TIME DEPENDENT PROPERTIES -EXAMPLE SA 240 316
TIME DEPENDENT PROPERTIES -EXAMPLE SA 240 316
(OP)
The note no T8 of Table 1A of ASME II Part D mentions "Allowable stresses for temperatures of 750F and above are values obtained from time dependent properties". How this will affect the vessel design?





RE: TIME DEPENDENT PROPERTIES -EXAMPLE SA 240 316
RE: TIME DEPENDENT PROPERTIES -EXAMPLE SA 240 316
brkmech1234 - It means that that allowable based on the lower of:
What this means from a design perspective is, in my opinion, the following:
a) Not much - vessels are designed in the creep regime all the time without much difficulty. However, the life will be limited, depending on the OPERATING stress levels and OPERATING temperature.
b) A fatigue analysis to ASME Section VIII, Division 2, Part 5 is not permitted, as the current rules are explicitly in the non-creep regime. If you will be cycling pressure or temperature or both, then I would recommend that you contact someone with creep-fatigue evaluation experience.
c) Evaluation of nozzle loads may or may not be more complicated. If you stick with WRC 537 (previously WRC 107), and the allowable stresses then, based on my experience, you'll be fine.
RE: TIME DEPENDENT PROPERTIES -EXAMPLE SA 240 316