ISO 20313:2018

Overview

ISO 20313:2018 - "Ships and marine technology - Cathodic protection of ships" provides internationally accepted guidance for the design, specification, commissioning, operation and maintenance of cathodic protection (CP) systems for ships. It specifies protection criteria and makes recommendations for both impressed current and galvanic anode systems applied to immersed hulls and seawater-containing tanks (e.g., ballast tanks). The standard covers common hull fixtures (rudders, propellers, shafts, stabilizers, thrusters, sea chests, water intakes up to the first valve) and applies to hulls made principally from carbon manganese or low-alloy steels (coated or bare). It does not cover hulls principally made of aluminium alloys, stainless steel hulls, concrete structures, or non–self-propelled floating structures.

Key topics and technical requirements

• Protection criteria and design basis: Defines objectives for CP effectiveness and the design process for shipboard systems.
• Design considerations: Zoning of external and internal areas, component characteristics, service conditions and current demand estimation.
• System types: Guidance on both impressed current and galvanic anode systems, including selection, placement and life estimation of anodes.
• Electrical continuity and bonding: Requirements and practices to ensure electrical continuity between hull and fittings for effective CP.
• Equipment and materials: Recommendations for power sources, monitoring and control systems, anode materials, dielectric shields, cables, permanent reference electrodes and cofferdams.
• Commissioning, operation and maintenance: Measurement procedures, pre-energizing checks, initial energizing, performance assessment, maintenance during service and dry-docking.
• Documentation and testing: Reporting requirements, as-built records and guidance for monitoring systems.
• Informative annexes: Practical design examples, current-density guidance, formulae for anode resistance/life, bonding systems, monitoring of propeller bonding, cofferdam arrangements and anode specifications.

Practical applications

• Designing CP systems for newbuild ships and retrofitting CP for in-service vessels.
• Specifying materials, anode types and placement for external hulls and ballast tanks.
• Establishing commissioning and maintenance procedures to ensure long-term corrosion protection.
• Assessing current demand and anode life for operational planning and dry-docking schedules.
• Integrating CP systems with hull coatings and electrical/propulsion components to prevent stray current and galvanic interactions.

Who should use this standard

• Marine and corrosion engineers
• Naval architects and ship designers
• Shipbuilders and shipyards (fitting-out teams)
• Classification societies and surveyors
• Shipowners, operators and maintenance contractors
• Suppliers of anodes, CP rectifiers and monitoring equipment

Related standards

• ISO 12473 - General principles of cathodic protection in seawater (referenced for fundamental CP principles)

Keywords: ISO 20313:2018, cathodic protection, ships, impressed current, galvanic anode, hull corrosion protection, ballast tanks, marine technology, ship design, seawater.