4.3 Rigging Equipment

Wire rope slings are constructed from multiple strands of steel wire twisted into a rope. They offer high strength, heat resistance, and resistance to cutting on sharp edges when properly padded. A wire rope is described by its construction — e.g., 6 × 19 means 6 strands of 19 wires each. Rope with more wires per strand (e.g., 6 × 37) is more flexible but less abrasion resistant than a 6 × 7 rope.

• 6 or more broken wires in one rope lay, or 3 or more in one strand
• Any kinking, crushing, birdcaging, or core protrusion
• Reduction in diameter exceeding ⅔ of nominal
• Heat damage or corrosion pitting
• Damage at end fittings (broken wires at termination)

Nylon or polyester flat-web slings are lightweight, flexible, and protect polished or painted surfaces from marring. They must be protected from cuts by sharp edges using corner protectors. Polyester slings are preferred in acid environments; nylon slings are preferred in alkaline environments.

• Cuts, tears, punctures, or abrasion exceeding 10% of sling width
• Missing or illegible load rating tag
• Acid or caustic burns; heat or UV damage causing stiffness or brittleness
• Broken or distorted fittings

Alloy steel chain slings are used for high-temperature applications and where wire rope or webbing slings would be damaged by sharp edges or high heat. Chain slings must be alloy steel Grade 80 or Grade 100.

• Elongation greater than 3% of original link length
• Nicks, gouges, or sharp surface marks
• Cracks in any link or fitting
• Distortion, bending, or twisting of links

• Pin fully engaged and moused with seizing wire
• No cracks, gouges, or deformation in the bow or pin
• No corrosion reducing cross-sectional area
• WLL marking is legible on the shackle body
• No heat damage or discolouration

A spreader bar is a rigid beam used to distribute lifting forces on a wide load and to keep sling legs from converging at a narrow angle — which would otherwise impose large inward horizontal forces on the load. Spreader bars are essential when lifting long air handlers or duct-mounted equipment that cannot accept point loading.

• Prevents damaging inward compression forces on sensitive equipment housings.
• Maintains a wider sling angle, increasing the effective angle factor and reducing leg tension.
• Must itself be rated for the compressive and bending forces imposed during the lift.

Hooks on cranes, hoists, and chain falls must be equipped with a safety latch to prevent accidental disconnection.

• Throat opening distortion exceeding 15% increase from original dimension
• Twisting of the hook body exceeding 10°
• Cracks or wear at the saddle (load-bearing curve)
• Hook has been overloaded — remove from service even if no visible damage is apparent