ISO 4778:2019

Overview

ISO 4778:2019 specifies requirements, rating methods and testing for round steel short link chain slings of welded construction - Grade 8. It covers single, double, three- and four‑leg chain slings built from compliant components (sling chains, links, hooks and forged components) and applies to nominal diameters dn from 4 mm to 45 mm. Chain slings under this standard are intended for use in the temperature range –40 °C to +400 °C and are designed for symmetrically distributed loads only. Mechanically joined chain slings are excluded.

Key topics and technical requirements

• Scope and construction: Applies to welded chain slings of Grade 8 using components meeting ISO 3076 (sling chains), ISO 16798 (links), ISO 7597 (hooks) and ISO 8539 (forged components).
• Component compatibility: Master links, intermediate links, joining links, end links and hooks must provide free articulation and be dimensioned to fit shank hooks and other terminal components (see Annex C).
• Working Load Limit (WLL): WLL values and load factors for single- to four-leg slings (including angle effects) are provided; Annex A gives bases for calculation.
• Mechanical testing: Proof load, manufacturing proof force (MPF), breaking force and static tensile testing of test sections are specified. Only authorized manufacturers or licensees may weld, heat‑treat or test slings.
• Dimensional tolerances and assembly: Nominal reach tolerance of +2/0 chain links; after proof loading, leg length differences under 20% WLL are limited (≤10 mm for legs ≤2 m; increases authorized for longer slings).
• Marking and certification: Requirements for marking and manufacturer’s certificates are included to enable traceability and conformity assessment.
• Limitations: For asymmetrical loading, maintenance and special rating see ISO 3056; mechanically joined slings refer to ISO 7593.

Practical applications and users

ISO 4778:2019 is intended for organizations and professionals involved in lifting and rigging, including:

• Chain manufacturers and licensed fabricators (welding, heat treatment, testing)
• Rigging engineers, lifting equipment designers and safety officers
• Inspection bodies and test laboratories
• Procurement and asset managers in construction, shipping, offshore, manufacturing and heavy industry

Use cases include design, fabrication, verification and in-service inspection of Grade 8 welded chain slings for cranes, hoists and other lifting systems where robust, high-strength chain slings are required.

Related standards

• ISO 3076 - Sling chains (Grade 8)
• ISO 16798 - Links of Grade 8
• ISO 7597 - Forged steel lifting hooks (Grade 8)
• ISO 8539 - Forged lifting components
• ISO 3056 - Use and maintenance; asymmetrical load rating
• ISO 7593 - Mechanically joined chain slings
• ISO 1834 - General conditions of acceptance

Keywords: ISO 4778:2019, chain slings, Grade 8, welded construction, round steel short link chains, working load limit, WLL, rigging, lifting standards.