Re: [MW:35522] WPS for Furnace PWHT

Dear Mr Karanth,

I am in full agreement with your observation. The real challenge arises during local PWHT of shop and field weld joints. Weld joints located within the heating band—defined as 75 mm or three times the material thickness, whichever is greater—of a joint requiring PWHT, are themselves required to be welded using a PWHT-approved WPS, even if their individual thickness does not mandate PWHT.

Furthermore, even when the PWHT-required joint is welded and heat treated first, residual heat and stress from the subsequent welding of nearby joints (using a non-PWHT-approved WPS) can still affect the integrity of the previously treated weld.

In situations where weld joints are distributed between shop and field locations, ensuring proper traceability and compliance with PWHT process requirements becomes increasingly complex. Unfortunately, in many cases, PWHT estimation is not adequately considered during the initial planning phase.

In such cases, the code limitations are unclear and do not provide sufficient guidance to address this issue effectively. Additionally, when the weld thickness is less than 20 mm (for girth, branch, or wear pad welds) and is located close to a butt or O'let weld joint requiring PWHT, the application criteria remain undefined.

Any body can suggest guidance!!

Prakash

On Saturday, April 5, 2025 at 7:39:13 PM UTC+4 Deerendra Karanth wrote:

Yes, performing furnace PWHT on any joint that was welded using a WPS not qualified with PWHT violates Clause 331.1.6(b) of ASME B31.3. It constitutes a quality non-conformance, even if the individual weld is below the threshold thickness for mandatory PWHT.

BR, 

Deerendra 

On Sat, 5 Apr, 2025, 18:49 Prakash Kumar Bontra, <prakas...@gmail.com> wrote:

As per ASME B31.3, Clause 331.1.6 (b):
Any required PWHT shall be carried out in accordance with the qualified WPS.

For furnace PWHT involving spools of different diameters and varying thicknesses, all weld joints subjected to PWHT must be welded using a WPS qualified with PWHT. This requirement remains applicable even when the individual joint thickness is less than 20 mm, despite the code-specified threshold of greater than 20 mm for P1 materials, as outlined in Table 331.1.1 of ASME B31.3 (2008).

Therefore, performing furnace PWHT on any joint that was welded using a WPS not approved for PWHT constitutes a non-conformance with the applicable quality requirements. Do you agree? If not please elaborate.

Prakash

On Sat, Apr 5, 2025 at 7:52 AM Hareesh K V <harees...@gmail.com> wrote:

Dear Sir,

I am not clear about the question.

Is the question is "The welding is done without following a WPS having  PWHT and actually the joints need the same" is it?

May I know the material ?

Also if it is of Carbon Steel material, is PWHT requirment is there based on design or based on ASME 31.3?

Regards,

Hareesh K V

On Mon, 27 Jan, 2025, 11:57 am Prakash Kumar Bontra, <prakas...@gmail.com> wrote:

For furnace PWHT as per ASME B 31.3 all the joints in the spool (1" to 36") need PWHT approved WPS and where to refer?

Prakash Bontra

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