Rigging angles: the 60 degree rule folks keep ignoring

I've been running cranes for 14 years now, mostly around the Gulf Coast, and I keep seeing operators rig loads with slings at angles way past what the chart says. Last month on a job in Mobile, a guy rigged a 4,000 pound steel beam with chokers at about 30 degrees from horizontal, said it was fine because the slings were rated for 6,000 pounds each. That math only works if the slings are vertical, once you add that angle the load on each leg jumps way up, and I've seen the numbers go from 2,000 to nearly 4,000 per leg. I asked him to recheck the chart and he got defensive, said I was being too careful. But I've also seen older guys argue the opposite, that charts are too conservative and they've never had a failure, so they just eye ball it. Which side are you on, do you stick to the exact angle math or trust your gut from years of experience, and has anyone actually had a sling slip or snap from ignoring the angle? I'd rather re rig a load twice than drop one once.

1 comments

1 Comment

bettyroberts4d ago

Maybe try rigging it with hope and a prayer next time, pal.