shell stresses in a carbon steel stack from sling loads while lifting
shell stresses in a carbon steel stack from sling loads while lifting
(OP)
We fabricated a 65ft long, 12ft diameter carbon steel stack, lined it with 4in of refractory and now we have to lift it onto the trailer for shipment to the customer. The current plan is to have a sling at each end in a basket configuration. The problem I have is that I don't know if the shell can handle the stresses from the slings. The worst case scenario is the shell delfecting significantly and the refractory cracking. I'm struggling to find a resource that addresses the stresses in the shell of a stack (or tank) due to sling loads. Any guidance or a resource other than FEA would help! Thank you





RE: shell stresses in a carbon steel stack from sling loads while lifting
I would be concerned about any deflection potentially causing cracking in the lining. For lifting onto transport, multiple cranes could be used, but the bigger problem will be at site when it has to be lifted into a vertical position.
RE: shell stresses in a carbon steel stack from sling loads while lifting
Since the ultimate tensile and compressive strenghts of the refractory are in the range of 300 to 550psi, I'm assuming that the refractory offers no additional strength to the steel itself.
RE: shell stresses in a carbon steel stack from sling loads while lifting
RE: shell stresses in a carbon steel stack from sling loads while lifting
1 - You designed something cumbersome without keeping in mind handling and lifting in your workshop ?? What about vibrations and shocks during transport ?? Whose responsibility is it ??
2 - on site You say that is their responsibility handling and lifting : they can't go to the moon with the bicycle You gave them !! If You deliver the stack horizontal how can they lift it in vertical position ??? You should inform them how to do and give them the lifting points !!
RE: shell stresses in a carbon steel stack from sling loads while lifting
RE: shell stresses in a carbon steel stack from sling loads while lifting
RE: shell stresses in a carbon steel stack from sling loads while lifting
A simple search found a bunch of YouTube videos about erecting stacks.
All of them seemed to have an external reinforcing ring of some sort at the lifting points.
One of the larger ones had a polygonal ring around it just above the midpoint with two trunnions extending radially out. It was lifted and rotated from horizontal to vertical with a single spreader that was a little longer than the stack diameter, and a single rope from each end of the spreader to each of the trunnions. I don't know whether the trunnions were permanent or not.
All of the stacks shown lying on the ground or on a truck were supported by U-shaped saddles, clearly custom bits, and not allowed to just lie on the ground or the truck bed.
Does your stack have _any_ external reinforcement, e.g. for attaching guy wires, or for tying it down to a truck bed without distortion?
Mike Halloran
Pembroke Pines, FL, USA
RE: shell stresses in a carbon steel stack from sling loads while lifting
RE: shell stresses in a carbon steel stack from sling loads while lifting