Overview
ISO 9351:2025 - Galvanic anodes for cathodic protection in seawater and saline sediments - defines requirements and recommendations for cast galvanic anodes made from aluminium, magnesium and zinc-based alloys for use in seawater, saline sediments and brackish water. The standard covers chemical composition, electrochemical properties, physical tolerances, and test & inspection procedures for cast anodes in various shapes (trapezoid, circular, half‑spherical, bracelet type, etc.). Information on salinity ranges is provided in Annex A.
Key technical topics and requirements
- Material specifications: Requirements for alloy composition and related electrochemical properties (potential, electrochemical capacity).
- Electrochemical testing: Procedures for performance testing and short‑term quality control tests to assess closed‑circuit potential, capacity and anode behaviour in electrolyte.
- Anode consumption rate: Definition and considerations for calculating mass consumed per ampere‑year - critical for CP system sizing.
- Design and acceptance criteria: Guidance on anode shape, net/gross mass, utilization factor, inserts/cores, cable connections and allowable physical tolerances (Annex B).
- Manufacturing quality & inspection: Sampling (ladle samples), detection of defects (cold shuts, gas holes, cracks, inclusions), and recommended Inspection and Test Plan (ITP) (Annex F).
- Personnel competence: Expectations for qualified personnel performing tests, welding, and inspections.
- Environmental impact: Guidance on environmental considerations for anode selection and deployment (Annex E).
- Supporting information: Informative annexes covering composition/performance data (Annex C) and descriptions of electrochemical test methods (Annex D).
Practical applications
ISO 9351:2025 is intended for specification, procurement, manufacture and verification of galvanic anodes used to protect:
- Offshore and nearshore structures (platforms, jackets)
- Subsea and submarine pipelines (including bracelet anodes for tubular items)
- Ship hulls, marine infrastructure and marine renewable energy components
- Port and coastal assets exposed to brackish or saline environments
Using this standard helps ensure predictable anode performance, accurate CP system design (sizing and lifetime), and consistent QA/QC during production and installation.
Who should use this standard
- Corrosion and cathodic protection engineers
- Anode manufacturers and foundries
- Inspection, testing and QA teams
- Procurement and specification engineers in maritime, offshore oil & gas, and utilities
- Regulatory bodies and certification agencies
Related standards
ISO 9351 references and aligns with other ISO/CEN documents (for example ISO 630, ISO 1461 and welding/inspection standards) that govern steel products, coating and welding practice - useful when integrating anode requirements into broader marine asset specifications.
