Rigging math got me on a 600-ton job in Corpus Christi

Last month we had a 600-ton crawler setting modules at a refinery in Corpus Christi. My foreman handed me the rigging plan and said check the sling angles before we hook up. I did the math quick like I always do, but I missed the load sharing factor on a 4-leg bridle. One leg had way more tension than I figured. The crane operator caught it during his pre-lift review and stopped everything. He showed me on his load chart how I was over by nearly 15,000 pounds on that one leg. Ever since then I double every bridle with a load cell on at least one leg, even on smaller jobs. Does anyone else use load cells regularly, or is that just overkill for most of you?

2 comments

2 Comments

barbarab5625d ago

Did that load cell cost more than the panic attack you must have had when the operator stopped everything? lol

the_joel25d ago

Load cells used to feel like overkill to me too, back when I was running smaller lifts. Figured a good tape measure and some trig was enough. Then I watched a guy on a 3-leg bridle get one leg completely slack while the other two carried damn near everything. Nobody caught it until the load started tilting. Now I rig a cell on at least one leg for anything over 10 tons. That 15,000 pound miss you had, that's a big deal, and the crane op saving you is a good reminder that the math only gets you so far when the ground shifts or the load settles. Cheap insurance compared to a dropped module or a bent boom.