RE: [MW:8441] HOTTAP on SOUR LINE (PWHT Required)

Dear Limesh & All;

 

Thanx for your replies & advices.

 

The materials is A 106 Gr B, pipe Dia is 4” Sch 40, & we are using split tee 15 mm thick.

 

The same I had in my previous works, the issue were to qualified the welders for Temper Bead Procedure (Half bead). As per QW-290.

 

The surprise here for the client & client TPI, that, client TPI is asking to make a heating up to 300C for 30 to 60 min after completing the welding (which I search everywhere, I didn’t find such procedure in any relevant standards.)

The second surprising thing is my client, is asking to make preheating to 350C for 3 hours before starting the work plus hydrogen baking.

 

My point is, the life line is wet LPG, H2S present 2500 PPM, which is very high, plus if I keep heating the line up to this temperature, I need to ensure it will not imply any unwarranted impacts , thus jeopardizing the operational LPG unit itself.

 

 

Regards

Majdi Elyyan

 

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of limesh M
Sent: Monday, November 29, 2010 7:56 AM
To: materials-welding@googlegroups.com
Subject: Re: [MW:8424] HOTTAP on SOUR LINE (PWHT Required)

 

Dear Majdi,

 

You didn't mention the material designation(pipe and split tee material) and thickness of the pipe/split tee material.If you could provide it,it will be easy for experts to analyse your query.I also have interest in this matter.

 

 

Regards,

 

Limesh

On Sun, Nov 28, 2010 at 6:45 PM, Majdi N Elyyan <melyyan@gmail.com> wrote:

Dear All;

 

We have a hot tap on LPG line (Sour service) which require PWHT.

The run Pipe is 4”, the branch is also 4”, split tee will be used.

As per shell DEP-31.38.60.10 – for Hot tapping, clearly mention:

Hot-tap welding should not normally be performed on materials which require post-weld

heat treatment. However, if stress relieving or post-weld heat treatment is required, a

specialist shall be consulted to assess whether it is feasible to make the specific

hot-tapping operation with post-weld heat treatment.

Note: Stress-relieving may be required if a material is susceptible to stress corrosion cracking and post-weld

heat treatment may be specified by the design code if the wall thickness is greater than a certain limit.

 

& since we have no other options, we have to do the hot tap on the same, kindly advice WPS & PWHT procedures

 

Thank all in advance..

 

Regards

Majdi Elyyan

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