I need help with a lifting ring calc/research

[longude17]

Hi everyone, I have just started a new job as an entry level mech eng working with steam turbines and steam compressors. Today I was asked to verify a proposed design for a two-pieced lifting collar / ring.

I have no clue on where to begin to analyze this and see if it will with stand the 7000lb that it will be lifting...so any help on how you would do the calcs would be greatly appreciated

ok heres the jist of it....it is a two piece collared lifting ring that will be placed around a machined notch on the rotor shaft. (picture a circular donut 1 in thick, 6 inches o.d.) the two pieces when placed around the shaft will be bolted together using a drilled and tapped 1/2 inch hex head bolt....90 degrees to the bolts is two bolted on swivel lifting trunions where the lifting rigging will attach.

I know the fail points will be either at the lifting trunions, or the bolts, prob is its been so long I dont know how to do the calcs for this.

how would you do the calcs to see if this thing is safe to use?

I will attach pics and a shop drawing if needed.

Thanks again

 

[unclesyd]

One point no one has made is Thai device comes under the heading of an "under hook lifting device" as define by OSHA. I don't have the new rules but under the old ANSI regulation it does and requires a proof test.

Could you use basket rope sling?

Also you may want to use a standard SHCS form someone like Unbrako or Hollowchrome. These SHCS will given you little more strength compared with Grade 8

You might want to use a standard SHCS from someone like Unbrako or Hollowc hrome.

 

[desertfox]

Hi longude17

I have assumed the angle of the bolts is at 15 deg off from the lifting hooks and that the lifting hooks are in the horizontal plane during the lift. (see file uploaded)
The way I see it all the load is virtually taken on one joining bolt as the other side of the split ring will try to act as a pivot,the bolt there will take very little load.
I have assumed the ring is rigid and the weak link is the joining bolts.
Finally I haven't calculated the resultant force which should be the tensile combined with the 452.9lbf shear force.

 

[chicopee]

I have taken a stab at your problem and it appears that the bolts holding the two split pieces together should be satisfactory.
If I understood your comments properly the bolts did not hold. You did not explain what happened and I am speculating that the failure could be thread engagement. The bolt material has higher strength than the collar material and possibly there was not enough engagement into the collar material.
The swivel hoist rings appear to be a Crosby product and you should be able to search for their ratings on line. I did not work out any analysis as they do not seem to be a problem.
Nonetheless I worked out an analysis for thread engagement, tensile and shear loads and stresses on the Allen screws. Refer to the JPEG attachment.