EN ISO 18086:2020 PDF

Overview

EN ISO 18086:2020 (ISO 18086:2019) - Corrosion of metals and alloys - Determination of AC corrosion - Protection criteria - specifies protection criteria and practical procedures for assessing and managing AC corrosion on buried, cathodically protected pipelines exposed to AC interference. It applies to pipelines influenced by AC traction systems and/or AC power lines and covers AC voltages at frequencies between 16.7 Hz and 60 Hz. The standard defines limits, measurement methods, mitigation measures and long‑term evaluation procedures for AC corrosion likelihood. It does not address electrical safety issues related to AC voltages (see EN 50443).

Key topics and requirements

• Scope and applicability: Buried cathodically protected pipelines subjected to conductive, inductive or capacitive coupling with AC power systems.
• Assessment of AC influence: Procedures to determine the level and character of AC interference on the structure.
• Evaluation of AC corrosion likelihood: Requirements for determining AC and DC current densities, current ratios, soil resistivity effects, coating condition and expected metal loss.
• Acceptable interference levels: Criteria and limits to judge when AC interference poses an unacceptable corrosion risk.
• Measurement techniques: Guidance on instrumentation accuracy, sampling rates, AC voltage measurements, DC potential measurements, and use of coupons/probes to obtain current densities and corrosion-rate data.
• Mitigation measures: Practical measures such as modifying bedding materials, installing isolating joints, mitigation wires, earthing schemes, adjustment of cathodic protection levels, and coating repairs.
• Commissioning, monitoring and maintenance: Procedures for commissioning mitigation systems, verifying effectiveness, and establishing ongoing monitoring programs.
• Informative annexes: Explanations of the AC corrosion phenomenon, coupon/probe methods, coulometric oxidation, soil influence, and selection of decoupling devices.

Practical applications and users

EN ISO 18086:2020 is intended for:

• Pipeline operators and owners assessing AC corrosion risk on buried steel pipelines.
• Cathodic protection engineers, corrosion specialists and consultants performing inspections, measurements and mitigation designs.
• Utilities and power‑line planners coordinating routes and minimizing interference.
• Inspectors and regulatory bodies requiring consistent evaluation methods and documentation for long‑term pipeline integrity.

Use cases include risk assessment near traction systems or high‑voltage lines, design of mitigation systems, commissioning checks, and ongoing monitoring programs to prevent AC‑induced metal loss.

Related standards

• ISO 15589‑1 - Cathodic protection for pipelines (protection criteria without AC interference).
• EN 50443 - Safety requirements for AC voltages on pipelines (national electrical safety/regulation).
• EN ISO 18086:2020 aligns with ISO/TC 156 (corrosion of metals and alloys) and supersedes earlier editions of ISO 18086.