required chain grade for overhead suspension

T

Tim Duffin

Armchair Instigator
Mar 3, 2011
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0
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CA
Hi there,

I was just curious if anyone has had issues with using grade 70 alloy chain to attach to ceiling beams for line array suspension. This is to extend the chain motor chain to a very high ceiling (50ft) and will be oversized compared to the links on the chain motors. I know that grade 80/100 is required for "overhead" suspension, but flying a line array is not exactly what that type of chain was created for. Plus its tremendously expensive and its weight rating is total overkill for most hangs.

Has anyone had issues with inspections/comments about the type of chain used? Been questioned about the chain used on a hang?

Thanks.
 
Re: required chain grade for overhead suspension

50 feet isn't really that high, standard motor chains should be more than long enough to get there. Since it seems your motors have nonstandard chains, you should really use steel to extend their reach. Steel is lighter than chain, and is the "industry standard" way to extend the reach of a motor. With that whole "if you have to ask..." thing on the table, please consult a rigger in your area for assistance.
 
Re: required chain grade for overhead suspension

Brandon G Romanowski said:
most industrial motors have short chains, its really only the concert production motors that have 80' of chain on them.
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But this is concert production not industry...

Tim, as you know, grade 70 is not rated for overhead lifting. If something were to happen you would be in deep shit as would anyone who told you over an internet forum that it is okay to misuse it. Rules in rigging are not meant to be broken, they are meant to be followed to the letter. You can use properly rated and terminated aircraft cable for suspending the motors. That will be a boatload cheaper than grade 80 chain and it will actually be a safe/approved use if done properly. That said, if you have to ask, you should be consulting a qualified local rigger.
 
Re: required chain grade for overhead suspension

Tim,

Whenever I have seen this done it was with steel, as Matt suggests. If you want to do it with chain and grade 80 is what is required, then that is what you need to get. I am not a rigger, but I have seen a few at work.
 
Re: required chain grade for overhead suspension

Hello,

As someone pointed out...if you have to ask in regards to rigging....you'd best HIRE a rigger.

If a chain motor's chain is too short...get longer chain (to it's spec'd length limit, and approved by the chain motor manufacturer), or within easy reach.....add a piece of rigging steel on the down end (easier for the riggers to handle).

Use only the type of chain motors designed for the entertainment industry.

Use only rated pear-rings, d-rings, shackles (clevises to some), wire rope, and well maintained spansets. Use steel safeties and burlap where necessary.

A rigger will know these things above and have proper rigging gear...harness, fall arrest, ropes, shivs (sheaves) etc...

Hire a rigger, get proper rigging gear, rig the hangs properly.... and everybody goes home a bit safer.

Hammer

ps. gotta be a big gauge of chain to get a shackle through
 
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Re: required chain grade for overhead suspension

Matt Young said:
50 feet isn't really that high, standard motor chains should be more than long enough to get there. Since it seems your motors have nonstandard chains, you should really use steel to extend their reach. Steel is lighter than chain, and is the "industry standard" way to extend the reach of a motor. With that whole "if you have to ask..." thing on the table, please consult a rigger in your area for assistance.
Click to expand...

+1

Hammer
 
Re: required chain grade for overhead suspension

Brandon G Romanowski said:
Are industrial CM's grade 70 chain ?
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AFAIK industrial rigging would be subject to the same overhead lifting rules as concert production would be. In fact, OSHA might even be more demanding in the industrial market. Most entertainment rigging gear originated with industry anyway.

I just purchased a length of grade 100 chain for a project, and after shopping around, I found it was cheaper than the grade 80. So what if it's expensive; I know it's not going to break and kill someone...a couple extra bucks is worth it.
 
Re: required chain grade for overhead suspension

Thanks guys. I actually like chain better than wire rope, it feels safer to me. I don't know if anyone has ever seen a steel cable snap, but its a lot more violent than a chain breaking.

For the record, the lead rigger didn't know the answer to the question.
 
Re: required chain grade for overhead suspension

Tim Duffin said:
Thanks guys. I actually like chain better than wire rope, it feels safer to me. I don't know if anyone has ever seen a steel cable snap, but its a lot more violent than a chain breaking.
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Except that you generally see it coming as individual strands will fail unless tremendous force is present.
Stress cracks in chain are almost impossible to find without magnification.

How do you plan to attach the chains to each other?
(hint, shackles are not the answer)
 
Re: required chain grade for overhead suspension

Milt Hathaway said:
I hope you didn't plan on wrapping that chain around a beam.
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I was going to use spansets with pads and shackle connection. Then I was going to cut the chain onsite to proper length and attach chain hoist chain to extension chain. It will be a single point pull.

BTW, this is not a union job and I am not the A1 at the convention center anymore, I'm not in a position to question the rigger. If he signs off on it, its signed off. I don't anticipate anyone doing anything dangerous.
 
Re: required chain grade for overhead suspension

Tim Duffin said:
I was going to use spansets with pads and shackle connection. Then I was going to cut the chain onsite to proper length and attach chain hoist chain to extension chain. It will be a single point pull.

BTW, this is not a union job and I am not the A1 at the convention center anymore, I'm not in a position to question the rigger. If he signs off on it, its signed off. I don't anticipate anyone doing anything dangerous.
Click to expand...

The point of attachment should be 3/8" wire rope sling for loads up to 2,000#; 1/2" wire rope for 2 ton points, probably a "basket" or "split basket" if the beam is particularly large. You should NEVER use a polyester round sling as the *primary* attachment to the building structure.

Wire rope and slings properly made therefrom are used every day to rig many tons of production equipment from arenas. Your fear is unfounded, and contradicted by "best practices" in rigging. The length of wire rope slings you need for a 'stinger' can be easily calculated if you know the hoist chain length, the height of the structural attachment (beam) and the desired trim height. Simple math.

Also note that Grade 80 chain of a size large enough to use a 5/8" shackle will be VERY expensive and unnecessary. This whole thing is a kludge, and I don't understand why you come here asking for guidance that you then summarily ignore.
 
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