RE: [MW:10044] piping modification after PWHT

Hi Abhay,

 

What' re the design requirements??

 

There're two issues out here,.ASME Code and NACE -Sour service.If you're asking a specific technical query related to PWHT  note and make sure that operating media has a strong influence on determining the applicability of PWHT and mention something about the media also. Plus what's the design code ???, B-31.3 or anything else.

 

 

1. Regarding the PWHT:-the thickness mentioned here,1 inch sch 80 and  thickness up to  10 inch sch 40 CS SA106 Gr B  would not call for any PWHT. Look up in B-31.3-Table 331.1.1.The minimum thickness for mandatory PWHT for carbon steels is 20mm (3/4") and above.
2. If there is NACE sour service requirement then PWHT is usually mandatory.However MR-0175 Clause A-2.1.4 provided some waiver from PWHT for some C-Mn steels and allows them to be accepted in as welded condition. You may find the details in MR-0175.

So for the pipes as mentioned above  based on the criteria  the design documents should specify if PWHT is a requirement or not. To be on the safe side if as welded hardness is below 22 HRC then you can pitch an argument for waving PWHT.

 

RT requirements  are mandated by  piping design code. One has to meet that criteria, every time any welding is performed.

 

Thanks.

 

Pradip Goswami,P.Eng.IWE

Welding & Metallurgical Specialist & Consultant

Ontario,Canada.

Email-pgoswami@sympatico.ca,

pgoswami@quickclic.net

 

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From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of renga raja
Sent: Friday, February 25, 2011 7:39 AM
To: materials-welding@googlegroups.com
Subject: Re: [MW:10013] piping modification after PWHT

Hai

 

first of all, SA 106 Gr.B Material above 19mm only we need to do the PWHT. at what specification you are following the PWHT for sch40 pipes.

 

in case of your specification, you have to do PWHT, then you have to go for the new modified joint also. then go for RT.

 

generally, modified weld also must do the similar way for other joints. RT also should take.

 

 

 

 

On Fri, Feb 25, 2011 at 10:02 AM, Abhonkar, Abhay (NAR) <AAbhonkar@dresser-rand.com> wrote:

Dear Sir,

This is case for discussion.

Let us assume that piping for SA106 Gr B pipes are fabricated and radiographed and found OK. Then as per the requirement, next stage is Post weld heat treatment.

Size of the piping is vary between 1 inch sch 80 and extends upto 10 inch sch 40 CS SA106 Gr b NACE material.

 

Now if one completed the PWHT cycle and during mounting of the piping it seems that without doing the re cutting and rewelding it will not fit then, how we should go forward,

 

1)       Can piping accepted by means of radiograph after rewelding and if RT OK then we can go ahead for final hydro test without PWHT.

2)       One has to do again PWHT for that modified joint.

3)       What is AEME verdict about that?

4)       Whether UCS – 56 is mentioned about that, as it will seems that code mentioned about repair weld only and not for new weld after modification.

 

Pl have your views on above.

 

 

Regards,

Abhay

Ext 448

 

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