ISO 24020:2022

Overview

ISO 24020:2022 defines a standardized laboratory test method for particle-free erosion corrosion of metallic materials using the jet‑in‑slit configuration. The method reproduces flow‑induced corrosion in single‑phase liquids (no solid particles or gas bubbles) and is intended for ranking material performance, selecting candidate materials and evaluating corrosion inhibitors under controlled hydrodynamic conditions.

Key Topics and Technical Requirements

• Test principle: A jet from a central nozzle impinges perpendicularly on a specimen and flows radially through a narrow slit, producing high shear, rebounding flow and localized turbulence - the conditions that drive erosion corrosion in service.
• Apparatus: Coaxial nozzle and specimen assembly, slit adjuster and transparent test chamber, and a corrosion‑resistant solution circuit (open or closed). Key dimensional requirements from the standard include a nozzle diameter of 1.6 mm, slit width 0.4 mm, and specimen diameter 16.0 mm (tolerances specified in the standard).
• Surface preparation: Meeting surfaces finished to JIS/ISO P600 or finer with a maximum surface roughness of 0.8 μm; edge chamfer/radius not to exceed 0.15 mm.
• Hydrodynamics: The standard describes vertical and horizontal velocity distributions, velocity fluctuations and typical dual‑ring damage patterns (inner ring from high shear, outer ring from turbulence).
• Test conditions: Flow rates may be varied typically from 0.01 to 1.0 L·min−1; temperature control and air saturation requirements are specified. For copper alloys, Annex A recommends a 12.7 g CuCl2·2H2O/L solution and 43 °C test temperature with a recommended duration (Annex A) of 5 h.
• Measurements and reporting: Mass loss, maximum penetration depth, surface topography/photos, cross‑sectional profiles, microstructural evaluation, test solution chemistry (pH, DO), flow rate, duration and full material description are required in the test report.

Applications

• Ranking and comparing metallic materials (e.g., copper alloys, steels) for components exposed to fast‑flowing corrosive liquids (seawater, industrial water, boiler water).
• Selecting candidate construction materials for pumps, valves, piping, heat‑exchangers and other components susceptible to flow‑induced metal loss.
• Testing and screening corrosion inhibitors and mitigation strategies under controlled, reproducible conditions.
• R&D and qualification testing to reproduce localized erosion‑corrosion modes observed in the field.

Who Uses This Standard

• Corrosion/materials engineers and testing labs
• R&D teams developing alloys and inhibitors
• Asset owners and plant designers responsible for water‑handling equipment
• Quality assurance and failure‑analysis specialists

Related Standards

• ISO 8044 - Corrosion of metals and alloys: Vocabulary (normative reference used by ISO 24020:2022).

Keywords: ISO 24020:2022, jet‑in‑slit, particle‑free erosion corrosion, corrosion testing, flow‑induced corrosion, copper alloys, steels, nozzle, slit, test method.