Grade 70 chain is the transport chain standard on American flatbeds, but it is not the only chain grade the FMCSA recognizes for tie-down — and knowing which grades are legal, which are marked, and which quietly cost you working load limit is the difference between a clean Level 1 inspection and an Out-of-Service order. Chain grade is stamped on the link for a reason. An officer reading that stamp knows exactly what capacity your assembly is allowed to claim, and so does the regulation.
This guide answers the question directly: Grade 30, Grade 43, Grade 70, Grade 80 and Grade 100 all appear in the working load limit table published in 49 CFR 393.108, so all five can legally contribute to your aggregate tie-down capacity. What separates them is the capacity per link size, the heat treatment behind that capacity, the price per pound of usable WLL, and one hard line about overhead lifting that transport chain must never cross.
The single most expensive mistake in this whole subject is simple: if your chain carries no legible grade marking, the regulation does not let you claim Grade 70 capacity — unmarked steel chain is rated at the Grade 30 proof coil column. On 3/8-inch chain that drops your claimable working load limit from 6,600 pounds to 2,650 pounds per leg. Same chain, same load, less than half the paper capacity, and an inspector who is entirely within the rules to write it that way.
What Chain Grade Actually Means
Chain grade is not a brand, a quality tier, or a marketing level. It is a number derived from the steel’s ultimate tensile strength, and it tells you how much load a given link diameter can carry before it is considered unsafe to continue using.
The Number Is a Material Property, Not a Size
The grade number refers to the tensile strength of the steel in the link, expressed in newtons per square millimetre. Grade 70 steel is stronger per unit of cross-section than Grade 43, which is stronger than Grade 30. That is why a 3/8-inch Grade 70 link carries more working load limit than a 3/8-inch Grade 43 link even though the two chains look almost identical on the deck.
- Grade is about steel, diameter is about geometry: going up a grade and going up a link size are two different ways to buy capacity, and they cost different amounts.
- Higher grade does not mean a heavier chain: a higher-grade chain reaches the same working load limit at a smaller link diameter, which is exactly why crews who throw chain all day care about it.
- Grade does not change with use: a worn, stretched or nicked Grade 70 chain is still stamped 70, but it is no longer entitled to Grade 70 capacity. That is an inspection question, not a grade question.
How Grade Is Marked on the Link
Transport chain is marked by embossing the grade onto the link body at regular intervals along the length. Grade 70 chain is typically stamped 7, 70 or G70; Grade 80 shows 8, 80 or G80; Grade 100 shows 10, 100 or G100. The marking repeats down the chain so that a damaged section does not leave the remaining length unidentifiable.
- Look on the flat of the link, not the weld: the emboss sits on the straight side of the link where it is least likely to be crushed by a binder.
- Gold chromate finish is a convention, not proof: the familiar yellow-gold colour is common on Grade 70 transport chain, but colour alone identifies nothing to an inspector. The stamp does.
- Tags fall off, stamps do not: this is why the regulation ties capacity to the marking on the component rather than to the paperwork in your cab.
Truck Trailer Pro Rule: before a chain goes in the rack, walk it and find the grade stamp. If you cannot read a grade marking anywhere along the length, that chain is Grade 30 on paper no matter what the invoice said, and it belongs in the scrap pile rather than on a paying load.
Why Unmarked Chain Costs You Capacity
Section 393.108 lets you establish working load limit two ways: from the manufacturer’s marking on the component, or from the tables published in the regulation. When a steel chain carries no identifiable grade, the default applied is the Grade 30 proof coil column — the lowest values in the chain table.
- The penalty is roughly 60 percent on 3/8-inch chain: 6,600 lb Grade 70 versus 2,650 lb Grade 30, per leg, on the same physical chain.
- It cascades into your aggregate WLL: under FMCSA cargo securement rules, aggregate working load limit must be at least half the weight of the cargo. Losing per-leg capacity means you needed more legs than you ran.
- It is the easiest violation to avoid: buy marked chain, inspect the marking, retire chain when the marking is gone.
The FMCSA Chain Table, Grade by Grade
Below are the working load limits published in the 49 CFR 393.108 chain table, in pounds, for the link sizes that matter on a flatbed. These are the numbers an officer will use, and they are the numbers you should be using when you plan a load.
| Chain size | Grade 30 proof coil | Grade 43 high test | Grade 70 transport | Grade 80 alloy | Grade 100 alloy |
|---|---|---|---|---|---|
| 1/4 in (7 mm) | 1,300 lb | 2,600 lb | 3,150 lb | 3,500 lb | 4,300 lb |
| 5/16 in (8 mm) | 1,900 lb | 3,900 lb | 4,700 lb | 4,500 lb | 5,700 lb |
| 3/8 in (10 mm) | 2,650 lb | 5,400 lb | 6,600 lb | 7,100 lb | 8,800 lb |
| 1/2 in (13 mm) | 4,500 lb | 9,200 lb | 11,300 lb | 12,000 lb | 15,000 lb |
| 5/8 in (16 mm) | 6,900 lb | 13,000 lb | 15,800 lb | 18,100 lb | 22,600 lb |
Grade 30 Proof Coil
Low-carbon steel, the general-purpose chain sold in hardware stores for gates, guard rails and light utility work. It appears in the regulation and it is legal as a tie-down, but its capacity is so low that using it on commercial freight means running far more legs than anyone wants to throw.
- Where it belongs: non-load-securement utility work around the yard.
- Why it still matters to you: it is the column your unmarked chain gets rated at.
Grade 43 High Test
A carbon steel chain roughly double the capacity of proof coil at the same size. It was the common tie-down chain before Grade 70 became the flatbed default, and it still shows up in older equipment, logging and agricultural use.
- Capacity gap versus Grade 70: about 18 percent less at 3/8 inch (5,400 lb against 6,600 lb).
- Why fleets moved on: the same securement job needs more legs, more hooks and more time on the deck.
Grade 70 Transport
Heat-treated high-strength low-alloy carbon steel, purpose-built for cargo tie-down. This is the chain the flatbed industry standardised on, and the reason it is often simply called transport chain, binder chain or trucker’s chain. Our G-70 transportation chains with grab hooks are supplied in 5/16, 3/8 and 1/2 inch in the lengths that match standard flatbed practice.
- Capacity where you need it: 4,700 lb at 5/16 inch, 6,600 lb at 3/8 inch, 11,300 lb at 1/2 inch.
- Weight you can actually handle: it reaches those numbers at a link size a driver can throw over a load repeatedly through a shift.
- Never rated for overhead lifting: Grade 70 is a tie-down chain and nothing else. That line is absolute.
Grade 80 Alloy
Alloy steel, heat treated, and the first grade in the table designed for overhead lifting service. It carries slightly more working load limit than Grade 70 at 3/8 inch and above, and slightly less at 5/16 inch — a detail that surprises people who assume the grade number tracks capacity in a straight line.
- Legal for tie-down: yes, at the marked values in the table.
- Usually bought for a different reason: crews that also rig and lift keep alloy chain because a lifting chain can tie down, while a tie-down chain cannot lift.
- Cost: alloy steel and lifting-grade certification put it above transport chain per foot.
Grade 100 Alloy
The highest grade in the FMCSA table, roughly 33 percent more working load limit than Grade 70 at the same link size. It is a lifting chain used where weight savings genuinely pay — rigging, crane work, and heavy equipment recovery.
- Legal for tie-down: yes, and it will let you secure the same load with lighter chain.
- Rarely the right purchase for flatbed freight: you pay a lifting-chain price for capacity that ordinary flatbed loads do not need.
Truck Trailer Pro Reminder: notice the 5/16-inch row. Grade 80 gives 4,500 lb where Grade 70 gives 4,700 lb. Paying more for a higher grade number can actually buy you less claimable capacity at that size. Read the table, not the number.
Which Grades Are Legal for Tie-Down
The Short Answer
All five grades in the table — 30, 43, 70, 80 and 100 — are recognised, and each contributes its marked working load limit to your aggregate. There is no rule that says “Grade 70 only.” What the regulation cares about is that the component is identifiable and that the total capacity satisfies the requirement for the load.
Why Grade 70 Became the Standard Anyway
Grade 70 sits at the point where capacity, handling weight and price meet. It carries enough working load limit that ordinary flatbed loads are secured with a sensible number of legs, it is light enough to throw repeatedly, and it costs a fraction of alloy lifting chain. Every part of the flatbed supply chain — binders, grab hooks, chain racks, headboard storage — is built around it.
- Ecosystem fit: ratchet and lever binders are sized 5/16–3/8 and 3/8–1/2 precisely because that is what transport chain comes in.
- Replacement cost: chain is a consumable on a flatbed. Replacing transport chain hurts less than replacing alloy.
- Availability: a Grade 70 chain can be replaced at almost any truck stop in the country. Grade 100 cannot.
The Overhead Lifting Line
Grade 30, Grade 43 and Grade 70 are not rated for overhead lifting. Grade 80 and Grade 100 alloy chains are. This is not a paperwork distinction — it reflects how the steel behaves as it approaches failure and whether it gives warning before it lets go.
- Tie-down chain can never become lifting chain: not “in a pinch”, not for a short lift, not with a safety factor argument.
- Lifting chain can be used to tie down: the direction that is allowed is the one going down in service severity, never up.
- Mixed racks cause accidents: if your equipment carries both, mark and store them separately so nobody grabs the wrong one at 5 a.m.
Grade 70 vs Grade 80: The Comparison That Actually Matters
Capacity Difference by Size
Across the sizes a flatbed actually runs, the gap is smaller than the grade numbers suggest. At 5/16 inch Grade 70 is ahead. At 3/8 inch Grade 80 leads by about 8 percent. At 1/2 inch it leads by about 6 percent. None of those margins change how many legs you throw on a typical load.
Cost per Pound of Usable Capacity
This is the number that decides the purchase. Alloy chain is priced for lifting service, and lifting service is not what a flatbed tie-down does. When you divide price by claimable working load limit, transport chain wins clearly at every size in the table.
- Buy capacity by size, not by grade: stepping 3/8 Grade 70 up to 1/2 Grade 70 buys 4,700 lb more per leg — far more than any grade change does.
- Grade 80 earns its place when you also lift: if the same chain does rigging work, the premium is already justified.
Field Repair and Component Matching
Every component in the assembly must be at least as strong as the chain, and the assembly is only worth its weakest part. Repairing alloy chain requires alloy components of matching grade; a Grade 70 repair link in a Grade 80 chain quietly downgrades the whole leg.
- Match hooks to grade and size: our G-70 transportation chain hooks and chain connectors are supplied in 5/16, 3/8 and 1/2 to match the chain sizes they attach to.
- Never repair with a bolt, shackle or wire: a field-improvised repair is an automatic violation and a genuine failure risk.
Choosing Chain Size for Real Loads
Once you have settled on Grade 70, the decision that remains is size — and size is driven by the aggregate working load limit the load requires, not by habit.
The Aggregate WLL Requirement
The combined working load limit of all tie-downs must be at least 50 percent of the weight of the cargo being secured. Every leg counts at its marked value, and every component in that leg must carry at least that value. If you are new to the arithmetic, start with what WLL means on straps and chains and then work the numbers for your own freight.
- Worked example, 40,000 lb load: you need 20,000 lb of aggregate WLL. Four legs of 3/8-inch Grade 70 gives 26,400 lb and clears it comfortably.
- Same load in 5/16 inch: four legs gives 18,800 lb and does not clear it. You either add legs or step up a size.
- Minimum tie-down counts still apply separately: meeting the WLL number does not excuse you from the count and spacing rules.
5/16, 3/8 and 1/2 in Practice
Most flatbed operations standardise on one primary size of grade 70 chain and carry a second as backup. The choice follows the freight rather than the trailer.
- 5/16 inch: lighter freight, hotshot and gooseneck work, and anywhere the load weight genuinely does not demand more. Easiest on the shoulders.
- 3/8 inch: the flatbed default. Enough capacity for the majority of steel, machinery and building-material freight without becoming punishing to handle.
- 1/2 inch: heavy machinery, large steel and the loads where 393.130 equipment rules push you toward four tie-downs of real capacity.
Matching the Binder to the Chain
A binder is rated for a chain size range, and using one outside its range is both a capacity problem and a safety problem. Binders in the binders range are marked 5/16–3/8 or 3/8–1/2 for exactly this reason.
- Ratchet binders: controlled, gradual tensioning and no stored-energy handle release. Covered in detail in how to properly use a ratchet binder.
- Lever binders: faster, cheaper, and they store energy in the handle — the reason so many hand and face injuries trace back to them.
Professional Driver Tip: when you step up chain size, check the binder range before the first load, not on the shoulder in the dark. A 3/8–1/2 binder will not close properly on 5/16 chain, and a 5/16–3/8 binder has no business anywhere near half-inch chain.
Buying Checks and Retirement Criteria
What to Verify Before You Buy
- Grade marking on the link: embossed and repeating, not printed on a tag alone.
- Stated working load limit that matches the table: a 3/8-inch Grade 70 chain advertised at anything other than 6,600 lb deserves a question.
- Hook and connector grade: supplied at matching size and grade so the assembly is not downgraded at the ends.
When the Chain Comes Off the Truck
Grade 70 chain is a consumable. It is retired on condition, not on a calendar, and the criteria are visual and measurable rather than a matter of judgement.
- Cracks, gouges, nicks or burns: any of them retires the chain immediately.
- Stretched or deformed links: a link that has opened up or lost its shape has already been overloaded.
- Illegible grade marking: as covered above, an unreadable chain is a Grade 30 chain on paper.
- Any improvised repair: bolts, wire, mismatched links or welded repairs all retire the assembly.
For the full size and strength reference across every grade and link diameter, keep the chains size chart to hand, and browse the complete chains and binders range when it is time to replace.
Related guides: chains size chart, chain hooks and connectors, when to retire a transport chain and what WLL means.
Frequently Asked Questions
Is Grade 70 chain required by law for tie-down?
No. Grade 30, 43, 70, 80 and 100 all appear in the working load limit table in 49 CFR 393.108 and all may be used as tie-downs at their marked values. Grade 70 is the industry standard because it offers the best combination of capacity, handling weight and price for cargo securement, not because the regulation names it.
What is the working load limit of 3/8-inch Grade 70 chain?
6,600 pounds. For comparison at the same 3/8-inch size: Grade 30 is 2,650 lb, Grade 43 is 5,400 lb, Grade 80 is 7,100 lb and Grade 100 is 8,800 lb.
Can I use Grade 80 or Grade 100 chain to secure cargo?
Yes. Both are in the regulation’s table and both may be used as tie-downs at their marked working load limits. They are alloy lifting chains, so they cost more per foot than transport chain, which is why most flatbed operations buy Grade 70 unless the same chain also does rigging work.
Can Grade 70 transport chain be used for overhead lifting?
Never. Grade 70 is rated for cargo tie-down only. Overhead lifting requires alloy chain rated for lifting service, which means Grade 80 or Grade 100. A lifting chain may be used to tie down; a tie-down chain may never be used to lift.
What happens if my chain has no grade marking?
Unmarked steel chain is rated at the Grade 30 proof coil values in the regulation’s table. On 3/8-inch chain that means 2,650 lb instead of 6,600 lb per leg, which can put an otherwise correctly secured load below the required aggregate working load limit.
Does the hook or binder change my working load limit?
Yes. A tie-down assembly is rated at the lowest working load limit of any component in it — chain, hook, connector, binder and anchor point. Fitting a lower-rated hook to a Grade 70 chain reduces the whole leg to the hook’s rating.
Grade 70 vs Grade 80 — which should I buy for a flatbed?
Grade 70, unless you also lift with the same chain. Grade 80 leads by roughly 8 percent at 3/8 inch and 6 percent at 1/2 inch, and actually trails Grade 70 at 5/16 inch, while costing considerably more. Stepping up a chain size buys far more capacity than stepping up a grade.
The Bottom Line on Chain Grade
Chain grade is a compliance question before it is a purchasing question. The regulation recognises five grades, it rates every one of them from the marking on the link, and it defaults an unmarked chain to the weakest column in the table. Get the marking right and the rest follows: buy transport chain in the size your freight demands, match the hooks and binders to it, and retire it on condition rather than on hope.
That is the quiet confidence a professional flatbed operator runs on — not guessing at the scale house, but knowing that every leg on the deck is stamped, rated and accounted for. Truck Trailer Pro supplies Grade 70 transport chain, matching hooks and connectors, and the ratchet and lever binders sized to run with them, so the whole assembly is rated end to end rather than downgraded at the weakest link.
