ISO 24042:2020

Overview

ISO 24042:2020 defines requirements for tandem mooring winches used in crude oil offloading systems of liquid cargo handling equipment. The standard covers design, operation, performance and acceptance tests for winches and associated quick‑release mechanisms, and is intended for the design, manufacture and acceptance of mooring winches employed during ship-to-ship or ship-to-shore crude oil offloading.

Key topics and technical requirements

• Scope and types: Specifies left (L), right (R), bottom (B) and top (T) drive arrangements relative to the operator.
• Design requirements: Winch design must meet ISO 7825 and related clauses (material stresses, basic calculations, drum and hawser, quick release, brake, operating devices and auxiliary equipment).
• Material stresses & calculations:
  • Allowable calculated stress under hawser deployment/recovery load ≤ 0.4 × upper yield strength.
  • Allowable calculated stress under safe working load (SWL) ≤ 90% × upper yield strength.
  • Actuator power in dynamic calculations ≤ 80% of rated power.
  • Hawser deployment/recovery load ≤ 33% of hawser design breaking load at nominal speed.
  • SWL ≤ 80% of hawser design breaking load.
• Drum and hawser:
  • Drum diameter for polyester/nylon ropes ≥ 6 × rope diameter; for polypropylene ≥ 4 × rope diameter.
  • Drum flange must project ≥ 1.5 × main rope diameter above outermost layer.
  • Hawser components include main rope, chafe chains, thimbles, shackles, messenger rope and buoys; tail chafe chain requirements differ if quick‑release is independent vs integrated.
• Quick release mechanism:
  • Can be integrated or independent; must monitor mooring pull in the 1.1–1.3 × SWL range.
  • Alarm thresholds at 60% and 75% of SWL.
  • Maximum allowable release delay: 4 seconds.
• Brake & operating device:
  • Drum brake must resist deployment/recovery loads.
  • Controls should auto‑return to stop when released and have permanent directional signage.
• Acceptance tests:
  • No‑load run: 30 min at nominal speed (15 min forward, 15 min reverse).
  • Hawser deployment/recovery: 30 min at nominal speed under specified load.
  • Braking test, SWL test (30 min under SWL with no significant plastic deformation), quick release tests at 1% and 100% SWL (release time ≤ 4 s).
• Marking and designation: Product model designation example and required nameplate data (product name/model, weight, serial, manufacturer, etc.).

Applications and users

ISO 24042:2020 is used by:

• Winch manufacturers and designers
• Shipyards and offshore terminal builders
• Marine and offshore engineers
• Classification societies and flag administrations
• Purchasers/operators of crude oil offloading systems

It ensures safety, interoperability and verifiable performance for tandem mooring winches in crude oil offloading operations.

Related standards

Key normative references include:

• ISO 3828 - Deck machinery vocabulary and symbols
• ISO 7825 - Deck machinery general requirements
• ISO 3730:2012 - Mooring winches
• ISO 7365:2012 - Towing winches for deep sea use

Keywords: ISO 24042:2020, tandem mooring winches, crude oil offloading system, hawser quick release, safe working load (SWL), drum diameter, acceptance tests, liquid cargo handling equipment.