Vessel and Head Weights

[rick44028]

I have been using a formula for finding the weight of a vessel, Wt.(lbs)=A(40.8)t; where A=surface area (Sq. Ft.)
t=thickness of shell in inches
40.8= density of steel (lbs/in/sq.ft.)

I have seen a reference to using 41.15 instead of 40.8

Can anyone help me refind the reference

Thanks

 

[twjag]

40.8psf/in is correct for steel.
I have never seen the 41.15psf/in used.
Possiblilties for the larger number:
1. Slightly higher wt is used for ss if you are using warehouse billing wts for ss.
2. The user has included extra for mill overtolerance.
3. If for formed heads, manufacturer may include factor based upon experience.

You are accurate if you calculate weights of components based upon actual wts & the 40.8psf/in for plates + a nominal allowance (say 5%-10%) to account for mill/part overtolerance, welds, paint, + misc small items for which it is a waste of time to add (i.e., small couplings, bolts, gaskets, etc.)

 

[prex]

Your second figure is close to what I currently adopt for austenitic stainless steels: in SI 7850 kg/m3 for carbon steel and 8000 kg/m3 for austenitic ss.
prex
motori@xcalcsREMOVE.com

http://www.xcalcs.com

Online tools for structural design

 

[Halket]

The difference is in the material. Carbon steel factors to 0.2833 lbs/in3 (40.8 lbs/ft3). Stainless steel is 0.2857 lbs/in3 (41.1408 lbs/ft3).
Weight CS: Length x width x thick x 0.2833
Weight SS: length x width x thick x 0.2857
(Above in US units)