Overview
ISO 3108:2017 - Steel wire ropes - Test method - Determination of measured breaking force - specifies a tensile test-to-destruction procedure to determine the actual (measured) breaking force of steel wire ropes referenced in ISO 2408. The method is also applicable to other rope types unless a specific standard excludes it or prescribes another method. The standard updates and consolidates sample preparation, machine requirements, procedure, safety and reporting for reliable breaking-force measurement.
Key topics and requirements
- Scope and principle: Tensile loading of a prepared rope specimen until fracture or until the required minimum breaking force is reached.
- Sample preparation methods:
- Molten metal or resin socketing (see ISO 17558) - for many rope constructions (molten metal method for d ≥ 6 mm or wire diameter ≥ 0.5 mm).
- Ferrule pressing - uses metal fittings; fibre cores require replacement with a tapered steel bar at the pressing section.
- Direct gripping - wedge grips/liners suited to rope diameter.
- Wrapping - use of sheaves with a sheave-to-rope diameter ratio of at least 16:1.
- Minimum test length: Specified in Table 1 and depends on nominal diameter and rope construction (stranded vs spiral); larger ropes may require multiple lay lengths.
- Test equipment and calibration: Testing machines must comply with ISO 7500-1 (calibration and verification of force-measuring systems).
- Procedure and test conditions:
- Ambient temperature typically 10 °C to 35 °C (strict control at 23 °C ± 5 °C).
- Alignment of specimen axis with grips; measures to prevent specimen rotation.
- Loading can be rapid until 80% of the minimum breaking force (Fmin) is reached; thereafter load shall increase at no more than 0.5% of Fmin per second.
- Tests may be discounted if fracture occurs within six rope diameters from the grip/termination and Fmin is not reached.
- Safety: Use adequate shielding to protect operators and observers from uncontained broken wires and fragments.
- Test report: Must include reference to ISO 3108, rope identification, nominal diameter, condition (used/unused), sampling/termination method, test conditions (length, speed, temperature) and results (measured breaking force and required minimum breaking force).
Applications and users
ISO 3108:2017 is used by:
- Rope manufacturers for quality control and specification verification
- Independent test laboratories and certification bodies
- Procurement, inspection and quality assurance teams in lifting, marine, offshore, mining, crane and construction sectors
- Design engineers and safety managers who need verified breaking-force data for selection and risk assessment
Related standards
- ISO 2408 - Steel wire ropes - Requirements
- ISO 17558 - Steel wire ropes - Socketing procedures
- ISO 7500-1 - Calibration and verification of testing machines
- ISO 17893 - Steel wire ropes - Vocabulary and classification
Keywords: ISO 3108:2017, steel wire ropes, measured breaking force, tensile test, socketing, ferrule pressing, direct gripping, testing machine calibration.
