ISO/TC 22/SC 34/WG 4 - Piston rings

This document specifies the essential dimensional features of expander/rail oil-control rings, without providing a complete product description (because expander‑rail designs vary from piston-ring manufacturer to piston-ring manufacturer, the interaction between the manufacturer and the client will determine specific design details). This document applies to expander/rail oil-control rings of nominal diameters ranging from 40 mm to 140 mm for reciprocating internal combustion engines for road vehicles and other applications. It also applies to piston rings for compressors working under analogous conditions.

This document specifies the essential dimensional features of rectangular rings made of cast iron, Types R, B, BA and M, having diameters up to and including 200 mm, used in reciprocating internal combustion piston engines. It is also applicable to piston rings of compressors working under similar conditions.

This document classifies materials intended for the manufacture of piston rings, based on their mechanical properties and the stresses the materials are capable of withstanding. This document is applicable to piston rings for reciprocating internal combustion engines up to and including those of 200 mm in diameter. It is also applicable to piston rings of compressors working under similar conditions.

This document defines the measuring principles to be used for measuring piston rings; it applies to piston rings up to and including 200 mm diameter for reciprocating internal combustion engines. This document can be used for piston rings for compressors working under analogous conditions.

This document specifies quality aspects that can be defined but that are 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; and — 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. In addition to specifying some of the limits of acceptance relating to inspection measuring principles (covered by ISO 6621‑2), this document also covers those features for which no recognized quantitative measurement procedures exist and which are only checked visually with normal eyesight (glasses if worn normally) and without magnification. Such features (superficial defects) are additional to the standard tolerances of ring width, radial wall thickness and closed gap. This document does not establish acceptable quality levels (AQL), it being left to manufacturer and customer to decide the appropriate levels jointly. In this case, the recommendations of ISO 2859‑1 are followed. This document specifies the quality requirements of piston rings for reciprocating internal combustion engines for road vehicles and other applications. It is applicable to all such rings of a nominal diameter from 30 mm up to and including 200 mm.

This document specifies the essential dimensions of coil-spring-loaded oil control rings made of steel, of piston ring types SOR (with R-shaped groove) and SOV (with V-shaped groove). This document applies to coil-spring-loaded oil control rings made of steel with a diameter from 60 mm up to and including 160 mm for reciprocating internal combustion engines. It can also be used for piston rings in compressors working under analogous conditions.

ISO 6621-1:2018 defines the most commonly used terms for piston rings. These terms designate either types of piston rings or certain characteristics and phenomena of piston rings. The terms and definitions in this document apply to piston rings for reciprocating internal combustion engines. They may also be used for piston rings of compressors working under analogous conditions. NOTE 1 Further terms and definitions covering measuring principles are given in ISO 6621-2:2003. NOTE 2 This document gives the equivalent terms in the Chinese, English, French, German, Italian, Japanese, Portuguese, Russian and Spanish language.

ISO 6624-1:2017 specifies the essential dimensional features of keystone rings made of cast iron, types T, TB, TBA, TM, K, KB, KBA and KM, having diameters from 70 mm up to and including 200 mm, used in reciprocating internal combustion piston engines.

ISO 6624-3:2017 specifies the essential dimensional features of keystone rings made of steel, types T, TB, TBA, TM, K, KB, KBA and KM, having diameters from 70 mm up to and including 160 mm, used in reciprocating internal combustion piston engines.

ISO 6624-4:2016 specifies the essential dimensional features of half keystone rings made of steel, types HK, HKB and HKBA, having nominal diameters from 50 mm up to, and including, 160 mm, used in reciprocating internal combustion piston engines for road vehicles and other applications.

ISO 6624-2:2016 specifies the essential dimensional features of half keystone rings made of cast iron, types HK, HKB and HKBA, having nominal diameters from 38 mm up to, and including, 160 mm, used in reciprocating internal combustion piston engines for road vehicles and other applications.

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.

ISO 6622-2:2013 specifies the essential dimensional features of rectangular rings made of steel, types R, B, BA, and M having nominal diameters from 30 mm up to and including 160 mm, used in reciprocating internal combustion piston engines for road vehicles and other applications.

ISO 6626-2:2013 specifies the essential dimensional features of coil-spring-loaded oil control rings made of cast iron, types DSF-C, SSF, GSF, DSF, SSF-L, DSF-NG and DSF-CNP. It is applicable to those piston rings in sizes 60 mm to 110 mm, inclusive, for reciprocating internal combustion engines for road vehicles and other applications.

ISO 6623:2013 specifies the essential dimensional features of scraper rings made of cast iron, types N, NM, E, and EM, having diameters from 30 mm up to and including 200 mm, used in reciprocating internal combustion engines for road vehicles and other applications.

Specifies the essential dimensions of piston ring types DSF-C, DSF-CNP, SSF, GSF, DSF, DSF-NG and SSF-L coil-spring-loaded oil control rings. The normal range for the axial width of coil-spring-loaded oil control rings (3 to 8 mm inclusive) is divided into 0,5 or 1,0 mm steps. Applies to coil-spring-loaded oil control rings up to and including 200 mm diameter for reciprocating internal combustion piston engines and may also be used for piston rings of compressors working under similar conditions.

Specifies the essential dimensional features of S-, G-, D- and DV-oil control piston ring types. The normal range for the axial width of oil control rings (2,5 to 8 mm inclusive) is divided into 0,5 or 1,0 mm increments. Applies to oil control rings up to and including 200 mm diameter for reciprocating internal combustion piston engines and may also be used for piston rings for compressors working under similar conditions.

ISO 6621-5:2013 specifies those quality aspects that are capable of definition but not normally found on a drawing specification. It is applicable to 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. In addition to specifying certain of the limits of acceptance relating to inspection measuring principles (covered by ISO 6621-2), ISO 6621-5:2013 also covers those features for which no recognized quantitative measurement procedures exist and which are only checked visually with normal eyesight (spectacles if worn normally) and without magnification. Such features (superficial defects) are additional to the standard tolerances of ring width, radial wall thickness, and closed gap. ISO 6621-5:2013 does not establish acceptable quality levels (AQL), it being left to manufacturer and client to decide the appropriate levels jointly. In this case, the recommendations of ISO 2859 are followed. ISO 6621-5:2013 specifies the quality requirements of piston rings for reciprocating internal combustion engines for road vehicles and other applications. It is applicable to all such rings of a nominal diameter from 30 mm up to and including 200 mm.

ISO 6627:2011 specifies the essential dimensional features of expander/segment oil-control rings, without providing a complete product description (because expander‑spacer design varies from piston-ring manufacturer to piston-ring manufacturer, the interaction between the manufacturer and the client will determine specific design details). It applies to expander/segment oil-control rings of nominal diameters ranging from 40 mm to 125 mm for reciprocating internal combustion engines for road vehicles and other applications. It also applies to piston rings for compressors working under analogous conditions.

ISO 6626-3:2008 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). ISO 6626-3:2008 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.

ISO 6622-1:2003 specifies the essential dimensional features of rectangular rings made of cast iron, types R, B, BA and M, having diameters up to and including 200 mm, used in reciprocating internal combustion piston engines. It is also applicable to piston rings of compressors working under similar conditions.

ISO 6621-2:2003 specifies the principles to be used in the measuring for inspection purposes of piston rings for both reciprocating internal combustion engines and compressors working under analogous conditions. It is applicable to all such rings of a diameter greater than or equal to 200 mm.

ISO 6624-4:2003 specifies the essential dimensional features of half keystone rings made of steel, types HK and HKB, having diameters of from 38 mm up to and including 160 mm, used in reciprocating internal combustion piston engines.

ISO 6624-2:2003 specifies the essential dimensional features of half keystone rings made of cast iron, types HK and HKB, having diameters of from 38 mm up to and including 160 mm, used in reciprocating internal combustion piston engines.

This part of ISO 6621 classifies materials intended for the manufacture of piston rings, based on their mechanical properties and the stresses the materials are capable of withstanding. This part of ISO 6621 is applicable to piston rings for reciprocating internal combustion engines up to and including those of 200 mm in diameter. It is also applicable to piston rings of compressors working under similar conditions.