316L Service Temperature.

[22west]

What is the allowable service temperature for 316L?

B31.3 allows up to 1500F for custom flanges.
B16.5 allows only up to 850F for standard flanges.

This doesn't make sense because, theoretically I could have a flange custom made to standard dimensions and put it into service for 1500F.

Any help would be appreciated.

 

[metengr]

ASME B16.5 provides a maximum temperature limitation for 316L ss (in Table 2-2.3) because of the lower carbon content in comparison to 316 ss (review Table 2-2.2). Carbon content has a direct impact on creep and creep rupture properties for austenitic stainless steels. This is the reason for the temperature restriction. You don't want the lower carbon 316L ss flange to exhibit stress relaxation from local creep deformation in service.

 

[metengr]

As a side note, many ASME Codes and Standards committees are really independent bodies of various subject matter experts who focus on assuring a safe and technically acceptable standard. In many cases, you will see obvious similarities and subtle or significant differences between Standards that one may think should overlap. Not the case. Factors such as external exposure, personnel safety, process application all must be factored by each committee assigned to development of a particular standard.

 

[EdStainless]

The ASME B&PVC has allowed stresses listed (VIII) up to 1500F for 316 and up to 850F for 316L. The difference is related to the creap resistance.
As a side note: almost all 316L made today meets the strength requirements for 316. And since 316 has no minimum C level this modern 'higher strength' 316L can be certified as 316 straight grade. Will it have the same creap strength? I think not. It is important to make sure that you understand all of those little notes in the B&PVC when you select allowed stress values, especially G5.

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