Chain Grades

Quick Answer

Chain grade affects rated capacity, but securement planning should use marked WLL and manufacturer information rather than assumptions about chain appearance.

How chains are graded and marked

Chain grade in the US is typically expressed as a number (grade 30, grade 43, grade 70, grade 80, grade 100) and corresponds to a minimum breaking strength per unit of chain diameter. Higher grade numbers indicate stronger chain at the same diameter.

Grade markings are typically stamped, embossed, or raised on the chain links — often on every third link or at intervals set by the manufacturer. A common marking pattern includes the grade designation (e.g., '7' or '70' for grade 70, 'G8' for grade 80) and may include the manufacturer's identifier.

Grade marking is a starting point, not a WLL certification by itself. A chain that is unmarked, has illegible markings, or whose markings are inconsistent with its apparent diameter and construction should not be credited based on an assumed grade.

Determining WLL from grade and size

WLL tables published by chain manufacturers and included in carrier-approved equipment guides convert chain grade and nominal link diameter to working load limit. For example, grade-70 transport chain in 5/16-inch diameter is commonly rated at approximately 4,700 lb WLL, while the same grade in 3/8-inch diameter is commonly rated around 6,600 lb WLL.

Do not use these example values for live planning. Use the manufacturer's published table, the carrier's approved table, or the marked WLL on the chain assembly's tag or certification. Nominal chain diameters can vary slightly from actual dimensions, and WLL values depend on the specific manufacturing standard the chain was built to.

When in doubt about the grade or size of a chain, remove it from service rather than making an assumption. A chain credited at grade-70 capacity that is actually grade-30 creates a significant securement gap.

Hooks, binders, and the full assembly

Chain hooks and binders carry their own WLL ratings. Under 49 CFR 393.108, the working load limit of a tiedown is the lowest-rated component in the assembly. A high-grade chain run through a hook or binder with a lower WLL operates at the lower limit.

Hook condition matters: inspect the throat opening for deformation, check the latch for proper engagement, and look for wear at the load-bearing curve. A hook that has been overloaded may show subtle throat deformation that is not obvious from a distance.

Lever binders and ratchet binders each have their own rated capacity and inspection considerations. Check for bent handles, cracked welds, damaged threads (for ratchet binders), and worn or sticky locking mechanisms. A binder that does not stay locked is a road hazard.

Condition and out-of-service criteria

A chain should be removed from service for: any cracked, bent, twisted, or stretched link; wear that has reduced link diameter below the acceptable threshold for the grade; gouges, cuts, or heat damage; links that have been welded or modified; corrosion deep enough to affect link integrity; and any marking that is unreadable or inconsistent.

Many companies use a maximum wear threshold — often 10-15 percent reduction in link cross-section — as the out-of-service criterion, but this can vary by policy and manufacturer recommendation. Use the applicable company or manufacturer guideline, not a rough visual estimate.

Questionable chains should be tagged and removed from service. A note on why the chain was removed — and what was found during inspection — is more useful to the next person than a chain simply removed without explanation.

Practical Notes

Treat this page as a planning reference. Verify the current regulation, carrier policy, shipper instructions, manufacturer ratings, and equipment condition before a truck moves.