Dual Design Temperature for Low Alloy Steel SA-204 Gr. A

[r0nciS]

Hi everyone,

I just wanted to know if it is really possible to design a pressure vessel to have dual design temperature.

As we know, almost, if not all, low alloy steel or carbon steel is only capable of handling design temperature of up to 537 deg C (1000 deg F). but in full vacuum condition, the allowable design temperature is only limited up to 480 deg C so Process wanted to have it dual design (internal to design at 537 deg C and external (full vacuum) to design at 480 deg C).

Is it really acceptable based on the governing Codes and Standards?.If not, should I recommend a high alloy metal or a stainless steel as material of construction for design temperature of 537 deg C.

Hope for your quick response. Thank you.

 

[fegenbush]

It is certainly possible, but you must consider startup and shutdown conditions since it is not possible for the vessel to instantaneously transition from one state to another.