A lifting sling is a lifting accessory made of flexible material — rope, wire rope, chain or woven webbing — with an eye or loop at each end. What distinguishes it from an endless sling lies precisely in those ends: on a sling with eyes, the ends cannot be passed through themselves.
In everyday site language you will more often hear webbing sling, chain sling or wire rope sling. The Dutch term leng is now regarded as somewhat archaic; strop has largely replaced it.
Types
- Wire rope sling. Steel wire rope with ferrule-secured or spliced eyes. Strong and more heat resistant than webbing, but stiff and vulnerable to kinking.
- Chain sling. Alloy steel chain links, often in one-, two-, three- or four-leg configuration with hooks. Indifferent to sharp edges and adjustable with a shortening hook.
- Webbing sling. Woven polyester, light and supple, kind to the surface of the load, but cut through by a sharp edge.
- Round sling. A closed loop of yarn bundles inside a cover; strictly speaking not a sling with eyes, but in practice the most widely used type.
Working load limit and the effect of sling angle
Every lifting accessory carries a WLL (working load limit) — the maximum load it may carry. That figure applies to a straight pull. As soon as you lift with two or more legs at an angle, the force in each leg increases: the further the legs are spread, the greater the tension in each.
Rule of thumb for a two-leg sling: up to an angle of roughly 45 degrees from the vertical you may reckon on a mode factor of about 1.4 times the WLL of one leg; up to roughly 60 degrees only about 1.0. Beyond 120 degrees included angle you should not be lifting at all. Two slings each rated at 1 tonne therefore do not always carry 2 tonnes — the most common miscalculation on site.
Colour coding of webbing slings
Woven webbing slings follow a fixed European colour code for working load limit: violet 1 tonne, green 2 tonnes, yellow 3 tonnes, grey 4 tonnes, red 5 tonnes, brown 6 tonnes, blue 8 tonnes and orange 10 tonnes and above. A useful memory aid, but the label governs: only it carries the actual WLL, the length, the standard and the certificate number.
Practical tips
- Inspection is mandatory. Lifting accessories must be examined by a competent person at regular intervals — at least annually, and more often under heavy use.
- Protect sharp edges. Fit a corner or edge protector under the sling at any edge sharper than the sling material can take.
- When in doubt, take it out of service. Cut yarns, heat damage, knots, deformed hooks, stretched chain links or an unreadable label: withdraw and destroy, never “use it one more time”.
- Never tie a knot to shorten a sling; use a shortening hook or a shorter sling.
- Never stand under the load and use a tag line to guide it.
Related terms
- Hoisting beam
- Hoisting hatch
- Treadwheel crane
- Scaffolding
- Site safety
Want to know more about building terms? Take a look at our knowledge base on fredsdiyplans.com.