B31.3 Occasional Load Factor For Elevated Temperature Fluid Service

[rhino27]

I am trying to calculate what occasional load factor that I need to use for elevated temperature fluid service. B31.3 para 302.3.6 states that the occasional load factor as an alternative to using 1.33 times the basic allowable stress may be taken as the "strength reduction factor" multiplied by 90% of the yield strength at temperature. What is the "strength reduction factor" and where can I find it. The only other places that I find "strength reduction factor" mentioned in the code is for the weld strength reduction factor. Please help. I am dealing with 1550F pipe and want to make sure that I am correctly calculating the factor.

 

[JohnGP]

You don't mention the material you are dealing with, but further in B31.3 para 3.2.6 it states that-

The strength reduction factor represents the reduction in yield strength with long-term exposure of the material to elevated temperatures and, in the absence of more applicable data, shall be taken as 1.0 for austenitic stainless steel and 0.8 for other materials.