ISO 18418-2:2022

INTERNATIONAL ISO
STANDARD 18418-2
Second edition
2022-11
Gasoline engines — High pressure
liquid fuel supply connections —
Part 2:
Pipe assemblies
Moteurs à essence — Connexions pour des lignes de combustible
liquide à haute pression —
Partie 2: Lignes assemblées
Reference number
© ISO 2022
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Material properties .1
5 Dimensions and tolerances .1
6 Cleanliness . 3
7 Minimum bend radii . 3
8 Pipe end connections . 3
8.1 General . 3
8.2 Type of connection ends . 3
8.3 Pipe end assembly for 60° concave cones . 4
9 Operating pressure . 5
10 Ovality of bending portion . 5
11 Tightening torque and sealing performance . 5
12 Designation . 6
12.1 Stainless-steel tube . 6
12.2 Surface-treated steel tube . 6
13 Packaging and identification .6
Bibliography . 7
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 second edition cancels and replaces the first edition (ISO 18418-2:2014), which has been technically
revised.
The main changes are as follows:
— high-strength steel tubes are required as fuel pressure increases;
— additional specification of tubes, already in use worldwide, are added.
A list of all parts in the ISO 18418 series can be found on the ISO website.
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
Some spark ignition (SI) engines use direct injection (DI) fuel systems which supply gasoline under
pressure to a rail and to the injectors via pipe assemblies with a 60° concave cone connector. Such
components are similar to ISO 2974 and ISO 13296 for the diesel injection systems except for the
relationship between the outside and inside diameters of the pipes due to the lower pressure range.
GDI fuel systems typically operate in a pressure range of around 35 MPa and are labelled “high
pressure”. In the context of all injections systems, including diesel, this same pressure range is
considered as medium pressure, as diesel injection operates at much higher pressures, however the
term “high pressure” is used in this document.
v
INTERNATIONAL STANDARD ISO 18418-2:2022(E)
Gasoline engines — High pressure liquid fuel supply
connections —
Part 2:
Pipe assemblies
1 Scope
This document specifies dimensions and requirements for high-pressure fuel pipe assemblies and
assembled pipe sets made of seamless stainless steel or surface-treated steel tubing to be used with
60°concave cone connectors on gasoline (spark-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 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 9329-4:1997, Seamless steel tubes for pressure purposes — Technical delivery conditions — Part 4:
Austenitic stainless steels
...