9.2 Alloy-Chain Assemblies and Approved Adjustment
Key Takeaways
Transport-chain strength does not establish overhead-lifting suitability.
Use only the shortener intended for the chain size and assembly.
Adjustment does not prove equal leg forces.
Select chain rated for overhead lifting
An alloy-steel chain sling is a manufactured or approved assembly of load chain and compatible fittings for lifting. Its rating comes from its grade, size, number of legs, angle, hitch and components. Do not select a transport chain for overhead lifting merely because it appears thick or has a high breaking strength.
Grades 80, 100 and 120 are common modern overhead-lifting products, but OSHA 1926.251 does not state that these are the only legally possible grades for every lifting assembly. The required decision is whether the actual alloy-chain assembly is identified and rated for overhead lifting under the applicable requirements and manufacturer instructions. A grade number or paint color alone is insufficient.
Grade 70 transport chain is generally supplied for load securement rather than overhead lifting. Its role in tie-down is separate from an approved lifting sling. Likewise, an ordinary utility chain or improvised welded connector does not become a rated sling when attached to a crane.
Match every fitting
Hooks, master links, connecting links, shortening devices and other attachments must be suitable for the chain system. OSHA construction provisions require fittings with capacity at least equal to the chain’s applicable demand and prohibit makeshift links or fasteners. A fitting that happens to fit through a link can still be incompatible in size, grade or load path.
| Component | Check |
|---|---|
| Master link | Assembly capacity and fit in the upper hook |
| Connecting link | Approved type, size and assembly procedure |
| Sling hook | Correct chain connection and permitted load seating |
| Shortener | Correct chain size and approved engagement |
| Chain leg | Identification, condition and required effective reach |
Use the rated assembly’s instructions when replacing or adjusting a component. A high-grade chain attached to a lower-rated fitting does not retain the chain’s full capacity. The assembly is limited by the applicable component and configuration demands.
Adjust through approved devices
A shortener changes the effective length using an approved chain-engagement arrangement. It must accept the correct link and maintain the intended bearing pattern. Some devices affect capacity or require particular engagement instructions; others are rated to retain capacity in specified use. Read the actual product instructions rather than applying one universal reduction.
Do not shorten by tying knots, bolting through links or using an unapproved hook or nail. Do not twist a chain leg to adjust its length. Twists change link bearing and can prevent the chain from aligning with the force. Make adjustments in the safely unloaded state unless the equipment is explicitly designed and approved for a particular loaded adjustment.
A turnbuckle or shortener can help establish the lengths required for a level lift. It does not automatically equalize all leg forces. Off-center loads still require correct reactions and geometry, and a multi-leg assembly still needs its approved rating basis.
Apply the right capacity table
Read the angle and leg count in the assembly table. A two-leg rating at 60 degrees from horizontal differs from a single-leg vertical rating. If the assembly is used at a flatter angle, use the corresponding permitted rating or approved analysis. Do not multiply the two-leg table value by two again.
A choker or basket arrangement may have separate capacity and engagement conditions. The load must seat in the hook’s bowl rather than on its tip or latch. Chain should not bear across a fitting in an unapproved bending pattern. A hook’s ability to rotate before loading does not authorize rotation under load unless it is designed for that service.
Capacity example
Assume a supplied table rates a particular two-leg chain assembly at 20,000 lb for 60-degree horizontal legs and 16,000 lb at 45 degrees. A complete supported load of 18,000 lb fits the first listed condition but exceeds the second. Shortening the upper geometry to clear a ceiling can therefore make the same assembly unsuitable. These are given training ratings, not a catalog chart to apply to another chain.
Temperature and surface contact
Chain can suit some abrasive or hot-service tasks, but its grade, fittings and manufacturer temperature instructions control. OSHA 1910.184 requires manufacturer capacity reductions for chain used above 600°F and permanent removal after exposure above 1,000°F. Particular products can have stricter conditions. Never heat chain to straighten a link or restore fit.
Chain can damage a finished surface or create high contact forces on thin material. Use an approved arrangement and compatible protection rather than assuming metal slings are suitable for any rugged-looking load. Protect the load and preserve the chain’s alignment as separate requirements.
Inspect every link and fitting, especially interlink bearing surfaces. Any observed stretch, distortion or cracking calls for removal/evaluation under the applicable criteria; a generic 5% stretch allowance is not safe permission. Required proof testing after manufacture or repair is a controlled qualification process, not a test the field crew performs by overloading the sling.
Sources: CCO reference materials, OSHA slings, CMCO chain-sling information.
A supplied two-leg chain assembly is rated 20,000 lb at 60° and 16,000 lb at 45°. Can an 18,000-lb supported load use the 45° condition?
Yes; add the two listed ratings
No; the supplied 45° rating is below the supported load
Yes; chain design factor is spare capacity
Yes; the 60° rating applies to all angles
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