ISO 13296:2025

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
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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
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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
...