The Pro Rigger by Mike Parnell of ITI

Synthetic Slings vs. Harsh Hooks

  

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A variety of industries use synthetic slings to move equipment and product on a daily basis. Like most other sling types, synthetic web slings and synthetic roundslings serve to help provide acceptable rigging methods for load handling. In the same locations, loads may be rigged using steel slings made from wire rope and alloy chain. Spreader bars and lifting beams get used on certain loads to help avoid sling-to-load contact, and increase sling angles thereby lessening the individual sling tensions.

Especially when a mix of rigging equipment is used at one location, the rigger should pay special attention to the crane hooks in use. Multiple lifts (hundreds and thousands) with steel rigging can result in peening, gouging and displacement of the material in the hook bowl or saddle. Though not exceeding the removal criteria established by the hook manufacturer, this phenomenon can result in sharp edges towards the outer face of the hook.

If synthetic slings are placed directly into a peened hook bowl, the edges can act like a razor and sever the sling during the rigging and lifting process. This same type of event can occur when rough shackles that are regularly used with steel rigging, are placed into service with synthetic slings.

Always look at the contact point to which synthetic rigging is connected. Sling protection used along the body can prevent friction or cutting damage. However, a peened hook or shackle can cause just as much devastation.

Inspect the contact points used with all rigging. If hardware or connection devices can cause damage or severing of a sling while under tension, tag out the component and get it repaired or replaced. Certain hardware manufacturers allow for hand filing and buffing of their components to help maintain smooth surfaces. Follow the manufacturer’s instructions about repair and maximum allowable loss of cross-section criteria when considering hardware repair.

Happy Trails to my Crane & Rigging Friends,

Mike Parnell
President - ITI Field Services