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Use of RT for TML (CML), in lieu of UT study

Use of RT for TML (CML), in lieu of UT study. Randall Bellard Bellard Consulting Services www.bellardcs.com (225) 993-2443. Purpose of trials. How does RT Profile thickness data compare with UT for both accuracy and repeatability?

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Use of RT for TML (CML), in lieu of UT study

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  1. Use of RT for TML (CML), in lieu of UT study Randall Bellard Bellard Consulting Services www.bellardcs.com (225) 993-2443

  2. Purpose of trials • How does RT Profile thickness data compare with UT for both accuracy and repeatability? • How accurate and repeatable are RT measurements in locations that are not adjacent to the comparator due to uneven blow-up? • Testing of different size test coupons to determine accuracy of computer radiography equipment for the determination of piping wall thickness • Determine the variance between insulated and un-insulated piping • Testing of techniques utilized by the technicians for comparable results

  3. Testing parameters-1st trial • Worked with NDT Vendor to produce the images on a GE Rhythm CR 100 • 1st trial utilized 2” and 6” coupons-piping and elbows-same technician with supervised instruction • UT readings were taken at the (10) selected TML locations • Placed 1” comparator balls on the coupons for each RT exposure • Performed the trial with (4) different exposure setups (Slides 5, 6, & 7) • Performed trial with insulation and without • Measured at all locations with calibrations performed next to ball and at the typical O.D. of elbow • Determined the extent of the accuracy of the Measuring Tool, as compared to UT data

  4. Testing parameters-2nd trial • 2nd trial performed on in-service field circuit – (3/4”, 4”, and 6”) • Tested (3) operators-no formal instructions provided, other than circuit and RT locations • Tested (2) additional technicians with technique specifics given (source location, ball, and film placement, etc…) • Computed RT readings were taken with the Manual Measuring Tool and with the Automated Wall Thickness Measurement Tool • Determined the variance from UT and RT readings acquired

  5. Setup details of 1st trial

  6. Setup details of 1st trial

  7. Setup details of 1st trial

  8. Trial 1 – 2” measurements

  9. Trial 1 – 2” variances from UT

  10. Trial 1 – 6” measurements

  11. Trial 1 – 6” variances from UT

  12. UT comparison

  13. Results of 2nd trial-3/4”, 4”, & 6”

  14. Summary of trials • The results from the 1st trial proved that the closer the Measuring Tool is to the ball comparator, the more accurate the actual wall thickness reading with RT • In most instances in the 1st trial, the UT/RT readings were very similar with a maximum isolated deviation of 0.027” which occurred on the 6” specimen at location 3 • In the 2nd trial, the results from the techs given a basic setup technique, the results had little variance from one tech to another, 0.006” in worst case • If a consistent technique is used to collect data using profile radiography it can be used to determine corrosion rates with a high degree of confidence

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