Synthetic slings were at fault in 87% of the sling-related accidents; of those, 80% of the failures were from cut slings, 10% were the result of friction, and the remaining 10% were the result of degradation from the sun's ultraviolet rays.
High on the List: Cut Slings
Cut and worn slings were among the leading causes of the worst crane accident in U.S. history.
Seven people died on March 15, 2008, when a tower crane collapsed—also in the heart of New York City—during a jumping procedure that turned disastrous when synthetic slings supporting tie-in components failed.
William Rapetti, owner of Rapetti Rigging Services Inc., Massapequa Park, N.Y., was acquitted of multiple charges of manslaughter, criminally negligent homicide, assault and reckless endangerment in connection with the accident.
An October 2009 report by the Washington River Protection Services for the Dept. of Energy addressing "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. But OSHA regulations on this subject are brief, saying only: "Slings shall be padded or protected from the sharp edges of their loads."
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 the industry establish a requirement covering the use of approved cut-resistant sling-protection devices. The report also called for manufacturers to supply clear protection and load ratings with their protective devices.
But as Parnell observes, OSHA, in general, is not prescriptive in its regulations. Standards and practices laid out by the American Society of Mechanical Engineers, however, provide more guidance along the lines of what to do, as opposed to what not to do.
