2.1 Five sling materials, five sets of rules

1 The five, side by side

Note what the third column has in common: almost none of it is overload. Slings are far more often destroyed by their environment and by handling than by being asked to carry too much — which is why the removal criteria in Part 4 are about condition, not about how many lifts a sling has made.

2 Chain: the one you can repair, and the one heat kills

Alloy steel chain is the sling for hostile work — foundry, forge, scrap, anywhere with heat, sharp edges and abuse. It is also the only sling type the standard lets you put back into service after damage, and it is very specific about how: 1910.184(e)(7)(i) requires repair, reconditioning and proof testing by the sling manufacturer or an equivalent entity where welding or heat testing is performed, and (e)(7)(ii) flatly prohibits using mechanical coupling links or low carbon steel repair links to repair broken lengths of chain.

Heat is its limit. 1910.184(e)(6): an alloy steel chain sling heated above 1,000°F is permanently removed from service, and above 600°F in service the maximum working load limits must be reduced per the chain or sling manufacturer's recommendations. Chain is also the sling type with a mandatory annual inspection regime and a written record — covered in Part 4.

A last point that catches people: chain stretches before it breaks, and a stretched chain sling has elongated links and a chain size smaller than the table minimum. 1910.184(e)(8) puts a chain out of service when the size at any point of a link falls below Table N-184-1, and (e)(3)(iii) makes the thorough inspection look specifically for wear, defective welds, deformation and increase in length.

3 Wire rope: strong, and unforgiving of geometry

Wire rope is the default for heavy construction rigging. Its weaknesses are geometric rather than chemical: it does not like being bent tightly, kinked, crushed or dragged over an edge, and each of those leaves permanent damage that the standard names in its removal list.

Three configuration rules exist that have nothing to do with capacity and everything to do with how a wire rope sling is built — 1926.251(c)(13):

• Cable laid and 6 × 19 and 6 × 37 slings: a minimum clear length of wire rope 10 times the component rope diameter between splices, sleeves or end fittings.
• Braided slings: a minimum clear length 40 times the component rope diameter between loops or end fittings.
• Grommets and endless slings: a minimum circumferential length of 96 times their body diameter.

And several fabrication prohibitions worth knowing because shortcuts are tempting: eyes in wire rope bridles, slings or bull wires may not be formed by wire rope clips or knots (1926.251(c)(4)(iii)); wire rope may not be secured by knots, except on haul back lines on scrapers (c)(3); an eye splice must have at least three full tucks (c)(4)(i)); and where U-bolt clips are used to form eyes, the "U" section goes against the dead end of the rope (c)(5)(i)). OSHA's sling guidance goes further and says not to use wire rope clips to fabricate slings at all, except where prefabricated slings cannot be used and the sling is designed for the application by a qualified person.

Temperature matters here too, in a way people forget: fiber core wire rope slings of all grades are permanently removed from service above 200°F — 1926.251(c)(14). The 400°F figure everyone remembers applies to nonfiber core slings, and above it the manufacturer's recommendations govern.

4 Fiber rope and web: gentle on the load, fragile everywhere else

Synthetic web slings and roundslings are what you reach for when the load's surface matters, when you need the sling to conform to an odd shape, or when you want grip without marring. They are also the least tolerant of the things a jobsite does to them.

Chemistry is not interchangeable. 1926.251(e)(6) splits them: nylon web slings must not be used where fumes, vapors, sprays, mists or liquids of acids or phenolics are present; polyester and polypropylene must not be used where caustics are present; and web slings with aluminium fittings must not be used in caustics either. That is not a preference — it is one of the few places where the standard names the chemical family.

Heat is low. Polyester and nylon: not above 180°F. Polypropylene: not above 200°F — 1926.251(e)(7). Compare that with chain's 1,000°F and it is clear these are not interchangeable materials.

Construction is prescribed. 1926.251(e)(5): stitching is the only method used to attach end fittings to webbing and to form eyes, with the thread in an even pattern and enough stitches to develop the full breaking strength.

Fiber rope slings carry the strictest rule of the five: 1910.184(h)(6) — only fiber rope slings made from new rope shall be used, and use of repaired or reconditioned fiber rope slings is prohibited. There is no repair path at all.

5 Metal mesh: the specialist

Metal mesh is a fabric of transverse coils joined by cross rods — 1910.184(b) defines the spiral and the cross rod — and it exists to do one job well: grip and spread the load on hot, abrasive or awkwardly shaped items, especially in metal fabrication.

Its marking rule is the giveaway about how it is meant to be used. 1910.184(g)(1) requires a durable marking stating the rated capacity for vertical basket hitch and choker hitch loadings — the two configurations the fabric is built for. Combined with the ban on using an unmarked sling, that answers the question of what a metal mesh sling may be rigged as.

Temperature range depends on the coating: uncoated mesh may be used from −20°F to +550°F without decreasing the working load limit, while mesh impregnated with polyvinyl chloride or neoprene is limited to 0°F to +200°F — 1910.184(g)(7). And (g)(4) prohibits applying coatings that diminish the rated capacity, which is a rule against improvised protection.

6 Choosing, in four questions

1. 1
   What is the environment? Heat, chemicals, sunlight, water, grit. This eliminates materials before anything else does.
2. 2
   What does the load's surface need? Something that must not be marked rules out chain and mesh; something with a sharp corner rules in edge protection whatever you pick.
3. 3
   What shape does the sling have to take? Round bodies and irregular items favour web, roundsling and mesh; fixed lugs favour eye-and-eye legs of anything.
4. 4
   What does it have to carry, in the hitch and at the angle you will actually use? Last, not first — and read it off the tag, which is the next chapter.