Does anyone have a copy of ASME VIII to hand?

I'm trying to confirm the adequacy of some burst discs fitted to vessels with a design pressure of 0.3 Barg.

API 520 helpfully includes a chart (taken from ASME 8), which shows that the max allowable accumulated pressure for fire exposure is 121% of the design pressure for vessels who's design pressure of 30 psig or above.

I need to find out the max allowable accumulated pressure for fire exposure, when the design pressure is only 0.3 barg. Can anyone help?

Best regards
Ian

Both sections AR-150 and UG-125 of ASME VIII just mention that for fire relief, pressure shall not rise more than 21% above the maximum allowable working pressure. This while for other reliefs they state that the device shall prevent the pressure from rising more than 10% or 3 psi, whichever is greater, above the MAWP.

Since in your case 21% of the MAWP of 2 psig is only 0.42 psig, I would use 3 psig instead. Reasoning is that in UG-125 it is stated that the base rule is "10% or 3 psi, whichever is greater", but that you are permitted to use 21% for fire case. In your case I would use the base rule.

Note that I am an engineer and not a lawyer...

Ian,
Typically a tank designed for such a low pressure would not be built to comply with ASME VIII. Build the tank to API Standards 620 or 650. It is not practical to design a large storage tank to withstand even 3 psig, and so they are not built to this standard.
Doug