Alternativeof external pressure calculation (external pressure dumped up to calculated pressue?!)

[SuhyunOh]

Hi, PV Gurus,

My pressure vessel manufacturer calculated thickness based on;
Calculated Pressure by adding up External Pressure and etc. to Internal Pressure
Did only internal pressure calculation (UG-27, AS1210 Cl. 3.7.3), without separate external pressure calculation (UG-28, AS1210 Cl.3.9) practice.

For example;
Internal Design Pressure 0.9 MPa
External Desgn Pressure 0.1 MPa (double skinned vessel, vacuum insulation)
The manufacture used Calculated Pressure as 1.xx MPa, adding up external pressure and static, etc. to internal design pressure.


Is this practice allowed?

Please note that they are designing according to AS 1210 and ASME VIII Sec.VIII. Hazard class is 1S according to AS 1210.
They are using their own calculation excel spreadsheet, not Compress nor PVElliot.

Thank you.

 

[prex]

If I understand you correctly, that's correct, the vacuum is from outside the vessel wall, so it adds up to the internal pressure. But you should also have a calculation for the outer wall of the interspace.

prex
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