ISO 9351:2025

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.

Keywords: ISO 9351:2025, galvanic anodes, cathodic protection, seawater, saline sediments, aluminium anodes, magnesium anodes, zinc anodes, electrochemical testing, anode consumption rate, inspection and test plan.