1/22 R. Long 1, P. Cawley 1, J. Russell 1,2 1. UK Research Centre in NDE, Imperial College 2. Rolls-Royce Marine, Derby

2/22 Contents 1.Introduction – The Inspection Challenge 2.Membrane device 3.FMC 4.CIVA Simulations 5.Experimental results 6.Summary

3/22 Introduction – The Inspection Challenge To develop phased array ultrasonic inspection for a thick-walled stainless steel component typically found in the nuclear industry Interest in detecting defects that might occur in the weld region Inspect during manufacture and in service Challenging inspection due to access constraints and complex geometry

4/22 Weld cap removal is an expensive, time-consuming task that can compromise the integrity of safety critical pipe-work For conventional phased array wedge coupled transducers placement of transducer can be limited by presence of weld cap One solution is to have a phased array that conforms over an irregular surface profile Incompatible weld cap surface profile and wedge/diffuser profile an irregular coupling layer leading to beam distortions Introduction – The Inspection Challenge

5/22 A single device is used for surface profile measurement (required for updating of delay laws) and inspection, allowing rapid scanning of components with irregular surfaces Optimized delay laws Irregular surface profile Conventional phased array Water path encapsulated by conformable membrane A cost effective and more durable solution that we have chosen is to couple a standard phased array to the surface under test via a water path which is made more convenient by encapsulating the fluid with a conformable synthetic rubber membrane. Membrane Device

6/22 3rd generation prototype Membrane device Shown in constant pressure configuration Irrigation feed Couplant distribution low profile Imasonic 2MHz 128 element array Header tank for constant pressure encapsulated water column Membrane Device

7/22 T T L T L L Direct shear wave Trivial All phased array controllers should be capable of this Mode converted shear-long wave Not so trivial Mode converted shear-long-long wave Not at all trivial Investigate capability of currently available phased array controllers to perform inspections Our preferred techniques often use waves reflected and mode converted at the inner surface of the pipe a) b) c) Beam forming software found on commercial phased array controllers do not readily provide for mode conversion beam forming FMC

8/22 Lower surface of block Upper surface of block Weld cap position Phased array location Bscan image can only be displayed on direct wave path Refection off defect No known current controller/display software allows display of on-skip/mode conversion inspections such that image superimposes defect location Location of defect Example of a displayed on-skip phased array shear wave inspection using AGR Focus scan We want to display image such that it superimposes the inspection area to aid defect location FMC

9/22 Wrote our own software to process data and display image Used a Peak NDT controller with FMC capability Our solution Collect data in FMC mode To allow us to do this FMC is a data acquisition technique where a signal is obtained for the transmission and reception for all possible pairs in the phased array FMC

10/22 Software for processing FMC data and displaying image FMC

11/22 Bscan scan of surface obtained with transducer located in a single position Bscan scan of plane surface Bscan scan of irregular surface Phased array Surface profile measurement 06/07 Comparison between results for mechanical stylus and Bscan ultrasonic measurement FMC

12/22 Develop technique for focusing at all points in a Bscan image Focusing at 30mm below surface upper sdh in focus lower sdh out of focus Focusing at 50mm below surface upper sdh out of focus lower sdh in focus CIVA simulation of direct shear wave inspection of test piece with 4 sdh 30mm 50mm FMC

13/22 ATFM AFTM focusing All points in Bscan image in focus CIVA simulation of direct shear wave inspection of test piece with 4 sdh FMC

14/ We model all inspections we are interested in using the CIVA v9.2 software and collecting FMC data 4 separate CIVA Simulations – 1 for each defect Transducer located in same position for Defect2&3 and Defect4&5 Unwelded test piece Processed and presented data using Imperial Software Fusion face Defect (rectangular slot 4x8) 80 el 2MHz angle- 8 o Approx 60mm Defect2&3=135mm Defect4&5=185mm 7mm CIVA Simulations

15/22 Direct L 45 deg 25el Direct T 45 deg 25el Mod con TL 29 deg 25el CIVA simulations processed with Imperial software Direct L 45 deg 30el Direct T 45 deg 30el Mod con TL 29 deg 25el On-skip TT 40 deg 30el Defect 1 Defect 2 T T L L T L T T L T CIVA Simulations

16/22 Direct L 73 deg 14el Mod con TL 29 deg 24el On-skip TT 45 deg 24el Mod con TLL 29 deg 24el On-skip LL 45deg 24el On-skip TT 45 deg 24el CIVA simulations processed with Imperial software Defect 3 Defect 4 Mod con TL 29 deg 24el Mod con TLL 29 deg 24el T L T T L T L T T L T L L L L T L CIVA Simulations

17/22 Obtain FMC data using Peak phased array controller (purchased and commissioned 08/09) Processed and presented data using Imperial Software One FMC data set can provide inspections for both primary and secondary inspections of both defects using a single transducer location. Experimental set-up - welded test piece (Defect 2 and 3 - 8mm through wall defects) Experimental Results Fusion face 128 el 2MHz angle- 7 o 58mm 7mm Defect 2 Defect 3 Austenitic weld Weld cap 143mm

18/22 T L TT Defect identificationDefect confirmation/sizing Experimental results welded test piece Defects 2 2 MHz, 128 element, 0.75mm pitch 3 rd Generation Device Bscans normalised to max amplitude in image Both images obtained from same data set TT inspection (-9dB relative to TL D10) 37 element Aperture 45 degree shear wave TT inspection 36 element Aperture 29 degree shear wave Experimental Results

19/22 TT T L L Defect identification Defect confirmation/sizing Experimental results welded test piece Defects 3 2 MHz, 128 element, 0.75mm pitch 3 rd Generation Device TT inspection (-12dB relative to TL D10) 21 element Aperture 40 degree shear wave Bscans normalised to max amplitude in image Both images obtained from same data set TLL inspection (-3.7dB relative to TL D10) 36 element Aperture 29 degree shear wave Experimental Results

20/22 Experimental set-up - welded test piece Through weld inspections using 3rd generation device 3rd generation membrane device Welded test piece Heat affected zone Defect 3/10 Experimental Results

21/22 Specular Reflection off Defect dB relative to feature Phased Array Weld fusion face profile Fluid Steel Dominant feature due to irregular surface Specular Reflection off Defect 10 Phased Array Fluid Steel Using delay laws for a plane surface 50 element Aperture 65 degree long wave Using updated delay laws for the weld cap profile 50 element Aperture 65 degree long wave Experimental results Defect 10 (direct wave through weld) Bscans normalised to max amplitude in image Both images obtained from same data set Experimental Results

22/22 Summary 1.FMC allowed us control over our data processing and display 2.ATFM – all point focused Bscans 3.One set of FMC data provides multitude of inspection possibilities 4.FMC allowed us to successfully conduct mode conversion inspections of a welded test piece using focused delay laws