UG-125(g)(1) "External"

[JSPCGY]

Please explain the meaning of Word " the source of pressure is external"

Please provide examples.

Thank you for your help.

 

[JohnGP]

The source of pressure for a vessel can be external when, for example, it is being charged with air from an air compressor, or being filled by a pump. As opposed to the source of pressure being internal, due to a chemical reaction.

Cheers,
John

 

[vesselfab]

or an external jacket or a pump pumping it down or condensation during steam out

 

[JohnGP]

Agreed all those sort of things can lead to the vessel experiencing external pressure, but the clause referenced is related to whether the external source of pressure is under positive control such that MAWP cannot be exceeded.

 

[vesselfab]

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on give us a hint
does it really say that?

 

[lizking]

JohnGP is correct. This clause is not referring to vacuum conditions.