Lifting/Tailing Lug Design

[KLee777]

I have two tanks that I need to design lifting lugs for and two towers for which I need both lifting lugs and tailing lugs. I haven't done these before and can't seem to find any reference material for guidance. My questions might sound silly, but please bear with me--I'm new to this and want to learn!

My questions:
1) For a horizontal tank, what type of lugs are typically used (flat or ear, does it matter?) and what do I need to take into consideration when locating these lugs (CG, bending moment of the plate material, etc.) assuming I am using two cranes?

2) For a tall tower comprised of a large cylinder joined to a smaller cylinder by a conical section, how would I go about checking that the tower will not bend when I first pick it up horizontally and then rotate it into the vertical position?

3) What books/reference materials would you recommend?

One note, I only have access to Coade's CodeCalc program to do this, which, as I see it, has limited capability for analyzing the forces on the lug at different crane angles. Maybe I'm missing something.

Thanks in advance.

 

[jte]

KLee777-

Take a look at thread794-104359, thread794-103507, thread794-87971, thread292-86860, thread794-75810, thread404-10292, and the several others which come up when you do a search on this site for "lifting lug."

As for your questions:
1) Usually no lugs. Unusually large vessels should be evaluated for adding rings at the saddle. Normally just use a spreader bar and a couple of straps at the saddles. If the loads during the lift are substantially different than at operating, you should check the bending stress. Otherwise, the bending stress should have been checked early in the vessel design in order to place the saddles.
2) Calc the bending and longitudinal stresses at every angle from 0° to 90° in 5° increments. Add or subtract the stresses to get a max. Compare with the allowable longitudinal compressive stress and the allowable tensile as applicable. Handle the various diameters as you would any other beam with a variable cross section and thus section modulus.
3) Read lots o' books, but equally importantly, don't sign your name to the calc's. You don't have the experience to do so without mentoring. A failed lift can have huge implications. You'll get book recommendations from the previously mentioned threads.

jt