This part of ISO 6626 specifies the essential dimensions of coil-spring-loaded, nitrided oil control rings made of steel, of piston ring types SOR (with R-shaped groove) and SOV (with V-shaped groove).

This part of ISO 6626 applies to coil-spring-loaded, nitrided oil control rings made of steel with a diameter of between 60 mm and 200 mm inclusive for reciprocating internal combustion engines. It can also be used for piston rings of compressors working under analogous conditions.