ISO 6972:2002

Overview

ISO 6972:2002 defines the requirements for cranked‑link mill chains of welded construction, their associated attachments and sprockets for conveying bulk materials. The standard specifies chain dimensions, tensile testing and marking to ensure interchangeability of complete chains and individual links for repair and replacement. ISO 6972:2002 applies to sprockets having 5 to 36 teeth and specifies eight attachment types for welded cranked‑link conveyor chains.

Key topics and technical requirements

• Chain design and operation
  • Cranked (offset) link design optimized so the closed end of each link runs forward to maximize scraping action for bulk materials.
  • Nomenclature and component identification (cranked plate, bush, connecting pin).
• Dimensions and interchangeability
  • Detailed dimensional limits (see Table 1 in the standard) for pitch, plate widths, bush and pin diameters, clearances and plate thickness to allow parts from different manufacturers to intermix.
  • Pitch used as the reference for chain length and sprocket geometry.
• Tensile strength and testing
  • Minimum tensile strengths given per ISO chain number; tensile testing procedure described (destructive test on at least three free pitches using shackles allowing universal movement).
  • Clarifies that minimum tensile strength is comparative, not a working load - consult manufacturers for application loads.
• Length accuracy and measuring force
  • Finished chain length measurement procedure (nominal length near 3 048 mm) and specified measuring force to ensure accurate matching and parallel operation where required.
• Attachments
  • Eight standardized attachment types: A1, A2, A22, F2, F4, K1, K2, W1, with dimensional tables (Tables 2–9) and mounting hole/bore guidelines.
• Sprockets
  • Diametral dimensions, tooth gap form, rim profiles, tolerances and marking requirements for sprockets compatible with the chain types specified.
• Marking and designation
  • Chains must be marked with manufacturer and ISO chain number (prefix “W” for welded designs).

Applications and who uses this standard

ISO 6972:2002 is intended for:

• Conveyor OEMs and designers specifying conveyor chains, attachments and sprockets for bulk handling (mining, cement, grain, steel mills, aggregates).
• Maintenance and reliability engineers who need interchangeable spare parts and accurate chain replacement.
• Manufacturers of welded cranked‑link chains and sprockets for compliance and product specification.
• Procurement teams requiring standard‑based specifications to ensure interoperability between suppliers.

Related standards

• Normative reference: ISO 286‑2 (ISO system of limits and fits - tolerance grades for holes and shafts).
• Prepared by ISO/TC 100 (Chains and chain wheels for power transmission and conveyors).

Keywords: ISO 6972, cranked-link mill chains, welded construction, conveyor chains, attachments, sprockets, interchangeability, tensile strength, chain dimensions, bulk material conveyors.