Re: [MW:25604] RE: 25596] Hydrogen back out - ASME sect IX

ASME B31.1 2016 édition requirements on P91 are a little bit different in case of interruption of welding until the PWHT is performed  (see 131.6.1).

Codes requires that the minimum preheat temperature to be maintained.

Please allow me to point out that the minimum preheat temp for P91 acc to table 131.4.1 us 200 degC 

Sent from my Samsung Galaxy smartphone.

-------- Original message --------

From: pgoswami <pgoswami@quickclic.net>

Date: 26/10/2016 06:26 (GMT+02:00)

To: materials-welding@googlegroups.com

Subject: [MW:25598] RE: 25596] Hydrogen back out - ASME sect IX

Hi Zakaria,

 

Hydrogen bake out is separate; it's not to be confused with PWHT. PWHT is mandatory for Grade91 (P-15E) steel. One can't reduce the PWHT cycle on the pretext of bake out was done for the welds. Bake out/DHT or the old terminology Post Heat are not considered to be an essential variable in PQR qualification as per Sec-IX. It may be followed during qualification of PQR or added separately during production welds.

 

Grade-91 steel is not just another Cr-Mo steel, one has to understand this first then proceed with the fabrication. Sec-IX does not address anything on P-91 welding. One needs to gather such information from various other resources and then go forward.

 

Typical bake out recommendation:- 300 Deg C, 1 Hr/inch of Thickness minimum. It needs to be done after the welds are cooled to the ambient  temperature for the total Martensitic transformation to be over. The delay between the bake out and PWHT shouldn't be too long.  What's recommended by your project?

 

Please see below the typical &recommended welding &PWHT cycle for grade-91(P No 15E) steel.

 

Thanks.

 

 

 

Pradip Goswami, P.Eng,IWE
Welding & Metallurgical Engineering Specialist ,

Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299

pgoswami@quickclic.net

pradip.goswami@gmail.com

 

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From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Zakaria ghrab
Sent: Tuesday, October 25, 2016 10:46 AM
To: materials-welding@googlegroups.com
Subject: [MW:25596] Hydrogen back out - ASME sect IX

 

Dear all,

 

For 15E Material P number, it's mandatory in our project to perform Hydrogen backout and then PWHT;

 

  Please confirm to us if Hydrogen Back out is considered as  part of PWHT accoeding ASME sect IX ?

 

If one PQR is performed without Hydrogen Back out, could us prepare production WPS with  this intermediate Heat cycle (Hydrogen back out) ?

 

Thank you.

--

 

Thanks and Regards, 

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زكرياء غراب
GHRAB Zakaria 

Tunisia : +216 96 635 805

Yesterday is the past, tomorrow is the future; and today? Today is the present, the gift: Enjoy it!

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