SA516-70 Properties over 750 deg F
SA516-70 Properties over 750 deg F
(OP)
I am designing a knock out drum that has low internal pressure (64psi), but the internal design temperature is 775 deg F. My concern is for the repads that are required for nozzles to satisfy my replacement area. How will the repads be affected by the material properties of 516-70 at this temperature?
cj
cj





RE: SA516-70 Properties over 750 deg F
RE: SA516-70 Properties over 750 deg F
RE: SA516-70 Properties over 750 deg F
RE: SA516-70 Properties over 750 deg F
Assuming ASME VIII Div. 1 here... As TGS pointed out, at 775°F you're in creep. I would expect that you have a bit of margin on your design temp vs operating temp, so chances are that the vessel will be operating out of the creep range or just barely in it. Either way, the allowable stresses already account for creep. They are governed by it - that's why the numbers are in italics in II-D.
jt
RE: SA516-70 Properties over 750 deg F
At a continuous operating temperature of 775F, you are at the threshold of a phenomena called "graphitization". This limit affects the usage of carbon steel materials.
The ASME BPV & Piping codes have for many years warned about the long term degradation of carbon steels at this temperature limit.
I do not believe that you should worry about only creep as graphitization is a much more well known threat to your material
-MJC
RE: SA516-70 Properties over 750 deg F
See:
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-MJC
RE: SA516-70 Properties over 750 deg F