MortenA, what I meant by reducing the "vessel wall temperature rise" was that the rate of increase of the vessel wall's temperature will be reduced if credit for insulation is take. This doesn't mean that the vessel won't reach its structural failure temperature, it'll just take more time (both...
joeycranston, After re-reading the thread, I think I understand your original question a little better. You asked why, according to API 521 ,external insulation can be considered an alternate means of protection for unwetted vessels, but not for wetted vessels.
The way I read API 521 (the...
joeycranston
My first time posting as well.
For PSV sizing, taking credit for insulation (assuming the API requirements are met), would only reduce the heat input rate (Q) from fire (lowering the F factor in the equation), reducing the relief flow rate if vaporization occurs. For a vessel...
