MAWP Listed in COMPRESS Table

[Keens5]

I am reviewing a vertical vessel that I recently designed with leg supports. The legs are wide flange beams. There is a MAWP listed in the pressure table, for the legs. I have reviewed the leg support calculations, and they do not use the MAWP or design pressure. I am a little confused as to why the vessel MAWP would be listed for the support legs, when they are not a pressure containing part. I am using the latest version of COMPRESS. Thanks for your help

Keens5

 

[SnTMan]

Keens5, is there an anakysis of the leg attachemnt to the shell? Your answer may lie there.

Regards,

Mike

 

[Keens5]

SnTMan,

Thanks for the response. I think I see where you are going, but do not see how the MAWP would come into play if we are not dealing with any pressure containing components. The attachment to the shell should be a weld strength calculation. This is what I am thinking. Thanks.....

Keens5

 

[TomBarsh]

What about stresses in the shell due to the loads the leg is putting into the shell (or vice versa)? How are those calculated?

 

[Keens5]

Tom,

The stresses in the shell are based off the design temperature, correct? I am thinking that the material stress of the shell material, that would be used to check the loads form the lags against, is based off the design temperature and not the MAWP. I went back through all the calcs and did not see anything with pressure. Thanks...

Keens5

 

[SnTMan]

Keens5, the way these things usually work is, whatever stresses are imposed due to external loadings subtracts from the allowable available to resist pressure. An external load therefore could produce a lower MAWP in a shell section than if the load were absent.

Regards,

Mike

 

[jte]

Keens-

Welcome to Eng-Tips!

Though you are getting good responses from two well known contributors in this thread, next time I'd suggest you post to either:
forum1259
or
forum794


You'll get a more focused audience at those forums as opposed to this "other topics" area.

 

[chicopee]

I see this post another way, depending on the diameter of the shell and the MAWP of the pressure vessel, thicker wall thickness for shell and heads may make these PV's lighter or heavier and thereby thinner or thicker legs to support vessel would be required.