Chain Links — Grade 80 vs Grade 100 — 3D Equipment Viewer

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Chain grade determines the WLL. Using the wrong grade in your calculation means the WLL is wrong — and the lift could fail catastrophically.

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Grade 80 = stamped “80” or “8” on every link. Grade 100 = stamped “100” or “10”. If unmarked — NEVER use for lifting.

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Grade 100 has a 25% higher WLL than Grade 80 at the same diameter. Same size chain, significantly more capacity.

The WLL of a single chain link (single-leg vertical) is calculated from the chain diameter and grade factor.

WLL = D² × 32

D = chain diameter in mm • Result in kg

WLL = D² × 40

D = chain diameter in mm • Result in kg

Remember: Grade 80 = ×32. Grade 100 = ×40. The factor difference (40 vs 32) is exactly 25%.

This table shows how the same chain diameter gives different WLLs depending on the grade. This is the core exam question.

Chain ø	Grade 80 WLL	Grade 100 WLL	Difference
7 mm	1,568 kg	1,960 kg	+392 kg
8 mm	2,048 kg	2,560 kg	+512 kg
10 mm	3,200 kg	4,000 kg	+800 kg
13 mm	5,408 kg	6,760 kg	+1,352 kg
16 mm	8,192 kg	10,240 kg	+2,048 kg
20 mm	12,800 kg	16,000 kg	+3,200 kg

Chain grade also determines maximum operating temperature. Grade 100 has double the heat tolerance of Grade 80.

Grade	Max Temp	Effect Above Limit
Grade 80	200°C	Alloy loses temper, WLL permanently reduced
Grade 100	400°C	Higher alloy maintains strength longer

Chain that has been overheated cannot be restored by cooling — the metallurgy is permanently changed
Discolouration (blue/purple tint) indicates the chain has exceeded its temperature rating
Remove from service and destroy — do not re-tag or re-test

On a real job, you need to positively identify the chain grade before calculating WLL. Here’s how.

Link stamps: Every link is stamped with the grade number — “80” or “8” for G80, “100” or “10” for G100
Tag colour: G80 slings often have a blue ID tag. G100 slings often have a green or yellow ID tag (varies by manufacturer)
Master link stamps: The master link (oblong top link) is stamped with WLL, grade, chain diameter, and serial number
Physical appearance: G100 links may appear slightly more compact/refined due to the higher-grade alloy and manufacturing process

If the grade stamp is worn, missing, or illegible on any link, the chain must be removed from service
Hardware store chain (proof coil, general purpose) is NOT rated for overhead lifting — regardless of how thick it looks
Only chain manufactured and certified to AS 2321 is suitable for lifting

NEVER mix grades in the same sling assembly — a G80 hook on a G100 chain means the entire sling is rated at G80
NEVER substitute G80 for G100 without recalculating — using a G80 chain where the lift plan specifies G100 means the WLL is 25% lower than planned
NEVER assume the grade from appearance alone — always verify the stamp on the links
NEVER use unmarked chain for any lifting operation, even a “light” load

Inspect chain links before every use. Run each leg through gloved hands checking every link.

Worn markings: grade stamp illegible on any link — remove from service
Stretched links: any link elongated >5% indicates overload — measure with go/no-go gauge
Gouges or cracks: any surface damage on any link — stress concentration = failure point
Twisted or bent links: links that do not lie flat or articulate freely
Corrosion: pitting or significant surface rust that reduces cross-section
Heat discolouration: blue or purple tint indicates temperature exceedance
Missing ID tag: no identification = no use
Mixed components: G80 and G100 parts in the same assembly