Vajira Jayasinghe, Chris Eaton, & Brian Millejours. Application of Flexible PAUT probes for small diameter FAC elbow inspection II

Transcription

1 Vajira Jayasinghe, Chris Eaton, & Brian Millejours Application of Flexible PAUT probes for small diameter FAC elbow inspection II 6 th International 6 th CANDU International ISI CANDU Workshop/NDT ISI Workshop/NDT in Canada in Canada Conference

2 O U T L I N E Introduction Background Challenges Scanner options 3D visualization Summary 6 th

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) 6 th 3

4 O U T L I N E Introduction Background Challenges Scanner options 3D visualization Summary 6 th

5 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 6 th 5

6 Current System Flexible Array Probe 0 E-scan setup targeting Flow Assisted Corrosion mechanism Calibration on pipe sample with T nom and T 50% 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 6 th 6

7 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 3 Defect 2 Defect 1 Defect 1 Defect 2 Defect 3 6 th 7

8 Current System - Probe Setup Primary Aperture Orientation Circumferential Can cover changing nominal thickness due to elbow intrados/extrados Allows probe design to wrap around piping Linear Type of PAUT Scan 0 simplifies focal law requirements (ie. Less customized setups) Double-backwall signal std for thickness measurement 6 th 8

9 O U T L I N E Introduction Background Challenges Scanner options 3D visualization Summary 6 th

10 Project Challenges 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 6 th 10

11 O U T L I N E Introduction Background Challenges Scanner options 3D visualization Summary 6 th

12 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 6 th 12

13 Scanner Flex Custom Housing Pads fit in between housing shell and the probe to distribute pressure Different inserts used for different pipe sizes Orange Foam insert a 6 th 13

14 Scanner Flex Custom Housing Difficult to maintain uniform pressure on the array Gaps in the coverage formed at specific points along the probe aperture Pipe backwall Elastomer reflection a 6 th 14

15 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 6 th 15

16 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-scan a E-scan b 6 th 16

17 Scanner X-Y custom housing 10MHz, 32 element probe Custom curved wedge Detachable encoder housing Y-encoder indexing accomplished by attached clicker box 6 th 17

18 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 1 Defect 2 Defect 3 6 th 18

19 O U T L I N E Introduction Background Challenges Scanner options 3D visualization Summary 6 th

20 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 6 th 20

21 3D Visualization Test piece 6 th 21

22 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. 6 th 22

23 3D Visualization Field sample 6 th 23

24 3D Visualization Laser mapping Laser scan Export 3D mesh Export CAD model Apply Position markers 6 th 24

25 3D Visualization Laser Mapping 6 th 25

26 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. 6 th 26

27 O U T L I N E Introduction Background Challenges Scanner options 3D visualization Summary 6 th

28 Summary Still looking for a superior encoded solution Good results mapping data onto preconstructed 3D models Good results mapping data on 3D laser scanning models, primary drawback being pipe thickness is only visible on UT data 6 th 28

29 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 6 th 29

30 QUESTIONS? 6 th 30