Dear All,
It is very good thought by member asking for WPS without PWHT for P91 Material , In fact this materials is very very critical with respect to service as well as welding point is concerned, This material once you start welding ,you can not stop and post heating is required to be used till you start stress relieving other wise you may not acheive the hardness and microstructure desired. In my previous project we had arrangement for alternative power source such as desiel welding generator as standby in case main power supply failure to avoid interruption in contnuity of welding . I do not think you have solution for the issue .
Regards,
----- Original Message -----
From: pgoswami
To: materials-welding@googlegroups.com
Sent: Tue, 31 Aug 2010 03:57:52 +0530 (IST)
Subject: [MW:6792] MW: 6787- RE: 6769] Any WPS for P91 Material without PWHT
Dear Faruk,
NO CODE WILL ALLOW
P-91 STEEL TO BE WELDED WITHOUT PWHT.
Further to the recommendations of John, I
would like to add a few points. P-91 is classified as P 5B Gr2 material in ASME
Sec-IX. Often in the past people thought this steel to be "just another Chrome
Moly" steel, till the "lessons were learnt". P-91 steel is never used in
ambient temperature or typically for
15psi (very low) design
pressure ranges. This material is recommended for design and pressure
ranges where any mishap (minor or major) could cause human fatalities. If you do
a google search with these keywords " p-91 steel, failure, fatalities",
you will see tons of articles.
The attached article would provide a good
general guidance on P-91 steel and understand the need for
PWHT.
Let me know if it
helps.
Thanks.
Pradip
Goswami,P.Eng.
Welding
& Metallurgical Engineer/Specialist
Ontario
Power Generation Inc.
Email-pgoswami@sympatico.ca,
From:
materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com]
On Behalf Of John Henning
Sent: Monday, August 30, 2010 10:01
AM
To: materials-welding@googlegroups.com
Subject: [MW:6787]
RE: 6769] Any WPS for P91 Material without
PWHT
Not a good
idea. Not only is 91 in the as welded condition rather brittle but it has
been shown to be subject to stress corrosion cracking in the presence of water
(condensation, dew, rain, etc.). You can find recommendations sprinkled
throughout open literature that discuss the need to keep as welded 91 warm and
dry between welding and PWHT. (A tedious Google search should reveal at
least four good references – a task left to you). There have been several
91 failures traced back to SCC due to improper handling of 91 in the as welded
condition. Some recommendations not only restrict storage conditions but
also time duration.
As previously pointed
out, all ASME codes require PWHT for all welded 91 without any
exemptions.
John
From:
materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com]
On Behalf Of Mohamed Farook
Sent: Sunday, August 29, 2010 11:00
PM
To: materials-welding@googlegroups.com
Subject: [MW:6769]
Any WPS for P91 Material without PWHT
Dear friends,
Greetings to all,
Please advise me if you
have WPS for P91 material without PWHT….
PWHT is time
consuming..
Thanks and Regards,
asfaruk
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