ISO 6622-2:2013

Internal combustion engines - Piston rings - Part 2: Rectangular rings made of steel

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.

Moteurs à combustion interne — Segments de piston — Partie 2: Segments rectangulaires en acier

General Information

• Status: Published
• Publication Date: 27-Oct-2013
• ICS: 43.060.10 - Engine block and internal components
• Technical Committee: ISO/TC 22/SC 34 - Propulsion, powertrain and powertrain fluids
• Drafting Committee: ISO/TC 22/SC 34/WG 4 - Piston rings
• Current Stage: 9092 - International Standard to be revised
• Start Date: 25-Jul-2025
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 6622-2:2003 - Internal combustion engines - Piston rings - Part 2: Rectangular rings made of steel
• Effective Date: 17-Oct-2009

Overview

ISO 6622-2:2013 defines the essential dimensional features and nominal sizes for rectangular piston rings made of steel used in reciprocating internal-combustion engines. It covers rings with nominal diameters from 30 mm to 160 mm and specifies four ring types - R (straight-faced), B (barrel-faced), BA (asymmetrical barrel-faced) for h ≥ 1.2 mm, and M (taper-faced). The standard includes designation examples, common features, coatings/nitriding options, and force-factor data relevant to piston-ring selection and manufacturing.

Key topics and technical requirements

• Ring types and geometry: Definitions and figures for Type R, B, BA and M with dimensional tables (width h, axial dimensions, gauge widths).
• Nominal diameter range: Rings from 30 mm up to 160 mm are covered.
• Surface finishes and treatments:
  • Chromium plating / spray coatings - thickness codes (e.g., CR1, CR2; CR2 = 0.100 mm min.) and guidance on fully faced vs. inlaid surfaces.
  • PVD coatings - thickness codes (e.g., PC001, PC003, PC006).
  • Nitriding - case depth codes (e.g., NT030, NT050, … NT130) with peripheral and side-face minimum depths.
• Edge and bevel details: Outside/inside rounding limits, internal bevel (IF/IFU) for ring twist types and tapered rings.
• Force factors and performance data: Tables provide tangential and diametral forces and dimensional/force relationships (used in sealing and friction calculations).
• Designation format: Standard naming convention examples (e.g., Piston ring ISO 6622-2 R - 60 × 1,2 - MC62/CR2).

Practical applications and who uses it

• Engine designers and OEMs use ISO 6622-2 to select appropriate rectangular steel piston rings for road-vehicle and other reciprocating engines, ensuring dimensional compatibility and intended sealing/force performance.
• Ring manufacturers rely on the standard for machining, heat treatment, surface coating/nitriding specifications, and part designation to meet customer requirements.
• Component suppliers and quality engineers use the dimensional tables and force factors for quality control, inspection, and specification of coatings (chromium, PVD) and nitriding depths.
• Aftermarket and repair services reference the standard when matching replacement rings by type, diameter, and surface treatment.

Related standards

• ISO 6622-1: Rectangular rings made of cast iron (same series).
• ISO 6621 series and other piston-ring standards (see ISO 6621-3 and ISO 6621-4 referenced in the introduction for complementary requirements).

Keywords: ISO 6622-2:2013, piston rings, rectangular rings, steel piston rings, internal combustion engines, ring types R B BA M, nitrided, chromium-plated, PVD coating, ring dimensions, force factors.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 6622-2
Second edition
2013-11-01
Internal combustion engines —
Piston rings —
Part 2:
Rectangular rings made of steel
Moteurs à combustion interne — Segments de piston —
Partie 2: Segments rectangulaires en acier
Reference number
©
ISO 2013
© ISO 2013
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
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Published in Switzerland
ii © ISO 2013 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Overview . 1
4 Ring types and designation examples . 1
4.1 Type R — Straight-faced rectangular ring . 1
4.2 Type B — Barrel-faced rectangular ring . 2
4.3 Type BA — Asymmetrical barrel-faced rectangular ring, h ≥ 1,2mm . 4
4.4 Type M — Taper-faced rectangular ring . 5
5 Common features . 6
5.1 Type R — Straight-faced rectangular ring . 6
5.2 Type B — Barrel-faced rectangular ring . 7
5.3 Type BA — Asymmetrical barrel-faced rectangular ring, h ≥ 1,2 mm. 8
5.4 Type M — Taper-faced rectangular ring . 9
5.5 Type R, B, BA, and M rings (positive twist type) — Internal bevel top side . .11
5.6 Type M rings (negative twist type), taper M3 to M5 — Internal bevel bottom side .11
5.7 Type R, B, BA, and M rings — Outside and inside rounded edges .12
5.8 Type R, B, BA, and M rings (fully faced and inlaid) — Plating/coating thickness .12
5.9 Type R, B, BA, and M rings — Nitrided case depth .13
6 Force factors .14
7 Dimensions and forces .14
Bibliography .21
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2. www.iso.org/directives
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received. www.iso.org/patents
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
The committee responsible for this document is ISO/TC 22, Road vehicles.
This second edition cancels and replaces the first edition (ISO 6622-2:2003), which has been
technically revised.
ISO 6622 consists of the following parts, under the general title Internal combustion engines — Piston rings:
— Part 1: Rectangular rings made of cast iron
— Part 2: Regular rings made of steel
iv © ISO 2013 – All rights reserved

Introduction
The ISO 6622 series is one of a number of series of International Standards dealing with piston
[2] [3] [4] [5] [6]
rings for reciprocating internal combustion engines. Others are ISO 6621, ISO 6623,
[7] [8] [9] [10] [12] [13] [14] [15]
ISO 6624,  ISO 6625, ISO 6626, and ISO 6627 (see Bibliography for details).
The common features and dimensional tables presented in this part of ISO 6622 constitute a broad
range of variables and, in selecting a particular ring type, the designer must bear in mind the conditions
under which it will be required to operate.
[4]
It is also essential that the designer refer to the specifications and requirements of ISO 6621-3 and
[16]
ISO 6621-4 before completing his selection.
INTERNATIONAL STANDARD ISO 6622-2:2013(E)
Internal combustion engines — Piston rings —
Part 2:
Rectangular rings made of steel
1 Scope
This part of ISO 6622 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.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
Not applicable.
3 Overview
The rectangular ring types are specified in Tables 1 to 5 and Figures 1 to 6. Their common features and
the dimensions of those features are specified in Tables 6 to 11 and Figures 7 to 22. Tables 12 and 13
give the force factors for the different ring types, while Table 13 gives the dimensions and forces of the
rectangular rings.
4 Ring types and designation examples
4.1 Type R — Straight-faced rectangular ring
4.1.1 General features
Figure 1 shows the general features of piston ring type R.
See Table 13 for dimensions and forces.
Key
1 reference plane
a
t = 0,005 × h .
Figure 1 — Type R
4.1.2 Designation
EXAMPLE Designation of a piston ring complying with the requirements of this part of ISO 6622 (i.e.
ISO 6622-2) being a steel, rectangular ring with a straight-faced peripheral surface (R), of nominal diameter
d = 60 mm (60), of nominal ring width h = 1,2 mm (1,2), made of CrSi alloyed steel, subclass 62 (MC62), and with
1 1
a chromium-plated peripheral surface of a minimum thickness 0,1 mm (CR2). Parameters in parenthesis are used
in the ISO ring designation:
Piston ring ISO 6622-2 R - 60 × 1,2 - MC62/CR2
4.2 Type B — Barrel-faced rectangular ring
4.2.1 General features
See Table 13 for dimensions and forces.
2 © ISO 2013 – All rights reserved

Key
1 reference plane
Figure 2 — Type B
Table 1 — Symmetrical barrel dimensions and gauge width (h )
Dimensions in millimetres
a
h h h h tol. h t , t h
1 25 26 26 27 2 3 8
0,8 0,20 0,40 ± 0,15 0,60 0,001.0,010 0,40
1,0 0,25 0,50 ± 0,15 0,75 0,001.0,011 0,50
1,2 0,30 0,60 ± 0,20 0,90 0,002.0,012 0,60
1,5 0,35 0,75 ± 0,25 1,15 0,80
1,75 0,35 0,85 ± 0,30 1,35 1,00
0,003.0,015
2,0 0,40 1,00 ± 0,30 1,60 1,20
2,5 0,45 1,25 ± 0,40 2,05 1,60
3,0 0,50 1,50 ± 0,50 2,50 2,00
0,005.0,020
3,5 0,55 1,75 ± 0,50 2,95 2,40
a
Gauge width (h ) only informative; may be used only if agreed between manufacturer and customer.
4.2.2 Designation
EXAMPLE Designation of a piston ring complying with the requirements of this part of ISO 6622 (i.e. ISO 6622-2)
being a steel, rectangular ring with a barrel-faced peripheral surface (B), of nominal diameter d = 60 mm (60),
of nominal ring width h = 1,5 mm (1,5), made of martensitic steel (17 % Cr), subclass 66 (MC66), nitrided on the
peripheral surface and side faces (NT), to a depth of 0,03 mm min. on the peripheral surface (030), and with an
associated side face depth of 0,010 mm min. Parameters in parenthesis are used in the ISO ring designation:
Piston ring ISO 6622-2 B - 60 × 1,5 - MC66/NT030
4.3 Type BA — Asymmetrical barrel-faced rectangular ring, h ≥ 1,2mm
4.3.1 General features
See Table 13 for dimensions and forces.
Key
1 referen
...