Hi all,
I am working on a steam system using ASME 31.1-2007. Using Caesar II 5.10.
The Pipe material is A335 P91. The temperature is 550 C (1022 F). At this temperature the allowable stress values are as follows.
Sc = 16753.9 N/sq.cm
Sh = 10540.5 N/sq.cm
As per code equation for allowable stress range Sa = f ( 1.25Sc + 0.25Sh ), the value should be Sa = 23577.5 N/sq.cm. But Caesar calculates the value as 19871.6 N/sq.cm. Please be informed that I am not using 'Liberal allowable stress' option in my file.
I also calculated the Sa value using material A335 P22 and the manually calculated Sa value matches with value calculated by Caesar. Also this calculation matches if I use the Code B31.3 in Caesar. So there is no problem with my Caesar file or configuration setup.
So why Caesar is calculating the Allowable stress range value different than the code equation, only for material A335 P91 if Code B31.1 is followed. Is there any specific clause or note mentioned in ASME 31.1 for calculating the allowable stress range for this particular material A335 P91??
Please reply
Thanks and regards.
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Zahid