NDT before or after PWHT
NDT before or after PWHT
(OP)
Hello everybody
any ASME code don't mentioned NDT after or before PWHT, anyone can explain for me understand why?
any ASME code don't mentioned NDT after or before PWHT, anyone can explain for me understand why?





RE: NDT before or after PWHT
RE: NDT before or after PWHT
normally, we performed RT before PWHT [i]as this saves the time and money of having to repair welds and again perform heat treatment on the repair. As the owner we are willing for the contractor to do the NDT before heat treatment, but at his own cost.
The NDT carried out before heat treatment should be the same as the NDT carried out after heat treatment. Generally the NDT before heat treatment has been radiography, but as the owner we have substituted this for UT after heat treatment. The theory being, that the only repairable defects likely after heat treatment (if this has not been performed correctly) is cracking and the preferred method for crack detection in this instance would be UT, so far lack of sidewall fusion defect may insufficient of RT method
RG
RE: NDT before or after PWHT
RE: NDT before or after PWHT
If you perform RT before PWHT and UT after PWHT you are asking for trouble.
Numerous linear defects can be missed by RT and the weld deemed acceptable (especially lack of sidewall fusion)then the weld will be rejected when it is UT tested.
What is the material ?
What is the applicable code ?
ASME B31.3
(a) For P-Nos. 3, 4, 5A, 5B, 5C, and 15E materials, examinations shall be performed after completion of heat treatment. However, examinations need not be repeated on welds or portions of welds that are subjected to additional heat treatments and have not been repaired by welding.
RE: NDT before or after PWHT
Material is CS P1
Applicable code is ASME B31.3
Defection is found after PWHT, that mean we must repair by welding - RT or UT - re-PWHT - UT right?
as ASME B31.3 2014 edition is preheating 95deg without PWHT, we can preheating over 95Deg for repair by welding without re-PWHT
RE: NDT before or after PWHT
RE: NDT before or after PWHT
Theoretically, the NDE is done after PWHT because cracks "might" occur because of the stress induced in the cooldown. Practically, you try to NDE before PWHT/hydrogen bakeout/cooldown so you DON'T have to reheat and re-PWHT if you find a crack.
RE: NDT before or after PWHT
For P1 materials, ASME B31.3 permits final NDE before PWHT. It is up to the Engineer/Owner to mandate final Code required NDE after PWFT.
RE: NDT before or after PWHT
where is para in B31.3 permitted performing NDT before PWHT?
RE: NDT before or after PWHT