MAP 1

[Manfred0406]

I'm a trainee engineer and am reviewing calculations of a pressure vessel done on COMPRESS. I have 2 questions regarding MAP.
1)I've noticed that when they calculate MAP for the bottom head, the formula is : P = 2*S*E*t / (K*D + 0.2*t) - Ps. The Ps calculated is 3.43 psi. Yet in the calculations for MAP they have taken the value of Ps as 0. Please explain.
2)Secondly, when i was going through the calculations for the cylindrical shell, they have not subtracted the static head at all. The formula used is : P = S*E*t / (R + 0.60*t). Why is Ps subtracted in the formula for the the bottom & top head but not
in the cylindrical shell??

 

[Nfroh]

I checked it and found that compress does not consider a hydro head neither for shell nor for head in the calculation for MAP. IMO the reason is not existing official Code definition of MAP. If you need it for the calculation of the hydro pressure UG-99(c) than the base is “calculated test pressure” . There is no any Code connection between MAP and hydro, for some reasons unknown to me everyone uses MAP in relation to UG-99(c). Compress shows in its test pressure report the values for calculated test pressure (and calls them IMO wrongly MAPs ). As UG-99(c) requires, the value 1,3*calculated test pressure (min)–hydrohead is nevertheless properly calculated.