Overview
ISO 8838:2024 - Plain bearings - Water-lubricated plain bearing materials defines requirements for the selection and use of water-lubricated plain bearing materials and their mating (shaft) materials. The standard covers bearings operating under fluid‑film, mixed, and non‑lubricated → fluid‑film conditions using water as the lubricant (pure, tap, river or seawater). It also addresses lubrication methods, design considerations, and material compatibility. This document excludes water solutions containing chemicals, refrigerants or liquid fuels.
Key topics and requirements
- Material families specified: wood‑based; carbon‑based; rubber‑based; thermosetting resin; fluoro resin (PTFE/PFA/FEP); thermoplastic resins (PA, POM, PPS, PEEK, PU, PES); ceramic (Si3N4, SiC, Sialon); and cermet (WC, TiC, Cr3C2 coatings).
- Mating (shaft) materials: guidance on corrosion resistance and high surface hardness (preferably HV 600 or higher) to resist wear from hard foreign matter; exceptions for rubber bearings where shaft hardness can be lower.
- Lubrication methods: describes water supply strategies - forced supply, circulating supply, and fully immersed operation - and associated selection implications.
- Design considerations: temperature effects (freezing/boiling limits), low viscosity and limited elastohydrodynamic support of water versus oil, corrosion risk, and foreign‑matter removal strategies.
- Material properties: notes on self‑lubricating vs non‑self‑lubricating materials (e.g., many resin and carbon types are self‑lubricating; ceramics and cermets generally are not) and seawater compatibility (risk of galvanic corrosion with some carbon materials).
- Scope limits and normative references: refers to ISO 4378 parts, ISO 1043‑1 and ISO 8044; cites ISO 19259 and ISO 20054 as additional material sources.
Practical applications and who uses this standard
ISO 8838:2024 is directly applicable to:
- Marine engineers (stern tubes, propulsion bearings)
- Pump and submersible equipment manufacturers
- Hydroelectric turbine and generator designers
- Water treatment and valve equipment OEMs
- Materials and tribology engineers specifying bearings for water-lubricated environments
- Maintenance and reliability teams assessing retrofit or replacement options
Use cases include selection of seawater‑compatible bearing linings, specifying shaft surface hardness and plating, defining water supply arrangements, and designing bearings to tolerate abrasive contaminants (sand, grit) and temperature limits.
Related standards
- ISO 4378 (Parts 1–3) - plain bearing terminology, properties, friction and wear, lubrication
- ISO 1043‑1 - plastics symbols/abbreviations
- ISO 8044 - corrosion vocabulary
- ISO 19259, ISO 20054 - additional bearing material references
Keywords: ISO 8838:2024, water‑lubricated plain bearings, bearing materials, mating shaft materials, seawater compatibility, fluid‑film lubrication, mixed lubrication, bearing design.
