Hi All,

I have a query. In Internal pressure calculations for shell/head/cone, Maximum Allowable Pressure, New and Cold [MAPNC] is calculated for each element.

At the same time, when we perform nozzle calculations by Selecting "Consider MAPnc" of Nozzle Design Options in Load Cases, MAPNC considered is less than the value calculated in INTERNAL PRESSURE CALCULATIONS.

Can anyone explain what is the reason behind it ?

Regards

Hello Mech Engg

First of all, you should set the "Nozzle/Clip Design Pressure Options" on the "Load Cases" tab to: "4. MAWP + Static Head to the Nozzle". This will in the first instance ensure that the nozzle reinforcement does not limit the MAWP of the main components of the vessel.

Now, if you have set PV Elite to "Consider MAPnc", PV Elite will do two calculation for the reinforcement. If the nozzle MAPnc is insufficient, you will get a warning. Consider this example from a sample PV Elite calculation:


INPUT VALUES, Nozzle Description: N1 From : 10

Pressure for Reinforcement Calculations P 328.677 psig
Temperature for Internal Pressure Temp 100 F
Maximum Allowable Pressure New & Cold 411.52 psig

Did you notice that moth the MAWP (329.677 psi) and the MAPnc (411.52 psi) are mentioned. You also get another column in the reinforcement table like this:


Results of Nozzle Reinforcement Area Calculations:
AREA AVAILABLE, A1 to A5 MAWP External Mapnc
Area Required Ar 1.498 NA 1.839 in²
Area in Shell A1 0.000 NA 0.000 in²
Area in Nozzle Wall A2 0.334 NA 0.483 in²
Area in Inward Nozzle A3 0.000 NA 0.000 in²
Area in Welds A41+A42+A43 0.169 NA 0.183 in²
Area in Element A5 1.266 NA 1.266 in²
TOTAL AREA AVAILABLE Atot 1.769 NA 1.932 in²

The MAP(nc) Case Governs the Analysis.

You are given a third column for the MAPnc. You are also told in this case that the MAPnc governs.