Protecting Slings from Sharp Edges
A sling can hold thousands of pounds, but a sharp corner can cut it in seconds. Synthetic slings, wire rope and chain are all damaged by sharp edges, and a damaged sling can fail without warning. Padding and protecting the sling at every sharp edge is basic rigging practice, and it’s required.
- Rigging
- Cranes
- Construction
What the rules say
- OSHA’s rigging rules for construction (29 CFR 1926.251) and the crane rules (1926.1400 series) require that slings be padded or protected from the sharp edges of their loads.
- Industry standards such as ASME B30.9 (slings) say the same, and manufacturers print warnings on sling tags.
- The employer must make sure rigging is inspected, and a qualified rigger chooses the protection. See Qualified Rigger Requirements.
What counts as a sharp edge
- Steel beam flanges, angle iron, plate edges and channel corners
- Pipe flanges, valve bodies, machinery frames and cast edges
- Concrete corners, precast panel edges and rough or abrasive surfaces
- Sheet metal, crates with metal bands and bolts, burrs and weld spatter
- Any corner where the sling bends sharply around the load
An edge doesn’t need to look razor sharp. A small radius at the corner of a steel beam, a corner with a radius smaller than the sling’s thickness or any edge that could cut or abrade the sling counts. When in doubt, protect it.
How edges damage slings
| Sling | What can happen |
|---|---|
| Synthetic web and round slings (nylon, polyester) | Cut easily. A cut or abrasion may hide inside a round sling, where the load-bearing core is under a cover. Even a partial cut greatly reduces strength. See Synthetic Slings |
| Wire rope slings | Sharp edges can crush or cut strands, kink the rope and cause broken wires. See Wire Rope |
| Chain slings | Links can be nicked and gouged, and bending over a sharp corner puts bending load on a link, which isn’t designed for it. See Chain Slings |
| Metal mesh slings | Mesh and edges can bind or be damaged, and are protected by design in some uses. Follow the maker |
Edge damage also changes how much the sling can hold. When a sling bends sharply around a corner, the load concentrates at the bend, which reduces strength. A larger bend radius helps spread the load.
Types of protection
- Corner protectors and edge guards: molded or steel protectors, often called softeners, made to fit over a corner and spread the load. Choose the size and rating for the sling and the load.
- Sling sleeves and wear pads: cut-resistant or abrasion-resistant sleeves that slide over the sling, such as polyurethane, nylon-reinforced or Kevlar-type sleeves. Position them over the contact point.
- Padding: wood blocks, rubber pads, heavy canvas or carpet, used as a temporary guard. Make sure the material is thick enough and strong enough to prevent a cut, and that it can’t slip out.
- Pipe or round-bar spacers on a corner to increase the bend radius.
- Use a larger sling or a different hitch. Choose a sling type suited to the load, such as a chain sling for a sharp-edged steel load, with correct rating and care. See Sling Hitches.
Protection must be tough enough for the edge. A thin piece of cloth won’t stop a steel edge under thousands of pounds of force. Use protection made for the job and rated by the maker.
Rigging practice
- Inspect the load for sharp edges and burrs before rigging. Grind off burrs if allowed, and cover rough areas.
- Place protection at every contact point, including where the sling wraps around the load and where it contacts bolts or fittings.
- Keep protectors in place as the load is lifted, since a sling can shift. Tie or secure them where you can.
- Avoid sharp bends in slings, and don’t let slings bunch or twist. Keep the sling bend radius as large as possible.
- Avoid dragging slings across sharp or rough surfaces or pulling them out from under a load, which causes abrasion.
- Mind the sling angle, since low angles raise tension. See Rigging Basics and Estimating Load Weight.
- Tag lines and slow handling keep the load from swinging against edges.
Inspection after contact
- Check the sling after every lift where it touched an edge: look for cuts, abrasion, melted spots, crushed areas, broken stitches and exposed core. See Sling Inspection.
- Remove damaged slings from service right away and tag them. Don’t repair synthetic slings in the field unless the maker approves. Slings with cuts that expose the core or damaged chain links must be taken out of service.
- A damaged sling is not “good enough for a light load.” Destroy or clearly mark rejected slings so they aren’t used again.
Sling protection checklist
- Load checked for sharp edges, corners and burrs
- Corner protectors, sleeves or padding rated for the load at every contact point
- Bend radius kept large; slings not twisted or bunched
- Protection secured so it won’t slip when the load is lifted
- Sling inspected after the lift; damaged slings removed from service
Standards & references
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