Overview
ISO 7593:1986 - Chain slings assembled by methods other than welding - Grade T(8) specifies requirements, rating methods and testing for single-, two-, three- and four‑branch chain slings assembled by non‑welded joining methods. It applies to Grade T(8) short‑link lifting chain (used with components such as master links, intermediate master links, lower terminals and mechanical joining devices) and excludes welded slings, endless slings, slings with unequal branch reaches and special‑purpose slings.
This standard supports safe lifting practice by defining design, material, testing and marking criteria for lifting equipment, chain slings and related components.
Key Topics and Requirements
- Scope and definitions: Clear definitions of chain sling, master link, intermediate master link, lower terminal, mechanical joining device, proof load and working load limit (WLL).
- Design & construction: Examples of single‑, double‑, three‑ and four‑leg sling configurations; requirements to prevent unintentional disconnection and to allow free articulation of links.
- Materials & heat treatment: Steel quality and heat‑treatment rules to achieve required metallurgical and mechanical properties; guidance on alloying elements and grain size. Limits on impurity content (e.g., sulfur and phosphorus) are specified to ensure material integrity.
- Dimensions & tolerances: Chain dimensions per ISO 3076 and dimensional rules for master and lower terminal links to fit crane hooks and permit safe hookup.
- Mechanical joining devices: Must have load‑carrying capabilities at least equal to the chain they connect.
- Testing & proof load: Manufacturing test loads, proof‑load testing of assemblies, and requirements for proof load values and minimum ultimate elongation after proof loading (ductility demonstrated).
- Rating methods: Two rating approaches for multi‑leg slings:
- Uniform load method - assigns uniform WLL across angles (tables provided).
- Trigonometric method - calculates WLL for specific branch angles using cosine factors.
- Final inspection: Visual or proof‑load examination by a competent person; marking and designation conventions for compliance and traceability.
Applications and Users
ISO 7593 is used by:
- Sling and lifting component manufacturers for design and testing
- Rigging companies, crane operators and lifting engineers for safe sling selection and use
- Inspection bodies and safety managers for compliance, acceptance testing and periodic inspections
- Procurement teams specifying certified Grade T(8) chain slings for industrial lifting, construction and maritime operations
Keywords: ISO 7593:1986, chain slings, Grade T(8), working load limit (WLL), proof load testing, master link, mechanical joining device, lifting equipment.
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