Overview
ISO 13755:2020 - Ships and marine technology - Ship's mooring and towing fittings - Steel rollers - specifies requirements for steel rollers used to lead mooring ropes on ships. The standard defines roller types, nominal sizes, dimensions, materials, construction, manufacturing/inspection and marking. It also provides a normative basis for strength assessment (Annex A) and links to IMO guidance for on-board towing and mooring equipment.
Key topics and requirements
- Types and classification
- Type A: steel casting without upper dust cover
- Type B: steel casting with upper dust cover
- Type C: fabricated from steel plate with dust cover
- Nominal sizes
- Preferred outside diameters D: 150, 200, 250, 300, 350, 400, 450, 500 mm
- Dimensions and drawings
- Detailed dimensional tables and figures for each type and nominal size are specified (assembly, axle, bush, welding details).
- Materials
- Roller: steel casting (yield ≥ 205 N/mm2) or steel plate (yield ≥ 235 N/mm2)
- Axle: weldable steel casting (yield ≥ 350 N/mm2) or equivalent
- Bush: brass, bronze or equivalent
- Construction and foundation
- Foundations and weld connections must transmit maximum loads to hull without plastic deformation or cracks (refer to ISO 13767/13776 for foundations).
- Strength, D/d ratio and rope effects
- Guidance on the D/d ratio (roller diameter to rope diameter) to reduce bend loss of rope strength; rope tensile capacity may be reduced by bend radius per rope manufacturer guidance.
- SWL (safe working load) values are given for nominal sizes and rope deflection angles (θ = 90° and θ = 0°) as reference; actual SWL must account for foundation and under-deck reinforcement.
- Manufacturing and inspection
- Surfaces (including welds) in contact with ropes must be free from flaws and roughness; all rotating parts greased; external anti-corrosion coating required.
- Marking
- SWL to be recorded on the ship’s towing and mooring plan (per IMO MSC/Circ.1175) and marked on the fitting/foundation in tonnes (t).
Applications and practical value
- Ensures safe, uniform design and supply of ship mooring fittings (steel rollers) used as shipside roller fairleads or pedestal fairleads.
- Practical for: shipbuilders, outfitting suppliers, deck machinery manufacturers, naval architects, classification societies, port and terminal engineers, and ship operators preparing towing/mooring plans.
- Helps select compatible rollers and mooring lines, verify foundations/welds, and set on-board SWL limits to reduce rope damage and operational risk.
Related standards
- ISO 13767 - Shipside roller fairleads
- ISO 13776 - Pedestal fairleads
- IMO MSC/Circ.1175 - Guidance on shipboard towing and mooring equipment
Keywords: ISO 13755:2020, steel rollers, ship mooring fittings, SWL, shipside roller fairlead, pedestal fairlead, mooring rope, D/d ratio, maritime standard.