Basis for establishing allowable stress values

[chalovadrio]

According to ASME VIII div 1 (1983) allowable stress values are calculated considering the lower of room-temperature tensile strength divided by 4 and yield strength at temperature divided by 1.5.
I have to validate some heat exchangers built in 1974 and designed according to ASME VIII div 1 (1971). I wonder should in 1971 criteria for allowable stress was the same.

 

[mk3223]

The ASME definition of the allowable stress are the same for the 1971 and 1983 Codes. You may compare the actual values of the material allowable stresses as published from ASME Codes.

 

[Soft2008]

I understand "validate" means you are about to rerate the exchanger. Of course ASME Sec VIII (allowable stresses from ASME Sec. II) Edition 1971 and 1983 should have the allowable stress of same because the factor of safety(FOS=4) remain same over these period. And since the subjected exchanger is prior to 1999 addendum and using the FOS 4, Test Pressure shall be 1.5 MAWP × (Stest temp/Sdesign temp)

More related info can be found from API 510 Clause 8.2 (Pressure Vessel Inspection Code: In-service Inspection, Rating, Repair, and Alteration).

 

[EdStainless]

The code allowable are based on the minimum specified properties, not actuals.

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P.E. Metallurgy, Plymouth Tube

 

[chalovadrio]

The point is that I have one non-ASME material for plates (BS-1501-26A). I need to calculate allowable stress from tensile and yield strengths according to ASME 1971 criteria (Su and Sy are available). If allowable stress for old and new design condition remains unchanged we could rerate the exchanger without any modification. This is the reason why I must confirm the criteria. I found a report stating that allowable stress values should be calculated considering the lower of room-temperature tensile strength divided by 4 and 5/8 of yield strength at temperature (instead of 2/3). I don't know where this criteria is coming from.

 

[CuMo]

Have you been through the mandatory appendices of ASME II Part D?