P91 2

[hvymet]

Folks:

Can anyone tell me how to get a copy of code case 2179-3? I'm trying to get information on P91 use in piping bends.

 

[metengr]

http://www.asme.org/

 

[stanweld]

The Code Case is now 2179-4 and pertains to P92 alloy steel. It has incorporated the Section I, Section VIII requirements regarding PWHT for P91 (P-5B, Group 2).
It does not provide heat treating parameters for bends. SA-234 WP91 provides N&T requirements for P91. ASME B31.1 only requires that bends be heat treated (Annealed, N&T or Tempered per the Engineer). ASME SEction I does not address heat treatment of induction bends.

While I would advise the use of SA-234 WP91 to be used to specify N&T requirements for induction bends, I would add a minimum hardness requirement of 200 BHN as well as the maximum specified.

 

[metengr]

Actually, the Code Case is 2179-5, which was approved effective April, 2006. The reason for this revision is that the allowable stress values appeared to deviate between Tube/Pipe and Forged Pipe product forms. This was rushed through our committee to handle the allowable stress differences.