NDE requirements and PWHT

By jm812 Date 10-26-2005 16:27

On normal fluid service piping is NDE required after PWHT or is this just a requirement of engineering design. If not if you perform NDE prior to PWHT is it required to perform NDE after? Where can I find the code requirements pertaining to this?

By chall

Date 10-26-2005 17:45

You should first determine what the code of construction is. The code will lay out PWHT and NDE requirements. Engineering design usually includes reference to the appropriate code of construction. If one isn't specified, I recommend ASME B31.3.

As a general rule, required NDE must be performed after PWHT.

When we have to do PWHT on a weld; we do NDE before the PWHT for info. When the PWH is completed we do the final NDE. We do this in order to find out if there is a known defect present before going through the costly practice of doing the PWHT only to have to do it agian if a repair is needed.

Charles.

By Shane Feder (****)

Date 10-27-2005 01:17

jm812,
You have mentioned normal fluid service so I presume you mean B31.3.
If this is the case you will find Section 331 and Table 331.1 will give you all the information you require,
Regards,
Shane

By NDTIII

Date 10-27-2005 05:23

If you look at B31.3 Paragraph. 341.3.1 (a) you'll see that examinations are to be performed after completion of any heat treatment for P-Nos. 3, 4 and 5 materials. It is not a requirement for P-NO. 1 materials unless specified in your engineering design or other contract documents.

By DLCH Date 10-27-2005 07:02

PWHT could be for service requirement, not neccessarily a code requirement to prevent weld or HAZ cracking during on stream.