An October 2009 report prepared by Washington River Protection Services for the U.S. Dept. of Energy to address “recurring problems of synthetic sling failure,” cited the 2008 crane collapse, among others, and found that “all cases in which the synthetic sling contacted the edge of its load resulted in sling failure.”

Sling protection is a requirement under federal regulations. The Occupational Safety and Health Administration requires that “slings shall be padded or protected from the sharp edges of their loads.”

But, as the DOE report noted, “there are no consensus codes or standards stating the type, material, or purpose of the type of protective device used to protect the sling from being cut.”

Contractors use a variety of materials to protect slings, from commercially available products to pipes with a quarter of the diameter cut out, to old tires.

The DOE report recommended that a requirement be established for the use of only of approved cut resistant sling protection devices. The report also called for manufacturers to supply clear protection and load ratings with their protective devices.

Industrial Training International also studied accidents in which rigging was at fault. That study found that 50% of the 60 accidents it reviewed were sling related. The other 50% were either crane related or a result of a faulty procedure.

Synthetic slings were at fault in 87% of the sling related accidents and of those, 80% of the failures were from cut slings, 10% of the failures were the result of friction and the remaining 10% were the result of degradation from ultraviolet light.

Synthetic slings are not necessarily bad, Parnell said, they just have to be protected.

“Synthetic slings are not the problem, riggers are the problem,” he said.