P1 Material Pipe welding Joints RT and MT before PWHT is Acceptable or not ?

[mpk mpk]

Dear experts,

P1 Material Pipe welding Joints  RT and MT examination  before PWHT  is Acceptable or not ?

As per 2010  ASME B.31.3 para 341.3 Examination requirements,

(a) for P.nos 3,4 and 5 materials Examination shall be performed after completion of any heat treatment.

Thank you

YEM.

[Ramchandra vichare]

----- Original Message -----
From: mpk mpk
To: materials-welding
Sent: Mon, 25 Jun 2012 15:18:08 +0530 (IST)
Subject: [MW:14676] P1 Material Pipe welding Joints RT and MT before PWHT is Acceptable or not ?

Dear friend,

It can be acceptable but, only for internal judgement of workmanship/quality of weld (i.e.to observed any repair etc.) but If your job requirement is heat treatment you must go for RT after Heat treatment eventhough you attend RT or any NDT (as required)  before heat treatment & it may be acceptable before heattreatment .

Regards,

RKVichare

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[Guoliang Xue]

RT / MPI before PWHT is internal inspection and RT / MPI after PWHT is
required by ASME B.31.3 para 341.3 Examination requirements,
(a) for P.nos 3,4 and 5 materials Examination shall be performed after 72 hours

completion of any heat treatment.

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[Mohamad Shah Gubah ahmad]

Hi friends

 

It is acceptable because your performend before PWHT is not ignore the code reference. This NDT to check any discontinuities ,if any finding  you can repair with out PWHT. .Most of the contrctor /company impliment NDT before PWHT because:

1. Check any discontinuities

2. To confirm and remove  the minor doscontinuities to ensure it did not contribute or accumulate become major defect

3.to reduce cost of repair better carry out before PWHT

4. To compare any discontinuities sizing before and after pwht

5. If NDT after  PWHT,you found non acceptable defect that become very costly for repair.

6.Normally NDT after PWHT check "0 tolerance defect" (crack)

regards

[Nisanth Mohan]

Dear Friends,

I agree with you guys still I would also like to add a piece of info.

Regarding PWHT,

• PWHT does not always have a positive effect and can cause distortion and degradation of the micro structure.
• PWHT can “open up” indications (due to heat cycle) that might not show by NDT before PWHT.
• There is a chance for delayed cracking or post heat treatment cracking may happen in or adjacent to welds after PWHT.

Considering the above reasons NDT is prefered after PWHT to make sure the weld quality

"RT before PWHT" would be an optional additional examination. 

If you noticed repair after PWHT, then you need repair and  re-PWHT required;to minimise/avoid this situation, NDT before PWHT is preferred.

And As per Shell DEP 30.10.60.18 , Clause 9.1 :  NDE for acceptance shall be carried out after final PWHT.

So before coming to a conclusion please refer your project specifications and accordingly.

Thanks,

Nisanth Mohan