Overview
EN ISO 7622-1:2013 / ISO 7622-1:2013 specifies a standardized, destructive test method for determining the elongation of steel cords that form the carcass of steel cord conveyor belts. The method measures cord elongation under longitudinal traction at 10 % and 60 % of the specified tensile strength. It applies exclusively to conveyor belts with a steel carcass and is intended primarily where manufacturer certificates are not available or in dispute.
Key topics and technical requirements
- Test principle: Traction test on individual steel cords extracted from the belt; elongation measured with an extensometer while tension is applied using a dynamometric tensile testing machine.
- Specimens: Four cords taken from a belt sample (minimum 400 mm), prepared as two S-twist and two Z-twist specimens; rubber coating stripped where gripped.
- Conditioning and atmosphere: Tests normally carried out at 23 °C ± 2 °C and 50 % ± 5 % relative humidity (see ISO 18573, Atmosphere B).
- Tensile machine requirements:
- Rate of jaw separation 25 mm/min ± 5 mm/min.
- Jaw separation capability at least 250 mm.
- Holding device: Must prevent slip; examples include two fixed grooved pulleys of diameter at least 50 mm or 10× cord diameter.
- Extensometer: Accuracy of at least 0.01 %; able to accommodate cord rotation. Measurement limited to 60 % of specified tensile strength due to extensometer sensitivity.
- Initial preload: Apply an initial tractive force equal to 50 × linear density (mass per metre) of the cord to define the zero point.
- Results:
- Record elongation at 10 % and 60 % of specified minimum tensile strength.
- Express elongation as percentage of initial length; report the arithmetic mean of the four specimens to the nearest 0.1 %.
- Report contents: Reference to ISO 7622-1, mean elongation values, and any optional or non‑specified operating details or incidents.
Practical applications
- Verifying the elongation behavior of steel cords during supplier acceptance testing, quality control, or forensic investigation.
- Supporting procurement specifications and contract disputes where manufacturer certificates are absent or questioned.
- Input for belt design considerations where cord elongation influences belt tensioning, tracking, and system performance.
- Laboratory accreditation and routine testing of conveyor belts with steel carcasses.
Who uses this standard
- Conveyor belt manufacturers and steel-cord suppliers
- Independent testing laboratories and research centers
- Mining, bulk-material handling and processing companies specifying or verifying belts
- Certification bodies, quality assurance teams and legal/forensic experts in dispute resolution
Related standards
- ISO 7622-2 - Measurement of tensile strength for steel cord conveyor belts (complements Part 1).
- ISO 18573 - Conveyor belts - Test atmospheres and conditioning periods (referenced for test environment).
Keywords: steel cord conveyor belts, longitudinal traction test, measurement of elongation, EN ISO 7622-1:2013, tensile strength, extensometer, dynamometer, conveyor belt testing.
