Sunday, June 15, 2008

June 12th, 2007


Dallas Texas. 1 dead from parted load line. The man killed was a cement truck driver cleaning up his truck about to leave the site. It sounds as if the concrete pour was ending and the crane was flying away when the line parted. The block fell striking the truck driver killing him.

Load lines on tower cranes are often non-rotating made by Casar or Python. The load line has three layers and are fairly complex. I worked with them for years until I took a class from a dealer and found it very useful. I was a qualified rigger and found it difficult to really picture what was going on in these ropes until I took that class and made use of Casar's material on inspection While operators should avail themselves to this information and do a daily inspection, inspection by a technician or qualified inspector should happen monthly or so depending on use. Nine times out of ten nothing will even be noted. The time that a cable is taken out of service for real reasons, you'll find the money well spent. Ekatrinburg Russia, lost a crane due to shock loading when a hoist line parted in 2008. I've found a line destroying itself after only six months on the crane. I've found a line in extremely bad condition after the technician said it was fine. I've found a load line inspected days before broken due to a unskilled worker crashing the block into the ground which resulted in a kink and valley break. Take the time to inspect your lines and have your rigger/bellman help you. You can't properly inspect a line from the cab.
1st picture in upper left. Triple wire break in one strand. This is happening because the line is old and rubbing at the kick point on the drum (normal). There were 100's of breaks in this line.
2nd picture to right is a break from crashing the block. The displaced wires along with a valley break is cause for removal from service. This line was about to be proof load tested when I noticed the break due to someone running the crane when they should not have been. A single valley break is cause for rejection as you can only see 20% of the line. If the rope is internally showing a break, you must remove it from service and you cannot Marlin Spike a "special" wire rope.
3rd picture is of a rope that was crushing in on itself for five feet then bircaging. The block was nearly at the ground and this was at a kick point. Essentially a good operator inspection performed alone may have missed this. The rope is not rotating properly between the outer and inner layers and failure will eventually result. The crane was only six months old.
Go to Casar and order the CD-ROM for free!

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