Repair after PWHT - B 31.1

[sevak hiren]

Dear Experts,

Piping Code : ASME B 31.1, Power Plant Piping, (P No.5A,11,12,15, 91 etc pipes) & ASME Sectin I

Contractor is doing piping fabrication stages in following manner,

Preheating & Welding of Piping joints then Post heating, then PWHT & then finally RT.

Contractor is arguing, RT is taken after PWHT  to reveal the defects causing due to delayed cracking.

My question

If RT repair is done for particular joint after PWHT then is it compulsory to perform PWHT again for particular joint ? if yes then please mention the clause of code.

Thanks & Regards

Hiren Sevak

[Siva]

PWHT shall be done after weld repair. So my understanding is, to find weld repairs, we need to perform NDT before PWHT. I have seen in my experience, normally, NDT will be done prior to and after PWHT also(i.e., twice on that joint).
If NDT done only after PWHT, found any defects, then after weld repair, again should perform PWHT, which might effect mechanical properties.

Hiren Sevak

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Regards,
G.Sivalingam., BE.,
Quality Control Inspector - Welding,
SAS Project, Abu Dhabi, UAE.

[Desai Jignesh (Mumbai - Piping)]

I would like to highlight requirement out lined in ASME B 31.3 as below.

 

# Refer Para 341.3.1(a)

 “For P-Nos. 3, 4, and 5 materials, examination shall be performed after completion of any heat treatment”

 

# Refer Note (11) in “NOTES FOR APPENDIX A TABLES “ (Pg 147 – 2010 edition)

“For use under this Code, radiography shall be performed after heat treatment”

This note(11) pointing P3, P4, P5A, P5B, P9A & P9B materials only as per table A-1.

 

And of course, Re-PWHT shall be carried out if any repair comes, in case of RT after PWHT.

 

Regds/Jignesh

[hemant]

Dear Jignesh Sir,

As per metallurgy point of view we can done PWHT cycle only one time if we go for second time we have to qualify Repair WPS.  Pls reply me for any suggestion.

 

Thanks,

HHS

[Biplab Pal]

Dear Hiren Sevak,

 

I have a very simple opinion.

Your WPS specifies about PWHT, if yes it is essential variable for Production Welding.

It is required by code/std./spec. that we sould perform RT after completion of welding. If PWHT is not done, i think the weld is not complete according to WPS. So you can not perform RT before completion of welding of any joint.

On Mon, Sep 10, 2012 at 9:10 AM, sevak hiren <hirens...@gmail.com> wrote:

Hiren Sevak

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Thanks & Regards
Biplab Pal
Mechanical Inspector (PMT)
YASREF Project

E-mail:   bipla...@gmail.com
 
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[Dindo]

First thing is you have to do your due dilligence by doing NDT prior to sending for PWHT, so that you wont get caught unaware of the repair before it goes to the oven.

 

Second thing is if there is a repair after PWHT, then you have to cut out the whole weld and redo the weld.

[PRAMODH NAIR]

Required PQR after secopnd time PWHT. Because its affect the mechanical properties.

 

Regards

Pramodh

From: Siva <siva7...@yahoo.com>
To: material...@googlegroups.com
Sent: Tuesday, September 11, 2012 12:19 PM
Subject: Re: [MW:15269] Repair after PWHT - B 31.1

PWHT shall be done after weld repair. So my understanding is, to find weld repairs, we need to perform NDT before PWHT. I have seen in my experience, normally, NDT will be done prior to and after PWHT also(i.e., twice on that joint).
If NDT done only after PWHT, found any defects, then after weld repair, again should perform PWHT, which might effect mechanical properties.

On Mon, Sep 10, 2012 at 9:10 AM, sevak hiren <hirens...@gmail.com> wrote:

Dear Experts,

Piping Code : ASME B 31.1, Power Plant Piping, (P No.5A,11,12,15, 91 etc pipes) & ASME Sectin I

Contractor is doing piping fabrication stages in following manner,

Preheating & Welding of Piping joints then Post heating, then PWHT & then finally RT.

Contractor is arguing, RT is taken after PWHT  to reveal the defects causing due to delayed cracking.

My question

If RT repair is done for particular joint after PWHT then is it compulsory to perform PWHT again for particular joint ? if yes then please mention the clause of code.

Thanks & Regards

Hiren Sevak






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The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.
 
 

--

Regards,
G.Sivalingam., BE.,
Quality Control Inspector - Welding,
SAS Project, Abu Dhabi, UAE.

[sachin sankhe]

If PWHT is process requirement (Sau caustic) then any repair on job after PWHT calls for re-PWHT(Of course you need to qualify welding procedure also)

However if PWHT requirement is due to base metal thk then depends if repair depth  after PWHT is less than thk that require PWHT as per code then i feel PWHT may not be required(But u need to qualify the welding procedure for this also)

Regards

Sachin.Sankhe

From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of Siva

Subject: Re: [MW:15269] Repair after PWHT - B 31.1

PWHT shall be done after weld repair. So my understanding is, to find weld repairs, we need to perform NDT before PWHT. I have seen in my experience, normally, NDT will be done prior to and after PWHT also(i.e., twice on that joint).
If NDT done only after PWHT, found any defects, then after weld repair, again should perform PWHT, which might effect mechanical properties.

On Mon, Sep 10, 2012 at 9:10 AM, sevak hiren <hirens...@gmail.com> wrote:

Dear Experts,

Piping Code : ASME B 31.1, Power Plant Piping, (P No.5A,11,12,15, 91 etc pipes) & ASME Sectin I

Contractor is doing piping fabrication stages in following manner,

Preheating & Welding of Piping joints then Post heating, then PWHT & then finally RT.

Contractor is arguing, RT is taken after PWHT  to reveal the defects causing due to delayed cracking.

My question

If RT repair is done for particular joint after PWHT then is it compulsory to perform PWHT again for particular joint ? if yes then please mention the clause of code.

Thanks & Regards

Hiren Sevak

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[Muhammed Ibrahim PK]

PWHT shall be done after repair. To avoid this issue better to perform RT before PWHT also.

Thanks & Regards
Muhammed Ibrahim PK

Hiren Sevak

[sabi sabi]

Dear gents,

 

Case-1: Normal practice

1.welding (with/without pre heat & post heat)

2.RT

3.Clear repair + RT

3.PWHT

4.RT

 

Case-2: Some agents are doing (with confidence of worker & Did not get a time fot RT)

1.welding (with/without pre heat & post heat)

2.PWHT

3.RT

4.Clear repair (with/without RT)

5.PWHT

6.RT

 

Solution of case-2: There is no problem for twice PWHT. It will not affect any meterial properties.

 

That is the reason, we are taking hardness test to meet requirement. Only time will take more.

 

Regards,

sabi

[Muhammed Ibrahim PK]

Double PWHT will reduce tensile strength.

Thanks & Regards
Muhammed Ibrahim PK

[Sanjay Yadav]

For repair carried out after pwht than pwht is mandatory after repair if service requirement.
If as per code than exemption clause shall be applicable based on depth of repair.