Overview
ISO 19097-2:2018 specifies an accelerated life test method for mixed metal oxide (MMO) anodes used in impressed current cathodic protection (ICCP) in soils and natural waters. The standard defines how to simulate aggressive electrochemical conditions in the laboratory so manufacturers, specifiers and end‑users can compare anode durability and assess whether anodes are likely to meet a designed service life at rated current output.
Key topics and technical requirements
- Test principle: operate MMO anodes at elevated current density in a controlled electrolyte to accelerate deactivation mechanisms (oxygen evolution at the anode).
- Electrolytes: chloride‑free solutions are required (to avoid chlorine evolution). Typical examples given in the standard include 1 M H2SO4, 1 M Na2SO4, and 180 g/L Na2SO4 with 0.1 N H2SO4 to maintain pH ≈ 1. Fresh electrolyte is used and concentration is controlled to ±5%.
- Temperature control: test solution maintained at 30 °C ± 5 °C.
- Apparatus and cell setup:
- Glass vessel (e.g., 1 L beaker), agitation (magnetic stirrer), thermometer/thermocouple, and secure fixtures for anode/cathode positioning.
- Typical anode‑to‑cathode gap ≈ 20 mm; anode edges kept ≥10 mm from liquid level and bottom.
- Cathode materials specified include zirconium, titanium, niobium or platinum.
- Constant‑current power supply with continuous voltage monitoring (high‑impedance voltmeter/data logger recommended).
- Specimens and replication: usually three, minimum two, duplicate specimens tested under identical conditions.
- Failure criterion: anode failure is identified by a rapid rise in cell voltage. The test standardises failure as a cell voltage increase of 1.5 V above the starting voltage (where starting voltage is measured after 3 hours’ stabilisation).
- Safety and continuity: tests must be carried out in well‑ventilated fume hood (oxygen/hydrogen evolution), minimise test interruptions, and maintain current stability.
Applications and who uses it
- MMO anode manufacturers - for product development, quality control and lifetime claims.
- Corrosion engineers and consultants - to select anodes and validate designs for buried pipelines, cathodic protection of marine structures, and rebar protection in chloride‑contaminated environments.
- Asset owners and specifiers - to compare anode options and set procurement requirements against expected service life.
- Test laboratories - to run reproducible accelerated life tests for certification or comparative evaluation.
Related standards
- ISO 19097 series (other parts addressing different environments or test correlations)
- ISO 8044 (corrosion terms and definitions)
- NACE TM0108‑2012 (noted source material referenced in the standard)
Keywords: ISO 19097-2, MMO anode, mixed metal oxide anode, accelerated life test, cathodic protection, impressed current, anode durability, soil and natural waters, service life evaluation.