Allowable Shear Stress per ASME B31.3 302.3.1(b)

[beh188]

ASME B31.3 302.3.1(b)defines the allowable shear stress to be 0.80 times the allowable tensile stress value. For austenitc stainless steel I normally would use a more conservative factor of 0.60. Am I being too conservative here? Is 0.80 OK for stainless?

Thanks.

 

[Duwe6]

If it didn't have a historical record of working well, that bigger derate would be documented in B31.3. There is an unbelieveable ammount of operating history that has provided input into the necessary design requirements for all ASME Codes.

Unlike the d@mnable government regulations, ASME revisits all their rulings and adjusts them based on operating history of thousands of plants. Look at the drop in Safety Margin that ASME took in 1999 -- went from 4X to 3.5X, based on excellent operating history of European vessels and boilers built to 3.5X!! That was a *massive* change! And it was fully justified, massively discussed & debated, and done in an informed and deliberate manner. Everything in ASME can be fully trusted. Only get nervous when using unlisted materials or configurations.