ISO 6621-5:2005 specifies those quality aspects of piston rings that are capable of definition but not normally found on a drawing specification.
It covers the following:
- single-piece piston rings of grey cast iron or steel;
- multi-piece piston rings (oil control rings) consisting of cast iron parts and spring components;
- single-piece and multi-piece oil control rings of steel, i.e. oil control rings in the form of strip steel components or steel segments (rails) with spring expander components.