4 replies to this topic

[amolbhvsr]

Why the Overpressure For Multiple Relief Device Is 16% And Why Not 10%?

[fallah]

amolbhvsr,

Because the set pressure for the last valve is to be considered at 105% of the design pressure; then 105 %*1.1= around 116 %.

[amolbhvsr]

Why the allowable accumulation is 105% of MAWP? Why not more than 5%?

[fallah]

amolbhvsr,

In the case of multiple relief devices, the maximum accumulated pressure would be 116% of the vessel's MAWP....

[Lowflo]

_{I think the question is, why is it considered safe to allow the accumulation to reach 116% when multiple valves are used. Pressure vessels are conservatively designed - they have a high safety factor. The safety risk caused by allowing the vessel to reach 116% MAWP is very small, and very tolerable.}