EN ISO 8434-1:2007

SLOVENSKI STANDARD
01-december-2007
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Metallic tube connections for fluid power and general use - Part 1: 24 degree cone
connectors (ISO 8434-1:2007)
Metallische Rohrverschraubungen für Fluidtechnik und allgemeine Anwendung - Teil 1:
24 grad- Rohrverschraubungen (ISO 8434-1:2007)
Raccordements de tubes métalliques pour transmissions hydrauliques et pneumatiques
et applications générales - Partie 1: Raccords coniques a 24 degrés (ISO 8434- 1:2007)
Ta slovenski standard je istoveten z: EN ISO 8434-1:2007
ICS:
23.100.40 Cevna napeljava in sklopke Piping and couplings
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 8434-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2007
ICS 23.100.40 Supersedes EN ISO 8434-1:1997
English Version
Metallic tube connections for fluid power and general use - Part
1: 24 degree cone connectors (ISO 8434-1:2007)
Raccordements de tubes métalliques pour transmissions Metallische Rohrverschraubungen für Fluidtechnik und
hydrauliques et pneumatiques et applications générales - allgemeine Anwendung - Teil 1: 24 grad-
Partie 1: Raccords coniques à 24 degrés (ISO 8434- Rohrverschraubungen (ISO/FDIS 8434-1:2007)
1:2007)
This European Standard was approved by CEN on 11 August 2007.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2007 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 8434-1:2007: E
worldwide for CEN national Members.

Contents Page
Foreword.3

Foreword
This document (EN ISO 8434-1:2007) has been prepared by Technical Committee ISO/TC 131 "Fluid power
systems" in collaboration with Technical Committee ECISS/TC 29 "Steel tubes and fittings for steel tubes", the
secretariat of which is held by UNI.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by March 2008, and conflicting national standards shall be withdrawn at
the latest by March 2008.
This document supersedes EN ISO 8434-1:1997.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 8434-1:2007 has been approved by CEN as a EN ISO 8434-1:2007 without any modification.

INTERNATIONAL ISO
STANDARD 8434-1
Second edition
2007-09-01
Metallic tube connections for fluid power
and general use —
Part 1:
24° cone connectors
Raccordements de tubes métalliques pour transmissions hydrauliques
et pneumatiques et applications générales —
Partie 1: Raccords coniques à 24°

Reference number
ISO 8434-1:2007(E)
©
ISO 2007
ISO 8434-1:2007(E)
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ii © ISO 2007 – All rights reserved

ISO 8434-1:2007(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope.1
2 Normative references.1
3 Terms and definitions .3
4 Materials.4
4.1 General.4
4.2 Connector bodies .5
4.3 Nuts.5
4.4 Cutting rings.5
4.5 O-rings.5
5 Pressure/temperature requirements.5
6 Designation of connectors .10
7 Requirements for tubes .12
8 Across-flats dimensions and tolerances .12
9 Design.12
9.1 Connectors.12
9.2 Dimensions.12
9.3 Passage tolerances.12
9.4 Angular tolerances .13
9.5 Contour details.13
9.6 Ports and stud ends .13
9.7 Stud end sealing .13
10 Screw threads.13
10.1 Cone ends and nuts.13
10.2 Stud ends (connection ends) .13
11 Manufacture.13
11.1 Construction.13
11.2 Workmanship.14
11.3 Finish.14
11.4 Corners.14
12 Assembly instruction .14
13 Procurement information.15
14 Marking of components .15
15 Performance and qualification test.15
15.1 General.15
15.2 Repeated assembly test.15
15.3 Proof test.15
15.4 Burst pressure test.15
15.5 Cyclic endurance (impulse) test.15
15.6 Vibration test.15
15.7 Leakage (gas) test.16
15.8 Overtightening test.16
16 Identification statement (reference to this part of ISO 8434) .16
Bibliography .46
ISO 8434-1:2007(E)
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 8434-1 was prepared by Technical Committee ISO/TC 131, Fluid power systems, Subcommittee SC 4,
Connectors and similar products and components.
This second edition of ISO 8434-1 cancels and replaces ISO 8434-1:1994 and ISO 8434-4:1995, of which it
constitutes a technical revision.
ISO 8434 consists of the following parts, under the general title Metallic tube connections for fluid power and
general use:
⎯ Part 1: 24° cone connectors
⎯ Part 2: 37° flared connectors
⎯ Part 3: O-ring face seal connectors
⎯ Part 6: 60° cone connectors with or without O-ring
iv © ISO 2007 – All rights reserved

ISO 8434-1:2007(E)
Introduction
In fluid power systems, power is transmitted and controlled through a fluid (liquid or gas) under pressure within
an enclosed circuit. In general applications, a fluid may be conveyed under pressure.
Components may be connected through their ports by connections (connectors) and conductors (tubes and
hoses). Tubes are rigid conductors; hoses are flexible conductors.

INTERNATIONAL STANDARD ISO 8434-1:2007(E)

Metallic tube connections for fluid power and general use —
Part 1:
24° cone connectors
1 Scope
This part of ISO 8434 specifies the general and dimensional requirements for 24° cone connectors using
cutting ring and O-ring seal cone (referred to as DKO) suitable for use with ferrous and non-ferrous tubes with
outside diameters from 4 mm to 42 mm inclusive. These connectors are for use in fluid power and general
applications within the limits of pressure and temperature specified in this part of ISO 8434.
They are intended for the connection of plain end tubes and hose fittings to ports in accordance with
ISO 6149-1, ISO 1179-1 and ISO 9974-1. (See ISO 12151-2 for related hose fitting specification.)
These connectors provide full-flow connections in hydraulic systems operating to the working pressures
shown in Table 1. Because many factors influence the pressure at which a system performs satisfactorily,
these values are not to be understood as guaranteed minimums. For every application, sufficient testing will
need to be conducted and reviewed by both the user and manufacturer to ensure that required performance
levels are met.
NOTE 1 For new designs in hydraulic fluid power applications, see the requirements given in 9.6. Where the
requirements of the application allow for the use of elastomeric seals, connector designs that conform to International
Standards and incorporate elastomeric sealing are preferred.
NOTE 2 For use under conditions outside the pressure and/or temperature limits specified, see 5.4.
This part of ISO 8434 also specifies a performance and qualification test for these connectors.
2 Normative references
The following referenced documents are indispensable for the application 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 48, Rubber, vulcanized or thermoplastic — Determination of hardness (hardness between 10 IRHD and
100 IRHD)
ISO 228-1:2000, Pipe threads where pressure-tight joints are not made on the threads — Part 1: Dimensions,
tolerances and designation
ISO 261, ISO general purpose metric screw threads — General plan
ISO 965-1:1998, ISO general-purpose metric screw threads — Tolerances — Part 1: Principles and basic
data
ISO 1127, Stainless steel tubes — Dimensions, tolerances and conventional masses per unit length
ISO 8434-1:2007(E)
ISO 1179-1, Connections for general use and fluid power — Ports and stud ends with ISO 228-1 threads with
elastomeric or metal-to-metal sealing — Part 1: Threaded ports
ISO 1179-2, Connections for general use and fluid power — Ports and stud ends with ISO 228-1 threads with
elastomeric or metal-to-metal sealing — Part 2: Heavy-duty (S series) and light-duty (L series) stud ends with
elastomeric sealing (type E)
ISO 1179-4, Connections for general use and fluid power — Ports and stud ends with ISO 228-1 threads with
elastomeric or metal-to-metal sealing — Part 4: Stud ends for general use only with metal-to-metal sealing
(type B)
ISO 3304, Plain end seamless precision steel tubes — Technical conditions for delivery
ISO 3305, Plain end welded precision steel tubes — Technical conditions for delivery
ISO 3601-3:2005, Fluid power systems — O-rings — Part 3: Quality acceptance criteria
ISO 4759-1:2000, Tolerances for fasteners — Part 1: Bolts, screws, studs and nuts — Product grades A,
B and C
ISO 5598:1985, Fluid power systems and components — Vocabulary
ISO 6149-1, Connections for hydraulic fluid power and general use — Ports and stud ends with ISO 261
metric threads and O-ring sealing — Part 1: Ports with truncated housing for O-ring seal
ISO 6149-2, Connections for hydraulic fluid power and general use — Ports and stud ends with ISO 261
metric threads and O-ring sealing — Part 2: Dimensions, design, test methods and requirements for heavy-
duty (5 series) stud ends
ISO 6149-3, Connections for hydraulic fluid power and general use — Ports and stud ends with ISO 261
metric threads and O-ring sealing — Part 3: Dimensions, design, test methods and requirements for light-duty
(L series) stud ends
ISO 9227, Corrosion tests in artificial atmospheres — Salt spray tests
ISO 9974-1, Connections for general use and fluid power — Ports and stud ends with ISO 261 threads with
elastomeric or metal-to-metal sealing — Part 1: Threaded ports
ISO 9974-2, Connections for general use and fluid power — Ports and stud ends with ISO 261 threads with
elastomeric or metal-to-metal sealing — Part 2: Stud ends with elastomeric sealing (type E)
ISO 9974-3, Connections for general use and fluid power — Ports and stud ends with ISO 261 threads with
elastomeric or metal-to-metal sealing — Part 3: Stud ends with metal-to-metal sealing (type B)
ISO 12151-2, Connections for hydraulic fluid power and general use — Hose fittings — Part 2: Hose fittings
with ISO 8434-1 and ISO 8434-4 24° cone connector ends with O-rings
ISO 19879:2005, Metallic tube connections for fluid power and general use — Test methods for hydraulic fluid
power connections
2 © ISO 2007 – All rights reserved

ISO 8434-1:2007(E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5598 and the following apply.
3.1
connector
connection
leak-proof device used to connect pipelines (conductors) to one another or to equipment
NOTE Adapted from ISO 5598:1985, definition 5.2.2.
3.2
fastening thread
terminal thread of a complete connector
3.3
run
two principal, axially aligned outlets of a tee or cross
3.4
branch
side outlet(s) of a tee or cross
3.5
chamfer
removal of a conical portion at the entrance of a thread, used to assist assembly and prevent damage to the
start of the thread
3.6
face-to-face dimension
distance between the two parallel faces of axially aligned outlets of a connector
3.7
face-to-centre dimension
distance from the face of an outlet to the central axis of an angularly disposed outlet
3.8
assembly torque
torque to be applied in order to achieve a satisfactory final assembly
3.9
maximum working pressure
highest pressure at which the system or part of the system is intended to operate in steady-state conditions
ISO 8434-1:2007(E)
4 Materials
4.1 General
Figures 1 and 2 show the cross-sections and component parts of typical 24° cone connectors.

Key
1 body
2 nut
3 cutting ring
Figure 1 — Cross-section of typical 24° cone connector with cutting ring

Key
1 body
2 nut
3 DKO-end (including O-ring)
Figure 2 — Cross-section of typical 24° cone connector with O-ring seal cone (DKO) end
4 © ISO 2007 – All rights reserved

ISO 8434-1:2007(E)
4.2 Connector bodies
Bodies shall be manufactured from carbon steel that will provide the minimum pressure/temperature
requirements specified in Clause 5. They shall have characteristics that make them suitable for use with the
fluid to be conveyed and that will provide an effective joint. Weld connector types and weld-on nipples shall be
made of materials classified as suitable for welding.
For bodies manufactured from stainless steel and copper alloys, the pressure/temperature ratings need to be
defined by the manufacturer.
4.3 Nuts
Nuts to be used with carbon steel bodies shall be made of carbon steel, and those for use with stainless steel
bodies shall be made of stainless steel, unless otherwise specified. Nuts to be used with copper alloy bodies
shall be made of a material similar to the bodies.
4.4 Cutting rings
4.4.1 The ring material shall be compatible with the fluid to be conveyed and provide an effective joint.
4.4.2 Steel cutting rings are to be used in combination with other steel connector components and steel
tubes.
4.4.3 Stainless steel cutting rings are to be used in combination with other stainless steel connector
components and stainless steel tubes.
4.4.4 Brass cutting rings are to be used in combination with other brass connector components and copper
tubes.
4.4.5 Other combinations of materials shall be agreed upon between the purchaser and supplier.
4.5 O-rings
Unless otherwise specified, for use with petroleum-based hydraulic fluids at the pressure and temperature
requirements given in Clause 5 and Table 1, O-rings for use with connectors in accordance with this part of
ISO 8434 shall be made of NBR (nitrile) with a hardness of (90 ± 5) IRHD, measured in accordance with
ISO 48, and shall conform to the dimensions given in Table 5 and shall meet or exceed the O-ring quality
acceptance criteria of ISO 3601-3:2005, grade N. In those cases where the pressure and temperature
requirements of this part of ISO 8434 and/or the hydraulic fluid used in the system differ from those specified
in Clause 5 and Table 1, the connector manufacturer shall be consulted to ensure that an appropriate O-ring
material is selected.
5 Pressure/temperature requirements
5.1 Connectors in conformance with this part of ISO 8434 made of carbon steel shall meet or exceed
without leakage the requirements from a vacuum of 6,5 kPa (0,065 bar) absolute pressure to the working
pressures given in Tables 1 to 3 when used at temperatures between −40 °C and +120 °C with
petroleum-based hydraulic fluids.
5.2 Connectors complying with this part of ISO 8434 may contain elastomeric seals. Unless otherwise
specified, connectors are made and delivered with elastomeric parts giving their specified working
temperature range with petroleum-based hydraulic fluids. The connectors may have a reduced working
temperature range or may be completely unsuitable for applications with other fluids. Manufacturers may
supply on request connectors with appropriate elastomeric seals meeting the required working temperature
range for use with different hydraulic fluids.
ISO 8434-1:2007(E)
5.3 The connector assembly shall meet or exceed all applicable performance requirements given in
Clause 15. Testing shall be conducted at room temperature.
5.4 For applications under conditions other than the pressure and/or temperature limits given in Tables 1 to
3 and in 5.1 and 5.3, the manufacturer shall be consulted.
5.5 According to different applications and different pressure ratings, there are three series of connector,
designated by
⎯ LL, for extra light-duty,
⎯ L, light-duty, and
⎯ S, heavy-duty.
NOTE Ranges of the tube outside diameters and pressure requirements are shown in Tables 1 to 3.
Table 1 — Working pressures for 24° cone connectors for fluid power and general use
Tube outside Cone and cutting ring connection ISO 6149-2 or ISO 6149-3 stud end
diameter (OD)
Maximum working Maximum working
Series
a a
pressure pressure
Thread Thread
b b
mm MPa (bar ) MPa (bar )
4 10 (100) — — —
M8 × 1
5 10 (100) — — —
M10 × 1
LL
6 M10 × 1 10 (100) — — —
8 M12 × 1 10 (100) — — —
6 25 (250) 25 (250)
M12 × 1,5 M10 × 1
8 25 (250) 25 (250)
M14 × 1,5 M12 × 1,5
10 M16 × 1,5 25 (250) M14 × 1,5 25 (250)
12 M18 × 1,5 25 (250) M16 × 1,5 25 (250)
15 25 (250) 25 (250)
M22 × 1,5 M18 × 1,5
L
18 16 (160) 16 (160)
M26 × 1,5 M22 × 1,5
22 M30 × 2 16 (160) M27 × 2 16 (160)
28 M36 × 2 10 (100) M33 × 2 10 (100)
35 10 (100) 10 (100)
M45 × 2 M42 × 2
42 10 (100) 10 (100)
M52 × 2 M48 × 2
6 M14 × 1,5 63 (630) M12 × 1,5 63 (630)
8 63 (630) 63 (630)
M16 × 1,5 M14 × 1,5
10 63 (630) 63 (630)
M18 × 1,5 M16 × 1,5
12 63 (630) 63 (630)
M20 × 1,5 M18 × 1,5
S
16 M24 × 1,5 40 (400) M22 × 1,5 40 (400)
20 M30 × 2 40 (400) M27 × 2 40 (400)
25 40 (400) 40 (400)
M36 × 2 M33 × 2
30 25 (250) 25 (250)
M42 × 2 M42 × 2
38 M52 × 2 25 (250) M48 × 2 25 (250)
For higher pressure ratings and for dynamic conditions, the manufacturer shall be consulted.
a
With a design factor of 4 to 1.
b 5 5
1 bar = 10 N/m2 = 10 Pa = 0,1 MPa.
6 © ISO 2007 – All rights reserved

ISO 8434-1:2007(E)
Table 2 — Working pressures for 24° cone connectors, for general use only
Cone and cutting ring
ISO 9974 stud end ISO 1179 stud end
connection
Tube OD
a a
Maximum working pressure Maximum working pressure
Maximum
Series
working
ISO 1179-4
ISO 9974-2 ISO 9974-3 ISO 1179-2
Thread a Thread Thread
c
pressure b c b
(type B)
(type E) (type B) (type E)
MPa (bar)
mm
MPa (bar) MPa (bar) MPa (bar) MPa (bar)
4 M8 × 1 10 (100) M8 × 1 — — 10 (100) G 1/8 A — — 10 (100)
5 M10 × 1 10 (100) M8 × 1 — — 10 (100) — — — — —
LL
— —
6 M10 × 1 10 (100) M10 × 1 — — 10 (100) — — —
8 M12 × 1 10 (100) M10 × 1 — — 10 (100) — — — — —
6 M12 × 1,5 25 (250) M10 × 1 25 (250) 25 (250) G 1/8 A 25 (250) 25 (250)
8 M14 × 1,5 25 (250) M12 × 1,5 25 (250) 25 (250) G 1/4 A 25 (250) 25 (250)
10 M16 × 1,5 25 (250) M14 × 1,5 25 (250) 25 (250) G 1/4 A 25 (250) 25 (250)
12 M18 × 1,5 25 (250) M16 × 1,5 25 (250) 25 (250) G 3/8 A 25 (250) 25 (250)
15 M22 × 1,5 25 (250) M18 × 1,5 25 (250) 25 (250) G 1/2 A 25 (250) 25 (250)
L
18 M26 × 1,5 16 (160) M22 × 1,5 16 (160) 16 (160) G 1/2 A 16 (160) 16 (160)
22 M30 × 2 16 (160) M26 × 1,5 16 (160) 16 (160) G 3/4 A 16 (160) 16 (160)
28 M36 × 2 10 (100) M33 × 2 10 (100) 10 (100) G 1 A 10 (100) 10 (100)
10 (100)
35 M45 × 2 10 (100) M42 × 2 10 (100) 10 (100) G 1 1/4 A 10 (100)
10 (100)
42 M52 × 2 10 (100) M48 × 2 10 (100) 10 (100) G 1 1/2 A 10 (100)

ISO 8434-1:2007(E)
8 © ISO 2007 – All rights reserved
Table 2 (continued)
Cone and cutting ring
ISO 9974 stud end ISO 1179 stud end
connection
Tube OD
a a
Maximum working pressure Maximum working pressure
Maximum
Series
working
ISO 1179-4
ISO 9974-2 ISO 9974-3 ISO 1179-2
Thread a Thread Thread
b c b c
pressure
(type E) (type B) (type E) (type B)
MPa (bar)
mm MPa (bar) MPa (bar) MPa (bar) MPa (bar)
6 63 (630) 63 (630) 40 (400) G 1/4 A 63 (630) 40 (400)
M14 × 1,5 M12 × 1,5
8 63 (630) 63 (630) 40 (400) G 1/4 A 63 (630) 40 (400)
M16 × 1,5 M14 × 1,5
10 M18 × 1,5 63 (630) M16 × 1,5 63 (630) 40 (400) G 3/8 A 63 (630) 40 (400)
12 M20 × 1,5 63 (630) M18 × 1,5 63 (630) 40 (400) G 3/8 A 63 (630) 40 (400)
S 16 40 (400) 40 (400) 40 (400) G 1/2 A 40 (400) 40 (400)
M24 × 1,5 M22 × 1,5
20 40 (400) 40 (400) 40 (400) G 3/4 A 40 (400) 40 (400)
M30 × 2 M27 × 2
25 M36 × 2 40 (400) M33 × 2 40 (400) 25 (250) G 1 A 40 (400) 25 (250)
30 M42 × 2 25 (250) M42 × 2 25 (250) 16 (160) G 1 1/4 A 25 (250) 16 (160)
38 25 (250) 25 (250) 16 (160) G 1 1/2 A 25 (250) 16 (160)
M52 × 2 M48 × 2
For higher pressure ratings and for dynamic conditions, the manufacturer shall be consulted.
a
With a design factor of 4 to 1.
b
Type E with elastomeric sealing.
c
Type B with metal-to-metal sealing.

ISO 8434-1:2007(E)
Table 3 — Working pressures for 24° cone weld-on nipples with various tube wall thicknesses
Dimensions in millimetres
Maximum working pressure
10 MPa 16 MPa 25 MPa 31,5 MPa 40 MPa 63 MPa
Tube
Series
(100 bar) (160 bar) (250 bar) (315 bar) (400 bar) (630 bar)
OD
Tube Tube Tube Tube Tube Tube
T T T T T T
ID ID ID ID ID ID
6 3 1,5 3 1,5 3 1,5
8 5 1,5 5 1,5 5 1,5
10 7 1,5 7 1,5 7 1,5
12 8 2 8 2 8 2
15 10 2,5 10 2,5 10 2,5
L
18 13 2,5 13 2,5
22 17 2,5 17 2,5
28 23 2,5
35 29 3
42 36 3
6 2,5 1,75 2,5 1,75 2,5 1,75 2,5 1,75 2,5 1,75 2,5 1,75
8 4 2 4 2 4 2 4 2 4 2 4 2
10 6 2 6 2 6 2 6 2 6 2 5 2,5
12 8 2 8 2 8 2 8 2 7 2,5 6 3
16 11 2,5 11 2,5 11 2,5 11 2,5 10 3
S
20 14 3 14 3 14 3 14 3 12 4
25 19 3 19 3 19 3 17 4 16 4,5
30 24 3 24 3 22 4
38 32 3 32 3 28 5
For pressure and/or temperature applications outside those given in this part of ISO 8434, the manufacturer shall be
consulted.
ID interior diameter
T tube wall thickness
ISO 8434-1:2007(E)
6 Designation of connectors
6.1 Connectors shall be designated by an alphanumeric code to facilitate ordering. They shall be
designated by the word “Connector” followed by ISO 8434-1, followed by a spaced hyphen, then the
connector style letter symbols (see 6.2), followed by a spaced hyphen, then the series letter(s) (see 5.5),
immediately followed by the outside diameter of the tube with which they are to be connected. For weld
nipples, a multiplication sign (×) shall then follow, then the tube wall thickness. There shall be no spaces on
either side of the multiplication symbol. For stud ends (connector ends), another spaced hyphen followed by
the thread designation of the stud end and the sealing type shall be added.
6.2 The letter symbol designation of the connector style shall have three parts: the connection end type,
immediately followed by the shape of the connector and by the indication that a complete connector is
ordered.
6.3 Tube ends are assumed and thus do not need to be included in the code. However, if another type of
end is involved, it shall be designated.
6.4 Reducing connectors and reducing elbows shall be designated by specifying the larger tube end first.
6.5 Stud connectors (see Figures 3 and 4) shall be designated by specifying the tube end first, then the
thread size for the stud end with the sealing type letter.
6.6 For tee connectors, the order of designation of the connection ends shall be from larger to smaller on
the run, followed by the branch end.
6.7 For cross connectors, the order of designation of the connection ends shall be from left to right, followed
by top to bottom, with the larger ends on the left and at the top.
6.8 If the connector has a tube union connection, it shall be designated first. Then the designation shall
proceed clockwise.
6.9 The following letter symbols shall be used.
Connection end type Symbol
Bulkhead BH
Swivel with O-ring SWO
Weld-on/weld-in WD
Stud SD
Reducer RD
Shape Symbol
Straight S
Elbow E
45° elbow E45
Tee T
Run tee RT
Branch tee BT
Cross K
10 © ISO 2007 – All rights reserved

ISO 8434-1:2007(E)
Component type Symbol
Nut N
Cutting ring CR
Locknut LN
Nipple NP
Plug PL
Completeness indication Symbol
Complete connector C
Stud end sealing types Symbol
Metal-to-metal sealing B
Elastomeric sealing E
O-ring sealing F
6.10 Examples of compression connectors and designations are given below and in Figures 3 to 5.
EXAMPLE 1 A stud straight connector, including O-ring without cutting ring and nut, with a heavy-duty stud connection
end having an M18 × 1,5 thread in accordance with ISO 6149-2, to be connected to a 12 mm OD tube, is designated for
ordering as follows:
Connector ISO 8434-1 - SDS - S12×M18 - F

Figure 3 — Stud straight connector (SDS) with stud end as per ISO 6149-2 (sealing type F)
EXAMPLE 2 A complete stud straight connector, including O-ring with cutting ring and nut, with a heavy-duty stud
connection end having an M18 × 1,5 thread in accordance with ISO 6149-2, to be connected to a 12 mm OD tube, is
designated for ordering as follows:
Connector ISO 8434-1 - SDSC - S12×M18 - F

Figure 4 — Complete stud straight connector (SDSC) with stud end as per ISO 6149-2 (sealing type F)
ISO 8434-1:2007(E)
EXAMPLE 3 A complete weld-on nipple, including O-ring, with a light-duty connection end, to be welded to a 15 mm
OD tube having a wall thickness of 1,5 mm, is designated for ordering as follows:
Connector ISO 8434-1 - WDNP - L15×1,5

Figure 5 — Weld-on nipple with O-ring (WDNP)
7 Requirements for tubes
Carbon steel tubes shall comply with delivery condition R37 NBK, as specified in ISO 3304 (cold-drawn and
normalized) or ISO 3305 (cold-drawn and normalized). Stainless steel tubes shall be in accordance with
ISO 1127 (annealed).
8 Across-flats dimensions and tolerances
8.1 For sizes up to and including 24 mm, tolerances for across-flats dimensions for forgings shall be
0 0
mm, and for sizes larger than 24 mm, they shall be mm.
−0,8 −1
8.2 Hex tolerances across flats shall be in accordance with ISO 4759-1:2000, product grade B. Minimum
across-corner hex dimensions are 1,092 times the width across flats. The minimum side flat is 0,43 times the
nominal width across flats. Unless otherwise specified or shown, hex corners shall be chamfered 10° to 30° to
a diameter equal to the width across flats, with a tolerance of mm. The dimensions across flats for nuts
−0,4
and on the bodies of the connectors shall be those given in Table 5 and Tables 9 to 21.
9 Design
9.1 Connectors
The connectors shall conform to the requirements given in Figures 6 to 25 and Tables 4 to 22. They shall be
designed so that resistance to flow is reduced to a minimum.
9.2 Dimensions
Dimensions specified apply to finished parts, including any plating or other treatments. The tolerance value for
all dimensions not otherwise limited shall be ± 0,4 mm. The sealing seats of connectors shall be concentric
with straight thread pitch diameters within 0,25 mm full indicator reading (FIR).
9.3 Passage tolerances
Where passages in straight connectors are machined from opposite ends, the offset at the meeting point shall
not exceed 0,4 mm. No cross-sectional area at a junction of passages shall be less than that of the smallest
specified passage.
12 © ISO 2007 – All rights reserved

ISO 8434-1:2007(E)
9.4 Angular tolerances
Angular tolerance on axes of ends of elbows, tees and crosses shall be ± 2,5° for connectors for tube sizes
10 mm and smaller, and ± 1,5° for all larger sizes.
9.5 Contour details
Details of contour shall be chosen by the manufacturer provided the dimensions given in Tables 4 to 22 are
maintained. Wrench flats on elbows and tees shall conform to the dimensions given in the relevant tables.
Abrupt reduction of a section shall be avoided. Junctions of small external sections and adjoining sections that
are relatively heavy shall be blended by means of ample fillets.
9.6 Ports and stud ends
These connectors are intended for the connection of plain end tubes and hose connectors to ports in
accordance with ISO 6149-1, ISO 1179-1 or ISO 9974-1. For new designs in hydraulic fluid power
applications, only ports and stud ends in accordance with the relevant parts of ISO 6149 shall be used.
9.7 Stud end sealing
Unless otherwise agreed upon between the supplier and purchaser, seals for stud ends and weld nipples shall
be included in the delivery.
10 Screw threads
10.1 Cone ends and nuts
The screw threads on the cone ends and the nuts of the connectors shall be ISO metric screw threads in
accordance with ISO 261, tolerance grade 6g, in accordance with ISO 965-1:1998.
Threads shall be chamfered at the face of the connector to an included angle of 45°. The diameter of the
chamfer shall be equal to the minor diameter of the thread, with a tolerance of mm.
−0,4
10.2 Stud ends (connection ends)
The thread for stud ends (connection ends) of connectors shall be chosen from ISO 228-1:2000, Class A, or
ISO 261, tolerance grade 6g, in accordance with ISO 965-1:1998. The dimensions of the stud ends shall be in
accordance with Tables 11 to 13 and the relevant stud end standards.
NOTE Parallel threads require an undercut with a sealing washer, O-ring or similar device to ensure a leak-proof joint,
unless the stud end undercut is designed for metal-to-metal sealing.
11 Manufacture
11.1 Construction
Carbon steel connectors made from multiple components shall be bonded together with materials having a
melting point of not less than 1 000 °C.
ISO 8434-1:2007(E)
11.2 Workmanship
The connectors shall be free from defects such as cracks and porosity and shall be deburred. Sharp edges
shall be removed on the outside. All machined surfaces shall have a material removal rate surface roughness
value of MRR Ramax u 6,3 µm, except where otherwise specified in the figures.
11.3 Finish
The external surface and threads of all carbon steel parts shall be plated or coated with a suitable material
that passes a 72 h neutral salt spray test in accordance with ISO 9227, unless otherwise agreed upon by the
manufacturer and the user. Any appearance of red rust during the salt spray test on any area, excepting the
following, shall be considered failure:
⎯ all internal fluid passages;
⎯ edges, such as hex points, serrations and crests of threads, where there may be mechanical deformation
of the plating or coating typical of mass-produced parts or shipping effects;
⎯ areas where there is mechanical deformation of the plating or coating caused by crimping, flaring,
bending and other post-plate metal-forming operations;
⎯ areas where the parts are suspended or affixed in the test chamber, where condensate can accumulate.
Internal fluid passages shall be protected from corrosion during storage. Weld components shall be protected
from corrosion by an oil film or phosphate coating, or by other means that do not negatively affect weldability.
Parts manufactured in accordance with this part of ISO 8434 shall not be cadmium-plated.
11.4 Corners
Unless otherwise noted, all sharp corners shall be broken to 0,15 mm maximum.
12 Assembly instruction
The assembly of the connectors with the connecting tubes shall be carried out without external loads.
The manufacturer shall draw up assembly instructions for the use of the connectors. These instructions shall
include at least the following:
⎯ details relating to material and quality of suitable tubes;
⎯ details concerning the preparation of the selected tube;
⎯ instructions regarding the assembly of the connector, such as the number of wrenching turns or assembly
torque;
⎯ recommendations regarding the tools to be used for assembly.
14 © ISO 2007 – All rights reserved

ISO 8434-1:2007(E)
13 Procurement information
The following information should be supplied by the purchaser when making an inquiry or placing an order:
⎯ description of connector;
⎯ material of connector;
⎯ material and size of tube;
⎯ fluid to be conveyed;
⎯ working pressure;
⎯ fluid working temperature range;
⎯ ambient temperature range.
14 Marking of components
Connector bodies, cutting rings, weld-on nipples and nuts shall be permanently marked with the
manufacturer's name, trademark or code identifier unless otherwise agreed by the user and manufacturer.
Nuts shall also be marked with the connector size and series.
15 Performance and qualification test
15.1 General
The connectors shall meet or exceed the pressure requirements given in Table 1 when tested in accordance
with this clause.
15.2 Repeated assembly test
The connectors shall pass a repeated assembly test in accordance with ISO 19879:2005, Clause 5.
15.3 Proof test
The connectors shall pass a proof test in accordance with ISO 19879:2005, Clause 7.
15.4 Burst pressure test
The connectors shall pass a burst pressure test in accordance with ISO 19879:2005, Clause 8.
15.5 Cyclic endurance (impulse) test
The connectors shall pass a cyclic endurance test in accordance with ISO 19879:2005, Clause 9. The cyclic
endurance test with vibration specified in ISO 19879 may be used in place of separate cyclic endurance and
vibration tests.
15.6 Vibration test
The connectors shall pass a vibration test in accordance with ISO 19879:2005, Clause 12. The cyclic
endurance test with vibration specified in ISO 19879 may be used in place of separate cyclic endurance and
vibration tests.
ISO 8434-1:2007(E)
15.7 Leakage (gas) test
15.7.1 Three samples shall be tested to confirm that they are capable of withstanding the test procedure
described in 15.7.2 to 15.7.4.
15.7.2 Install the samples in a basin filled with water.
15.7.3 After installation, fill the samples with air, nitrogen or helium up to a pressure of 10 MPa (100 bar).
15.7.4 Hold the samples at pressure for 3 min and watch for the presence of rising bubbles.
15.7.5 The samples shall be capable of withstanding the pressure of 10 MPa (100 bar) for 3 min without
leakage, indicated by rising bubbles.
15.7.6 The test f
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