9.1 Select and Use Wire-Rope Slings

Recognize the complete rated assembly

A wire-rope sling is an assembly of rope and approved terminations used to support a load. Rope construction, grade, core, size, termination and hitch affect its rated capacity and handling characteristics. A nominal diameter alone does not identify an interchangeable sling.

Wire rope consists of wires arranged into strands around a core. A fiber core and an independent wire-rope core have different behavior and temperature limitations. Construction influences flexibility, abrasion resistance and bending performance. Use the assembly identification and manufacturer information rather than estimating rating from the number of visible strands.

Common terminations include mechanically formed eyes, hand-spliced eyes and sockets in approved assemblies. The termination is part of the rating. A damaged sleeve is a removal/evaluation issue; it does not provide an unused percentage of rope strength that may safely be consumed. Never teach that an impaired eye remains usable because its original termination efficiency exceeded the working load.

Read the relevant capacity

The vertical, choker and basket ratings describe different load paths. A vertical single leg carries its full applied tension. A choker has bending and contact at the choke and uses its applicable rating. A basket can use two supporting portions, but capacity depends on angle, bend diameter, balance and the rated arrangement.

Do not multiply a table rating by a factor already included in its heading. If a table gives a two-leg assembly WLL at 45 degrees, its angle effect is already included. If it gives a single-leg vertical WLL, compare it with the calculated inclined leg tension or use an explicitly provided conversion. Mixing these approaches can double-derate or overrate the system.

Understand bend ratio

D/d compares the diameter of the object or bearing surface around which the sling bends, D, with the rope diameter, d. A smaller bend makes rope work harder and can reduce rated sling capacity. The applicable manufacturer bend guidance and table basis control the adjustment. There is no one D/d factor table valid for every rope construction, hitch and eye.

If an exercise explicitly supplies an unadjusted basket rating of 12,000 lb and an applicable bend factor of 0.80, the adjusted rating is 9,600 lb. Apply this only when the factor is required and not already included. It is not permission to use the same 0.80 factor on another diameter or construction.

Check eye bending and body bending separately where the instructions distinguish them. A sling body around a small pipe and its eye around a small hook present different contact conditions. A thimble protects an approved eye geometry but does not eliminate all other bend limitations.

Install without damaging the rope

Avoid kinks, twists, crushing and abrasion. Do not drag a loaded sling across a sharp edge, hammer a kink straight or pull the sling from beneath a landed load. Position the sling so its body and eyes follow the permitted path and protection remains in place. Hands must remain clear as tension develops.

A basket must be balanced to prevent slipping. A choker must tighten in its intended location without bearing the splice or fitting improperly against the load. Long bundles need a method that retains all pieces, not a belief that friction alone will prevent every loose piece from escaping.

OSHA 1926.251 prohibits forming sling or bridle eyes with wire-rope clips or knots. The blueprint’s separate clip topic concerns permitted rope terminations in their applicable uses; it does not authorize construction of a clip-made sling eye in conflict with that regulation. Use a compliant fabricated sling rather than field improvisation.

Inspect and protect the assembly

Look for broken wires, kinks, birdcaging, crushed areas, severe corrosion, heat damage and damaged attachments. A glove can help protect against sharp wires, but do not draw bare hands along the rope. Identify damage over the complete length and at terminations. The inspection chapter distinguishes ASME and OSHA broken-wire criteria instead of applying one number to every rope use.

For temperature, the cited OSHA rules require permanent removal of fiber-core slings exposed above 200°F. Non-fiber-core wire rope used above 400°F or below −60°F requires manufacturer recommendations. Do not apply a generic heat derating without checking the complete assembly and its fittings.

Selection scenario

Two slings have the same diameter, but one has a different core, construction and hitch rating. The rigger cannot substitute it based on appearance. Confirm its applicable WLL, bend limits and service conditions, recalculate if the geometry changes, and verify that its eye fits the selected hardware. After use, store it to avoid corrosion, kinking and mechanical damage, preserving readable identification.

Sources: CCO reference booklet, OSHA construction rigging, CMCO sling guidance.