Battelle’s technology is depicted in Figure 5. 
8 

Figure 5. Battelle Rotating Permanent Magnet 

Capacitive Sensor for Polyethylene Pipe Inspection – The National Energy Technology 

Laboratory (NETL) has developed a capacitive probe to resolve defects in plastic natural gas 

pipelines. This new technology uses a non-destructive and non-hazardous projected electric field 

to map voids and other anomalies. The probe can function autonomously and is intended for use 

in conjunction with existing “pigs” or on its own platform. NETL’s technology is depicted in 

Figure 6. 

Figure 6. NETL Capacitive Sensor 
9 

Demonstration Configuration 

The emerging inspection technologies were tested within a 40 by 100 foot high-bay area at 

Battelle’s PSF. Pipes selected for these tests had various types of natural and machined defects. 

A black tarp and bubble wrap covered the pipes to hide defect locations. Figure 7 shows the 

configuration of the pipes during the demonstration. These pipes included: 

Figure 7. High-bay Looking North 

Detection of Metal Loss

• One 8-inch diameter ERW seam welded pipe measuring 30-feet in length (0.188 inch wall 

thickness). The pipe sample contained two rows of simulated corrosion defects spaced 180° 

apart. 

• One 8-inch diameter ERW seam welded pipe measuring 35-feet in length (0.188 inch wall 

thickness). The pipe sample contained two rows of simulated corrosion defects spaced 180° 

apart. This sample also included a 5-foot section of natural corrosion from a pipe pulled 

from service. 

• One 8-inch diameter ERW seam welded pipe measuring 40-feet in length (0.188 inch wall 

thickness). The pipe sample contained two rows of simulated corrosion defects spaced 180° 

apart. 
10 

Detection of Mechanical Damage

• One 24-inch diameter pipe measuring approximately 28-feet in length (0.292 inch wall 

thickness) comprised of two separate pipes welded together with mechanical damage defects. 

Three rows of mechanical damage defects were located on this pipe sample spaced 120° 

apart but only one row with track hoe defects were used in the benchmarking. 

• One 24-inch diameter pipe measuring approximately 40 feet in length (0.292 inch wall 

thickness) with plain (or smooth) dent defects along one row. 

Detection of Stress Corrosion Cracking (SCC)

• One 26-inch diameter pipe measuring approximately 26 feet in length (0.281 inch wall 

thickness) with natural stress corrosion cracking. A separate 26-inch diameter SCC pipe 

sample was provided for calibration. 

Detection of Plastic Pipe Defects

• One 6-inch diameter polyethylene pipe measuring 13 feet in length (0.5 inch wall thickness) 

with cylindrical drill holes and saw cut defects along one row on the exterior of the pipe. 

Additional information on the pipe defect sets, pipe preparation, demonstration facility layout, 

and demonstration procedures can be found in the final benchmarking report, Pipe and Anomaly 

Configuration for the Phase II Benchmarking of Emerging Pipeline Inspection Technologies 

prepared by Battelle and included in Appendix D. 

DEMONSTRATION RESULTS 

This section provides an assessment of the test data relative to the benchmark data developed at 

the Battelle Pipeline Simulation Facility (PSF). The benchmark data is provided as Appendix A 

of this document and test results for the individual technologies, as prepared and submitted by 

the technology developers, can be found in Appendix B. 

Metal Loss Corrosion Assessment 

The three corrosion assessment technologies were demonstrated in an 8-inch diameter pipe4

. 

This diameter was chosen to match a specific crawler implementation, Explorer, being separately 

developed under NETL DOE and Northeast Gas Association (NGA) funding5

. The untethered 

platform is designed to traverse pipelines ranging from 6 to 8 inches inside diameter. The 

inspection technology developers were asked to include as many of the configuration and 

interface requirements of this platform as practical. 

Three 8-inch diameter pipes were inspected by each technology for corrosion. The first pipe 

(Pipe Sample 1) was a seam-welded pipe measuring approximately 35 feet in length. This 

sample consisted of three pipe sections welded together (two circumferential welds) and 

 

4

 In the first demonstration these technologies were demonstrated in 12-inch diameter pipe. 

5

 http://www.netl.doe.gov/technologies/oil-gas/publications/td/41155_Final.PDF 
11 

contained simulated corrosion defects set along two test lines 180° apart. The simulated 

corrosion was created using electrochemical etching techniques, an example of which is shown 

in Figure 8. A 5 foot section of Pipe Sample 1 also contained natural corrosion from a pipe 

recently pulled from service. 

Figure 8. Example Simulated Corrosion Defect using Electrochemical Etching Techniques 

The donated natural corrosion pipe sample had a field girth weld with corrosion on both sides of 

the weld. The weld drop through was too large for the inspection tool specifications and as such 

the pipe was trimmed to include roughly 2 feet of corrosion on one end, 3 feet of full thickness 

pipe at the other end, and no field welds. The pipe was then sandblasted and welded between 

two new pipes to comprise Pipe Sample 1. When the pipe was being fully characterized, an 

additional weld was found in the middle of the corrosion area (see Figure 9). This weld was very 

fine and did not have a significant crown. The natural corrosion defects were intended to be a 

“stretch goal” of these emerging inspection technologies. While the natural corrosion sample 

represents a real world problem, this additional weld adds a complex scenario that is most likely 

new to the technology developers. As such, these search areas are reported but are not included 

in the results evaluation. 
12 

Figure 9. Fine, Field Weld in Natural Corrosion Pipe Segment 

The second pipe (Pipe Sample 2) was a seam-welded pipe measuring approximately 30 feet in 

length. This sample consisted of two pipe sections welded together (one circumferential weld) 

and contained simulated corrosion defects set along two test lines 180° apart. The third pipe 

(Pipe Sample 3) was a seam-welded pipe measuring approximately 40 feet in length. This 

sample consisted of two pipe sections welded together (one circumferential weld) and contained 

simulated corrosion defects along two test lines 180° apart. 

All three technologies detected one false positive signal; however, none of the technologies had a 

false positive in the same location. None of the technologies failed to identify a defect and were 

fairly accurate in predicting the locations. These results are summarized in Table 1. In addition, 

the corrosion sizing results were plotted in a manner commonly used by pipeline inspection 

vendors to demonstrate commercial in-line inspection technology capabilities. For these graphs, 

benchmark data is plotted against the values reported by the technology developers. Care must 

be taken in interpreting these graphs since: 

• Error in the benchmark measurements is not zero 

• Only the maximum depth is compared while the corrosion pit depth varied throughout the 

defect; many corrosion areas had more than one area of local thinning. 

• Length and width were measured at the surface; however other measures can also be used 

that still accurately describe the anomaly. 

Overall these graphs show the results predicted by each technology correlated well with the 

benchmark data. 

Field Weld 
13 

Table 1. Detection Rates for the Corrosion Technologies 

Technology Detection 

Rate 

False Positive Rate False 

Negative 

Rate 

Mean 

Difference 

in Location 

of Defect 

Standard 

Deviation 

of Defect 

Location 

SwRI – RFEC 100% 

(32 of 32) 

3.3% (1 of 30) – Defect P2-8 

called as a repeatable signal, 

but does not have typical flaw 

signal characteristics; 0.17” 

deep, 1.38” long and 1.06” wide 

0% 

(0 of 32) 

0.33 1.71 

GTI – RFEC 100% 

(32 of 32) 

3.3% (1 of 30) – Defect P1-2 

called as an unknown feature 

resembling metal loss; 0.008” 

deep, <1” long, and >4” wide 

0% 

(0 of 32) 

0.08 1.18 

Battelle – 

Rotating 

Permanent 

Magnet 

100% 

(32 of 32) 

3.3% (1 of 30) – Defect P1-17 

called as a small single pit 0.02” 

deep, 0.7” long, and 0.75” wide 

0% 

(0 of 32) 

-0.31 2.05 

SwRI Results 

SwRI began testing the morning of Monday, January 9, 2006, and completed testing by mid-day 

Thursday, January 12, 2006. The SwRI RFEC tool acquired, processed, and displayed data in 

real time as it was continuously pulled through each pipe sample. Each scan took approximately 

5 minutes to complete with selected higher speed runs taking approximately one to two minutes 

to complete. A circumferential region of 60 degrees was inspected in each scan, and two scans 

were made along each defect line to ensure complete coverage of all defects. 

The SwRI RFEC technology detection rate was 100%, detecting all defect sites on Pipe Sample 

1, Pipe Sample 2, and Pipe Sample 3. On average, SwRI located anomalies slightly past the 

actual start of the defect location with a standard deviation of 1.71 inches. The SwRI RFEC

technology detected one false positive signal on Test Line 1 of Pipe Sample 2. The false positive 

signal was identified as a repeatable signal without typical flaw signal characteristics with a 

depth of nearly 90% of the wall thickness and approximately 1 5/8 -inch in length. SwRI’s 

sizing accuracy is depicted in Figures 10 through 12 in which the predicted and measured 

anomaly depths, lengths, and widths are presented. 
14 

Figure 10. Measured Depth vs. Predicted Depth for the SwRI RFEC

Figure 11. Measured Length vs. Predicted Length for the SwRI RFEC

0.0000

0.0188

0.0376

0.0564

0.0752

0.0940

0.1128

0.1316

0.1504

0.1692

0.1880

0.00000.01880.03760.05640.07520.09400.11280.13160.15040.16920.1880

Measured Depth (inches)

Predicted Depth (inches)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

Measured Length (inches)

Predicted Length (inches)
15 

Figure 12. Measured Width vs. Predicted Width for the SwRI RFEC

GTI Results 

GTI began testing on the morning of Monday January 9, 2006 and completed testing by the 

evening of Thursday January 12, 2006. The GTI RFEC sensor technology collected data by 

indexing through each defect region in 0.25 inch steps. The GTI RFEC technology was able to 

scan both test lines in each pipe sample at the same time but because of the small incremental 

data collection each pipe sample required a full day to collect data. GTI did attempt a continuous 

scan with the results of this scan provided in Appendix C. 

The GTI RFEC technology detection rate was 100%, detecting all defect sites on Pipe Sample 1, 

Pipe Sample 2, and Pipe Sample 3. On average, GTI located anomalies slightly past the actual 

start of the defect location with a standard deviation of 1.18 inches. The GTI RFEC technology 

detected one false positive signal on Test Line 1 of Pipe Sample 1 but identified the anomaly as a 

small unknown feature with a depth of only 4% of the wall thickness and approximately 1-inch 

in length. GTI’s sizing accuracy is depicted in Figures 13 through 15 in which the predicted and 

measured anomaly depths, lengths, and widths are presented. 

0

0.5

1

1.5

2

2.5

3

0 0.5 1 1.5 2 2.5 3

Measured Width (inches)

Predicted Width (inches)
16 

Figure 13. Measured Depth vs. Predicted Depth for the GTI RFEC

Figure 14. Measured Length vs. Predicted Length for the GTI RFEC 

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

Measured Length (inches)

Predicted Length (inches)

0.0000

0.0188

0.0376

0.0564

0.0752

0.0940

0.1128

0.1316

0.1504

0.1692

0.1880

0.00000.01880.03760.05640.07520.09400.11280.13160.15040.16920.1880

Measured Depth (inches)

Predicted Depth (inches)
17 

0

0.5

1

1.5

2

2.5

3

3.5

4

0 0.5 1 1.5 2 2.5 3 3.5 4

Measured Width (inches)

Predicted Width (inches)

Figure 15. Measured Width vs. Predicted Width for the GTI RFEC

Battelle Results 

Battelle began testing the afternoon of Tuesday January 10, 2006 and completed testing by the 

afternoon of Friday January 13, 2006. Battelle’s testing was periodically interrupted due to 

concerns from the other corrosion inspection technology developers that the permanent magnet 

was causing interference with their systems. The Battelle Rotating Permanent Magnet

technology was able to continuously acquire data through each pipe sample taking approximately 

10 to 15 minutes to scan one test line. During the demonstration Battelle processed signals and 

displayed inspection results in real-time. 

The Battelle Rotating Permanent Magnet technology detection rate was 100%, detecting all 

defect sites on Pipe Sample 1, Pipe Sample 2, and Pipe Sample 3. On average, Battelle located 

anomalies shy of the actual start of the defect location with a standard deviation of 2.05 inches. 

The Battelle Rotating Permanent Magnet technology detected one false positive signal on Test 

Line 2 of Pipe Sample 1 but identified the anomaly as a small single pit with a depth of only 11% 

of the wall thickness and approximately 3/4-inch in length. Battelle’s sizing accuracy is depicted 

in Figures 16 through 18 in which the predicted and measured anomaly depths, lengths, and 

widths are presented. 
18 

Figure 16. Measured Depth vs. Predicted Depth for the Battelle Rotating Permanent Magnet

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

Measured Length (inches)

Predicted Length (inches)

Figure 17. Measured Length vs. Predicted Length for the Battelle Rotating Permanent Magnet

0.0000

0.0188

0.0376

0.0564

0.0752

0.0940

0.1128

0.1316

0.1504

0.1692

0.1880

0.00000.01880.03760.05640.07520.09400.11280.13160.15040.16920.1880

Measured Depth (inches)

Predicted Depth (inches)
19 

Figure 18. Measured Width vs. Predicted Width for the Battelle Rotating Permanent Magnet

The benchmark data and test results for the three technologies that tested for metal loss on Pipe 

Samples 1, 2, and 3 are shown in Table 2 through Table 7.

0

0.5

1

1.5

2

2.5

3

0 0.5 1 1.5 2 2.5 3

Measured Width (inches)

Predicted Width (inches)
20 

This page intentionally blank. 
21 

Table 2. Benchmark Data vs. Results for Corrosion Pipe Sample 1; Test Line 1 

Simulated Corrosion Pipe Sample 1 Test Line 1 

Defect Number P1-1 P1-2 P1-3 P1-4 P1-5 P1-6 P1-7 Search Region (from End B) 328" to 340" 304" to 316" 280" to 292" 256" to 268" 232" to 244" 208" to 220" 184" to 196" 16

Start and End of Defect (inches)5

Benchmark Data Blank Blank 287.75 290.875 259.625 263.625 232.75 235.75 Blank 190.625 192.75 SwRI –RFEC 282.6 285.8 254.5 258.7 227.7 231.0 188.8 189.7 GTI – RFEC ~311.25 ~314.25 ~281.75 ~285.5 ~260.5 ~264.75 ~232 ~236.5 ~191.25 ~193.75 Battelle – Rotating Permanent Magnet 

288 

292.8 

260.1 264.9 

233.2 

237 

188.8 192.2 

Defect Length (inches)

Benchmark Data Blank Blank 3.125 4 3 Blank 2.125 SwRI –RFEC 3.16 4.20 3.30 0.95 GTI – RFEC < 1 2.875 3.375 3.75 1.625 Battelle – Rotating Permanent Magnet 3.8 3.8 2.8 2.4 

Defect Width (inches)

Benchmark Data Blank Blank 2 2 1 Blank 2 SwRI –RFEC 1.25 1.95 1.09 1.92 FGTI – RFEC > 4 1.5 ~3 > 3 1.5 Battelle – Rotating Permanent Magnet 1.0 1.5 1.0 1.5 

Maximum Defect Depth (inches)

Benchmark Data Blank Blank 0.096 0.063 0.081 Blank 0.147 SwRI –RFEC 0.10 0.06 0.08 0.09 GTI – RFEC 0.008 0.090 0.064 0.100 0.075 0.07 0.135 0.133 Battelle – Rotating Permanent Magnet 0.075 0.055 0.050 0.165 

Comments

SwRI –RFEC defect signal outside stated region 

appearregion thinning out of tregion. not chacalibrat

GTI – RFEC 

unknown feature resembling metal loss, 4% 

2 axially aligned pits, 48% and 34% 

2 axially aligned pits, 53% and 40% 

2 pits, deepest 37%. Additional features observed attributed to through hole of defect 18 sitting over drive coil 

2 pits offset diagonally, 72% and 71% 

Battelle – Rotating Permanent Magnet 

corrosion patch, multiple pits of different depths 

corrosion patch, multiple pits of different depths 

corrosion patch, multiple pits of different depths 

corrosion patch, multiple pits of different depths 

a slow in all sethe regmateriachange 
22 

Table 3. Benchmark Data vs. Results for Corrosion Pipe Sample 1; Test Line 2 

Simulated Corrosion Pipe Sample 1 Test Line 2 

Defect Number P1-13 P1-14 P1-15 P1-16 P1-17 P1-18 P1-19 Search Region (from End B) 330" to 342" 306" to 318" 282" to 294" 258" to 270" 234" to 246" 210" to 222" 186" to 198" 

Start and End of Defect (inches)

Benchmark Data 335.75 339.625 308.875 312 Blank Blank Blank 213.625 217.875 Blank SwRI –RFEC 335.8 339.9 309.5 312.8 214.0 218.1 GTI – RFEC ~336.375 ~340.25 ~309 ~312.75 214.75 218.875 Battelle – Rotating Permanent Magnet 

334.2 338.4 

306.9 310.8 

241.1 241.8 

212.5 216.8 

Defect Length (inches)

Benchmark Data 3.875 3.125 Blank Blank Blank 4.25 Blank SwRI –RFEC 4.04 3.31 4.13 GTI – RFEC 3 2.875 3.25 Battelle – Rotating Permanent Magnet 3.2 2.9 0.7 3.3 

Defect Width (inches)

Benchmark Data 1.75 1 Blank Blank Blank 2 Blank SwRI –RFEC 1.47 1.37 1.69 GTI – RFEC 1.75 1.5 2 Battelle – Rotating Permanent Magnet 1.0 1.25 0.75 2.0 

Maximum Defect Depth (inches)

Benchmark Data 0.095 0.115 Blank Blank Blank 0.145 Blank SwRI –RFEC 0.08 0.11 0.14 GTI – RFEC 0.122 0.070 0.113 0.132 0.188 0.111 Battelle – Rotating Permanent Magnet 0.075 0.115 0.020 0.155 

Comments

SwRI –RFEC GTI – RFEC 2 axially aligned pits, 65% and 37% 2 axially aligned pits, 70% and 60% 2 pits, through hole and 59% Battelle – Rotating Permanent Magnet 

corrosion patch, multiple pits of different depths 

corrosion patch, multiple pits of different depths 

 small single pit 

corrosion patch, multiple pits of different depths 
23 

Table 4. Benchmark Data vs. Results for Corrosion Pipe Sample 2; Test Line 1 

Simulated Corrosion Pipe Sample 2 Test Line 1 

Defect Number P2-1 P2-2 P2-3 P2-4 P2-5 P2-6 Search Region (from End B) 294" to 306" 270" to 282" 246" to 258" 222" to 234" 198" to 210" 174" to 186" 

Start and End of Defect (inches)

Benchmark Data Blank Blank Blank 227.25 229.375 Blank 180.25 183.375 SwRI – RFEC 227.6 229.8 180.2 183.5 GTI – RFEC 227.25 229.5 179.75 183 Battelle – Rotating Permanent Magnet 228.9 232.0 181.1 184.9 

Defect Length (inches)

Benchmark Data Blank Blank Blank 2.125 Blank 3.125 SwRI –RFEC 2.21 3.23 GTI – RFEC 2.25 3.25 Battelle – Rotating Permanent Magnet 2.1 2.8 

Defect Width (inches)

Benchmark Data Blank Blank Blank 2 Blank 1 SwRI –RFEC 1.57 0.99 GTI – RFEC 2 1 Battelle – Rotating Permanent Magnet 1.0 1.0 

Maximum Defect Depth (inches)

Benchmark Data Blank Blank Blank 0.079 Blank 0.114 SwRI –RFEC 0.07 0.11 GTI – RFEC 0.037 0.073 Battelle – Rotating Permanent Magnet 0.075 0.075 

Comments 

SwRI –RFEC GTI – RFEC Battelle – Rotating Permanent Magnet 

Corrosion patch, with multiple pits of different depths 

Corrosion patch, with multiple pits of different depths 

Cpmd
24 

Table 5. Benchmark Data vs. Results for Corrosion Pipe Sample 2; Test Line 2 

Simulated Corrosion Pipe Sample 2 Test Line 2 

Defect Number P2-12 P2-13 P2-14 P2-15 P2-16 P2-17 Search Region (from End B) 246" to 258" 222" to 234" 198" to 210" 174" to 186" 150" to 162" 126" to 138" 10

Start and End of Defect (inches)

Benchmark Data 248.125 250.25 Blank 202.625 205.75 Blank Blank 130 134.125 SwRI –RFEC 248.1 249.8 202.3 205.4 129.1 133.2 GTI – RFEC 249 251 201 204 129.5 133.5 Battelle – Rotating Permanent Magnet 250.0 253.0 204.9 209.0 132.8 137.4 

Defect Length (inches)

Benchmark Data 2.125 Blank 3.125 Blank Blank 4.125 SwRI –RFEC 1.72 3.10 4.14 GTI – RFEC 2 3 4 Battelle – Rotating Permanent Magnet 2.0 3.1 3.6 

Defect Width (inches)

Benchmark Data 2 Blank 1 Blank Blank 2 SwRI –RFEC 1.21 1.21 1.69 GTI – RFEC 1.5 1.5 2 Battelle – Rotating Permanent Magnet 1.5 0.75 1.5 

Maximum Defect Depth (inches)

Benchmark Data 0.14 Blank 0.105 Blank Blank 0.112 SwRI –RFEC 0.11 0.08 0.11 GTI – RFEC 0.148 0.081 0.159 Battelle – Rotating Permanent Magnet 0.115 0.075 0.105 

Comments

SwRI –RFEC GTI – RFEC Battelle – Rotating Permanent Magnet 

Corrosion patch, with multiple pits of different depths 

Corrosion patch, with multiple pits of different depths 

Corrosion patch, with multiple pits of different depths 
25 

Table 6. Benchmark Data vs. Results for Corrosion Pipe Sample 3; Test Line 1 

Simulated Corrosion Pipe Sample 3 Test Line 1 

Defect Number P3-1 P3-2 P3-3 P3-4 P3-5 P3-6 Search Region (from End B) 384" to 396" 360" to 372" 330" to 342" 300" to 312" 270" to 282" 222" to 234" 186

Start and End of Defect (inches)

Benchmark Data Blank Blank 335 337.25 305.625 306.375 275 277.25 Blank 18SwRI –RFEC 336.3 338.5 306.8 307.6 276.0 278.3 GTI – RFEC 335 337 306.5 307.75 275.75 277.75 Battelle – Rotating Permanent Magnet 338.0 341.0 307.8 309.3 276.4 279.5 

Defect Length (inches)

Benchmark Data Blank Blank 2.25 0.75 2.25 Blank 4SwRI –RFEC 2.19 0.78 2.29 GTI – RFEC 2 1.25 2 Battelle – Rotating Permanent Magnet 2.0 1.5 2.1 

Defect Width (inches)

Benchmark Data Blank Blank 2 0.75 2 Blank SwRI –RFEC 1.8 0.88 1.93 GTI – RFEC 1.5 1 2 Battelle – Rotating Permanent Magnet 1.75 0.75 1.5 

Maximum Defect Depth (inches)

Benchmark Data Blank Blank 0.133 0.148 0.103 Blank 0SwRI –RFEC 0.09 0.11 0.09 GTI – RFEC 0.164 0.158 0.142 0.119 0Battelle – Rotating Permanent Magnet 0.165 0.150 0.105 0

Comments

SwRI –RFEC GTI – RFEC Three pits Battelle – Rotating Permanent Magnet 

Corrosion patch, with multiple pits of different depths 

Single Pit 

Corrosion patch, with multiple pits of different depths 

Corropatchmultidifferdepth
26 

Table 7. Benchmark Data vs. Results for Corrosion Pipe Sample 3; Test Line 2 

Simulated Corrosion Pipe Sample 3 Test Line 2 

Defect Number P3-12 P3-13 P3-14 P3-15 P3-16 P3-17 P3-Search Region (from End B) 390" to 402" 356" to 368" 330" to 342" 306" to 318" 282" to 294" 248" to 260" 210" to 

Start and End of Defect (inches)

Benchmark Data 392.25 396.375 Blank 335.875 336.625 Blank Blank 250.625 253.75 214

217.

SwRI –RFEC 392.5 396.6 336.9 337.7 251.6 254.8 215

218

GTI – RFEC 393 396 335.75 336.75 251.25 254 214

217

Battelle – Rotating Permanent Magnet 392.4 397.0 337.1 338.0 250.5 254.4 214

218

Defect Length (inches)

Benchmark Data 4.125 Blank 0.75 Blank Blank 3.125 3.1SwRI –RFEC 4.18 0.72 3.21 3.1GTI – RFEC 3 1 2.75 2.7Battelle – Rotating Permanent Magnet 3.6 0.9 2.9 3.

Defect Width (inches)

Benchmark Data 2 Blank 0.75 Blank Blank 1 1 SwRI –RFEC 1.69 0.51 0.79 1.1GTI – RFEC 2.5 1 1.5 1.Battelle – Rotating Permanent Magnet 1.25 0.5 1.0 1.

Maximum Defect Depth (inches)

Benchmark Data 0.094 Blank 0.154 Blank Blank 0.07 0.0SwRI –RFEC 0.08 0.13 0.06 0.0GTI – RFEC 0.135 0.102 0.149 0.145 0.089 0.066 0.1

0.0

Battelle – Rotating Permanent Magnet 0.065 0.105 0.085 0.0

Comments

SwRI –RFEC GTI – RFEC Two pits axially aligned 

There was an increase in amplitude in this region. We concluded that the increase in the field was caused by the drive coil being located at P3-14. An actual defect may be "buried" in the field but it is not obvious. 

Two pits 

axially aligned 

Two 

axially a

Battelle – Rotating Permanent Magnet 

Corrosion patch, with multiple pits of different depths 

 Single Pit 

Corrosion patch, with multiple pits of different depths 

Corro

patch

multiple 

diffe

dep
27 

Mechanical Damage Assessment 

Only one technology, the PNNL Ultrasonic Strain Measurement technology, was tested for 

assessment of mechanical damage. Two 24-inch diameter pipes were inspected by PNNL for 

mechanical damage. The first pipe (Pipe Sample 1) consisted of two pipes welded together with 

mechanical damage defects along three rows separated by 120° and measured approximately 28-

feet in length. The test line on Pipe Sample 1 consisted of mechanical damage created using a 

50-ton track hoe. An example mechanical damage defect from Pipe Sample 1 is shown in Figure 

19. The second pipe (Pipe Sample 2) measured approximately 40 feet in length with plain (or 

smooth) dent defects along one test line. An example mechanical damage defect from Pipe 

Sample 2 is shown in Figure 20. 

Figure 19. Example Mechanical Damage Defect from Pipe Sample 1 

Figure 20. Example Mechanical Damage Defect from Pipe Sample 2 
28 

The benchmark data and test results for PNNL’s PNNL Ultrasonic Strain Measurement 

technology are shown in Table 8 and Table 9. 

Table 8. Benchmark vs. Test Results for Mechanical Damage Pipe Sample 1 

PIPE SAMPLE 1 

Dent Severity 

0 = No damage 

1 = Least Severe 

2 = Moderately Severe 

3 = Severe 

4 = Most Severe 

Defect 

Number 

Search 

Region 

(from End A) 

Benchmark PNNL 

Comments 

D1 64.5” 2 4 dent start at 63.5" end at 66.5", length 3" 

D2 68.5” 2 2 dent start at 67" end at 70", length 3" 

D3 77.5” 2 1 dent start at 77.3" end at 78.1", length 0.9" 

D4 105” 2 2.5 long dent along the axis dent start at 99.9" end at 110.4", 

length 10.5" 

D5 114” 1 2.5 long dent along the axis dent start at 113.8" end at 119.9", 

length 6.1" 

D6 162” Not Part of 

Benchmark 

detected, damage looks as significant as a 3 or 4, length 

approximately 6 inches long or two dents approximately 2 

inches long separated by 1 inch 

 195.5” 

damage detected; damage looks as significant as a 3, (1 

defect approximately 7 inches long or 2 defects, one 4 inches 

long and a second 2 inches long separated by approximately 

1 inch) 

D7 230” 2 3 dent start at 228.1" end at 234.7", length 6.7" 

D8 240” 1 2 dent start at 236.4" end at 242.1 length 5.7" 

D9 246” 1 0.5 dent start at 245.7" end at 246.2", length 0.5" 

D10 267.5” 4 4 similar to calibration defects dent start at 264" end at 270.1", 

length 6.1" 

D11 274” 2 4 similar to calibration defects dent start at 271" end at 276.1 

length 5.1" 

D12 280.5” 3 4 similar to calibration defects dent start at 277.3" end at 

282.6", length 5.3" 

D13 305.5” 4 NR out of scan range 

D14 310” 4 NR out of scan range 

D15 313” 3 NR out of scan range 
29 

Table 9. Benchmark vs. Test Results for Mechanical Damage Pipe Sample 2 

PIPE SAMPLE 2 

Dent Severity 

0 = No damage 

1 = Least Severe 

2 = Moderately Severe 

3 = Most Severe 

Defect 

Number 

Search 

Region 

(from End A) 

Benchmark PNNL 

Comments 

R03 109.25" 1 1 small degree of damage, start of dent 107" end 110" length 3" 

R04 144” 3 2 moderate damage, start of dent 140.25" end 147.5", length 

7.25" 

R05 183” 2 3 significant damage, start of dent 178.75" end 187.25, length 

8.5 

R06 217” 1 1 small degree of localized damage, start of dent 215.5" end 

220, length 4.5" 

R07 253” 2 2 moderate damage, start of dent 250.5" end 258.5, length 8" 

R08 289.5” 3 3 significant damage, start of dent 286.75 end 295.25, length 

8.5" 

R09 325” 2 2 moderate damage, start of dent 323" end 331", length 8" 

R10 360.5” 3 3 significant damage, start of dent 359" end 367", length 8" 

R11 397” 0 0 no dent 

The term “dent severity” is used in this report to describe relative severity of dents within a 

specific pipe sample. The absolute severity of each dent is not known. Determining the severity 

of mechanical damage is difficult since there are no standards such as those used for corrosion 

anomalies. The criteria used to establish the benchmark severity ratings could differ from 

PNNL’s severity criteria and as such may have led to the discrepancies. 

PNNL began testing the afternoon of Monday January 10, 2006 and completed testing by the 

afternoon of Friday January 13, 2006. The PNNL Ultrasonic Strain Measurement technology

only assesses the relative severity of mechanical damage defects. Location of dents is more 

practically performed by caliper tools and as such was not part of the evaluation criteria for this 

technology. Additionally, because PNNL was only required to identify dent severity at a specific 

location the scan speed was also not assessed. 

PNNL’s technology performed well on the mechanical damage sample with plain dents (Pipe 

Sample 2). There was discrepancy between the PNNL data and the benchmark at defect sites 

R04 and R05 on Pipe Sample 2; however the remaining defect locations correlated well. 

There were a number of differences between the benchmark data and the PNNL data for Pipe 

Sample 1. PNNL noted that the multiple dents and the non-circular nature of the pipe from the 

three rows of dent defects on Pipe Sample 1 created a significant amount of background 

deformation and thus stress and strain within the pipe sample. Due to these factors, the PNNL 

Ultrasonic Strain Measurement technology was not optimized for the degree of background 

deformation and is possibly the reason for the discrepancies between the benchmark data and 

PNNL’s results. PNNL indicated that additional tests would be desirable to help classify the 

dent severity for Pipe Sample 1. 
30 

Stress Corrosion Cracking 

Only one technology, the ORNL Shear Horizontal EMAT, was tested for detection of stress 

corrosion cracking. ORNL began testing the afternoon of Tuesday January 10, 2006 and 

completed testing by mid-day Thursday January 12, 2006. The ORNL Shear Horizontal EMAT 

technology acquired data as their inspection tool was continuously pulled through the pipe 

sample at the rate of about an inch per second. ORNL took multiple scans through each line to 

assess the consistency of the signal. Results were not displayed in real time; rather ORNL post 

processes the captured data to develop final results. ORNL claims post processing is minimal 

and could easily be performed during data acquisition with current generation computing power. 

As shown in Table 10 the technology ran three lines on a 26-inch diameter pipe with natural 

stress corrosion cracking. The EMAT technology detected one false positive signal on each test 

line. The configuration of the SCC defects could have contributed to the false positive readings. 

Because the EMAT configuration scans a minimum of 9-inches of the pipe’s circumference, 

some of the false positives could be the result of other cracks located in close proximity to the 

SCC defects under evaluation. 

Only one defect site (SCC2) provided no discernable signal; however magnetic particle analysis 

showed that these cracks are small and difficult to detect. Additionally, the location of the crack 

colony listed as SCC3 is off by a couple of inches. This is possibly due to defect (18), not 

considered as part of the test and located approximately 3-inches away in the circumferential 

direction, which may have been detected over the smaller SCC colony in SCC3. The most 

significant cracks (SCC8, SCC9, and SCC10) in the test sample were detected by the ORNL 

Shear Horizontal EMAT technology. An example SCC defect is shown in Figure 21. The 

benchmark data and test results for ORNL’s Shear Horizontal EMAT technology are shown in 

Table 10. 

Figure 21. Example SCC Defect 
31 

Table 10. Benchmark vs. ORNL Test Results; SCC Testing 

Benchmark ORNL 

Defect 

Number 

Search 

Region 

(from End 

B) 

Start of 

Crack 

Region (from 

End B) 

End of Crack 

Region (from 

End B) 

Type of SCC 

Start of Crack 

Region (from 

End B) 

End of Crack 

Region (from 

End B) 

Type of SCC 

Test Line 1 

SCC1 242" to 

254" Blank 

SCC2 

(5 & 4) 

226" to 

242" 225.25 238.25 Isolated 

SCC3 

(8) 

210" to 

222" 209.25 212.25 Colony 214 216 Isolated 

SCC4 175" to 

187" Blank 

SCC5 140" to 

152" Blank 145 148 Colony; another 

isolated at 142 

Test Line 2 

SCC6 246" to 

258" Blank 

SCC7 234" to 

246" Blank 236 237 Isolated 

SCC8 

(6) 

210" to 

222" 210.75 213.5 Colony 210 211 Isolated 

SCC9 

(7) 

188" to 

200" 189.25 193.5 Colony 194 196 Colony 

SCC10 

(9) 

140" to 

152" 141.5 145.5 Colony 144 149 

Colony; looks like 

gap in the middle; 

may be 2 sets 

separated by 1-inch. 

Test Line 3 

SCC11 

(16) 

225" to 

245" 224.25 241.25 Colony 237 239 

Isolated; After 

scanning, we 

documented large 

dirt patches along 

line 3 We believe 

EMATs lifted off the 

surface due to dirt 

inside pipe. 

Reliability of data in 

this area is low 

SCC12 210" to 

222" Blank 

SCC13 188" to 

200" Blank 

SCC14 140" to 

152" Blank 139 141 Isolated 

Polyethylene Pipe Defects 

Only one technology, the NETL Capacitive Sensor for Polyethylene Pipe Inspection, was tested 

for detection of plastic pipe defects. This technology inspects for small volumetric anomalies 

with an NETL specified detection threshold of approximately 0.015 cubic inches. The 

measurement technology is localized and therefore anomalies in close proximity and pipe end 

effects do not influence its detection capabilities. 

A measure of defect significance was established based on the calibration defect which was 3/8-

inch in diameter and 50% deep (0.028 cubic inches). The volume of the calibration defect was 

set at a significance of one. The significance of all other defects was based on the volume of the 
32 

calibration defect. An example defect is shown in Figure 22. This defect was calculated to have 

a volume of 0.04 cubic inches which equals a significance of 1.43. As shown in Table 11, the 

technology ran one test line on a 6-inch diameter polyethylene pipe sample. 

Figure 22. Example Plastic Pipe Defect 
33 

Table 11. Benchmark vs. NETL Test Results; Plastic Pipe Testing 

Benchmark NETL 

Defect 

Number

Search Region

Defect Location 

from Side A (to 

center) 

Significance of 

Defect (volume 

ratio from 

calibration defect) 

Defect 

Volume 

Defect 

Diameter 

Defect 

Location from 

Side A (to 

center) 

Significance of 

Defect (volume 

ratio from 

calibration defect) 

Defec

Volum

 inches inches ratio in3 inches inches ratio in3

D1 21" to 27" 25” 1.57 0.044 0.375” 25.06” 1.38 0.039 D2 28" to 34" Blank None D3 35" to 41" Blank None D4 42" to 48" 46” 0.79 0.022 0.25” 45.62” 0.99 0.028 D5 49" to 55" 53” 0.89 0.025 1/8” wide 1” long saw cut 52.55” 1.31 0.037 D6 56" to 62" Blank None D7 62" to 70" 67” 1.57 0.044 0.375” 66.36” 1.15 0.033 D8 70" to 76" Blank None D9 77" to 83" Blank None 

D10 84" to 90" 88” 0.61 0.017 0.25” 87.15” 0.43 0.012 D11 91" to 97" Blank None D12 98" to 104" 102” 1.43 0.04 1/8” wide 1” long saw cut 101.03” 1.61 0.045 D13 105" to 111" 109” 1.43 0.04 0.75” 107.84” 0.71 0.02 D14 112" to 118" 116” 0.54 0.015 0.375” 114.75” 0.57 0.16 D15 119" to 125" 123” and 123.5” 0.61 (each) 0.017 (each) 0.25” (each) 121.89” 0.74 0.74 D16 126" to 132" Blank None? D17 132" to 138" Blank None? D18 138" to 144" 140” 1.25 0.035 0.75” 138.3” 1.13 0.032 D19 144" to 150" 148” 1.11 0.031 0.75” 146.76” 0.71 0.020 

Not part of the benchmarking demonstration 
34 

This page intentionally blank.
35 

While this was the second demonstration for all other technology developers, this demonstration 

was the first for the NETL Capacitive Sensor technology and should be taken into consideration 

when evaluating the results. During the demonstration, the NETL Capacitive Sensor technology 

collected data at a frequency of 1-hertz but has the capability to collect data up to a frequency of 

45-hertz. 

NETL’s accuracy in assessing defect severity is depicted in Figure 23. The NETL Capacitive 

Sensor technology detection was excellent detecting all defect sites to within 1% of the actual 

centerline location and did not report any false positive signals. The percentage difference in 

defect significance was approximately 25%. 

0.0000

0.2000

0.4000

0.6000

0.8000

1.0000

1.2000

1.4000

1.6000

1.8000

0.00000.20000.40000.60000.80001.00001.20001.40001.60001.8000

Measured Significance

Predicted Significance

Figure 23. Measured Severity vs. Predicted Severity for the NETL Capacitive Sensor

SUMMARY 

Four pipeline anomaly conditions were evaluated by six different sensor technology developers. 

Three technologies assessed corrosion anomalies while individual technologies assessed 

mechanical damage, SCC, and plastic pipe material loss. 

The corrosion detection techniques demonstrated significant promise for inspection of 

unpiggable pipelines. Accurate detection and sizing of natural corrosion appears to be reachable 
36 

but additional development may be required to refine sizing algorithms especially when pipe 

material properties are unknown and calibration defects are not available. Additional data 

processing for some of the technologies and collection of larger natural corrosion defect libraries 

to conduct repeatable testing needs to be established. Future collection of data towards target 

corrosion on pipe samples pulled from service will improve system capabilities. In addition, the 

speed at which data is collected could be improved for all of the technologies. The usability of 

these technologies will rely on their ability to collect data for long pipeline segments in a 

relatively short amount of time as well as their ability to meet the design and power requirements 

of the Explorer robotic platform. 

PNNL’s mechanical damage detection technique also achieved reasonably good results 

especially in the pipe sample containing only plain dents. Considering the uniqueness of Pipe 

Sample 1 (multiple dents in close proximity), more accurately assessing the dent severity for this 

type of pipe sample would be a future goal for PNNL’s technology. In-service pipelines with the 

amount of denting evident on Pipe Sample 1 is highly unlikely and does not represent a realistic 

pipeline operating scenario. Track hoe defects; however, would be typical of third party damage 

evident on operating pipelines. 

The ORNL EMAT system also performed well detecting natural stress corrosion cracks that 

formed while the pipeline was in-service. The ORNL EMAT technology did detect some false 

positives on each test line but was also able to detect the most significant SCC locations. Given 

the nature of SCC, it is difficult to accurately size crack depths. Some of the cracks used in the 

benchmarking program may have been too small to clearly detect. Collection of additional SCC 

defect libraries and crack sizing would be a valuable addition to this benchmarking program. 

The NETL Capacitive Sensor was quite accurate in identifying defect locations. Sizing of 

plastic pipe defects is reachable but will require additional research to develop defect sizing 

algorithms. While this was a successful demonstration of the inspection sensor technology, 

inspection variables need to be considered in future evaluations. 

Following the submittal of their test data, the technology developers were sent the benchmark 

data. They were given an opportunity to comment on their results and to provide their 

perspective on their technology’s performance relative to the benchmark data. Appendix C 

contains the developer’s comments. Overall, the technologies performed well and the results are 

encouraging. As the development of these technologies progresses and future testing takes 

place, it is envisioned that improvements in the technology and data analysis techniques will 

continue to improve the false positive rate and enhance the precision and accuracy of the defect 

signals. 

PATH FORWARD 

As noted, PHMSA Pipeline Safety R&D Program goals are to understand the gaps between 

existing technologies and those needed to resolve the key pipeline issues. One recognized path 

forward is to integrate successfully demonstrated sensor technologies into a robotic 

platform/sensor system that can be deployed remotely as part of an integrated package. This 

effort is driven in large part by new PSIA regulations which require inspection of gas 
37 

transmission pipelines and distribution mains in high-consequence areas. A large percentage of 

these pipes cannot be inspected using typical “smart-pig” techniques because of diameter 

restrictions, pipe bends and valves. In addition, pressure differentials and flow can be too low to 

push a pig through some pipes. To help solve these problems, the PHMSA Pipeline Safety R&D 

Program has established an aggressive schedule to develop a prototype remote system which 

includes continued co-funding with industry partners. It is anticipated that upon completion of 

the prototype systems, they will be able to traverse all pipes (including unpiggable lines) of 

various diameters while providing continuous, real-time detection of pipe anomalies or defects. 
38 

This page intentionally blank. 
APPENDIX A – BENCHMARK DATA

A-1 

Calibration Metal Loss 

Location Depth of Metal Loss Measured Length & Width of Defect Measured Max. Depth of Defect 

inches from End B to 

center of defect inches

361" (59" from End A) See profile

Defect 

Number

Search Region 

(Distance from End B)

Start of Metal Loss Region 

from Side B

End of Metal Loss Region 

from Side B Total Length of Metal Loss Region Width of Metal Loss Region Maximum Depth of Metal Loss Region Additional Data Attached? 

inches inches inches inches inches inches Y/N

Defect 

Number

Search Region 

(Distance from End B)

Start of Metal Loss Region 

from Side B

End of Metal Loss Region 

from Side B Total Length of Metal Loss Region Width of Metal Loss Region Maximum Depth of Metal Loss Region Additional Data Attached? 

inches inches inches inches inches inches Y/N

N

YY

P1-13 330" to 342" 335.75"

BLANK 1

Y 

BLANK 4 

YY

N

Y

N

---

WELD 120"

339.625" 3.875" 1.75" 0.095"

P1-14 306" to 318" 308.875" 312" 3.125" 1" 0.115"

Y

NNNN

YY

--- ---

WELD 180"

P1-1 328" to 340" --- ---

---

290.875" 3.125"

---

3"

2.125"20.25"

--- ---

WELD 120"

P1-22

WELD 180"

---

--- --- ------ --- N ---

4.125"

P1-11 76" to 88" --- --- ---

P1-12 52" to 64" 2"

---

P1-10 100" to 112" --- ---P1-15 282" to 294" --- ---P1-16 258" to 270" --- ---

--- --- N

---

P1-17 234" to 246" --- ---

P1-18 210" to 222" 213.625" 217.875" 4.25" 2" 0.145" YP1-19 186" to 198" --- --- --- --- --- N

P1-20 160" to 172" --- --- --- --- --- N

P1-21 120" to 144" 120" 140.75" 20.75" Full Circumference 0.127" Y

98" to 110" 108" 110" 2" 2" 0.12" Y

0.122"0.063"

2" 0.096"1"

--- ---

56.75" 60.875" 

P1-2 304" to 316" --- --- --- --- ---P1-5P1-3 280" to 292" 287.75"P1-4 256" to 268" 259.625"

2" 0.147"

263.625" 4" 2"

0.081"

Detection of Metal Loss - Page 1

Sensor Design:Name:Date:Company:

TEST LINE 1

TEST DATA

8" Diameter, 0.188" Wall Thickness Pipe Sample; Schedule 10; Length = 34' 11.75"

Pipe Sample:Defect Set:

PIPE SAMPLE 1

Calibration P1-1:

Metal Loss Length & Width

inches

2 x 2

CALIBRATION DATA

PIPE SAMPLE 1: 

Pipe Sample

0.146"

---

P1-9 120" to 144" 120" 140.25"

--- --- --- ---

Full Circumference

---

P1-8P1-6 208" to 220" ---P1-7 184" to 196" 190.625" 192.75"

160" to 172"232" to 244" 232.75" 235.75"

P1-23

TEST LINE 2

74" to 86" 79.75" 83.75" 4" 2" 0.097"
A-2 

Calibration Metal Loss 

Location Depth of Metal Loss Measured Length & Width of Defect Measured Max. Depth of Defect 

inches from End B to 

center of defect inches

301.5" (58.5" from End A) See profile

275" (85" from End A) See profile

Defect 

Number

Search Region 

(Distance from End B)

Start of Metal Loss Region 

from Side B

End of Metal Loss Region 

from Side B Total Length of Metal Loss Region Width of Metal Loss Region Maximum Depth of Metal Loss Region Additional Data Attached? 

inches inches inches inches inches inches Y/N

Defect 

Number

Search Region 

(Distance from End B)

Start of Metal Loss Region 

from Side B

End of Metal Loss Region 

from Side B Total Length of Metal Loss Region Width of Metal Loss Region Maximum Depth of Metal Loss Region Additional Data Attached? 

inches inches inches inches inches inches Y/N

WELD 120"

Y

Y

NNN

TEST LINE 2

--- --- ---

60.875"

Y

N

P2-9 102" to 114" 108.125"P2-7

Detection of Metal Loss - Page 2

Name:Date:Company:

Benchmarking of Inspection Technologies

250.25"

WELD 120"

P2-12 246" to 258" 248.125" 2.125" 2" 0.14"P2-13 222" to 234" --- --- --- --- --- N

P2-14 198" to 210" 202.625" 205.75" 3.125" 1" 0.105" Y

P2-15 174" to 186" --- --- --- --- --- N

P2-16 150" to 162" --- --- --- --- --- N

P2-17 126" to 138" 130" 134.125" 4.125" 2" 0.112" YP2-18 102" to 114" --- ---P2-19 78" to 90" --- --- --- --- ---

TEST LINE 1

Sensor Design:

--- --- ---

P2-20 54" to 66" 57.75" 3.125" 1" 0.188"

112.25" 4.125" 2" 0.158"

--- --- ---

150" to 162" 153.125" 156.375"

P2-8 126" to 138" --- ---

PIPE SAMPLE 2:

Calibration P2-1: 3 x 1Calibration P2-2: 2 x 2

CALIBRATION DATA

Pipe Sample Metal Loss Length & Width

inches

3.25" 1" 0.085"

3.125" 0.114"

YY

P2-5 198" to 210" ---

TEST DATA

Pipe Sample: PIPE SAMPLE 2

Defect Set:

---

P2-6 174" to 186" 180.25" 183.375"

--- ---

1"

--- N

P2-4 222" to 234" 227.25" 229.375" 2.125" 2" 0.079" YP2-3 246" to 258" --- --- --- --- --- NP2-2 270" to 282" --- --- --- --- --- N

P2-11 54" to 66" --- ---

P2-1 294" to 306" --- ---

P2-10 78" to 90" 80.125" 84.5" 4.375" 2" 0.147" Y 

8" Diameter, 0.188" Wall Thickness Pipe Sample; Schedule 10; Length = 30' 0.375"

--- --- --- N 
A-3 

Calibration Metal Loss 

Location Depth of Metal Loss Measured Length & Width of Defect Measured Max. Depth of Defect 

inches from End B to 

center of defect inches

421" (59" from End A) See profile

Defect 

Number

Search Region 

(Distance from End B)

Start of Metal Loss Region 

from Side B

End of Metal Loss Region 

from Side B Total Length of Metal Loss Region Width of Metal Loss Region Maximum Depth of Metal Loss Region Additional Data Attached? 

inches inches inches inches inches inches Y/N

Defect 

Number

Search Region 

(Distance from End B)

Start of Metal Loss Region 

from Side B

End of Metal Loss Region 

from Side B Total Length of Metal Loss Region Width of Metal Loss Region Maximum Depth of Metal Loss Region Additional Data Attached? 

inches inches inches inches inches inches Y/N

WELD 240"WELD 240"

N

Y

Y

N

Y

N

4.125" 2" 0.094"

0.75" 0.75"

P3-12 390" to 402" 392.25" 396.375"

P3-14 330" to 342" 335.875" 336.625" 0.154" N P3-15 306" to 318" --- --- --- --- --- NP3-16 282" to 294" --- --- --- --- --- NP3-17 248" to 260" 250.625" 253.75" 3.125" 1" 0.07" Y

P3-18 210" to 222" 214.5" 217.625" 3.125" 1" 0.091" Y

P3-19 180" to 192" 185.765" 186.485" 0.72" 0.72" 0.139" NP3-20 156" to 168" --- --- --- --- --- NP3-21 126" to 138" 130" 134.125" 4.125" 2" 0.103" Y

--- --- ---

4.125" 2" 0.088"

--- ---

P3-22 102" to 114" --- ---P3-23 66" to 78" 69.5" 73.625"

384" to 396" --- --- ---

P3-11 66" to 78"

TEST LINE 2

--- --- --- --- --- N 

P3-2 360" to 372" --- --- --- --- --- N

P3-3 330" to 342" 335" 337.25" 2.25" 2" 0.133" Y

P3-4 300" to 312" 305.625" 306.375" 0.75" 0.75" 0.148" N

P3-5 270" to 282" 275" 277.25" 2.25" 2" 0.103" Y

P3-6 222" to 234" --- --- --- --- --- NP3-7 186" to 198" 189.875" 194" 4.125" 2" 0.115" Y

P3-8 162" to 174" --- --- --- --- --- NP3-9 138" to 150" 143.665" 144.335" 0.67" 0.67" 0.120" N

Defect Set: 8" Diameter, 0.188" Wall Thickness Pipe Sample; Schedule 10; Length = 40' 0.25"

TEST DATA

Pipe Sample: PIPE SAMPLE 3

Benchmarking of Inspection Technologies

Company:Sensor Design:

P3-13 356" to 368" --- --- --- --- ---

Detection of Metal Loss - Page 3

Name:Date:

1" 0.156"

inches

PIPE SAMPLE 3:

TEST LINE 1

Calibration P3-1: 2 x 2

P3-1

CALIBRATION DATA

Pipe Sample Metal Loss Length & Width

P3-10 102" to 114" 106.375" 109.625" 3.25"
A-4 

This page intentionally blank. 
A-5 
A-6 

This page intentionally blank. 
A-7 
A-8 

Pipe Sample: 993

Calibration 

Crack 

Location

Length Depth Measured Length Measured Depth

inches from 

end B inches

% wall 

thickness

186.4 2.5

58.7 586.4 582.4 2.544.4 3

Defect 

Number

Search Region 

(Distance from 

End B)

Start of Crack

Region from 

Side B

End of 

Crack 

Region 

from Side B

inches inches inches

Isolated CrackColony of Cracks

Isolated CrackColony of CracksIsolated Crack

Colony of Cracks

Isolated Cracks

Colony of Cracks

Isolated CrackColony of Cracks

TEST LINE 1

SCC2

(5 & 4) 226" to 242" 225.25 238.25 None

SCC1

(Blank 3) 242" to 254" --- --- None

None

Blank 1

SCC3

(8) 210" to 222" 209.25 212.25 None

SCC5 

(Blank 1) 140" to 152" --- ---

multiple cracks; mamultiple cracks; ma

23

Blank Area:

Comments

26" Diameter Pipe with Stress Corrosion Cracks; Length = 26 feet

Pipe Sample:

Comments

1 multiple cracks; ma

Defect Set:

893

Benchmarking of Inspection Technologies

Detection of SCC - Page 1

Sensor Design:Name:Date:Company:

CALIBRATION DATA

TEST DATA

multiple cracks; ma

multiple cracks; max 

SCC4

(Blank 2) 175" to 187" --- --- None

Type of SCC

45

Blank 2

Multiple 1/4" cracks; cracked a

Two isolated cracks; cracked area 4

crack; cracked area 5 1/4" by 1 1

Blank 3
A-9 

Defect 

Number

Search Region 

(Distance from 

End B)

Start of Crack

Region from 

Side B

End of 

Crack 

Region 

from Side B

inches inches inches

Isolated Crack

Colony of Cracks

Isolated Crack

Colony of Cracks

Isolated Crack

Colony of Cracks

Isolated CrackColony of Cracks

Isolated CrackColony of Cracks

Sensor Design:

Type of SCC Comment

TEST DATA

Pipe Sample: 893

TEST LINE 2

None

141.5 145.5

NoneNone

Blank

Benchmarking of Inspection Technologies

Detection of SCC - Page 2

Name:Defect Set: 26" Diameter Pipe with Stress Corrosion Cracks; Length = 26 feetDate:Company:

SCC6

(Blank 5) 246" to 258" --- ---

188" to 200" 189.25 193.5

SCC8

(6) 210" to 222" 210.75 213.5 None

SCC7

(Blank 4) 234" to 246" ---

Blank

---

None

Multiple cracks; max ~1/4" long; crMultiple cracks; max ~1/4" long; cr

Multiple cracks; max ~1/2" long; 

SCC10

(9) 140" to 152"

SCC9

(7)
A-10 

Defect 

Number

Search Region 

(Distance from 

End B)

Start of Crack

Region from 

Side B

End of 

Crack 

Region 

from Side B

inches inches inches

Isolated CrackColony of Cracks

Isolated CrackColony of CracksIsolated CrackColony of CracksIsolated Crack

Colony of Cracks

TEST LINE 3

None

140" to 152" --- ---

SCC13

(Blank 7) 188" to 200" --- ---

None

Date:Company:

SCC14

(Blank 6)

BlankBlankBlank

SCC12

(Blank 8) 210" to 222" --- --- None

None

Multiple cracks; max ~3/4" long; c

SCC11 (16) 225" to 245" 224.25 241.25

Benchmarking of Inspection Technologies

Detection of SCC - Page 3

Name:Sensor Design:

Type of SCC Comment

TEST DATA

Pipe Sample: 893

Defect Set: 26" Diameter Pipe with Stress Corrosion Cracks; Length = 26 feet
A-11 

Calibration Defect 

Location Volume of Defect Depth of Defect Diameter of Defect

inches from end A cubic inches inches inches

C1: 18 0.028 0.25 0.375

Defect 

Number

Search Region 

(Distance from End 

A)

Location of Defect 

Region from Side A

Significance of Defect 

(based on volume ratio

from calibration 

defect)

Volume of Defect (in3) 

(provided to 

participant after defect

signif reported)

Depth of Defect (in) 

(provided to participant 

after defect signif reported)

Diameter of Defect 

(in) (provided to 

participant after defect

signif reported)

inches inches

Calibration Defect = 1Less Severe <1More Severe >1 cubic inches inches inches

----

0.750.75

Comments

0.25

----

0.125

----

0.25

0.125

----

BLANK 0 ---- ----

53" 0.89

D6 56" to 62" BLANK

49" to 55"

D2D4 42" to 48" 46"D3 35" to 41" BLANK 0

28" to 34" BLANK 0 ----

D1 21" to 27" 25" 1.57 0.044 0.4

---- ----

0.375

CALIBRATION DATA

Defect

LINE 1

TEST DATA

6" Diameter, 0.5" Wall Thickness Pipe Sample, ~13' in length

Pipe Sample:Pipe Parameters:

PLASTIC PIPE SAMPLE

Benchmarking of Inspection Technologies

Detection of Plastic Pipe Defects - Page 1

Sensor Design:Name:Date:Company:

---- ----

0.022 0.45

0.2

0 ---- ----

0.025

0.79

D5D7 63" to 69" 67" 1.57 0.044 0.4

Saw Cut ~

D8 70" to 76" BLANK 0 ---- ----

0.375

----

D9 77" to 83" BLANK 0 ---- ----

D12 98" to 104" 102" 1.43 0.04 0.35 Saw Cut ~0

D11 91" to 97"D13 105" to 111" 109" 1.43 0.04 0.09 0.75D14 112" to 118" 116" 0.54 0.015 0.14 0.375

D15 119" to 125" 123" and 123.5" 0.61 (each) 0.017 (each) 0.35 (each) Defect consists of 

0.25 (each)

D16 126" to 132" BLANK 0 ----

D17 132" to 138" BLANK 0

D19 144" to 150" 148" 1.11D10 84" to 90" 88" 0.61

0.031 0.070.017 0.35

---- -------- ----

D18 138" to 144" 140" 1.25 0.035 0.08

----
A-12 

This page intentionally blank.
APPENDIX B – DEMONSTRATION TEST DATA

B-1 

SOUTHWEST RESEARCH INSTITUTE (SWRI) 

DEMONSTRATION TEST DATA
B-2 

This page intentionally blank. 
B-3 

Calibration Metal Loss 

Location Depth of Metal Loss Measured Length & Width of Defect Measured Max. Depth of Defect Com

inches from End B to 

center of defect inches

359 (59 from End A) See profile

298.5 (58.5 from End A) See profile

277 (85 from End A) See profile

(59 from End A) See profile

Defect 

Number

Search Region 

(Distance from End B)

Start of Metal Loss Region 

from Side B

End of Metal Loss Region 

from Side B Total Length of Metal Loss Region Width of Metal Loss Region Maximum Depth of Metal Loss Region Additional Data Attached? Com

inches inches inches inches inches inches Y/N

Defect 

Number

Search Region 

(Distance from End B)

Start of Metal Loss Region 

from Side B

End of Metal Loss Region 

from Side B Total Length of Metal Loss Region Width of Metal Loss Region Maximum Depth of Metal Loss Region Additional Data Attached? Com

inches inches inches inches inches inches Y/N

No in

309.5 N

N

No inNo inNo inNo inNo in

Appears to be large region of gene

the designated region. Signal pa

calibrati

No in

N

Defect type signal 

Two defects in regio

Appears to be large region of gene

the designated region. Signal pa

calibrati

No in

NNN

WELD 120"

312.8

P1-13 330" to 342" 335.8 339.9 4.04 1.47 0.08

3.31 P1-14 306" to 318" 1.37 0.11

NNNN

WELD 180"

P1-1 328" to 340"

0.95 1.92

a=2.25, b=0.77 a=1.82, b=Full Circ.

WELD 120"

P1-10 100" to 112"

WELD 180"

Calibration P3-1:

3.32

P1-11 76" to 88"

1.63

2 x 23 x 12 x 2

P1-15 282" to 294"P1-16 258" to 270" No inP1-17 234" to 246"

4.13 1.69 0.14 N P1-18 210" to 222" 214.0 218.1

P1-19 186" to 198"

0.06 N

P1-20 160" to 172"

160.0 172.0 12.00 Full Circ. 0.18 N

P1-21 120" to 144" 128.9 129.7P1-22 98" to 110" 108.1 110.1

0.13 P1-12 52" to 64" 56.9 60.2

P1-2 304" to 316"

0.06

P1-5P1-3 280" to 292" 282.6 285.8 3.16 1.25 0.10

1.99 1.82 0.08 N0.79 Full Circ.

0.09

258.7 4.20 1.95

1.09

189.7

Benchmarking of Inspection Technologies

Detection of Metal Loss - Page 1

Sensor Design:Name:Date:Company:

Gary Burkhardt

27-Jan-06Southwest Research InstituteRFEC

TEST LINE 1

TEST DATA

Calibration P2-1:

8" Diameter, 0.188" Wall Thickness Pipe Sample; Schedule 10; Length = 34' 11.75"

Pipe Sample:Defect Set:

PIPE SAMPLE 1

2 x 2

CALIBRATION DATA

PIPE SAMPLE 1: 

PIPE SAMPLE 3:

Pipe Sample

PIPE SAMPLE 2:

Calibration P2-2:Calibration P1-1:

Metal Loss Length & Width

inches

a=0.066, b=.083

12.00

P1-9 120" to 144" a=120, b=128.5 a=122.3, b=129.3

160.0 172.0 Full Circ. 0.18

P1-8P1-6 208" to 220"P1-7 184" to 196" 188.8

160" to 172"232" to 244" 227.7 231.0 3.30 0.08

P1-4 256" to 268" 254.5

P1-23

TEST LINE 2

74" to 86" 79.9 81.4 1.48 1.72 0.09
B-4 
B-5 
B-6 

This page intentionally blank. 
B-7 

Comments on Tests Performed During Demonstration at Battelle: 

“Phase II Benchmarking Emerging Pipeline Inspection Technologies” 

January 9–13, 2006 

APPLICATION OF REMOTE-FIELD EDDY CURRENT (RFEC) TESTING TO 

INSPECTION OF UNPIGGABLE PIPELINES 

OTHER TRANSACTION AGREEMENT DTRS56-02-T-0001 

SwRI

®

 PROJECT 14.06162 

PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMNISTRATION 

U.S. DEPARTMENT OF TRANSPORTATION 

SOUTHWEST RESEARCH INSTITUTE

® 

January 2006 

 

Demonstration tests of the remote-field eddy current (RFEC) method for inspection of 8-inch 

pipe were performed by Southwest Research Institute

®

 (SwRI

®

). The target application of the 

inspection technology is to integrate it with the Explorer II robot under development by Carnegie 

Mellon University. Therefore, the approach taken by SwRI was to perform the demonstration 

using a tool that meets the requirements and specifications for the Explorer II robot. All of the 

instrumentation (except for external power, which will be supplied by the robot), including 

excitation signal generation, amplification, filtering, multiplexing, analog-to-digital conversion, 

and digital signal processing (to provide phase-sensitive signal detection), was located on the 

RFEC tool. Total power required was less than half of the power budget available from the robot. 

Communication of commands and transfer of the processed signal data to an external computer 

were accomplished using a CAN bus—the same bus that will be used on the robot. Although the 

tool incorporated 8 channels (coverage of 60 degrees circumferentially) instead of the 48 

channels intended for the robot tool (to achieve 360 degrees coverage), the circuitry is readily 

scalable to the full number of channels. Data were acquired by all 8 channels simultaneously 

during a single scan. The scans were made at a velocity of 1.5 inches/sec, and it was 

demonstrated that 4 inches/sec (the maximum scan speed of the robot) was possible. The data 

were post-processed for analysis to determine defect characteristics (length, width, and depth) 

using software that is readily adaptable to field inspections 

The development of hardware that meets constraints associated with factors such as scan speed, 

power, and size always results in compromises that are not factors if, for example, laboratory 

instrumentation is used and if scan speeds are very slow. For example, slow scan speeds mean 

that significantly greater noise-reduction filtering can be used because time constants can be very 

long compared to those necessitated by fast scan speeds. Laboratory instrumentation can 

incorporate additional filtering and signal processing that cannot readily be performed by 

circuitry that must meet size and power constraints. Since the SwRI tool met the robot 

constraints, it can be expected that results similar to those achieved in these tests can be expected 

from the final integrated hardware. 
B-8 

It should be noted that defect characterization has a strong subjective element. In this 

demonstration, we were working with a brand new system, looking at defect types we had not 

seen before. That meant we had to use our best judgment and understanding of the RFEC method 

to interpret the indications. After the system has been used more extensively, experience will 

allow the operator to know quickly what type of defect is being detected based on the signal 

characteristics. The quantitative interpretation of the signals will then be improved over the 

present level. For example, the natural corrosion region in the demonstration pipes gave a signal 

unlike any of the calibration defects in our lab or supplied by Battelle. Furthermore, the signal 

extended beyond the designated region. As a result, we used our best judgment and reported the 

wall loss indicated by our depth algorithms. Magnetic field effects or the simple nature of RFEC 

response to very large area defects could cause our estimate to be in error. Familiarity with this 

type defect over a period of time would assure us of making a quicker and potentially more 

accurate appraisal of the corrosion.
B-9 

GAS TECHNOLOGY INSTITUTE (GTI) 

Demonstration Test Da 

Defect 

Number

Search Region 

(Distance from End B)

Start of Metal Loss Region 

from Side B

End of Metal Loss Region 

from Side B Total Length of Metal Loss Region Width of Metal Loss Region Maximum Depth of Metal Loss Region Additional Data Attached? 

inches inches inches inches inches inches Y/N

Defect 

Number

Search Region 

(Distance from End B)

Start of Metal Loss Region 

from Side B

End of Metal Loss Region 

from Side B Total Length of Metal Loss Region Width of Metal Loss Region Maximum Depth of Metal Loss Region Additional Data Attached? 

inches inches inches inches inches inches Y/N

WELD 120"

TEST LINE 2

Detection of Metal Loss - Page 2

Name:Date:Company:

Benchmarking of Inspection Technologies

WELD 120"

Sensor Design:

P2-18 102" to 114"P2-19 78" to 90"

P2-4

2 1.5 0.1483 1.5 0.081

P2-12 246" to 258" 249 251P2-13 222" to 234"P2-14 198" to 210" 201 204P2-15 174" to 186"P2-16 150" to 162"

4 2 0.159 P2-17 126" to 138" 129.5 133.53 1.5 0.176 P2-20 54" to 66" 57.5 60.5

TEST LINE 1

P2-9 102" to 114" 107.75 111.75 4 1.5 0.142

P2-7 150" to 162" 152.75 155.75P2-8 126" to 138"

8" Diameter, 0.188" Wall Thickness Pipe Sample; Schedule 10; Length = 30' 0.375"

1

3 2 0.026

3.25 0.073

P2-5 198" to 210"

TEST DATA

Pipe Sample: PIPE SAMPLE 2

Defect Set:

P2-6 174" to 186" 179.75 183

222" to 234" 227.25 229.5 2.25 2 0.037

P2-3 246" to 258"P2-2 270" to 282" 

P2-11 54" to 66"

P2-1 294" to 306"

2.5 0.188 P2-10 78" to 90" 80.25 84 3.75
B-10 
B-11 

Analysis of Sensor Benchmarking Tests 

Remote Field Eddy Current Technique 

Prepared by: 

Julie Maupin, Albert Teitsma, Paul Shuttleworth 

Gas Technology Institute 

1700 S. Mount Prospect Road 

Des Plaines, Illinois 60018 

27 January 2006 
B-12 

Abstract

During the week of 9 January 2006, GTI staff travelled to the Battelle Lab’s West Jefferson 

facility in Columbus, OH to test a prototype RFEC inspection vehicle in 3 samples of 8” pipe. We 

report briefly on the apparatus and its design, the electronic readout and data acquisition, and 

the analysis of the data. Where appropriate, we have discussed effects which lead to 

uncertainties in the location and size of reported defects. We also discuss uncertainties which 

may affect whether a defect would have been observable by our apparatus. 

Introduction

The remote field eddy current (RFEC) technique is an electromagnetic, through-wall inspection 

technique for detecting defects and wall thinning in pipe walls. A simple exciter coil can be 

driven with a low frequency sinusoidal current to generate an oscillating magnetic field that 

small sensor coils can detect. This low frequency (10’s of Hz) oscillating field will propagate via 

two paths. It will propagate directly down the pipe a short distance. It will also propagate out 

through the wall, along the exterior of the pipe, and will re-enter the pipe --- the so-called indirect 

field. At axial distances of 2-3 pipe diameters from the exciter coil, the indirect field re-entering 

the interior of the pipe is much larger than the direct field coming from the exciter coil. Since it 

passes through the pipe wall, the indirect field contains information regarding the condition of 

the pipe. Changes from nominal value of the amplitude and phase of the indirect field indicate 

defects in the wall. 

Figure 1: Paths of Energy Flow in the RFEC Technique. The remote field re-entering 

the pipe is the one containing the information regarding the condition of the pipe wall.

We constructed a vehicle (“jig”) for carrying the RFEC apparatus. Near its front end it carried a 

solenoidal exciter coil, approximately 4” in diameter and 5” in length. It was comprised of1300 

windings of 26 gauge wire. The sensor coils are located at distances of approximately 17” 

upstream of the exciter coil. They are 3⁄4” in diameter, 3/8” in width, and contain approximately 

20K windings of 50 gauge wire. Configured on the jig as two sets of 8 sensor coils, each set 

covered an angle of approximately 60o circumferentially at 1⁄4” spacing. 

Mechanical Design 

The RFEC vehicle was composed of three parts, front support, rear support, and the center 

body. The front and rear supports had steering mechanisms on the wheels that helped keep the 

device upright and prevented any major rotation of the vehicle. The supports were coupled to 
B-13 

the center body, which contained all the equipment necessary to the RFEC technique. A picture 

of the center body is shown in Figure 2. 

Figure 2: Center body of RFEC vehicle. 

GTI used two sets of 8 sensor coils to measure two defect lines simultaneously. The coils were 

mounted on shafts that served as pegs to attach the coils to plastic guides as shown in Figure 3. 

The guides were rounded to match the circumference of the pipe and routed on the leading 

edge to avoid jamming the welds. The guides were held against the pipe wall by spring-loaded, 

parallelogram configured arms. An end view of the sensor coil mounts is shown in Figure 4. 

Sensor 

Coils

MUX 

Board 

Mock Explorer 

Module 

Drive 

Coil

Support

Plastic Coil Guide 

Coil 

Shaft 

Figure 3: Diagram of sensor coils mounted to plastic guides. 

Direction 

Of Travel
B-14 

Figure 4: Sensor coil mounts inside an 8” pipe. 

The drive coil has been placed between two support modules, one having been built to imitate a 

module on the Explorer II robot. These support modules were important to keeping the drive coil 

centered in the pipe. 

GTI used an automatic winch system to pull the vehicle through the pipe. A tether line was 

attached to the front end of the vehicle. The tether wraps once around an encoder and then is 

wound onto a motor. The system is mounted directly onto the pipe and is controlled by 

LabVIEW to move the vehicle in 1⁄4” steps. 

Uncertainties Related to Mechanics 

The jig suffered from some rotation inside the pipe. Each coil could have experienced rotations 

of up to ±10°. There were some encoder losses. After traveling 25’ in the pipe, we were 

measuring about 5” short of the actual location of the sensor coils. We eventually attached a 

fiberglass tape measure to the back end of the vehicle so we could always double check the 

encoder readings. In order to get good wall coverage from the coils, they had to be staggered, 

meaning half were closer to the drive coil than the other half. We have made provisions to 

correct the offset in the data analysis but there will still likely be an effect on the results. 

Mounting 

Spring 

Plastic Coil 
B-15 

Electronics and Data Acquisition (DAQ) System 

GTI’s embodiment of a Remote Field Eddy Current inspection system is as follows: Signal 

Recovery 7265 DSP lock-in amplifier, Kepco BOP36-6M excitation coil driver, ADG407 16 

channel multiplexer, Ni GPIB+ Gpib board and Ni PCI-6601 Counter Timer board. The 

preceding hardware is controlled by a Dell Pentium 4 workstation running at 2.99MHz with 1Gb 

of main memory and executing Lab View 7.1 under Windows XP Professional operating system. 

A general schematic of the DAQ system is shown in Figure 7. 

Channel addressing and distance gauging is accomplished using a Ni 6601 time/counter PCI 

circuit board. Distance measurements are made using a relative incremental encoder having a 

resolution of 1/16”. 

Figure 5: Schematic of DAQ System. This figure schematically shows a 4-channel system. The 

system we operated at Battelle was a 16-channel version of this schematic. 

GTI’s RFEC machine is using a 100 count per revolution quadrature encoder. The encoder is 

interfaced to the system using a National Instrument PCI-6601 counter/timer circuit board. This 

circuit board supports 5 encoders; the encoder interface is done in hardware. The counter chip 

used in the NI circuit board has 32 bit registers giving a counting range of 268,435,453 inch. 

Data Collection 

Three LabView programs were used to collect data from the instrumentation on the jig. One 

read the encoder, one controlled the motor, and the other controlled the lock-in amplifier and 

acquired data from the coils. Acquiring the phase angle and magnitude of each coil was 

achieved by using a sequence of binary addressing to the multiplexer board. The program 

cycles through each coil sequentially. Once the data has been acquired for all 16 coil channels, 

the motor program fires the motor until the encoder program realizes it has traveled to the next 

1⁄4” step. Once the motor stops, the coils are again read and the phase and magnitude data is 

recorded to Excel. The process repeats. 

 

The lock-in amplifier has a programmable time constant for the low pass filter at its output. The 

program was written so that the operator could set the number of time constants that the 

program would wait at each coil address. Having a wait of multiple time constants ensured that 
B-16 

unsettled data would be flushed out and the readings would be accurate. The drawback to 

waiting for a certain number of time constants is slower acquisition time. It takes a significantly 

longer time to obtain data for 16 coils making overall inspection speed slow. No problems were 

encountered with LabVIEW. 

Analysis 

Pipe Sample 3 

Analysis of defect depth on Pipe Sample 3 was primarily done using Russell NDE Systems 

Inc.’s Adept Pro program. This program is the result of decades of research and focuses on the 

Voltage Plane for analysis. The display produced by the program is shown for Defect Line1 in 

Figure 6. 
B-17 

Figure 6: Adept Pro display of Defect Line 1 from Pipe Sample 3.

Weld

Defects

φ
B-18 

The display shows a strip chart of the phase angle on the left, followed by a C-Scan of the 

phase. Although the C-Scan provides a good overview of the defects, often as in this case, the 

strip chart is better for seeing the smaller defects. The magnitude information (strip chart and Cscan) is displayed to the right of the phase information. The top right hand panel shows the 

Voltage Plane. The black spiral is the attenuation spiral: as the wall thickness increases, the 

remote filed eddy current signal strength decreases while the phase also decreases, resulting in 

a spiral polar plot. The blue curve on the plot is the signal from the defect at the horizontal 

marker that runs across the strip charts and C-scans. The two red lines on either side of the 

marker delimit the range of data analyzed. 

If the blue line is extended to intersect the wall-thinning spiral, the vector from the origin of the 

polar plot to the intersection point makes an angle φ with the x-axis. Angle φ is used to 

determine the depth of the defect. The length of the blue line is used to find the circumferential 

extent of the defect. As in Figure 6, Figure 7 shows the analysis of Line 2 of Pipe 3. 
B-19 

Figure 9: Adept Pro Display of Defect Line 2. 

Adept Pro’s function is primarily to determine defect depth. Defect length and width are best 

obtained from axial and circumferential scans across the defect. Remote field eddy current 

signals spread in both the axial and the circumferential directions. To get length and width 

Weld

Defects
B-20 

requires corrections for the spread. Axial lengths estimated from the data should be reasonable. 

However, the combination of much greater spread in the circumferential direction combined with 

sensor separation means circumferential precision is poor. 

Pipe 2 was analyzed with an internally written MATLAB program. The fundamental equations 

are the same as used by Russell‘s Adept Pro software but there are some differences in the 

calibration. This can lead to small differences in the results for this pipe. This approach was 

used because Pipe 2 has two calibration defects with different depths. We expect the new 

calibration to give better results over a wide range of defect depths. 
B-21 

 Table 1: C-scan Plots of defects found on Pipe 3 Test Line 1. 

 P3-10 P3-09 

 

 P3-07 P3-05 

 

 P3-04 P3-03 
B-22 

Table 2: Line 1 Defects 

Defect 

Location 

Max Depth (% 

of wall thick.) 

Defect 

Length 

Defect 

Width 

106” 96% 3” 2” 

143.5” 78% 1.25” 1” 

190” 92% 3.5” 2” 

275.75” 75% 2” 2” 

306.5” 84% 1.25” 1” 

335” 87% 2” 1.5” 

C-Scan plots 

The C-scan plots for all found defects are attached as a separate document. The tables 

containing Pipe 1 defects show the strip chart and C-scan for the phase only. The tables 

containing Pipe 2 defects show the C-scan for the phase only. Finally, the tables containing 

Pipe 3 defect information show the strip chart and C-scan for both the phase and magnitude. 

Summary Results Table 

The Excel spreadsheet summarizing the results is attached as a separate document. Pipe 2 

data was only analyzed for the deepest pit. Data from Pipes 1 and 3 that showed dual pits are 

recorded in the spreadsheet as two measurements representing the maximum depth of each 

pit. 
B-23 

Table 1: C-scan Plots of defects found on Pipe 1 Test Line 1. 

 P1-12 P1-09 

 

 P1-07 P1-05 

 

 P1-04 P1-03 
B-24 

 P1-02 
B-25 

Table 2: C-scan Plots of defects found on Pipe 1 Test Line 2. 

 P1-23 P1-22 

 

 P1-21 P1-18 

 

 P1-14 P1-13 
B-26 

Table 3: C-scan Plots of defects found on Pipe 2 Test Line 1. 

 P2-10 P2-09 

 

 P2-07 P2-06 

 

 P2-04 
B-27 

Table 4: C-scan Plots of defects found on Pipe 2 Test Line 2. 

 P2-20 P2-17 

 

 P2-14 P2-12 

 

 

 
B-28 

Table 5: C-scan Plots of defects found on Pipe 3 Test Line 1. 

 P3-10 P3-09 

 

 P3-07 P3-05 

 

 P3-04 P3-03 
B-29 

 Table 6: C-scan Plots of defects found on Pipe 3 Test Line 2. 

 P3-23 P3-21 

 

 P3-19 P3-18 

 

 P3-17 P3-14 
B-30 

 P3-12 
B-31 

BATTELLE 

DEMONSTRATION TEST DATA
B-32 

This page intentionally blank. 
B-33 

Defect 

Number

Search Region 

(Distance from End B)

Start of Metal Loss Region 

from Side B

End of Metal Loss Region 

from Side B

 Total Length of Metal Loss Region Width of Metal Loss Region Maximum Depth of Metal Loss Region Additional Data Attached? 

inches inches inches inches inches inches Y/N

Defect 

Number

Search Region 

(Distance from End B)

Start of Metal Loss Region 

from Side B

End of Metal Loss Region 

from Side B

 Total Length of Metal Loss Region Width of Metal Loss Region Maximum Depth of Metal Loss Region Additional Data Attached? 

inches inches inches inches inches inches Y/N

184" to 196"160" to 172"

 192.2 188.8

TEST LINE 1

TEST DATA

8" Diameter, 0.188" Wall Thickness Pipe Sample; Schedule 10; Length = 34' 11.75"

Pipe Sample:Defect Set:

PIPE SAMPLE 1

Benchmarking of Inspection Technologies

Detection of Metal Loss - Page 1

Sensor Design:Name:Date:Company:

Bruce NestlerothJanuary 26,2006BattelleRotating Permanent Magnet Eddy Current Inspection System

0.110

0.050

 Various depths up to 

0.150 inches 

TEST LINE 2

 0.075 1.0

Greater than 5 inches

0.165

1.5

 0.075 1.0

120" to 144"

P1-1 328" to 340"

1.0

1.75

P1-4 256" to 268"

P1-23 74" to 86"

 106.3 103.1

P1-3 280" to 292"

Corrosio

P1-2 304" to 316"

0.055

P1-5

0.115

 Various depths up to 

0.150 inches 

No Metal Loss Detected

Yes. Raw Signals

 138.0 126.0 12.0

No Metal Loss DetectedNo Metal Loss Detected

P1-12 52" to 64"P1-22 98" to 110"

P1-9 120" to 144"P1-8P1-6 208" to 220"P1-7

No Metal Loss Detected

Yes. Raw SignalsYes. Raw Signals

P1-18 210" to 222" 216.8 212.5 3.3 0.155 2.0 Yes. Raw Signals

P1-17 234" to 246" 0.020 0.75 Yes. Raw SignalsP1-16 258" to 270" Yes. Raw Signals

No Metal Loss Detected

P1-11 76" to 88" No Metal Loss Detected

 62.3 58.1 3.2 1.75

WELD 180"

 0.115 1.25

Corrosio

P1-10 100" to 112"P1-20 160" to 172" No Metal Loss Detected

 32.0 12.0

2.4 1.52.2

No Metal Loss Detected

 132.0 120.0

No Metal Loss Detected

Yes. Raw SignalsYes. Raw SignalsYes. Raw SignalsYes. Raw Signals

P1-13

Yes. Raw SignalsYes. Raw SignalsYes. Raw SignalsYes. Raw Signals

WELD 120"P1-14 306" to 318" WELD 180"

232" to 244"

P1-15 282" to 294"P1-19 186" to 198"P1-21WELD 120"

Corrosio

Yes. Raw SignalsYes. Raw SignalsYes. Raw SignalsYes. Raw Signals

Corrosio

A area of genera

A slow change in 

Yes. Raw SignalsYes. Raw Signals

CorrosioCorrosioCorrosioCorrosio

A large area of genera

corrosion is close to t

A slow change in 

Yes. Raw SignalsYes. Raw Signals

330" to 342" 338.4 334.2 3.2 0.075 1.0 Yes. Raw Signals

CorrosioCorrosio

 237.0 233.2 2.8 264.9 260.1 3.8 292.8 288.0 3.8

 79.1 74.8 3.3

 241.8 241.1 0.7 310.8 306.9 2.9

No Metal Loss Detected
B-34 
B-35 
B-36 

This page intentionally blank. 
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 1 - Page 1

Pipe 1

Raw data output on same scale

420 inches, 2 welds @ 120 and 180 inches

Search Region

Extra data

for noise

assessment

Extra data

for noise

assessment

348

354

360366372 CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Cal 1-1

Distance (inches)

Sensor Output
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 1 - Page 2 322 328 334 340 346

P1-1

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

298

304310316

322

P1-2

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 1 - Page 3

P1-3

274

280286292

298

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

P1-4

250

256262268

274

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 1 - Page 4

P1-5

226

232238244

250

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

P1-6

202

208214220

226

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 1 - Page 5

P1-7

178

184190196

202

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Weld Signal

P1-8

Distance (inches)

Sensor Output 154

160166

172

178

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Weld Signal
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 1 - Page 6

P1-9 note reporting area larger, 120 to 144 inches

114120

126

132138

144

150

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

P1-10

94

100106

112

118

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Weld Signal
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 1 - Page 7

P1-11

70

76

8288

94

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

P1-12

46

5258

6470

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 1 - Page 8 324 330 336 342 348

P1-13

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

300

306312318

324

P1-14

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 1 - Page 9 276 282 288 294 300

P1-15

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

252

258264270

276

P1-16

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 1 - Page 10 228 234 240 246 252

P1-17

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

204

210216222

228

P1-18

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 1 - Page 11 180 186 192 198 204

P1-19

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

154

160166

172

178

P1-20

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 1 - Page 12 114 120 126 132 138 144 150

P1-21 note reporting area larger, 120 to 144 inches

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Weld Signal

92

98

104

110

116

P1-22

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Weld Signal
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 1 - Page 13 6874808692

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

P1-23
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 2 - Page 1

Pipe 2

Raw data output on same scale

360 inches,1 weld @120 inches

Search Region

Extra data

for noise

assessment

Extra data

for noise

assessment

Cal 2-1

292

298

304

310

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 2 - Page 2

Cal 2-2

264

270

276282288

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

P2-1

288

294300306

312

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 2 - Page 3

P2-2

264

270276282

288

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

P2-3

240

246252258

264

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 2 - Page 4

P2-4

216

222228234

240

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

P2-5

192

198204210

216

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 2 - Page 5

P2-6

168

174

180186

192

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

P2-7

144

150156162

168

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 2 - Page 6

P2-8

120

126132138

144

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Weld Signal

P2-Weld

108

114120126

132

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

P2-9 Signal
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 2 - Page 7

P2-9

96

102108114

120

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

P2-10

72

78

84

9096

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 2 - Page 8

P2-11

48

5460

66

72

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

P2-12

240

246

252

258

264

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 2 - Page 9

P2-13

216

222

228234240

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

P2-14

192

198204210

216

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 2 - Page 10

P2-15

168

174

180186192

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

P2-16

144

150

156162168

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 2 - Page 11

P2-17

120

126

132138144

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Weld Signal

P2-18

96

102108

114

120

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 2 - Page 12

P2-19

72

78

84

9096

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

P2-20

48

5460

6672

Distance (inches)

Sensor Output

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 3 - Page 1

Pipe 3

Raw data output on same scale

480 inches, 1 weld @ 240 inches

Search Region

Extra data

for noise

assessment

Extra data

for noise

assessment

Cal 3-1

409

415421

427

433

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 3 - Page 2

P3-1

378

384390396402 CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output

P3-2

354

360

366372378 CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 3 - Page 3

P3-3

324

330

336342348 CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output

P3-4

294

300306

312

318

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 3 - Page 4

P3-5

264

270276

282

288

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output

P3-Weld

228

234240

246

252

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 3 - Page 5

P3-6

216

222228

234

240

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output

P3-7

180

186192

198

204

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 3 - Page 6

P3-8

156

162

168174180 CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output

P3-9

132

138

144150156 CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 3 - Page 7

P3-10

96

102108

114

120

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output

P3-11

60

66

72

7884

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

0 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 3 - Page 8

P3-12

384

390396

402

408

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output

P3-13

350

356

362368374 CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 3 - Page 9

P3-14

324

330336

342

348

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output

P3-15

300

306312318

324

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 3 - Page 10

P3-16

276

282288

294

300

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output

P3-17

242

248254

260

266

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 3 - Page 11

P3-Weld

228

234240

246

252

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output

P3-18

204

210216

222

228

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 3 - Page 12

P3-19

174

180

186192198 CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output

P3-20

150

156

162168174 CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 3 - Page 13

P3-21

120

126132

138

144

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output

P3-22

96

102

108114120 CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output
Battelle – Rotating Magnetic Field Inspection

January 2006 Pipe 3 - Page 14

P3-23

60

66

72

7884

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

CCW 2.5”

CCW 2”

CCW 1.5”

CCW 1”

CCW 0.5”

180 deg

CW 0.5”

CW 1”

CW1.5”

CW 2”

CW 2.5

Axial Sensors Radial Sensors 

Distance (inches)

Sensor Output
B-76 

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B-77 

PACIFIC NORTHWEST NATIONAL LABORATORY (PNNL) 

DEMONSTRATION TEST DATA
B-78 

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B-79 
B-80 

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B-81 
B-82 

0

10203040506070

0 50 100 150 200 250 300 350 400 

Distance (inches)

Ultrasonic Amplitude

Amplitu

2 Cylindrical 1 Spherical 1 Spherical 2 3 1 Spherical 2 3 2 3 0 No dent Ultras

birefrin

PNNL Ultrasonic measurements along the axis on Pipe 2, R Defec

degrees (approximately 3”) from TDC
B-83 

OAKRIDGE NATIONAL LABORATORY (ORNL) 

DEMONSTRATION TEST DATA 
B-84 

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B-85 

Pipe Sample: 993

Calibration 

Crack 

Location

Length Depth Measured Length Measured Depth

inches from 

end B inches

% wall 

thickness

186.4 2.5

58.7 586.4 582.4 2.544.4 3

Defect 

Number

Search Region 

(Distance from 

End B)

Start of Crack

Region from 

Side B

End of 

Crack 

Region 

from Side B

inches inches inches

Isolated CrackColony of Cracks

Isolated CrackColony of CracksIsolated CrackColony of CracksIsolated CrackColony of CracksIsolated CrackColony of Cracks

TEST LINE 1

None

SCC2 226" to 242" 

None

SCC1 242" to 254"

None

SCC3 210" to 222" 214" 216"

Another isolated 

SCC5 140" to 152" 145" 148"

None

Defect Set:

893

Commen

1 multiple cracks; m

multiple cracks; mmultiple cracks; m

23

TEST DATA

Type of SCC

45

Blank Area:

Commen

26" Diameter Pipe with Stress Corrosion Cracks; Length = 27 feet

Pipe Sample:

CALIBRATION DATA

Benchmarking of Inspection Technologies

Detection of SCC - Page 1

Sensor Design:Name:Date:Company:

Venugopal K. Varma, Austion Albrught, and Philip Bingham1/27/2006Oak Ridge National LaboratoryEMAT shear Horizontal wave design

multiple cracks; m

multiple cracks; ma

SCC4 175" to 187" 

None
B-86 
B-87 
B-88 

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B-89 

Calibration Note 

For calibration of SCC, a 26” pipe was provided with five SCC’s. These were located using 

liquid fluorescent magnetic particle inspection method. During the week of the testing we used 

the liquid fluorescent magnetic particle inspection to relocate the defects and had a hard time 

locating them. SCC 4 and SCC 5 could not be located and SCC3 and SCC 2 were 

indistinguishable from the scratches surrounding them. We could make out something SCC 2 

&# area, but could not be confirmed. We cleaned the area using a wire brush and cleaner, but 

could not definitely identify the region having SCC. Only SCC1 could easily be identifiable, but 

this is more likely a manufacturing defect than an SCC. Due to lack of credible calibration data 

on 26 “ pipe, we had to base all algorithms on a previous 30” diameter training set. 

Venu, Philip, and Austin 

1/27/2006 
B-90 

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B-91 

NATIONAL ENERGY TECHNOLOGY LABORATORY (NETL) 

DEMONSTRATION TEST DATA
B-92 

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B-93 

Calibration Defect 

Location Volume of Defect Depth of Defect Diameter of Defect Comments

inches from end A cubic inches inches inches

C1: 18 0.028 0.25 0.375

Defect 

Number

Search Region 

(Distance from End 

A)

Location of Defect 

Region from Side A

Significance of Defect 

(Output/Calibration Output)

Volume of Defect (in3) 

(provided to 

participant after defect

signif reported)

Depth of Defect (in) 

(provided to participant 

after defect signif reported)

Comments

inches inches cubic inches inches

None

52.55 1.31

D6 56" to 62" None

48" to 56"

D2D4 42" to 48" 45.62D3 34" to 42" None

Volume = 0.028

28" to 34" None

D1 18" to 28" 18.14 & 25.06 18.14" = 1, 25.06"=1.38 For significance: defect calibration h

Vol @ 18" = 0.028 , Vol @ 25.0

CALIBRATION DATA

Defect

LINE 1

TEST DATA

6" Diameter, 0.5" Wall Thickness Pipe Sample, ~13' in length

Pipe Sample:Pipe Parameters:

PLASTIC PIPE SAMPLE

Benchmarking of Inspection Technologies

Detection of Plastic Pipe Defects - Page 1

Sensor Design:Name:Date:Company:

Jim Spenik, Chris Condon, Bill Fincham, Travis KirbySubmitted 01/23/06NETL Capacitive sensor for Polyethylene Pipe Inspection

0.99

D5D7 62" to 70" 66.36 1.15

Volume= 0.037

Volume = 0.033

D8 70" to 76" NoneD9 76" to 84" None

D12 98" to 104" 101.03 1.61 Volume = 0.045D11 90" to 98"

Volume = 0.02 D13 104" to 112" 107.84 0.71

Volume = 0.016 D14 112" to 118" 114.75 0.57Volume = 0.020 D15 118" to 126" 121.89 0.74

We have indications that a consistant amoun

been removed along the entir

D16 126" to 132" None ?D17 132" to 138" None ?D19 144" to 150" 146.76 0.71D10 84" to 90" 87.15 0.43

Volume = 0.020

We have indications that a consistant amoun

been removed along the entir

D18 138" to 144" 138.3 1.13 Volume = 0.032

Volume = 0.012
B-94 

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APPENDIX C – DEVELOPER COMMENTS

C-1 

SOUTHWEST RESEARCH INSTITUTE (SWRI) 

COMMENTS ON PIPELINE INSPECTION TECHNOLOGIES 

DEMONSTRATION REPORT
C-2 

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C-3 

Final Comments on 

“PIPELINE INSPECTION TECHNOLOGIES 

DEMONSTRATION REPORT” 

APPLICATION OF REMOTE-FIELD EDDY CURRENT (RFEC) TESTING TO 

INSPECTION OF UNPIGGABLE PIPELINES 

OTHER TRANSACTION AGREEMENT DTRS56-02-T-0001 

SwRI® PROJECT 14.06162 

PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMNISTRATION 

U.S. DEPARTMENT OF TRANSPORTATION 

SOUTHWEST RESEARCH INSTITUTE® 

February 2006 

Southwest Research Institute (SwRI) believes that the results of the demonstration testing indicate that the SwRI RFEC system is very promising as an inspection tool that can accurately 

detect and characterize wall-loss defects in pipelines. The report showed a comparison of predicted vs. measured defect parameters with error bands of ±10% of wall thickness for defect 

depth and ±0.5 inch for defect length and depth. For the SwRI data, 68% of the predicted depths, 

88% of the predicted lengths, and 88% of the predicted widths were within those error bands. If 

the error band is increased to ±20%, then 91% of the predicted depths would be within the band. 

The depth prediction had a systematic error in that the predicted depths were generally less than 

the measured ones. If corrections are made to the SwRI depth prediction algorithm to reduce the 

systematic error (for example, by using the demonstration test defect responses to correct the 

calibration approach), then even better results can be obtained. 

It is emphasized that the SwRI RFEC tool was designed to meet the specifications and constraints of the Explorer II robot under development by Carnegie Mellon University (as discussed 

in the SwRI comments on page B–4 of this report). The demonstration tests were thus conducted 

with sensors, instrumentation, data processing, scan speeds, etc. that are very representative of a 

field inspection system as integrated with Explorer II. SwRI therefore expects that results similar 

to those obtained in this demonstration would be obtained with an actual inspection system and 

that no degradation in performance would be experienced by transitioning to field hardware and 

inspection conditions. 
C-4 

Additional Information on the SwRI Remote Field Eddy 

Current Technology and Design as Integrated with the 

Explorer II Robotic Platform 

SwRI Remote-Field Eddy Current – Through funding support from PHMSA/OPS, Southwest 

Research Institute® has developed a remote-field eddy current (RFEC) technology to be used in 

unpiggable lines. The SwRI RFEC tool is capable of detecting corrosion on the inside or outside 

pipe surface. Since a large percentage of pipelines cannot be inspected using “smart pig” techniques because of diameter restrictions, pipe bends, and valves, a concept for a collapsible 

excitation coil was developed but found unnecessary for the pipe sizes and materials of interest 

in this demonstration. A breadboard system that meets the size, power, and communication 

requirements for integration into the Carnegie Mellon Explorer II robot was developed and used 

in the demonstration tests. This system is shown in Figure 1. The demonstration system incorporates eight detectors, and data from all eight channels are acquired and processed simultaneously as the system is scanned along the pipe at speeds up to 4 inch/sec. All of the instrumentation, except for a DC power supply and a laptop computer (used for storage of the processed 

data), is located on the tool. Figure 2 shows the system design as integrated with the Explorer II 

robot under development by Carnegie Mellon University. The RFEC system can expand to 

inspect 6- or 8-inch-diameter pipe and can retract to 4 inches to pass through obstructions. 

Laptop Computer with CAN Bus Interface

Encoder Wheel

Electronics Sensors Excitation Coil

DC Power Supply

Figure 1. SwRI RFEC tool used in demonstration tests 
C-5 

Detector 

Module

Explorer Support 

Module

Exciter 

Module

Figure 2. SwRI RFEC tool design as integrated with Explorer II robot: 

Top–Expanded for inspection with cover removed from exciter module, 

Bottom–Retracted to pass through restricted areas.
C-6 

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C-7 

GAS TECHNOLOGY INSTITUTE (GTI) 

COMMENTS ON PIPELINE INSPECTION TECHNOLOGIES 

DEMONSTRATION REPORT
C-8 

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C-9 

Comments on the Comparison of Benchmarks and GTI Results 

Albert Teitsma, Julie Maupin, and Paul Shuttleworth 

Gas Technology Institute 

1700 S. Mount Prospect Rd. 

Des Plaines, IL 60018 

25 October 2004 

Introduction 

During the week of 9 January 2006, GTI staff came to the West Jefferson facility of Battelle 

Labs in Columbus, OH to test a prototype RFEC inspection vehicle in 3 sections of 8 inch pipe. 

We reported on our test results in a previous document.6 In this document we comment on the 

benchmarks reported in “Pipeline Inspection Technologies Demonstration Report” by Stephanie 

A. Flamberg and Robert C. Gertler. 

Comparison of Benchmarks and GTI Results 

Table 1 below compares GTI results to the benchmark data. There are two types of error in these 

results, systematic and random. The systematic errors are the average readings in Table 1, while 

scatter gives the random error. A different researcher analyzed the data from each pipe and the 

subjective components of the data analysis do show. All three underestimated the defect lengths, 

in one case by half an inch with a scatter of .4 inches. Particularly for small deep defects, this is 

too large an error, but the table also shows that proper analysis does give an acceptable precision 

(average=-0.139”, scatter=0.133). Precision in the circumferential direction was not as good, but 

as pointed out in a previous report, remaining strength calculation such as B31G or RSTRENG 

do not use circumferential extent in the calculations. 

Figure 1. Data with Pipe 3 corrected for calibration error. 

There was a serious depth calibration error for pipe three, which made the scatter for the GTI 

results look worse than it was. Figure 1 shows the improvement with recalibrated data. GTI 

expected that the anticipated error would be about +/- 10% of the full wallthickness, as indicated 

by the lines in Figure1. Table 1 shows that more experienced analysts can achieve that, the 

scatter for Pipe 1 being 10%, while that for Pipe 3 was a mere 7%. 

GTI’s sizing of the natural corrosion areas was excellent. 

 

6

 “Analysis of Sensor Benchmarking Tests: Remote Field Eddy Current Technique”, Julie Maupin, Albert Teitsma, 

and Paul Shuttleworth. 
C-10 

Time to Take the Data 

Since time to take the data has become an issue, GTI has included results from its run with 

Russell NDE Systems, Inc. equipment, which GTI plans to use in its modules, in this report. 

Figure 2. A faster run using Russell NDE Systems, Inc. instrumentation. 

GTI inspected 23’ of Pipe 3 in 7 minutes using this instrumentation, which GTI brought along 

for demonstration purposes only. The speed was limited by the speed of our tow motor. The 

instrumentation can easily handle the 4” per second specified for Explorer II. The unfiltered data 

in Figure 2 is a little noisier than that obtained from the laboratory lock-in amplifier, but more 

than good enough for the size of the signals obtained during the benchmark tests. GTI 

concentrated on maximizing signal strength and minimizing power consumption. Speed at the 

very low speeds used by Explorer II was never an issue. 

For most of the measurements, it took GTI a little over half a day per run in Pipes 1 and 5, and a 

little longer in Pipe 3 using a single lock-in amplifier to measure all sixteen channels. To ensure 

superior data quality the lock-in was allowed to settle nearly a second before reading the data 

from a sensing coil. 

C-Scans 

C-scans obtained with the RFEC inspection do not have the resolution of the benchmark scans, 

but the correlation between them are excellent. Figure 3 compares the natural corrosion defect, 

P1-23. Similar results are obtained for the other defects. 
C-11 

Figure 3. Excellent correlation between the RFEC results and the natural corrosion benchmark 

data. 

Conclusion 

The results clearly demonstrate that the RFEC technique is eminently suited for inspecting 

transmission and distribution piping. The measurements had excellent quality. However GTI’s 

analysis indicates that it takes experienced analysts to translate the measurements into precise 

defect severity estimates. Although most of the results were not obtained at inspection speeds, 

the short run with more realistic field equipment showed that inspection at Explorer II speeds 

will not reduce the quality of the defect severity measurements. 
C-12 
C-13 

BATTELLE

COMMENTS ON PIPELINE INSPECTION TECHNOLOGIES 

DEMONSTRATION REPORT
C-14 

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C-15 

Comments on Demonstration Results for the 

ROTATING PERMANENT MAGNET 

INSPECTION TOOL 

Prepared by Battelle 

February 17, 2006 

Theory of Operation 

The rotating permanent magnet inspection method employed by Battelle at the Pipeline 

Inspection Technologies Demonstration is an alternative to the common concentric coil methods 

to induce low-frequency eddy currents in ferromagnetic pipe and tubes. Battelle’s technology 

consists of a pair of permanent magnets that rotate around a central axis in proximity to the inner 

surface of the pipe sample. The rotating permanent magnet pairs are used to induce high current 

densities in the material undergoing inspection. Following fundamental laws of electrical 

induction, rotating permanent magnet pairs inside a pipe along its longitudinal axis establishes an 

alternating electrical current in the wall of the pipe. Figure 1, a cutaway drawing showing the 

rotating permanent magnet exciter, illustrates this concept. The current flows in an elliptical path 

around the magnets. When the magnetizer is vertical, strong currents flow axially along the top 

and bottom of the pipe and circumferentially at the sides. When the magnetizer is horizontal, 

strong currents flow circumferentially at the sides of the pipe and axially at the top and the 

bottom. Finite element modeling shows that a two-pole magnetizer produces strong current 

densities at distances reasonably far away from the magnetizer. Although the current is complex 

at the magnet poles (where it is strongest), at distances of a pipe diameter or more away from the 

magnetizer it is uniform and sinusoidal. With this uniform energy induced in the pipe, simple 

magnetic field sensors can be used to detect the change in current densities in the pipe wall and 

thus pinpoint the location of defects and anomalies. 

The development of this technology began in fall 2003 and is sponsored by The U.S. Department 

of Energy’s National Energy Technology Laboratory with cofunding from the Pipeline Research 

Council International. The first known use of this inspection method to detect corrosion was 

performed in September 2004. 
C-16 

Figure 2. Illustration of the rotating permanent magnet exciter and sensor location

System Configuration as Demonstrated 

Figure 2 shows the prototype used for the 8 inch corrosion inspection benchmark demonstration. 

A pair of NdFeB magnets is mounted on a steel core machined from 1018 steel. The magnets are 

2 inches long, 1 inch wide, and 0.5 inch thick; the magnet strength is 38 MegaGauss-Oersted. 

While the strong holding force secures the magnets on the steel core, copper covers keep the 

magnets precisely aligned. The air gap between the magnet and the pipe wall is 0.5 inch. 

Wheeled support plates keep the magnet centered in the pipe. A variable speed direct current 

motor is used to rotate the magnetizing assembly. The rotational speed used in this 

demonstration was 300 rpm or 5 Hz. The power required to rotate the magnets at this speed was 

about 70 watts. While this is above the available power of 50 watts budgeted by Explorer II, this 

power requirement is significantly better than the 200 watts required in prior designs. Three 

pairs of axial and a radial Hall Effect sensors were mounted in 4 sensor shoes designed to ride on 

the ID of the pipe. While sensor to magnet spacing of 8 to 10 inches provides stronger signal 

changes from corrosion anomalies, the distance from the magnet to the sensor was 13 inches to 

meet EXPLORER II specifications. To continuously monitor rotational speed, a small magnet 

was attached to the shaft and an additional Hall Effect sensor was used to produce a synchronous 

signal. 
C-17 

Figure 3. Rotating permanent Magnet Inspection system as configured for the technology demonstration 

A 24 channel real-time data recorder system was implemented and fundamental experiments 

were conducted to provide data to aid in the design of the rotating magnetizer. A system was 

designed to simultaneously record and process 11 sensor pairs, the sync signal and one open 

channel. The block diagram of the data recorder system is shown in Figure 3. The heart of the 

recorder is the National Instruments PXI-4472, an eight-channel dynamic signal acquisition 

module for making high-accuracy frequency-domain measurements. The eight NI PXI-4472 

input channels simultaneously digitize input signals over a bandwidth from 0.5 Hz to 45 kHz. 

Three PXI-4472 modules were synchronized to provide 24 channel input using the PXI chassis 

and a star trigger bus. The PXI chassis communicates with a desktop computer using a fiber 

optic link. The desktop computer is used to analyze the signals using a lock-in amplifier 

approach, as described in a previous DOE semiannual report. LabVIEW software modules for 

lock-in amplifier measurements were used in the development of a custom data acquisition and 

display program. 

Figure 3. The block diagram of the data acquisition system 

Display of results 
C-18 

The data acquisition and processing hardware and software processed signals and displayed data 

in real time during the demonstration. A typical output of the data recording package is shown in 

Figure 4. In real time display mode, the data scrolls along the monitor as the inspection tool 

traverses the pipe. The upper and lower graphs show the axial and radial sensors respectively 

using a stacked line plotting routine, a format familiar to pigging vendors and users of pipeline 

inspection technologies. In this figure, the signal from an axially short, circumferentially wide 

metal loss anomaly can be seen in the middle channels of each sensor type. 

Figure 4. Screen capture of custom LabVIEW data acquisition and display program 

The results submitted by Battelle on January 26, 2006 (contained in appendix B) included signals 

from each reporting area in a uniform format. An example signal is shown in Figure 5 for pipe 

sample 2, search area 10. The upper and lower stacked graphs show the signals from the axial 

and radial sensors respectively; the color codes repeat so that sensor pairs can be correlated. 

Since only about 70 degrees of the pipe was instrumented, the center sensor was positioned so 

that it traversed the centerline of the defect. In some of the graphs in appendix B it is evident 

that the tool rotated slightly as it was pulled through the pipe because some of the corrosion 

signals are greater in other sensors. The signals provided with the report were plotted on the 

same scale for quick visual comparison. For detection and assessment, signals were amplified so 

that smaller corrosion areas could be more easily detected and assessed. Other graphical 

representations, including plotting axial versus radial signals, are proving to be useful in 

assessing corrosion. A scaled topographical map of the corrosion depth is included at the bottom 

of Figure 5 after it was flipped (the tool was pulled from right to left). The two humps in the 

stacked graphs correspond to the two pits in the image. In the reported results, the presence of 

single or multiple pits was indicated in the comment section. The depth assessment was based 

on the largest signal since the data reporting form specifically requested maximum depth. 
C-19 

Figure 5. Signal from pipe sample 2, search area 10 

Comments on Results 

The results presented in the main section of the demonstration report are representative of the 

current capability of the rotating permanent magnet tool. This comparatively new inspection 

methodology is in its third year of development. Specific comments on detection and sizing 

results are provided next. 

Detection. The results of the demonstration showed that all corrosion anomalies were detected 

and one additional anomaly was falsely detected. The false call anomaly was assessed as small 

and not detected in all pulls. The spacing between sensors (sensor pitch) of the demonstration 

configuration was 0.5 inches. For corrosion with shallow depth and a width and length 

nominally the same as the sensor pitch, a detectable signal may only be produced by a sensor 

traveling directly underneath the anomaly. Two sensors straddling the same anomaly may not 

produce a signal. Future implementations may need a finer sensor pitch to improve results. 

Corrosion sizing. A corrosion anomaly locally increases the density of the currents that are 

induced by the rotating magnetizer. The local change in current density is also influenced by the 

length and width. The algorithm for estimating the depth of the corrosion anomaly includes 

these three measures, in a manner similar to magnetic flux leakage data analysis methods. Data 

from the calibration anomalies and the first benchmark demonstration were used to establish the 

sizing algorithm. The unity plot shown in the main report indicates a good correlation between 

measured and predicted values, however there is a general tendency to under-call the depth. This 

was the first algorithm developed for corrosion anomaly depth assessment. Additional data and 

algorithm refinement should help improve results. 
C-20 

Natural Corrosion Sample. The natural corrosion sample was difficult to assess because of the 

unexpected weld. In hindsight, the signals were quite clear. Figures 6 and 7 show the reported 

raw data with new annotations for lines 1 and 2 respectively. In the results reported on January 

27, 2006 for these lines Battelle discussed: 

• Line 1 - A large area of general corrosion of variable depth that spans the entire sensor 

width. The corrosion is close to the weld, altering both signals. A large wide corrosion 

area at 128" 

• Line 2 - An area of general corrosion of variable depth that spans most sensors. A large 

wide corrosion area at 128" 

The signal 128 inches from the end was the unexpected weld signal. The general corrosion on 

either side of the weld corresponds to the measured results; however the close welds caused 

interference and sizing was not attempted at this time. While the natural corrosion pipe was 

complex, it is only one of many unique challenges that must be faced when implementing 

inspection technology and the experience will be valuable in future developments. 

Summary 

The benchmarking results are a representative assessment of the current state of development of 

the rotating permanent magnet inspection system. The planned improvements of this technology 

should advance the capability of this inspection system. Battelle is currently working on 

reducing magnetizer size, increasing rotation speed, and increasing the separation distance 

between the magnet and the pipe. Separations of over an inch appear to be practical, which will 

aid in the implementation of this technology. The rapid advances of this new inspection 

technology should make this methodology useful for unpigable pipeline applications in the near 

future. 

Acknowledgement 

The U.S. Department of Energy’s National Energy Technology Laboratory is sponsoring this 

development with cofunding from the Pipeline Research Council International. However, any 

opinions, findings, conclusions, or recommendations expressed herein are those of the authors 

and do not necessarily reflect the views of these sponsors. 
C-21 

Figure 6. Natural corrosion results line 1 

Figure 7. Natural corrosion results, line 2 
C-22 

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C-23 

PACIFIC NORTHWEST NATIONAL LABORATORY (PNNL) 

COMMENTS ON PIPELINE INSPECTION TECHNOLOGIES 

DEMONSTRATION REPORT
C-24 

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C-25 

Comments on NETL and Pipeline & Hazardous Materials Safety 

Administration pipeline inspection technologies demonstration 

Submitted by: Paul D. Panetta 

Pacific Northwest National Laboratory 

Richland, WA 99352 

paul.panetta@pnl.gov

(509) 372-6107 

The Pacific Northwest National Laboratory (PNNL) participated in the Pipeline Inspection 

Technologies Demonstration during the week of January 9, 2006. The main focus of the 

demonstration was to rank the severity of dents based on ultrasonic measurements of the 

mechanical properties and the presence of plastic strain. This approach is dramatically different 

than the current assessment based solely on dimensional measurements. The advantage of this 

approach is that the reliability of the pipeline can be determined based on material properties and 

how they change with time and damage, rather than the size and shape of a dent. 

Measurements were performed on two 24 inch diameter pipes containing dents and dents with 

gouges. Pipe 1 contained 3 rows of dents from a track how with a very small separation 

distance, on the order of a few inches in some cases. The total number of dents exceeded 40 

dents. The operation of creating these dents and dents with gouges created a significant amount 

of distortion to the pipe and ovalization of the pipe. In-service pipelines with the amount of 

denting are highly unlikely and this pipe does not represent a realistic pipeline operating 

scenario. Despite this significant distortion results were promising. Pipe 2 contained 10 dents 

and 11 reporting locations. All dents were successfully detected and estimates of the size were 

provided. The ultrasonic strain measurement correctly ranked 7 out of the 9 reporting locations 

for 100% detectability and 77% accuracy on ranking severity. 

The sensor was a non contact electromagnetic acoustic transducer (EMAT) that was scanned 

along the axis of the pipe at several distances from the dents placed at top dead center. The 

sensor and cart are shown in Figure 1. Figure 2 shows the amplitude and ultrasonic 

measurements along pipe 2 with the sensor placed 15 degrees from top dead center. The 

amplitude clears shows a deviation at each reporting location with a dent and no deviation where 

there is no dent. The ultrasonic shear wave birefringence is independent of thickness which is 

critical for characterizing mechanical properties due to deformation because a simple thickness 

measurement is NOT an accurate assessment of strain. 

The inspection speed was as fast as 5 inches per second and the electronics can operate as fast as 

4 or 5 feet per second (~3 MPH). The measurements were performed in a 24 inch pipe and are 

amenable to pipes as small as 4 inches in diameter. The technology proved to be very sensitive 

to mechanical damage due to dents and is also ideal for application where pipelines are bent due 

to subsidence or other earth movement. This technology is ready for incorporation onto robotics 

platforms and for field testing and subsequent commercialization for specific applications. 
C-26 

EMAT Sensor

Motor for 

sensor 

rotation

Springs for 

smooth 

motion past 

dents

Figure 1. Photo of the ultrasonic sensor and scanning cart. 

0

10

20

30

40

50

60

70

0 50 100 150 200 250 300 350 400 450

Distance (inches)

Ultrasonic Amplitude

-0.10

0.00

0.10

0.20

0.30

0.40

0.50

Ultrasonic thickness 

independent measurement

Amplitude

2 

Cylindrical

1 

Spherical

1

Spherical 

2 3 1

Spherical 

2 3 2 3 0 

No 

dent 

Ultrasonic 

birefringence

PNNL Ultrasonic measurements along the axis on Pipe 2, R Defects, at 15 

degrees (approximately 3”) from TDC

Figure 2. Amplitude and ultrasonic birefringence as a function of distance along pipe 2. 
C-27 

OAKRIDGE NATIONAL LABORATORY (ORNL) 

COMMENTS ON PIPELINE INSPECTION TECHNOLOGIES 

DEMONSTRATION REPORT
C-28 

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C-29 

SCC detection using Shear Horizontal EMAT 

Based on the results, we feel that the ORNL SCC detection system using shear horizontal wave 

EMAT detection has performed very well for the test conditions. In this response, we address 

areas pertaining to: training data issues, lack of data on SCC depth, additional defects along test 

line 1, and false positives. With these comments concentrating on issues where the results are in 

question, we would like to emphasis that the system performed very well for the test and 

addressing these issues will only improve or better clarify the results. 

Training Data: 

The current ORNL set-up for detecting SCCs with the shear horizontal wave EMAT uses 

transmitted signals to assess the presence of a crack. The signals from ‘no-flaw’ regions are 

compared to the signals from ‘flaw’ regions to identify cracks. The key issue in performing this 

measurement is the determination of features, derived from the response signals that separate 

flawed regions from those with no flaws. In the current algorithm, wavelet based features from 

both ‘flaw’ and ‘no-flaw’ regions are used to establish classes (SCC, no-flaw, other anomaly). 

Since this technology requires training data of known defect and no-defect regions, a 26” 

training pipe was provided in addition to the test pipe during our visit to the test facility. 

Unfortunately, we were unable to generate a proper training set from this test pipe due to the 

quality and the discrepancy in the location of the flaws. Instead, previous data collected from a 

30” pipe for training were used. Although the mode frequencies were different for the 26" and 

30" pipe due to change in wall thickness and pipe diameter the results were still satisfactory. 

This indicates a robustness of the training sets across pipe diameters and thicknesses. The 

system performance would have only improved had we used a training set generated out of 

similar pipe geometry. 

SCC Depth Data: 

Defect sizes were given in terms of length and area of crack on the pipe with no depth 

information. Liquid fluorescent magnetic particle inspection for detecting SCCs does not 

contain any information on the depth of the crack, while the EMAT based approach has a direct 

dependence on it. Hence, some very small cracks detected by magnetic particle method may not 

be detected by EMAT due to their depth being small. This is a possible reason for SSC2 not 

being detected. With the knowledge of SCC depth, we could have determined how well the 

system is able to detect the severity of the crack. 

Additional Known Defects in Test Line 1: 

In testing, we were instructed to test along three different lines of the test pipe to determine the 

presence of defects over particular spans along each line. Figure 1 shows the pipe layout for the 

test. Each test box (blue boxes labeled SCC1 – SCC14) along with every defect previously 

identified on the pipe (pink boxes labeled 4-9, 15-20) are pictured. The dashed lines represent 

the three scan lines. As mentioned in the results, the SCC defect we were to locate in SCC3 is 

defect 8 (far left side of box). However, we positioned this defect to the right by several inches. 

Since the EMATs scans an arc of ~12 inches around the circumference of the pipe, the SCC 

boxes within the figure have been drawn with 12 inch height to show the area covered by the 

sensor. From the figure, we see that defects 17, 18, and 19 are all on the upper edge of SCC3. 

 
C-30 

Figure 4. Test setup. 

Our defect detection signal is essentially a distance measurement from the no-defect class within 

our feature space. This distance is pictured in Figure 2 for the SCC3 region. Red lines show 

boundary of box SCC3 and the approximate locations of defects 8, 17, 18, and 19 are shown in 

pink text. In our response to the test, we listed the defect in the SCC3 box based on the large 

signal that appears to correspond to defect 18 (a fairly large inclusion). From the signal, we do 

feel that we are seeing the intended defect 8 as well but did not list it due to its location 

straddling the boundary of the SCC3 region. 
C-31 

Figure 5. Defect response signal for SCC3 area. 

False Positives:

As mentioned in the results, we also identified a false positive on each scan line. The EMATs 

did indicate flaws in areas where they were none, and this could be the result of not having the 

baseline data or the algorithm needing further refinement. Lack of good natural SCC data has 

been one of the difficulties we faced while developing this technology. We have created 

synthetic SCCs using electrical discharge machining (EDM), however, EDM machined SCCs do 

not give a signature truly characteristic of a natural SCC. Figure 3 shows the signals returned for 

the three false positives that have peaks similar to our previous experience with SCC signatures. 

Red lines delineate the regions of interest. The false positive on line 1 (Figure 3a) shows a series 

of peaks each similar in shape to an SCC response. The false positive in line 2 (Figure 3b) 

shows a well-isolated peak typical of an SCC response. The false positive in line 3 (Figure 3c) 

shows an SCC type response on the right side of SCC14 box. Similar bumps also can be seen 

near 160" mark but were not marked as SCCs due to the low dome shape of the response. 
C-32 

(a) (b)

(c) 

Figure 6. False positive signals for scan lines 1, 2 and 3 are shown in (a), (b) and (c) respectively 

Conclusion: 

As mentioned earlier, we feel the ORNL SCC detection system performed well in this test. 

Lessons learned from the tests are: 1) Training data may not be necessary for each pipe geometry 

being investigated, and 2) Information on SCC depth is needed to fully characterize the system 

performance. We feel that the system performance will continue to improve as more training 

data from natural SCCs are collected and used to train the algorithm. 
C-33 

NATIONAL ENERGY TECHNOLOGY LABORATORY (NETL) 

COMMENTS ON PIPELINE INSPECTION TECHNOLOGIES 

DEMONSTRATION REPORT
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C-35 

 

Analysis of Sensor Benchmark Tests 

Capacitive Sensor for Polyethylene Pipe Inspection 

 Prepared by: 

James Spenik, Chris Condon, Bill Fincham, Travis Kirby 

National Energy Technology Laboratory 

3610 Collins Ferry Road 

Morgantown, WV 26505 

February, 15, 2006 
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Introduction: 

Representatives from the National Energy Technology Laboratory demonstrated polyethylene 

pipe inspection technology at Battelle’s West Jefferson Pipeline Simulation Facility near 

Columbus, OH. The technology was demonstrated January 10 – 12, 2006 by James Spenik 

(REM), Chris Condon (REM), Bill Fincham (Parsons) and Travis Kirby (WVU). 

Battelle provided a 13-foot length of 6-inch nominal diameter, 0.5-inch wall thickness 

polyethylene pipe. Holes and saw cuts were placed into the top outer surface of the pipe along 

an axial line. Twelve defects were placed within nineteen 6-inch long search regions. Eight of 

the regions did not contain a defect, one region contained two defects. The line of defects was 

covered thus the experimenters did not know their location when data was collected. However, a 

calibration defect was available whose characteristics and location was known to the 

experimenters. 

The probe was able to identify the defect in every search region without false positives. 

Technique:

Abnormalities in the pipe wall are determined by changes in the dielectric properties of the wall 

material. An electric field is projected through the pipe wall by the probe head (Fig. 1). The 

wall material behaves as the dielectric component of a capacitor. This arrangement formed the 

probe head of the sensor device. Since the dielectric constant of polyethylene is greater than that 

of air (or natural gas) an absence of material within the electric field will manifest itself as a 

decrease in capacitance. 

Figure 1 Projection of Electric Field through Pipe Wall 

The probe head and associated electronics were mounted on a platform designed for this 

particular test (Fig. 2). The probe head was mounted 5.5 inches from the back circular disk of 

the 9.25-inch long platform. A 5.5 inch diameter disk was mounted at each end of the platform. 

In future use, the probe could be incorporated on existing platforms. 

The platform was propelled through the pipe using a stationary stepper motor and nylon 

filament. An optical encoder was used to determine probe position within the pipe. Data were 

transmitted using RF transmission via Bluetooth technology. Another option would be to store 

the data onboard and retrieved at a later time. Power was supplied using an on-board 9-volt 

Dielectric Material (wall)

Probe head

Defect Field Lines
battery. The data transmission rate for this particular demonstration was controlled by the 

optical encoder and stepper motor. Capacitance data were to be transmitted every forty counts of 

the optical encoder (0.09 inch axial movement) but this value may have varied a few counts. 

The stepper motor moved the platform at a rate of approximately 0.09 in/s. The sampling rate 

was approximately 1 Hz for this configuration due to the constraints previously mentioned. Thus 

the transit time through the pipe was approximately 15 minutes. However, the electronics 

package used is capable of transmission rates of between 45 – 90 Hz and modifications to the 

package would allow transmission rates in the MHz range. 

Figure 2 Platform with Probe Electronics 

Data collection/analysis:

Twenty traverses were performed during the three days of data acquisition. The first ten were 

preliminary to identify problems. These difficulties were not related to the function of the pipe 

defect sensor but rather sensor movement. Initially, the optical encoder did not react to 

movement along the surface of the yellow polyethylene pipe. This was an unforeseen problem 

since, in an earlier test, the encoder reacted in black polyethylene pipe. The problem was 

resolved by placing a strip of material visible to the encoder on the interior lower surface of the 

pipe. Movement of the platform would be halted due to a slightly underpowered stepper motor. 

The edges of the platform disks were lubricated with graphite which minimized the problem. 

The deviation of the probe head from a linear path was minimized using guide line attached to 

the bottom of the pipe and through the bottom of both platform disks. These problems were 

identified and solved during the first ten traverses. Data from the second set of ten traverses were 

useful and provided data for statistical analysis. 

Tests commenced with the rear disk approximately 1.5 inch from the “B” end of the pipe placing 

the sensor head at the 149 inch position of the 156 inch (13 foot) pipe (Fig. 3). Tests concluded 

with the probe head at the 7 inch position. Run11 – Run 20 were compiled to determine the 

position of anomalies within the polyethylene pipe. 

Probe Head 
Figure 3 Path of Probe Through Pipe 

The average number of data points accumulated for each run was 1619 points corresponding to a 

measurement for each 0.0877 inches of travel. However, this number varied between runs with a 

standard deviation of 46. These discrepancies can be attributed to either binding of the stepper 

motor or variations in the triggering level of the optical sensor. The focus of the research was 

creation of the probe; the platform was designed only after conformation of the teams’ 

participation in the demonstration was received. Data were post processed to determine the 

exact position of each defect within each search region in the following manner: 

1. Data were aligned so the minimum capacitance for each run near the calibration hole 

coincided. (Minimum capacitance corresponds to the center of the anomaly) 

2. Since the total length of the traverse and the total number of data points were known, the 

ratio of these numbers yielded an initial estimate of step size for each run. 

3. The data for each run was separated by search region. 

4. The position and value of the minimum capacitance value within the search region for 

each run was determined. 

5. The average position of the minimum within the region was determined. 

6. Each run was realigned within the region so the minimum was located at the average 

minimum position. 

This method was effective; however, cumulative error caused the position of the anomaly within 

a search region to be progressively misinterpreted. The measured position and actual position of 

the defect in search area D1 was at 25 inch, however, the actual position of the defect in search 

area D19 was 148” and the measured position was 146.8” Again, this is not due to sensor error 

but rather due to positioning error. All defects were identified with the exception of a binary 

defect (two holes separated by 0.5 inch on centers) located at position D15 which we identified 

as a single entity. The probe in its current configuration was not designed to separate binary 

anomalies separated by less than an inch. 

Although it was not part of the benchmarking demonstration, an attempt was made to provide a 

comparative value of volume of material removed by the defect. Only moderate success was 

achieved in this endeavor. The reason that definitive volumetric values could not be determined 

was because the defects presented in the pipe could be considered to have three variables: 

diameter, depth and type (round hole or saw cut). Due to the nature of the electric field produced 

A B 

Traverse Direction
by the probe, the depth and diameter cannot be combined into the single variable volume. Since 

the electric field strength diminishes as a function of distance from the probe head, a smaller 

volume closer to the probe head is seen as equivalent to a larger volume further away. The 

output from the current probe design yields two values: capacitance and change in capacitance 

with respect to axial position. Therefore there were three unknowns and only two equations and 

thus the volume of material removed was indeterminate. A future design of the probe allowing 

circumferential measurements will allow the development of an algorithm to define defect 

volume. 

 

Figures 4 through 7 illustrate the typical probe response when a defect was encountered. Each 

figure compiles the ten runs taken within an eight-inch long region of interest. The abscissa is 

the variation from minimum capacitance within the region and the ordinate is the linear position. 

Figure 4 shows the calibration defect and the probe response. Figure 5 shows a typical response 

to a round defect and Figure 6 indicates the response to a saw cut. Figure 7 indicates the probe 

response in a region with no known defects. The presence of an anomaly typically produced a 

variation of 4000 aF. Variations in a region without defined anomalies were typically 500 aF. 

Conclusion: 

The probe successfully identified the position of all defects within the search regions and had no 

false positive results. Deviations from the precise position of the defects within the search region 

can be attributed to the means of locomotion and position identification procedures. The data 

acquisition rate can be markedly increased with a superior locomotion scheme. Further 

devlopment to this technology will produce a device that can be inserted into in situ natural gas 

pipelines and determine their integrity. 

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Figure 4 Calibration Hole and Probe Response (18” position) 
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Figure 5 Round Hole Defect and Probe Response (25” position) 

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Figure 6 Saw Cut Defect and Probe Response (102” position) 
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