ISO 6621-4:2015 specifies the general characteristics of piston rings for reciprocating internal combustion engines for road vehicles and other applications (the individual dimensional criteria for these rings are given in the relevant International Standards). It also provides a system for ring coding, designation, and marking. It is applicable to all such rings of a nominal diameter from 30 mm up to and including 200 mm.
A standard is reviewed every 5 years
Stage: 90.92 (To be revised)
Will be replaced byUnder development