G80 lifting components are the forged alloy steel master links, coupling links and hooks used to build Grade 80 chain slings for overhead lifting. In the United States they are specified by ASTM A952/A952M, assembled into slings under ASTM A906/A906M and used within ASME B30.9 at a minimum 4:1 design factor; the grade number reflects a nominal stress of about 800 N/mm² at the chain’s minimum breaking force. Before stocking them, an importer or distributor should confirm which standard the supplier builds to, how parts are proof tested, how they are marked and traced, and that every fitting matches the size and grade of the chain already on the shelf.
What does “Grade 80” mean on chain and fittings?
Grade 80 describes strength per unit of cross-section: 80 decanewtons, or 800 newtons, per square millimetre of nominal stress when the chain reaches its minimum breaking force, calculated over both legs of the link. In the NACM Welded Steel Chain Specifications, 10 mm (3/8 in) Grade 80 chain has a minimum breaking force of 126 kN across a combined cross-section of about 157 mm², and a working load limit of 7,100 lb (3,200 kg), one quarter of that breaking force.
The neighbouring grades are not interchangeable. Grade 70 is heat-treated carbon steel transport chain, covered by ASTM A413 and intended for load securement; NACM states it is not to be used in overhead lifting. Grade 100 (ASTM A973/A973M) is also alloy chain but carries roughly 25 percent more working load at the same size, so its fittings are dimensioned and rated differently. Grade 120 is a newer, largely manufacturer-specific category that neither ASTM chain specification covers. Under NACM’s rule, a mixed assembly is rated at the working load limit of its lowest-rated chain or component.
Which standards govern G80 rigging hardware in North America?
- ASTM A391/A391M: Grade 80 alloy steel chain for slings, lifting assemblies and load binding.
- ASTM A973/A973M: the Grade 100 equivalent.
- ASTM A952/A952M: forged alloy steel lifting components and welded coupling and master links for Grade 80 and Grade 100 chain slings. It sets steel chemistry plus proof, breaking-force, deformation and fatigue tests.
- ASTM A906/A906M: assembly, rating and testing of Grade 80 and 100 chain slings from those parts; it excludes use above 400°F (204°C).
- ASME B30.9: sling use and inspection. It calls for chain to A391 or A973 and fittings to A952; other hooks must meet ASME B30.10 and other rigging hardware ASME B30.26.
- ASME B30.26: detachable rigging hardware, including shackles, links and master link subassemblies, rings, swivels, turnbuckles, eyebolts, hoist rings, wire rope clips, wedge sockets and blocks.
- OSHA 29 CFR 1910.184: the federal rule for slings in general industry.
The National Association of Chain Manufacturers (NACM) publishes the Welded Steel Chain Specifications that US makers use for grade definitions, embossing and load tables. In Europe the counterpart is the EN 1677 series, which covers Grade 8 forged components, latch hooks, self-locking hooks and links for chain slings built to EN 818-4.
What does each G80 component do in a chain sling?
A chain sling is a master link, one or more chain legs and a lower fitting on each leg, joined by couplers.
- Master links and master link assemblies: the oblong link that sits on the crane hook. Three- and four-leg slings add intermediate master coupling links.
- Coupling links: mechanical couplers, commonly of the hammerlock type, that join chain to master links and hooks without welding, so slings can be assembled from stock. ASME B30.9 bars using them as repair links inside the chain body unless they replace a mechanical link originally approved for that position.
- Sling hooks with latches: the standard eye or clevis lower fitting. The latch only retains a slack sling; it is not meant to carry load.
- Self-locking hooks: the hook closes automatically and stays locked until deliberately released, and ASME B30.10 requires it to be locked during use.
- Grab hooks, shortening hooks and clutches: fittings that seat a chain link to shorten a leg or form an adjustable choker. Ask whether the maker rates them at the full chain working load limit or requires a reduction.
Lifting hooks and fall-protection snap hooks are different products built to different standards (fall-protection connectors fall under ANSI/ASSP Z359.12, not ASTM A952), and one must never be substituted for the other.
How are G80 fittings rated for load, proof test and temperature?
The design factor for alloy steel chain slings is a minimum of 4 under ASME B30.9, so the working load limit is no more than one quarter of the minimum breaking force. Our article on kN ratings, breaking strength and working load limit explains that relationship in general; in service, the WLL on the fitting is the figure that counts.
Proof testing is a manufacturing integrity check, not a design value. ASME B30.9 requires fittings attached to single legs to be proof loaded to at least 2 times the single-leg straight-line rated load, master links for two-leg slings to at least 4 times, and master links for three- and four-leg slings to at least 6 times. Hardware governed by ASME B30.26 has its own minimums (the 2015 edition sets a design factor of 5 for links, rings and swivels), so a swivel or ring sold alongside G80 fittings is not automatically rated on the same basis.
Heat reduces capacity. The ASME B30.9 table for Grade 80 chain gives:
- Below 400°F (204°C): no reduction.
- 400°F: 10 percent while at temperature, no permanent loss.
- 600°F (316°C): 20 percent while hot, 5 percent permanent after exposure.
- 1,000°F (538°C): 60 percent while hot, 25 percent permanent.
- Above 1,000°F: remove from service, which OSHA 1910.184 also requires.
Consult the sling manufacturer before use at −40°F (−40°C) or below.
What markings and traceability should G80 components carry?
ASME B30.26 requires each link, master link subassembly, ring and swivel to be durably marked with the manufacturer’s name or trademark, the size or rated load, and the grade where it is needed to identify the rated load. ASME B30.10 requires hooks to carry the manufacturer’s identification and rated load, forged, cast or die-stamped in a low-stress, non-wearing area. Grade 80 chain is embossed with 8, 80 or 800 at intervals. The finished sling is tagged with manufacturer, grade, size, number of legs, rated load and angle, reach and a serial number, and ASME B30.9 requires removal of any sling whose identification is missing or illegible.
Many manufacturers also add a lot code, and for a distributor that code is what limits a field failure to a defined batch: it ties a hook to a steel heat, forging run and heat-treatment load, so a recall covers one lot rather than every part ever sold. Our article on material traceability and mill test certificates covers the documentation side.
Colour is not a grade indicator. NACM allows a coating of the manufacturer’s or customer’s choice and conventions differ between makers, so grade is confirmed by marking, never by paint.
How are G80 lifting components manufactured?
Most G80 fittings start as closed-die forgings in a fully killed, fine-grained alloy steel; ASTM A952 sets requirements for nickel, chromium, molybdenum, phosphorus and sulfur. After trimming, parts are heat treated, typically quenched and tempered, for the strength and toughness the grade demands. They are then inspected for surface cracks, with magnetic-particle inspection a common method, and proof loaded. Finishing is usually powder coat or paint for corrosion protection, followed by marking and latch assembly. Our articles on hot versus cold forging and on heat treatment cover those processes in depth.
What should you ask a G80 supplier before you stock their parts?
- Standard: which specification the parts conform to (ASTM A952, EN 1677 or an in-house specification), stated in writing.
- Proof testing: what proof load is applied, whether to every part or a sample, and whether records are kept by lot.
- Material: which alloy steel is used, and whether material certificates are available for each heat.
- Marking: manufacturer identification, grade, size or WLL, and a traceability code on every part.
- Latches: whether latches and springs are supplied and fit the hook throat correctly.
- Interchangeability: whether pins, coupler widths and hook throats suit the chain you already sell, so couplers seat without forcing.
- Ratings: whether every fitting, including shortening hooks and clutches, is rated at the full chain WLL.
Buying from a stock programme or commissioning a custom OEM part changes who defines that documentation, not the questions.
Working with Power Honour
Power Honour’s catalogue includes G80 hooks, master links and coupling links alongside stainless shackles, turnbuckles, swivels and quick links, produced with in-house forging, heat treatment and surface finishing in Taiwan. If you are building or extending a lifting hardware range, send the grade, standard and working load limit you need with your drawing or target part, and our engineers will review manufacturability and quote.