Ultrasonic Application Solutions

Large Diameter Tubing – UT & EC Inspection
Application
The Customer needed a mobile inspection systemThe team was challenged to find very small
cracks, pitting, corrosion and inclusions on thethick, 5’ long high strength, magnetic steel) that are

ID and within the tube wall of large diameterin the field. The system should be self-contained

ferromagnetic tubing for a military customer.
The solution included a method of delivering thelocation.

probes down and around the lengths of the pipe

To inspect a large diameter pipe (mobile enough towhich provided 100% coverage, overlapped

be placed into a tank) for ID surface flaw as well as

raster scans and full digital data capture

subsurface defects in the tube wall and on the OD,verifying precise positional accuracy.

an inspection system was needed to include both

for large diameter tubes (around 5” diameter, 0.25”

watertight and be able to move from location toCustomer challenge

For the UT inspection, the solution required aUT and EC techniques.

waterproof encloser that enabled the probes toUltrasonic Inspection Strategy – Probe with Multiple

be coupled to the test pipe. In order to find all

Inspection Angles - Optimal Defect Coverage

theEddy Current Inspection Strategy – An array probe

differently oriented transducers were used in thewith coils small enough and in the optimalsetup.

configuration to detect small flaws in magneticmaterial.

various orientations

ofdefects,

threeFor the eddy current inspection, a flexible arrayprobe was used which was configured to findboth axial and circumferential flaws at the sametime. Scan plan developed for 100% coverage,
overlap and complete digital data capture.

The critical flaw size requirement was for 0.005”
Depth and 0.010” Length in both axial andcircumferential orientations.

A means of transport down the length of the ID
is required for both UT (flooded) and EC (Dry)probes. For complete coverage, the pipe also
had to be rotated as the probes traversed slowly
down the length.

Our Solution:
The team successfully built a prototype which demonstrated both techniques.
•A Calibration Ring (including notches of various sizes and orientations) was machined toattach to the end of the tube.

•Self-contained motor-driven mechanical assembly - A Prototype self-contained Test System
was designed and built that included an encoded lead screw assembly that allowed probes
to be driven axially down the length of tube. It also used motor-driven engagement forencoded rotation of the tube around the lead screw and probes.

•Ultrasonic Inspection Strategy – A probe with Multiple Inspection Angles for Optimal DefectCoverage

0º Longitudinal Wave Radial Examination – which targets embedded flaws (voids,inclusions, etc.)

45º Axial Shear Wave Inspection - Flaws oriented in the radial/circumferential planeconnected to the OD or ID



45º Circumferential Shear Wave Inspection - Flaws oriented in the axial/radial planeconnected to the OD or ID•

Eddy Current Inspection Strategy – An array probe with coils small enough and in the optimal
configuration to detect small flaws in magnetic material. Array probes can determine theorientation of an indication (axial or circumferential) by multiplexing the coils excitation
patterns. Also, different configurations of coils were explored for this material by using acustom probe which was designed for the 3 different topologies:
Impedance – Standard Absolute Coils - this topology can detect discontinuities
oriented in any direction, especially where there is very little liftoff variation.

SDD – Short Double Driver (Transmit/Receive) - This topology uses two coils, excited
simultaneously, acting as one large transmitter. The large area (ergo higherresolution) offers — over the single-driver topology — a better response and sensitivity
to small defects



LDD - Long, Single Driver (Transmit/Receive) —Longer distance between coils – SingleDriver/Single Pickup - is the best to detect large and/or subsurface defects, and offersa better tolerance to liftoff than the double-driver topology.

Solution benefits:
Designed motor and encoder electronics for accurate control and positioning. This was arequirement for accurate analysis and location of flaws along the length of tubing.
Achieved the required Probability of Detection to ensure the capability of finding the very small

required flaw sizes
Integrated two separate inspection methodologies into one inspection system

Test Equipment:
UT: Mentor UT Platform – Modified PA connector toallow 3 single channel UT channels using“MultiGroup” capability

ET: Array Multiplexing Instrument and Hi Res Array
Probe. 32 coils 2mm diameter