Gray Cast Iron A126B Maximum Allowable Stress

[jolivers]

Hi everyone,

Where can I find the maximum allowable stress values of A126B in order to justify the desing calculation of valve body wall thickness and flange thickness?
According to ASME B16.1 this is the cast iron which has to be used for flange fitting but, on the other hand, there is no mention of it neither in ASME VIII Div. 1 Table UCI-23 nor in ASME II Part D.

Thanks in advance.

 

[EnergyMix]

Maybe you're not finding in ASME VIII or ASME II because people don't make pressure vessels out of grey cast iron.

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[jolivers]

Main manufacturers of safety valves have gray cast iron variants. Most of them are using the material 0.6025/GG-25 which is A126 Class B, the same one that appears in ASME B16.1 for flange fittings. For that reason, I was wondering where I can find its stress values in ASME VIII or ASME II.

Thanks!

 

[metengr]

Stress lines for material for use in any of the ASME Boiler and Pressure Vessel Code book sections would appear only in BPV II, Part D. With that being said, if the material above does not have published stress lines in BPV II, Part D, or is not approved by Code Case it is not permitted for use.

ASME Piping Code and ASME Reference Standards have their own standards committee's and can do as they please. For the example you cited, ASME B16.1 determines acceptable materials and provides pressure temperature ratings. However, there are no stress lines because the design of these standard components is proven by either FEM or burst testing by a vendor.