ISO 16625:2025

Overview

ISO 16625:2025 - "Cranes and hoists - Selection of wire ropes, drums and sheaves" provides a structured proof-of-competence framework and selection criteria for steel wire ropes used in cranes (as defined in ISO 4306-1). The standard covers how rope-drive geometry and drum / sheave geometry influence rope stresses and life expectancy. It replaces the 2013 edition and introduces a cycle-based approach and a new mathematical method for assessing fatigue strength (S–N curves and a characteristic reference point).

Key topics and technical requirements

• Scope and terminology: Definitions for running ropes and stationary ropes, design life, work cycles and rope bending diameter.
• Proof of competence: Methodologies for demonstrating adequate performance, separated into:
  • Static strength proofs (including limit design rope forces).
  • Fatigue strength proofs using a new reference point and S–N curves that account for different D/d ratios (drum/sheave bending diameter over rope diameter).
  • Multilayer spooling specific proofs for ropes that coil in multiple layers on drums.
• Geometry effects: Incorporation of rope-drive geometry, drum and sheave groove radii, fleet angles, and reeving arrangements into force and fatigue calculations.
• Rope types and terminations: Guidance on rope selection, rope terminations (ferrules, socketing, swage terminals) and how termination type affects allowable forces.
• Operational and inspection criteria: Discard criteria, estimated number of relevant bending cycles, and assumed number of hoist ropes over the design life.
• Symbols and parameters: Comprehensive symbol set (design forces, limit forces, factors for lubrication, diameter influence, etc.) used in proofs.

Applications and users

ISO 16625:2025 is intended for practical use by:

• Crane and hoist designers - to select ropes, drums and sheaves and to verify static and fatigue competence.
• Manufacturers and rope suppliers - for specification and testing of wire ropes and terminations.
• Safety engineers and inspectors - to assess discard criteria, inspection intervals and maintenance planning.
• Consultants and certifying bodies - performing conformity assessments and design reviews.

Typical applications include hoist rope specification, verifying multilayer drum arrangements, calculating design rope forces under different reeving and fleet-angle conditions, and using S–N based fatigue proofs to predict rope life in cycles.

Related standards

ISO 16625:2025 is intended to be used alongside relevant standards such as:

• ISO 2408, ISO 4301-1, ISO 4306-1, ISO 4309
• ISO 8686 (design loads series), ISO 17893, ISO 20332
• EN 13411 series (rope terminations)

Keywords: ISO 16625:2025, wire ropes, cranes, hoists, drums, sheaves, rope selection, proof of competence, fatigue strength, static strength, multilayer spooling, D/d ratio, S–N curve.