When can pressure due to static head be ignored - sec VIII

[arvi]

When designing any pr. vessel we consider additional pressure due to static head which is a normal practice in design and also a requirement by the CODE. However sometimes, if the static head is low it is ignored by few designers. Does anyone know what the criteria or thumb rule can be used when this can be ignored. Any references?

Thanks a lot in advance for your responses and thoughts.

Arvi

 

[SnTMan]

arvi, in the shell & tube world, static head is routinely ignored for all but the largest horizontal units and routinely applied to even the smallest vertical units. Doesn't exactly make sense, but there it is.

I don't know any definitive answer. It should probably be considered if more than a few psi.

Regards,

Mike

 

[JoeTank]

Ignoring the staic head is not permitted by ASME, even though it may make no differnce in the result. If you always include it (however trivial it may be) you never have worry about this issue. Just do it.

Joe Tank

 

[SnTMan]

JoeTank's right, just do it.

Regards,

Mike

 

[arvi]

Thanks Mike and Joe for your input. I am reviewing design of another company, not doing design myself. If I was doing it I would always consider it and if I decide to ignore, I will add my reasoning for ignoring it.

But when you are commenting on someone's design you have to be more careful. This is for a vertical type of Heat exchanger. In most of the cases this company considers static head but for this case the pr due to static head is only 1 psi so they have not considered. They have not even provided any justification for ignoring it.

I was trying to find if there is any rule of thumb industry follows.

Thanks a lot