Overview
ISO 22074-3:2021 specifies a proof load test method for pull-out resistance of rail fastening system components (inserts) anchored in sleepers or other supporting elements. The procedure confirms that the force needed to pull an anchorage out of its support exceeds a prescribed proof load value. The standard applies to inserts that are cast-in, glued-in or screwed/attached to concrete, wood, polymeric composite or steel sleepers and supporting elements. It is not applicable to embedded rails.
Key topics and technical requirements
- Test principle: Apply a vertical upward force to the anchored fastening element directly above the anchorage until the prescribed proof load is reached; there must be no evidence of damage that reduces strength or durability.
- Apparatus:
- Actuator capable of at least 25% more than the specified proof load, with a linkage that prevents unrepresentative bending or torsional moments.
- Force-measuring instruments complying with ISO 7500-1:2018 (class 2) over the required force range.
- Test specimens:
- Use a full sleeper, half-sleeper or representative support block (for ballastless track) made without modification.
- Concrete blocks shall have cube strength not greater than the specified in-track concrete and avoid close reinforcement unless representative.
- Inserts must be tested “as made”; for screw-type inserts, load via screw inserted to design depth.
- Procedure parameters:
- Load applied at a constant rate not exceeding 100 kN/min until proof load is reached.
- Maintain proof load for 3 minutes, then remove load without shock/impact.
- Loading geometry: centre line to inner support edge = (100 ± 5) mm (exceptions noted when sleeper geometry restricts this).
- Inspection & reporting:
- Visual inspection post-test for any damage affecting integrity/durability.
- Test report must include ISO reference, lab name/address, test date, specimen description (cast-in/glued-in), origin, maximum applied load and inspection result.
Applications and users
ISO 22074-3:2021 is used to verify mechanical anchorage performance during manufacturing, type approval and quality control. Typical users:
- Rail infrastructure engineers and designers specifying fastening performance
- Sleeper and fastening component manufacturers (concrete, timber, composite, steel)
- Test laboratories performing certification, acceptance or QA testing
- Procurement and compliance teams assessing conformity of fastening systems
Related standards
- ISO 22074-1 - Vocabulary for rail fastening systems
- ISO 7500-1:2018 - Calibration and verification of static testing machines (tension/compression)
- EN 13481 series - Performance requirements for fastening systems (referenced in ISO bibliography)
Keywords: ISO 22074-3:2021, rail fastening systems, proof load test, pull-out resistance, sleepers, cast-in inserts, glued-in inserts, test procedure, track engineering.