Pressure Vessel Wall Thickness

[Northeastengineer]

Hi,
Looking for some advise in relation to pressure vessels. As in I have been asked to estimate the weight of a vessel during a concept study. I have the ID, length and material (CS). When I complete the calculation( ref

http://www.engineersedge.com/calculators/

shell_internal_pres_pop.htm) to determine wall thickness the value is extremely small, which will give result in the estimate being much lighter than actual weight.
Any advise would be appreciated.
Regards,
NEE

 

[scsheorayan]

Hi,
How did you get the thickness ? What Pressure Vessel Code have you followed. Need to get correct material thickness for the pressure and material of the vessel. / Cheers

 

[JStephen]

If the vessel is small and/or the pressure is low, the calculated thickness may be very small. In that case, the ASME code specifies a minimum thickness, and fabricators may use a larger thickness still just to be able to work with it.

The design pressure is taken as the pressure at the top of the vessel, and if it is filled with liquid, the pressure at the bottom will be somewhat greater.
With low-pressure applications, it is not uncommon to specify a pressure higher than what is needed.
It is common, but not required, to specify a corrosion allowance as well.
If it is supported on saddles, stresses due to the saddles may mandate increased thickness.
If it is subject to partial or complete vacuum, that may control the thickness.

Assuming low pressure (say 20 or 30 psi or something like that), figure that if it is 24" or less in diameter, use standard-weight pipe, and if it is larger than that, use 3/8" minimum. You won't be able to get too close until the design is finalized.

 

[chicopee]

If it is an ASME/NB tank with a NB number, get a copy of the manufacturer's data sheet for the thicknesses of the shell and heads. I would not be surprised if API has equivalent reports on API pressure vessels.