Skirt buckling
Skirt buckling
(OP)
Hello all. I've to verify a separator skirt during erection. I think I've to verify the compressed side for buckling failure. Can you help me to find in ASME code the limit stress value for cylinder under axial compression?
Thanks a lot.
Thanks a lot.





RE: Skirt buckling
prex
http://www.xcalcs.com
Online tools for structural design
RE: Skirt buckling
A couple of books describe the design and analysis of vertical vessel skirts:
1) Megyesy, E. F. 1986. "Pressure Vessel Handbook" 7th ed. Pressure Vessel Handbook Publishing Inc.: Tulsa.
2) Henry H. Bednar, P.E. "Pressure Vessel Design Handbook", Second Edition, Van Nostrand Reinhold Company Inc.115 Fifth Avenue, New York, NY
Good luck...... let us know how you make out
MJC
RE: Skirt buckling
N.Gilbert & J.R.Polani, "Stability Design Criteria for Vessels Subjected to Concurrent External Pressure & Longitudinal Pressure Loads," Trans. ASME Jnl P.V. Tech. Vol. 101 May1979, pp178-81
RE: Skirt buckling
But since you are specially concerned about the handling/erection condition there are additional issues:
1- Without the base ring (if no shop-installed) the skirt will be much more limber (and susceptible to local damage/bending) than when the vessel is operating.
2- "Pressure Vessel Design Manual" by Dennis Moss recommends that the skirt D/t not exceed 400 (2nd Edition page 172, note 9)...in part to address the limberness issue.
3- AISC (American Institute of Steel Construction) ASD manual specifies a maximum D/t ratio of 3300/Fy for hollow circular sections in axial compression or bending. This is pretty low for vessel support skirts. AWWA and other groups have published criteria for large diameter-thinwall shells based on column buckling as well as local crippling (what the AISC rule is meant to preclude). But Moss's rule is probably sufficient.
Just don't use the bottom of the skirt as a fulcrum point while tilting the vessel vertical. All bets are off then.