4 replies to this topic

[jawbkk]

Hello All,

 

I have a load on a pressure vessel of 3000N from the internal trays.

 

How do I convert this to a longitudinal stress due to the trays?

 

I can't seem to find any formula's only for pressure such as PD/4t

 

The pressure within the vessel is 9 bar.

 

Regards

 

John

[kkala]

This is a deadweight stress (compressive), usually considered as equally distributed on peripheral vessel thickness (excluding corrosion allowance). Not only trays, but also metal vessel weight and any insulation should be taken into account. So dead weight stress (compressive) would be σ=W/[π(D+t)t], W=dead weight (*), D=diameter, t=thickness of vessel, concerning vertical cylindrical vessels.

See Coulson and Richardson's "Chemical Engineering Vol 6", mainly example 13.3 in Chapter 13 "Mechanical Design of Process Equipment". This can be helpful for your whole task too.

 

(*) I think liquid hold up of trays (not a pressure load) should be also considered.

[Bobby Strain]

I never heard of such an exercise.

 

Bobby

[kkala]

Mentioned example 13.3* (post no 2) calculates  "dead weight stress" in a distillation column.

3000 N will cause a rather insignificant stress, but it may not be so when all weight loads are considered.

 

* in para 13.8, design of vessels subject to combined loading

Edited by kkala, 09 March 2013 - 12:49 PM.

[jawbkk]

Many thanks kkala.