Proper use of round slings

[SteelAndSteel]

Hi

There are people using round slings as in the picture below. Is that a correct way to use round slings and if
not, why? . When i look in google picture i do not see cases where it is being lifted in that way, that is
why i ask.

 

[ztengguy]

That sketch is not really telling us anything. What are you getting at?

 

[SteelAndSteel]

I am getting at that the width of the round sling may be compressed at a corner which would no happen if it would be placed over a surface which is horisontal.

 

[SlideRuleEra]

When lifting heavy loads with a sling a "spreader bar" should be used to keep from putting the load in compression. The spreader bar is in compression instead, but it is designed for that purpose. Here is a typical photo:

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[DDBPE]

SlideRuleEra is absolutely correct, you would need a spreader bar.
If I were picking the frame you sketched, I would use nylon slings and "choke" the top horizontal member at each of the legs (after I checked the horizontal connection can support the weight). I would also add some type of corner protection pads to prevent the steel from cutting into the sling when the load is applied. It is also good to know where the center of gravity is, as you may need to adjust/slide your slings slightly towards each other to balance the load.
I would not use steel cables, this will damage the steel you are picking or the finish and they tend to get crimped at corners under loads. Steel is better suited for round objects or with shackles.

 

[ztengguy]

Ah, ok. Round slings are steel cables?

Yes, use some webbing or even weld on some lifting eyes and use a shackle with cables.

 

[DDBPE]

ztengguy
Round slings can be either steel or nylon. I was just adding there is a difference between steel and nylon and what could happen with steel.
Your added suggestion to weld a lifting eye is also a good method provided what you are lifting allows it.
Also, most competent crane companies have all the rigging necessary and if someone is not sure in proper rigging techniques, they should get them involved.
OSHA and State Safety Organizations have started requiring a competent rigger to rig the load in addition to the crane operator certifications.
The heavy highway construction company I used to work required anything other than routine lifting, to have engineered lifts, where one of the engineers in the company had to get involved.

 

[SteelAndSteel]

I didn't knew that round slings chould be made out of steel? if you search on round slings on google image you only see textile round slings. The method that is being used is that they put a round sling around each beam then it is being adjusted so the round slings meet above the center of mass. I don't think they use, a spreader bar.

Also if you have a long welded structure they would need two cranes if they use a spreader bar, with the method where the slings meet above the center off mass you only need one crane.

But i wonder if this may cause damage to the round slings?

 

[DDBPE]

Not to add confusion, slings, can also be made of chain.

Look at the photo from SlideRuleEra, you use a spreader bar with 1 Crane.
If you have a long structure, you may not be able to use 1 crane with a spreader, it depends on the reach and crane boom height and many other factors, that is why most safety agencies are requiring experienced riggers that know all the small things to look for. If you use two cranes, you do not need a spreader bar as each crane picks directly over the load and the sling is vertical as is the case with large structural steelor concrete beams.