Wednesday, September 22, 2010

[MW:7153] RE: 7143] ISR of P-91 pipes.

ISR is beneficial in reducing hydrogen and thereby minimizing the potential for hydrogen assisted cracking (cold cracking).  ISR is typically performed by heating for 2 to  4 hours at temperatures between 800 and 1100 F (usually a customer requirement will apply)

 

More importantly – As Welded 91 is susceptible to stress corrosion cracking in the presence of water.  ISR may increase the potential for SCC by promoting secondary hardening.  You must provide a means to keep these welds warm and dry – no rain, no splashing, no dew formation, etc – best kept indoors in controlled environment.    Additional warning - SCC can be very difficult to detect.

 

John

 

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Ravinder Sharma
Sent: Wednesday, September 22, 2010 5:49 AM
To: materials-welding@googlegroups.com
Subject: [MW:7143] ISR of P-91 pipes.

 

Hi All,

 

I have welded joint of P91 of 400DN and 40 mm thickness, due to unavoidable reasons we have to do the heat-treatment after 60 days,

 

Is there requirement of ISR?

 

If yes, what should be the heating cycle?

 

Regards

Ravinder Sharma

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