safety factors for suspended scaffold ropes (steel chokers)

[black79ta]

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.

 

[dicksewerrat]

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.

http://WWW.amlinereast.com

 

[black79ta]

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

 

[JStephen]

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.