[MW:4898] Post Heating -Q&T Pipes

Dear Mr. Babu,

 

Attached is a generic guidelines for welding T1 (Q& T)steel.Based on the design codes/specifications these recommendations may change. A few things to note while welding Q&T steel:-

• Controlled heat input , preheating and post heating
• Typically high strength welding electrodes to be used, hence H-4 grade is a must.
• Post weld heat treatment usually to be avoided.Post heating or hydrogen bake out is followed.
• If at all PWHT has be done depending on the recommendations of design code, then it must be done below the tempering temperature of steel, otherwise mechanical properties, especially  UTS would be reduced on the weld and HAZ.
• Preheating , post heat especially in thick sections should be done with electrical resistance heating pads.

As pointed out by Mr. Bathula, it  would be most appropriate to know the steel, design codes, design requirements(including impact and hardness) before successful welding guidelines could be formulated.

 

Appreciate your response.

 

Thanks.

 

Pradip Goswami,P.Eng.

Welding & Metallurgical Engineer/Specialist

Ontario Power Generation Inc.

Email-pgoswami@sympatico.ca,

pgoswami@quickclic.net

 

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From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Raghuram Bathula
Sent: Monday, April 19, 2010 10:32 AM
To: materials-welding@googlegroups.com
Subject: Re: [MW:4876] Post Heating -Q&T Pipes

what is the code of construction, product specification and thickness?

On Mon, Apr 19, 2010 at 11:12 AM, Kathalingam Babu <kathalingam.qaqc@ppl.com.sg> wrote:

Dear all,

 

Is any body have experience of post heating on the Q&T pipes for high pressure (3000psi) service ?

Please share ur experience.

 

Thanks & Regards,

 

K.Babu

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