National foreword

This British Standard is the UK implementation of ISO 2974:2026. It supersedes BS ISO 2974:2018, which is withdrawn.

The UK participation in its preparation was entrusted to Technical Committee MCE/22, Engines for road vehicles.

A list of organizations represented on this committee can be obtained on request to its committee manager.

Contractual and legal considerations

This publication has been prepared in good faith, however no representation, warranty, assurance or undertaking (express or implied) is or will be made, and no responsibility or liability is or will be accepted by BSI in relation to the adequacy, accuracy, completeness or reasonableness of this publication. All and any such responsibility and liability is expressly disclaimed to the full extent permitted by the law.

This publication is provided as is, and is to be used at the recipient’s own risk.

The recipient is advised to consider seeking professional guidance with respect to its use of this publication.

This publication is not intended to constitute a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 October 2026.

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 document should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

ISO draws attention to the possibility that the implementation of this document may involve the use of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s) which may be required to implement this document. However, implementers are cautioned that this may not represent the latest information, which may be obtained from the patent database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.

Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISO's adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 34, Propulsion, powertrain and powertrain fluids.

This tenth edition cancels and replaces the ninth edition (ISO 2974:2018), which has been technically revised.

The main changes are as follows:

language inclusivity was improved;
new thread option M16 × 1,0 in Table 1;
updated reference standard ISO 21920‑1 for roughness indication.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

Introduction

To comply with recent exhaust gas regulations and fuel consumption regulations for internal combustion engines, the fuel injection pressure of automobile diesel engines is generally 2 000 bar or more. Fuel injection systems operating at pressures of approximately 2 700 bar are also being introduced to the market.

Since this fuel injection pressure is extremely high, the dimensions and specifications of the 60° concave cones for high pressure fuel connections are standardized. This is to prevent fuel leaking from the joint or other failures.

1 Scope

This document specifies the dimensional requirements of end-connections for high-pressure fuel injection equipment components, including fuel injectors, CR injectors, common rails, distribution blocks, injection pumps and high-pressure supply pumps used on diesel (compression-ignition) engines.

It is applicable to externally threaded 60° concave cones (see Figures 1, 2, 5, and 6) and intended for use with high-pressure fuel injection pipe assemblies with tube outside diameters of:

up to and including 12 mm for integral concave cones (see Table 1); and
up to and including 9 mm for fabricated concave cones (see Table 2).

2 Normative references

3 Terms and definitions

4 Requirements

4.1 Dimensions and tolerances

4.2 Materials

5 Designation

6 Figures and tables

6.1 Integral 60° concave cone

6.2 Fabricated 60° concave cone

Bibliography