Differences, where they exist, are shown in Appendix A.

This document specifies the quality aspects that are capable of definition but not normally found on a drawing specification.

The difficulty of trying to define in absolute terms the quality attainable in normal commercial manufacture of piston rings is well known. In this document the commonly encountered aspects of quality in terms of casting defects and other departures from ideal are quantified. Many minor defects are clearly quite acceptable; other defects because of size or numbers are inadmissible.

This document covers the following:

a

Single piece piston rings of grey, carbidic, malleable, spheroidal graphite cast iron or steel;

b

Multipiece piston rings (oil control rings) consisting of cast iron parts and spring components;

c

Single piece and multipiece 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 limits of acceptance relating to inspection measuring principles (covered by SAE J1589) this document also covers those features for which no recognized quantitative measurement procedures exist and which are only checked visually with normal eyesight and without magnification. Such features (superficial defects) are additional to the standard tolerances of ring width, radial wall thickness, and closed gap.

The requirements of this document apply to all rings up to and including 200 mm diameter covered by the above classification for both reciprocating internal combustion engines and compressors.