ISO 13296:2025

Diesel engines - High-pressure fuel injection pipe assemblies - General requirements and dimensions

This document specifies dimensions and requirements for high-pressure fuel injection pipe assemblies and assembled pipe sets for both integral and fabricated 60° concave cones used on diesel (compression-ignition) engines.

Moteurs diesels — Lignes assemblées d'injection de carburant à haute pression — Exigences générales et dimensions

General Information

• Status: Published
• Publication Date: 04-May-2025
• ICS: 43.060.40 - Fuel systems
• Technical Committee: ISO/TC 22/SC 34 - Propulsion, powertrain and powertrain fluids
• Drafting Committee: ISO/TC 22/SC 34 - Propulsion, powertrain and powertrain fluids
• Current Stage: 6060 - International Standard published
• Start Date: 05-May-2025
• Due Date: 16-Feb-2025
• Completion Date: 05-May-2025

Relations

• Revises: ISO 13296:2016 - Diesel engines - High-pressure fuel injection pipe assemblies - General requirements and dimensions
• Effective Date: 29-Oct-2022

Overview - ISO 13296:2025 in brief

ISO 13296:2025 specifies general requirements, dimensions and assembly details for high‑pressure fuel injection pipe assemblies and assembled pipe sets used on diesel (compression‑ignition) engines. It applies to both integral and fabricated 60° concave cone connection geometries and is intended to ensure safe, leak‑free joints at very high injection pressures (the introduction notes typical modern diesel systems operate at 2 000 bar and higher).

Key topics and technical requirements

• Scope and references: Cross‑references important related standards such as ISO 2974 (60° concave cones), ISO 8535‑1/‑2 (steel/composite tube requirements), ISO 12345 (cleanliness) and ISO 7876‑4 (vocabulary).
• Dimensions and tolerances: Requirement and configuration drawings must state conformity, outside/inside diameters, thread sizes, connector nut hex sizes, connection end types, centre‑line coordinates (x,y,z), bend radii and developed length.
• Pipe end connections: Defines two fundamental connection end types:
  • Type C - conical sealing face (58° ± 1° included angle).
  • Type S - spherical sealing face to mate with 60° concave cones. Tables provide common thread sizes (e.g., M10–M26 for integral designs, M14–M19 for fabricated designs) and preferred connector‑nut hex sizes.
• Assembly details: Requirements for integral vs fabricated 60° cone assemblies, connector nuts, loading/crimp sleeves (subclause 7.5 added in this edition), and bore‑entrance configuration so the pipe ID is not reduced after assembly.
• Manufacturing and quality controls:
  • Cleanliness: Bore cleanliness assessed per ISO 12345 and designated with component cleanliness codes.
  • Minimum bend radii: Bends must be at least 2.5× the pipe outside diameter (measured from the centerline).
  • Materials and surface finish: Conformity with ISO 8535 parts for tube material and finishing.
  • Tightening torque, sealing performance, packaging and identification: Specified performance and traceability requirements.
• Additional topics: Assembly clamps, external coatings, operating pressure considerations (Annex A), and pipe inside diameter limits.

Practical applications and users

Who uses ISO 13296:2025:

• OEMs and Tier‑1/2 manufacturers designing and producing diesel fuel injection systems.
• Tube and connector manufacturers, assembly shops and suppliers of high‑pressure pipe assemblies.
• Design and application engineers specifying component interchangeability and joint sealing performance.
• Quality, test and inspection laboratories verifying dimensional conformity, cleanliness and sealing.
• Procurement and regulatory/compliance teams ensuring parts meet recognized international requirements.

Why use it:

• To ensure interchangeability, mechanical integrity, and leak‑free performance of high‑pressure fuel lines.
• To reduce risk of joint failure at ultra‑high injection pressures and to standardize drawing/data requirements for fabrication and inspection.

Related standards

• ISO 2974, ISO 7876‑4, ISO 8535‑1, ISO 8535‑2, ISO 12345

Using ISO 13296:2025 helps manufacturers and specifiers align design, production and inspection practices for safe, reliable high‑pressure diesel fuel injection pipe assemblies.

Standards Content (Sample)

International
Standard
ISO 13296
Fifth edition
Diesel engines — High-pressure fuel
2025-05
injection pipe assemblies — General
requirements and dimensions
Moteurs diesels — Lignes assemblées d'injection de carburant à
haute pression — Exigences générales et dimensions
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Dimensions and tolerances . 1
5 Cleanliness . 3
6 Minimum bend radii . 3
7 Pipe end connections . 3
7.1 General .3
7.2 Types of connection ends .3
7.3 Pipe end assembly for integral 60° concave cones .4
7.4 Pipe end assembly for fabricated 60° concave cones .6
7.5 Connection end with crimped sleeve .7
7.6 Bore entrance configuration .10
8 Assembly clamps . 10
9 External coatings. 10
10 Operating pressure . 10
11 Pipe inside diameter .11
12 Tightening torque and sealing performance .11
13 Packaging and identification .11
Annex A (informative) Operating pressure .12
Bibliography .13

iii
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 (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 fifth edition cancels and replaces the fourth edition (ISO 13296:2016), which has been technically
revised.
The main changes are as follows:
— some combinations of dimensions of pipe end connections were added for integral 60° concave cones
with a pipe outer diameter 8;
— subclause 7.5 on the connection end with crimped sleeve was added.
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.

iv
Introduction
To comply with recent exhaust gas regulations and fuel consumption regulations for internal combustion
1)
engines, the fuel injection pressure of automobile diesel engines is generally 2 000 bar or more. Engines of
2 700 bar are also being introduced to the market.
Since this fuel injection pressure is extremely high, the dimensions and specifications for the assembly
of high-pressure fuel injection pipes are serialised. This is to account for failure due to high stress and to
prevent fuel leaking from the joint.
5 2
1) 1 bar = 0,1 MPa = 10 Pa; 1 MPa = 1 N/mm .

v
International Standard ISO 13296:2025(en)
Diesel engines — High-pressure fuel injection pipe
assemblies — General requirements and dimensions
1 Scope
This document specifies dimensions and requirements for high-pressure fuel injection pipe assemblies and
assembled pipe sets for both integral and fabricated 60° concave cones used on diesel (compression-ignition)
engines.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 2974, Diesel engines — 60° concave cones for high-pressure fuel injection components
ISO 7876-4, Fuel injection equipment — Vocabulary — Part 4: High-pressure pipes and end-connections
ISO 8535-1:2016, Diesel engines — Steel tubes for high-pressure fuel injection pipes — Part 1: Requirements for
seamless cold-drawn single-wall tubes
ISO 8535-2:2003, Compression-ignition engines — Steel tubes for high-pressure fuel injection pipes — Part 2:
Requirements for composite tubes
ISO 12345, Diesel engines — Cleanliness assessment of fuel injection equipment
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7876-4 apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Dimensions and tolerances
The requirement and configuration drawing for a pipe assembly shall include at least the following:
a) an indication of conformity with this document;
b) the outside diameter and inside diameter of the pipe and an indication of conformity with ISO 8535-1 or
ISO 8535-2;
c) the thread and the hexagon size of the connector nuts according to Table 2 or Table 4;
d) the type of connection ends as specified in 7.2;
e) a graphic representation of the centre-line of the pipe with the connection ends and each bend
intersection labelled as a point, with each point listed in a table with Cartesian coordinates x, y and z
with the orthogonal distance from the axis and the bend radius (the beginning and end points are given
as the “S” dimension for the defined configuration);

NOTE The coordinates are used to specify the theoretical exact centre-line of the pipe. See the example given
in Figure 1.
f) the developed length of the pipe as an approximated value;
g) the material and surface finish requirements of the pipe and connector nuts according to ISO 8535-1 or
ISO 8535-2.
The dimensional tolerance of a pipe assembly shall be stated in terms of the actual outside contour of the
tube in relation to the specified maximum outside contour and the variance of the actual pipe connection
end from the specified position, as agreed between supplier and customer.
Point x y z Radius
A 0 0 0 0
B 65 0 0 15
C 65 50 0 15
D 100 50 -50 15
E 100 120 -50 15
F 40 120 0 15
G 100 200 0 0
Key
1 connector nut: thread M12; hexagon size of the connector nut 17
2 pipe: tube outside diameter 6 mm
3 connector nut: thread M14; hexagon size of the connector nut 19
4 pipe connection ends: both of Type C
R bend radius at the pipe centre axis
a
Developed length.
Figure 1 — Example of a requirement and configuration drawing

5 Cleanliness
The bore of a high-pressure fuel injection pipe assembly shall be clean, and this shall be assessed in
accordance with ISO 12345. Unless otherwise agreed between supplier and customer, cleanliness of pipe
assemblies shall be designated using the component cleanliness code, as defined in ISO 12345.
6 Minimum bend radii
The radius of any bend made in fabricating high-pressure pipe assemblies shall be not less than two and a
half times (2,5×) the outside diameter of the pipe as measured from the pipe centre-line. Bends shall be a
sufficient distance from the end connections so as to allow easy fitting
...