how would i calculate the capacity for a piece of equipment which has a MOP of 800# and it's MAWP is 110% of that - 880#. the relief valve is set for 850#.
from API 520, the total relieving pressure equals set pressure + 10% of set pressure + atmospheric, then obviously it would exceed the MAWP (850+85+~15=950 > 850). my question: is the relieving pressure now limited to the MAWP (850) & consequently, the overpressure term is ~1.7% instead of 10%? or are you allowed to determine capacity at 110% of setpressure (i.e. 950#) even though the reliving pressure term is greater than the MAWP of that equipment?
from API 520, the total relieving pressure equals set pressure + 10% of set pressure + atmospheric, then obviously it would exceed the MAWP (850+85+~15=950 > 850). my question: is the relieving pressure now limited to the MAWP (850) & consequently, the overpressure term is ~1.7% instead of 10%? or are you allowed to determine capacity at 110% of setpressure (i.e. 950#) even though the reliving pressure term is greater than the MAWP of that equipment?