Decode chain grades, alloys, and WLL. Learn to read link markings, compare G30-G120, pick the right chain.
Chains may look like nothing more than “black shiny steel,” yet the stamped codes G30, G43, G70, G80, G100 (and higher) set the safety margin for every lift or tie-down. This guide blends basic science with side-by-side comparisons so you can quickly grasp each grade’s alloy recipe, minimum breaking load (MBL), and typical color coding, then learn how to read the common stamps you’ll find on every link.
Different safety factors – For the same diameter, higher grades deliver greater breaking strength and therefore a higher Working Load Limit (WLL).
Different material costs – Plain low-carbon steel covers G30; alloying elements are required to reach G80 or G100.
Legal requirements – In the U.S., 49 CFR § 393 demands tie-down capacity be calculated from the stamped WLL; EN 818-2 specifies that Grade 8 short-link chain must break at ≥ 8 × WLL.
Grade | Main Standards | Typical Material Mix | Min. Breaking-Force Ratio* | Common Color Code** | Typical Uses |
G30 | ASTM A413 | Low-carbon steel (Q235B) | 4 × WLL | Black or bare | Light cargo, fencing |
G43 | NACM 96 | Carbon steel + Mn | 4 × WLL | Blue | Towing, lumber tie-down |
G70 | ASTM 80 | 20Mn steel + case-hardening | 4 × WLL | Gold-plated zinc | Truck tie-downs, pipe transport |
G80 | EN 818-2 | 20Mn2 alloy, quenched & tempered | 8 × WLL | Purple / Red (red in some U.S. specs) | Sling assemblies, mining |
G100 | ASTM A973 / EN 1677 | 23MnNiMoCr5-4 alloy | 8 × WLL | Dark blue | Crane slings, offshore lifts |
G120 | DIN 5692 | 17CrNiMo6 ultra-strength alloy | 8 × WLL | Green | Premium offshore lifting, wind-farm erection |
* Ratio = Minimum Breaking Force ÷ WLL.
** Color bands vary by maker; always verify the stamped grade.
Click on the image to see details.
G30 G43 G70 G80 G100
8 – 10x30 – TOP – 21T – 0523
| | | | └── Batch / heat code (May 2023)
| | | └──────── WLL = 21 t
| | └──────────── Manufacturer code
| └────────────────── Nominal size: 10 mm dia. × 30 mm pitch
└────────────────────── Grade: 8 (G80)
Numbers 8, 10, 100 denote the grade; North American and European makers often add a “G” (e.g., G80).
Letter codes such as TOP, YOKE, CWC identify the manufacturer.
WLL or CAP marks the Working Load Limit, normally in tonnes or pounds.
HEAT / CAST tracks back to the furnace batch.
Reading order: confirm the grade → check the WLL → jot down the batch code.
Scenario | Difference: G70 vs G80 | Selection Tip |
Flatbed hauling a 20-t excavator | G70, 3/8 in chain, WLL ≈ 6.6 t → need ≥ 4 legs.G80, same size, WLL ≈ 8 t → 3 legs meet the rule. | If budget allows, G80 saves time by reducing chain count. |
Tower crane lifting a 5-t module | G80, 10 mm single-leg WLL ≈ 3.2 t → needs a 2-leg bridle.G100, 10 mm, WLL ≈ 4 t → higher redundancy. | When headroom is tight, go G100 to shorten sling length. |
Steel mill at 400 °C | Carbon-steel G43 loses > 30 % strength. | Switch to heat-resistant alloy (G80+) and apply maker derate chart. |
Q1 Is color coding always reliable?
No. Paint can be over-sprayed or worn away. Rely on stamped numbers and test certificates.
Q2 Can I use a G80 chain where G70 is specified?
Up-grading is usually fine, but never down-grade. Remember: higher grades often have lower bend radii; check the standard.
Q3 Are grades the same worldwide?
Only if standards match. G80 ≈ Grade 8 ≈ EN 818-2 Grade 8, but JIS G3525 Grade 6 sits between G70 and G80, so direct swaps are risky.
Chain = Grade number + stamp + certificate.
When you understand the materials and safety factors behind each number, you can select chains confidently for lifting, cargo tie-down, or offshore heavy duty. Always demand laser-etched stamps, a complete WLL and batch code, plus third-party break-test reports. Combine those with scheduled inspections, and every link in the chain truly lives up to its nameplate. Click me to learn more →
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