API-650 MDMT for Stainless Steel tanks 2

[Schuppert]

How does one determine the MDMT for Appendix S tanks. I see where impacting testing is not required.

Thank you.

 

[IFRs]

MDMT is independent of the tank - it is a process and environmental condition.

 

[fegenbush]

ASME Section VIII Division 1 UHA-51(d)(1)(a) exempts impact testing for austenitic stainless steels down to -320°F. Since this temperature is only obtainable by refrigeration (-128.6°F is the lowest recorded temperature in nature) and refreigerated tanks are outside the scope of API 650 and Appendix S, impact testing is outside the scope for any tank constructed in accordance with Appendix S of API 650.

If you really need the DMT (MDMT is an ASME term), you could use -128.6°F + 15°F

 

[IFRs]

I did not deserve a star, but fegenbush really did!