Environmental modification factor fe in fatigue analysis

[Biss73]

Hi,
I am doing a fatigue analysis and I was having questions regarding the environmental modification factor fe (as per ASME Section VIII, div 2, art 3.F.2.2.c). Note that this vessel is div 1, so I don’t have a user's design specification from the client specifying this factor.

The code says "A value of fe= 4.0 shall be used unless there is specific information to justify an alternate value based on the severity of the material/environmental interaction."

Does anyone know how and based on what this value can be changed? Is there some guidelines to define this factor?

Thanks,
Biss

 

[TGS4]

Right now, no, there is nothing that can be done to assist you. However, there is an item working its way through the ASME Code Committees to address this issue.

What is your "environment"? Are you in a high-cycle regime or low-cycle? Is there the potential for stress corrosion cracking? How about hydrogen-induced cracking? At the location of interest, can there be a passivation layer? Could such a passivation layer be eroded by the flow?