p m said:
Poor argument - Thom, do you see cranes using synthetic line (not web slings)?
Hi there, I work with Cranes as an Ironworker, and we use a wide variety of Rigging Materials and Practices. I have Erected Iron Buildings, Bridges, and my Specialty is in Wind Turbine Erection... what we call "Heavy Rigging". I would like to talk about a few Things like Riggin safety and share a few experiences ive had in my career.
I took a Riggin course and part of it was a day trip to a Rigging Manufacturer, where we toured the factory and had lunch at their facility. After we took the tour and got a little look into how Wire Rope is made, it was time to get a lesson in "Breaking Strength". The testing machine has a hydraulic Ram with a plate and a hook welded to the plate, to attach a choker to. the choker was a 1/2 inch double eye sling with swaged ends. ()------() sorta looks like that... the choker was placed in the machine and a BULLETPROOF GLASS hatch was closed over the choker, and the ram began pulling the choker taut.
A Gauge on the Machine showed how much force was applied to the choker, and as more force was applied, the choker stretched and the line between the eyes got narrower, and it continued to stretch until the needle on the gauge held a certain spot, when the choker suddenly exploded and it violently sent wire up against the glass! pretty scary shit when you think about that, knowing your life depends on that wire rope...
I witnessed a synthetic starp cut loose one day whan a 15 ton Beam was lifted 3 stories up and it had no softeners on the edges, the piece was almost in place when the weight of itself cut thru the nylon straps and landed on the top of a column.... it was dead quiet after it happened, everybody stopped working and looked around to see if everybody was okay, everybody checked their underwear for shtains.
We use Kevlar Endless Loop Slings to pick the Heavy Sections of Wind Turbines and to Lift the Heaviest Part of the Turbine, the Nacelle.
There are Stress Indicators weaved into the fibers that show up in red or blue when a sling has been overloaded, and when that happens, its time to render it useless to personnel...
So Always use a softener when using synthetic line, especially when running the line around a sharp edge, and when using steel line, its always a good idea to double the line for safety as the capacity is doubled.
DONT SADDLE A DEAD HORSE: when using wire rope and forming a loop in the line, use the proper size cable clamps for the size line you are using, and install the clamps with the u shaped bolt going around the DEAD part of the line, so that it cannot run thru the clamp. always put the saddle on the LIVE part of the line so that you dont reduce the capacity of the wire rope.
KNOTS: knots reduce the capacity of a line at the point where it is tied, so if you must tie a knot in a line, make sure you tie a good knot that wont run and slip out of itself. with any knot, always try to leave some extra dead end so in case the knot cinches up you have that extra "tail" in the end to hold the load...
I think that about covers it, any Questions im always willing to talk Riggin and I hope this wasnt too boring for you guys...