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safety factors for suspended scaffold ropes (steel chokers)

safety factors for suspended scaffold ropes (steel chokers)

safety factors for suspended scaffold ropes (steel chokers)

(OP)
i am designing the cable support system for a work platform that we fabricated years ago.  we have updated the platform to the DL + 4LL as required by OSHA.  during my review of OSHA subpart L  -  scaffolds, under General Requirements (a) (3) it states " Each suspension rope, including connecting hardware, used on non-adjustable suspension scaffolds shall be capable of supporting, without failure, at least 6 times the maximine intended load applied or transmitted to that rope."  i have used the industry standard F.S.=5.0 for wire slings before but i think i have to upgrade to F.S.=6.0.  the main question is the connecting points top and bottom (read 'picking eyes')  if i design the lugs by ASME BTH 2005, they are factored by 2 or 3 to 1.  i am wondering if i can use the ultimate capacity of the lug and factor it 6:1 and be in conpliance with OSHA.  for example, we have 3/8" pick lugs that are good for about 7k with N=2.0.  the DL+LL =2250. X6 = 13500lbs.  i am multiplying safety factors unless i can factor back from ultimate capacity of the lug

thanks in advance for anybody's thoughts.  

 

RE: safety factors for suspended scaffold ropes (steel chokers)

You should go with the Safety factor of 6. Also look in the section that talks about manlifts and cables fr lifting personnel. And you can always call OSHA for a consultation. There is supposed to be no penalty and they were always helpful to me.

Richard A. Cornelius, P.E.
WWW.amlinereast.com

RE: safety factors for suspended scaffold ropes (steel chokers)

(OP)
thanks for your reply, Richard.  i agree that i will use the FS=6.0 for the steel chokers.  but the lugs that the chokers are suspended from,  are designed already with a FS=2.  so i am wondering if the intent of the OSHA spec is 6.0 from failure or 6.0 from the asme bth spec which has a 2.0 built in.dont know if this is making any sence i dont want to multiply safety factors if the codes do not require it.  how does that work contacting OSHA for a consultation?  i will check the manlift section and the section for lifting personell.  thanks for your help.

thanks,
George  

RE: safety factors for suspended scaffold ropes (steel chokers)

I would assume if you the connecting piece was designed with a SF of 2, that you could take 1/3 of that and say you had a SF of 6.

It's not clear to me whether the "connecting hardware" applies to the picking eyes, either.  I suspect they mean the cable clips or hooks or shackles or similar items, as opposed to the load itself.

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