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Radiography (RT) Before or after PWHT
- Thread starter GemmellG
- Start date
david339933
Industrial
Try a search on the site...this has been discussed many times.
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- #3
Guest
kingnero said:
RT is not good at detecting fine cracks. Furthermore, reheat cracks are frequently quite short.
Why do you suspect reheat cracking? It is typically associated with creep-resistant steels, but can happen in carbon steel.
"Everyone is entitled to their own opinions, but they are not entitled to their own facts."
I don't suspect reheat cracking, I just find it very peculiar that RT is chosen as NDT when PWHT needs to be done.
I'd have all testing done as required by the standard(s) before PWHT, and additional testing depending on the type of defects you'd suspect after PWHT (e.g. UT for most applications, macrography for microcracks).
I'd have all testing done as required by the standard(s) before PWHT, and additional testing depending on the type of defects you'd suspect after PWHT (e.g. UT for most applications, macrography for microcracks).
ISO 17635:2016 states the following "The testing should be carried out after completion of all required heat treatments."
In practice, and to ensure that PWHT time isn't wasted on a flawed weld, sample NDE can be done on sections of the weld in advance of PWHT - It depends how long your PWHT takes / costs compared to the time / cost of UT/RT
In practice, and to ensure that PWHT time isn't wasted on a flawed weld, sample NDE can be done on sections of the weld in advance of PWHT - It depends how long your PWHT takes / costs compared to the time / cost of UT/RT
One reason for requiring RT as the final volumetric examination is that the record (radiograph) could be reviewed by others (AI, Purchaser, etc.) at a later date and the old UT methods could not, relying on the expertise of the Level II Examiner. With modern UT methods the same cannot be said and more UT is being performed. The problem with the new methods is the ability of the AI or Purchaser's inspector to properly review the electronically stored data.
I did have one case where the data was corrupted and we had the weld seams involved re-examined. We also employed a third party, trusted Level III review the data as well as the original test calibrations, test setup, etc.
I did have one case where the data was corrupted and we had the weld seams involved re-examined. We also employed a third party, trusted Level III review the data as well as the original test calibrations, test setup, etc.
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