application of flexible paut probes for small diameter · pdf fileapplication of flexible...

6th International CANDU ISI Workshop/NDT in Canada 2016 Conference 6th International CANDU ISI Workshop/NDT in Canada 2016 Conference

Application of Flexible PAUT probes

for small diameter FAC elbow inspection II

6th International CANDU ISI Workshop/NDT in Canada 2016 Conference

Vajira Jayasinghe, Chris Eaton,

& Brian Millejours

http://catou-ogwspuwdc:9015/webpublishing/nuclear/ns/im/Logos/IMS Logo.jpg



Introduction

Background

Challenges

Scanner options

3D visualization

Summary

O U

T L

I N

E


6th International CANDU ISI Workshop/NDT in Canada 2016 Conference 6th International CANDU ISI Workshop/NDT in Canada 2016 Conference 3

Introduction

Phased Array UT (PAUT) Development Lab

• Active in several incarnations since late 90s

• Specializing in piping & rotating equipment

Application of PAUT to a variety of plant components:

• Blade root / Steeple examination of steam turbines

• Carbon-steel piping weld inspections

• Heat Exchanger shell and tube-sheet inspections

• MIC attack thinning inspections

• Dissimilar Metal Weld inspections

Diversifying to other specialized NDT methods (guided wave,

RFT, 3D laser mapping, GPR)



Introduction

Background

Challenges

Scanner options

3D visualization

Summary

O U

T L

I N

E



Project Background

Radiography testing (RT) currently used as part of our plant FAC

program for smaller diameter piping

Usage mitigates removal of insulation

Required for inspection of socket welds

Degradation values provided as a %wall loss

Provides visual image of degradation for the engineer

PAUT in lieu of RT

Introduced this year as a production inspection, field trialed in 2015

Preferable for lower manpower requirements (4-man crew vs. 2 techs)

Minimizing safety/dose risk (source)

Minimize overhead (setting up exclusion zones, stopping other work, etc.)

Part of an overall strategy to reduce RT in stations by examining

areas where alternatives can be utilized



Current System

Flexible Array Probe

0° E-scan setup targeting Flow Assisted

Corrosion mechanism

Calibration on pipe sample with

Tnom and T50% values

Un-encoded scan

Confirmation Manual PAUT probe

Imasonic custom probe with small footprint design

Custom curved rexolite wedges with step wedge shape

Can utilize Sectorial scan for better defect characterization

(in the event degradation mechanism is not FAC)

Encoded capability



Current System – Test Pieces

Test pieces developed based on FAC samples from field

Range of diameters (NPS ¾”, 1”, 1½”, 2”, 2½”, 3”, 4”)

Three defect patches were machined based into relevant FAC

mechanisms using specially formed EDM electrodes

Defect 1 = 25%, Defect 2 = 50%, Defect 3 = 40%

Defect 2

Defect 1

Defect 3

Defect 2 Defect 1 Defect 3



Current System - Probe Setup

Primary Aperture Orientation

Type of PAUT Scan

Circumferential

Can cover changing nominal thickness due to elbow

intrados/extrados

Allows probe design to ‘wrap’ around piping

Linear

0° simplifies focal law requirements (ie. Less customized

setups)

Double-backwall signal std for thickness measurement



Introduction

Background

Challenges

Scanner options

3D visualization

Summary

O U

T L

I N

E


6th International CANDU ISI Workshop/NDT in Canada 2016 Conference 6th International CANDU ISI Workshop/NDT in Canada 2016 Conference

Piping elbows in scope are small diameter (< 4”)

Most encoded PAUT solutions target piping NPS 4” and greater

Looked for a ‘simple’ solution which can work on a variety of

diameters

System Engineers prefer

‘visual’ provided by RT film to

understand degradation

mechanism

Maintaining complete

coverage along intrados

10

Project Challenges



Introduction

Background

Challenges

Scanner options

3D visualization

Summary

O U

T L

I N

E



Scanner – Flex Custom Housing

Designed to fit an e2sense

flexible array probe

Detachable housing mount

Single-line encoder

Foam inserts used to control

flexibility of the probe

a



Pads fit in between housing shell and the probe to

distribute pressure

Different inserts used for different pipe sizes

a


Orange Foam

insert



Difficult to maintain uniform pressure on the

array

Gaps in the coverage formed at specific points

along the probe aperture

Elastomer

reflection

Pipe

backwall

a




Scanner – ECA scanner

Repurposing Olympus Eddy-

Current Array flexible probe

scanner

Scanner comes with a series

of different pipe cutouts for

it’s flexible probe



Scanner – ECA scanner

PAUT flex probe is not as flexible as the ECA model

so some care had to be taken when contouring it

Shape of the scanner creates a cantilever on pipe

elbow, affecting either probe contact or encoder

contact

b

a

E-scan

B-scan



Scanner – X-Y custom housing

10MHz, 32 element probe

Custom curved wedge

Detachable encoder housing

Y-encoder indexing accomplished by

attached clicker box



Scanner – X-Y custom housing

Encoding along an elbow profile has inherent errors,

difficult to follow single path even with griding

Custom X-Y scanner was developed for NPS 3-4”, not

as effective for smaller piping

Defect 2 Defect 1 Defect 3



Introduction

Background

Challenges

Scanner options

3D visualization

Summary

O U

T L

I N

E



3D Visualization – Test piece

Simplify presentation of the inspection data

Enhance characterization of defect to aid in

prioritizing repair/replacement

Develop streamlined approach to data mapping

Aided by relatively simple application to thickness

measurements



3D Visualization – Test piece



3D Visualization – Field sample

Step by step process:

Importing data-file from either an MX-2/Topaz into

UltraVision

Import custom geometry as the specimen

Map the scan path of the probe over the same area

inspected onto the CAD model.

Set up contours in UltraVision to adjust the volumetric

merge parameters (ie. eliminate multiple backwalls,

extraneous scan data).

Perform a volumetric merge.

Evaluate the alignment between D-scan, B-scan and

the projection for accuracy and adjust process as

necessary.



3D Visualization – Field sample



3D Visualization – Laser mapping

Apply Position markers

Laser scan

Export 3D mesh

Export CAD model



3D Visualization – Laser Mapping



3D Visualization – Laser mapping

A lab trial was conducted to determine the viability of

such a solution in the field.

Scan creates a ‘shell’, any thickness of the part is

inferred or provided by PAUT

Considered as an additional step that could be

undertaken for greater accuracy.

Possible to approach this process inversely:

through utilizing 3D laser mapping pipe-check software

with the import of UT data as a CSV file

Process provides an ideal testing ground for the

development to more complex surfaces such as

nozzles or weldolets which may possess significant

variability.



Introduction

Background

Challenges

Scanner options

3D visualization

Summary

O U

T L

I N

E



Summary

Still looking for a superior encoded solution

Good results mapping data onto pre-

constructed 3D models

Good results mapping data on 3D laser

scanning models, primary drawback being

pipe thickness is only visible on UT data



Summary - Next Steps

Improve encoding options for scan

Challenging to maintain uniform contact with elbow

Most flexible probe holders involve rigid casing to hold

the probe which creates difficult in maintaining proper

contact

Evaluate and streamline use of 3D laser

mapping for component accuracy

Would enhance existing visualization for engineer

Adds complexity to mapping data onto component

Unclear if increased accuracy justifies workload



QUESTIONS?


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