MAWP & Static Pressure

[sbush]

Regarding pressure vessels intended to be designed per ASME Code Section VIII, Division 1, I have seen calculations produced by various fabricators that included static pressure and some that do not. Which is correct?

S. Bush

http://www.water-eg.com

 

[metengr]

The answer to this question depends on a designer or fabricators understanding of Part UG-22 "Loadings" in ASME Section VIII, Div 1. If you carefully read thru this section, paragraph (b) sums it up. This paragraph requires a designer to take into account the weight of the vessel and contents including additional pressure from static head.
In some cases, the loadings of UG-22 could be negligible in comparison to internal pressure.


The part on determining minimum wall thickness under internal pressure (UG-27) also requires the designer to take into account loadings from UG-22.

 

[JoeTank]

ASME VIII requires that the static head be added to the MAWP for the design of each component. The design pressure used for each component is the max pressure on the component. When static head is involved, it will be the presuure at the lowest point of the part. As noted by metengr, the contribution of static head is often small for vessels designed for high pressure.

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com