Overview
ISO 16798:2004 - "Links of Grade 8 for use with slings" specifies requirements for forged or welded steel master links, intermediate master links, master link assemblies and lower terminal links of Grade 8 with Working Load Limits (WLL) up to 132 t. The standard covers design, materials, heat treatment, manufacture, mechanical performance and testing for links primarily used with chain slings (ISO 4778 / ISO 7593), wire rope slings (ISO 7531) and textile slings (EN 1492-1 / EN 1492-2). It is not applicable to hand‑forged links.
Key topics and technical requirements
- Link types & geometry: Parallel‑sided (forged or welded) and pear‑shaped (forged with integral joining devices). Internal dimensions are specified relative to WLL to ensure articulation and correct load direction.
- Materials & chemistry: Steel must be fully killed, electric or oxygen‑blown, stabilized against strain‑age embrittlement (Al ≥ 0.025 %) and meet limits for sulfur/phosphorus. Forged and welded links must include specific alloying elements (e.g., Ni, Cr, Mo) as required.
- Heat treatment: Links shall be hardened above AC3 and tempered (minimum 400 °C, typically 1 h at 400 °C or equivalent) prior to manufacturing proof testing; surface hardening is prohibited.
- Manufacture & workmanship: Forged links - hot‑forged in one piece with clean finishes; welded links - resistance or flash butt welds centered in the leg with controlled heat‑affected zones.
- Mechanical performance:
- Manufacturing Proof Force (MPF) = 2.5 × WLL (account for g) - links and load‑bearing pins must sustain MPF without permanent deformation beyond tolerances.
- Breaking Force (BF) = 4 × WLL (account for g) - forged links must deform; welded links require ≥20% total ultimate elongation.
- Fatigue resistance: links with WLL ≤ 32 t must withstand at least 20,000 load cycles per specified force range.
- Testing & verification: Type tests (deformation, static tensile, fatigue, bend deflection) on three samples per size/design; testing by a competent person with calibrated equipment (ISO 7500‑1).
- Traceability & documentation: Marking requirements, traceability codes, manufacturer’s certificate and instructions for use are specified.
Applications and users
ISO 16798:2004 is used by:
- Manufacturers of lifting links, master links and lower terminals
- Sling assemblers and riggers (chain, wire rope, textile slings)
- Test laboratories and quality assurance personnel
- Procurement specialists, safety officers and inspectors ensuring compliance with lifting equipment safety and WLL ratings
Practical applications include crane slings, multi‑leg assemblies, lifting accessories and any situation requiring certified Grade 8 links for load handling.
Related standards
- ISO 4778, ISO 7593 (chain slings)
- ISO 7531 (wire rope slings)
- EN 1492‑1 / EN 1492‑2 (textile slings)
- EN 818 series (chain lifting components)
- ISO 7500‑1 (test machine verification)
Keywords: ISO 16798:2004, Grade 8 links, master link, working load limit (WLL), manufacturing proof force, breaking force, fatigue resistance, chain slings, wire rope slings, textile slings, lifting equipment.
