ISO/DIS 8434-2:2026(en)

2025-11-22

ISO/TC 131/SC 04/WG 6

Secretariat: ANSI

Metallic tube connections for fluid power and general use — Part 2: 37° flared connectors

© ISO 2026

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Contents

Foreword iv

Introduction vi

1 Scope 1

2 Normative references 1

3 Terms and definitions 3

4 Materials 5

5 Pressure/temperature requirements 6

6 Designation of connectors 7

7 Requirements for tubes 9

8 Across flats dimensions and tolerances 11

9 Design 12

10 Screw threads 13

11 Manufacture 13

12 Assembly instructions 14

13 Procurement information 14

14 Marking of components 15

15 Performance and qualification test 15

16 Identification statement 17

Annex A (normative) Length reduction factors for reducing connectors 46

Bibliography 55

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/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 131, Fluid power systems, Subcommittee SC 4, Connectors and similar products and components.

This third edition cancels and replaces the second edition (ISO 8434-2:2007), which has been technically revised.

The main changes are as follows:

— Introduction, Clause 10…ISO 263 references replaced with ISO 725.

— Clause 1 “Scope” updated to include tubes with outside diameters from 4 mm to 50,8 mm. Sizes 4, 5, and 22 mm have been added to all applicable tables.

— Clause 2 “Normative references” updated.

— Clause 3 “Terms and definitions” updated. Figure 1 added.

— Clause 4.2…Removed all references to connector bodies made from copper alloys.

— Clause 5.3, removed pressure derating for connectors made from stainless steel.

— Clause 6.7, added material and letter designations.

— Clause 7 “Requirements for tubes” rewritten to remove references to ISO 3304 and ISO 3305.

— Clause 8.1, added forging size criteria.

— Clause 9.4 “Wall Thickness” added.

— Clause 10 “Screw Threads” rewritten.

— Clause 11.3 “Corrosion protection” rewritten.

— Clause 12 “Assembly Instructions” rewritten.

— Clause 13 “Procurement information” seal material added.

— Clause 15.1 “Performance requirements” rewritten.

— Clause 15.1.3 “Cyclic endurance (impulse) test” and 15.1.4 “Overtightening test” test block information added.

— Clause 15.1.5 “Repeated assembly test” added, “Re-use of test samples” removed.

— Clause 16 “Identification statement” rewritten.

— All figures have been renumbered and redrawn.

— Figure 5, tolerance added to R0,5 radius.

— Figure 7 and Table 8 were added for the recommended chamfer for single flares.

— Table 9, note “a” added.

— Figure 10, R0,26 ± 0,13 changed to R0,25 ± 0,15.

— Figure 11/Table 12, added “L₆” dimension and subsequent “L” dimensions were adjusted in following figures and tables.

— Table 13, removed Tube OD 50.

— Figure 18/Table 19 and Figure 19/Table 20, Optional dual angle seat design added.

— Figure 19/Table 20 added “L₄₇”.

— Table A.3 factor for 9/16-18 and 16 updated to -0,4.

— Bibliography updated.

A list of all parts in the ISO 8434 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.

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), tubes and hoses. Tubes are rigid conductors; hoses are flexible conductors.

This document is based on the US standard ANSI/SAE J514-1 ^[1] and J533 ^[3]. The threads for the 37° flared connection are unified inch threads in accordance with ISO 725. The inch threads were not changed to metric threads according to ISO 261 to allow connectors complying with this International Standard to be used in existing applications without requiring a change to tube or hose assemblies. Also, the thread-to-nut overtightening and seal performance have been extensively tested; to change to metric threads would require an extensive test program at considerable cost without providing any functional improvement. The threads are integral to themselves, connectors of this type match only to themselves and, other than having metric threads, no value in changing could be found. Major international companies that have used these connectors have adopted the design without noting any problems. All wrench flats specified in this document are dimensioned to be used with ISO standard metric wrenches.

Metallic tube connections for fluid power and general use — Part 2: 37° flared connectors

This document specifies general and dimensional requirements for the design and performance of 37° flared connectors that are suitable for use with ferrous and non-ferrous tubes with outside diameters from 4 mm to 50,8 mm, inclusive. These connectors provide full-flow connections with metal-to-metal sealings. These connectors are for use in fluid power and general applications within the limits of pressure and temperature specified in this document.

They are intended for the connection of tubes and hose fittings to ports in accordance with ISO 6149‑1, ISO 1179‑1, ISO 9974‑1 and ISO 11926‑1. (See ISO 12151‑5 for related hose fitting specification.)

NOTE 1 For new designs in hydraulic fluid power applications, see the requirements given in 9.7. 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 limits for pressure or temperature, or both, see 5.4.

Both metric and inch tubing can be accommodated by changing the sleeve (see Figure 9). In the past, these connectors have been used predominantly with inch tubing. For new and future designs, the use of metric tubing is preferred.

This document also specifies performance and qualification tests for 37° flared connectors.

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 228‑1, Pipe threads where pressure-tight joints are not made on the threads — Part 1: Dimensions, tolerances and designation

ISO 725, ISO inch screw threads — Basic dimensions

ISO 1127, Stainless steel tubes — Dimensions, tolerances and conventional masses per unit length

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 1179‑3, Connections for general use and fluid power — Ports and stud ends with ISO 228-1 threads with elastomeric or metal-to-metal sealing — Part 3: Light-duty (L series) stud ends with sealing by O-ring with retaining ring (types G and H)

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 3651‑2, Determination of resistance to intergranular corrosion of stainless steels — Part 2: Ferritic,austenitic and ferritic-austenitic (duplex) stainless steels — Corrosion test in media containing sulfuric acid

ISO 4759‑1, Tolerances for fasteners — Part 1: Bolts, screws, studs and nuts — Product grades A, B and C

ISO 5598, 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 6149‑3, 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 6892‑1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature

ISO 8493, Metallic materials — Tube — Drift-expanding test

ISO 8495, Metallic materials — Tube — Ring-expanding test

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 10763, Hydraulic fluid power — Plain-end, seamless and welded precision steel tubes — Dimensions and nominal working pressures

ISO 10893‑1, Non-destructive testing of steel tubes — Part 1: Automated electromagnetic testing of seamless and welded (except submerged arc-welded) steel tubes for the verification of hydraulic leaktightness

ISO 10893‑10, Non-destructive testing of steel tubes — Part 10: Automated full peripheral ultrasonic testing of seamless and welded (except submerged arc-welded) steel tubes for the detection of longitudinal and/or transverse imperfections

ISO 11672, Connectors for fluid power and general use — Designation and nomenclature

ISO 11926‑1, Connections for general use and fluid power — Ports and stud ends with ISO 725 threads and O-ring sealing — Part 1: Ports with O-ring seal in truncated housing

ISO 11926‑3, Connections for general use and fluid power — Ports and stud ends with ISO 725 threads and O-ring sealing — Part 3: Light-duty (L series) stud ends

ISO 19879, Metallic tube connections for fluid power and general use — Test methods for hydraulic fluid power connections

For the purposes of this document, the terms and definitions given in ISO 5598 and the following apply.

ISO and IEC maintain terminological 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/

3.1

adjustable stud end

stud end connector that allows for connector orientation through final tightening of the locknut to complete the connection

Note 1 to entry: This type of stud end is typically used on shaped connectors (e.g. tees, crosses and elbows).

3.2

non-adjustable stud end

stud end connector that does not require specific orientation before final tightening of the connection because it is only used on straight connectors

3.3

run

two principal, axially aligned outlets of a tee connector or cross connector

Figure 1 — Run and branch illustration

3.4

branch

side outlet(s) of a tee connector or cross connector

3.5

chamfer

removal of a conical portion at the entrance of a thread to assist assembly and prevent damage to the start of the thread

3.6

assembly torque

torque required to achieve a satisfactory final connection

3.7

qualification test torque

the torque used to verify conformance of the connector to the requirements of this standard

3.8

overtightening

the torque the nut shall withstand without deformation that renders it unusable

3.9

face-to-face dimension

distance between the two parallel faces of axially aligned outlets of a connector

3.10

face-to-centre dimension

distance from the face of an outlet to the central axis of an angularly disposed outlet

3.11

jump size connector

connectors with dis-similar end connections, for example, -6 male flare with a -12 stud end

3.12

size designation

connector size, designated by the nominal outside diameter of the tubing or nominal inside diameter of hose

3.13

contact surfaces

mating interfaces within a connection

Note 1 to entry: These can include, but are not limited to threads, flare seat, and shoulders of nut and sleeve.

Figure 2 shows the cross-section and components of a typical 37° flared connector.

Key

1 straight stud connector body

2 tube nut

3 tube

4 sleeve

5 O-ring

^a Stud end in accordance with ISO 1179-3, ISO 6149-3, ISO 9974-2 or ISO 11926-3.

Figure 2 — Cross-section of typical 37° flared connection

Bodies shall be manufactured from carbon steel or stainless steel, which will provide the minimum requirements for the pressure and temperature ratings specified in Clause 5 when tested in accordance with Clause 15. They shall have characteristics that make them suitable for use with the fluid to be conveyed and to provide an effective joint.

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.

Sleeves shall be manufactured from a material similar to the bodies.

5.1 The working pressure of the connector shall be the lower of the working pressure of the 37° flared connector connection given in Table 1 and the working pressure of the respective stud end.

5.2 Flared connectors in conformance with this document made of carbon steel shall meet or exceed without leakage the requirements to the working pressures given in Table 1 when used at temperatures from −40 °C to +120 °C with petroleum base hydraulic fluids.

5.3 Connectors made of stainless steel complying with this document shall be suitable for use at the working pressures given in Table 1 when used at temperatures from −60 °C to +50 °C.

5.4 For applications under conditions outside the limits for pressure or temperature, or both given in Table 1 and in 5.2 and 5.3, the manufacturer shall be consulted.

5.5 Connectors conforming to this document shall be tested in accordance with Clause 15 to ensure that they meet or exceed the pressure requirements given in Table 1.

5.6 The pressure and temperature requirements given in Table 1 and in 5.2 and 5.3 are for tube connections and connector bodies only. For port and stud end pressure and temperature ratings, the values in the respective port and stud end standards shall apply.

5.7 To achieve these maximum working pressures with a 4:1 design factor, the maximum tube wall thicknesses shown in Table 1 are sufficient. See ISO 10763 to confirm the necessary tube wall thickness for a specific working pressure.

Table 1 — Working pressures for 37° flared connections

6.1 Connectors shall be designated by an alphanumeric code to facilitate ordering. They shall be designated by the word “Connector”, followed by ISO 8434-2, followed by a space, then the connector style letter symbols (see 6.2), followed by a hyphen, then, for the ends, the outside diameter of the tube with which they are to be connected, each separated by a multiplication symbol, ×. There shall be no space on either side of the multiplication symbol. For stud ends (connector ends), the thread designation of the stud end shall be added followed by a hyphen, and followed by connector material symbol.

6.2 The letter symbol designation of the connector style shall have three parts: 1) the connection end type immediately followed by 2) the shape of the connector and 3) by the indication that a complete connector is being ordered. The letters A and B shall be used to distinguish different styles, where such options exist.

6.3 Reducing connectors and elbows shall be designated by specifying the larger tube end first.

6.4 Stud connectors shall be designated by specifying the tube end first, then the thread size for the stud end.

6.5 For tee connectors, the order of designation of the connection ends shall be from the larger to the smaller tube end on the run, followed by the branch end.

6.6 For cross connectors, the order of designation of the connection ends shall be from left to right, followed by from top to bottom, with the larger ends on the left and at the top.

6.7 The following letter symbols shall be used:

6.8 Examples of 37° flared connectors and designations are given in Figures 3 and 4.

EXAMPLE A straight stud connector (SDS), including O-ring without sleeve and nut, for use with 12 mm OD tubing with an 3/4-16 UNF stud end in accordance with ISO 11926-3, made with steel, is designated for ordering as follows:

Connector ISO 8434-2 SDS-12×3/4-16F-S

Figure 3 — Straight stud connector (SDS) with stud end in accordance with ISO 11926-3

EXAMPLE A complete straight stud connector (SDSC), including O-ring with sleeve and nut, for use with 12 mm OD tubing with an M16 × 1,5 stud end in accordance with ISO 6149-3, made with stainless steel, is designated for ordering as follows:

Connector ISO 8434-2 SDSC-12×M16F-SS

Figure 4 — Straight stud connector, complete (SDSC) with stud end in accordance with ISO 6149-3 (sealing type F)

7.1 The connectors shall be suitable for use with tubes with dimensions as given in Table 2 and Table 3. The outside diameter tolerances include ovality. Tubes shall be free of scratches, damage, and imperfections that would be considered detrimental to the function of the tubing.

7.2 Carbon steel tubes

7.2.1 Carbon steel tubes shall be seamless, cold drawn, and normalized. The steel tubes shall be weldable and the content of carbon in its chemical composition shall not exceed 0,22 %.

7.2.2 Mechanical properties in normalized condition at room temperature shall be as follows.

Yield strength: R_{eh min.}: 225 MPa

Tensile strength: R_m: 340 to 630 MPa

Elongation after fracture: A_min.: 25 % for R_m < 480 MPa

                                                                22 % for R_m 480 to 630 MPa

7.2.3 The following surface protections are recommended.

Tubes for welding purpose: phosphated or unplated.

Tubes for flaring purpose: zinc plated, passivated, phosphated, or unplated.

Platings applied should not exceed the tube outside diameter tolerance specified in Table 2 and Table 3 and shall be compatible with the flaring process such that flare quality and cleanliness are not impacted.

7.2.4 Inspection and testing documentation shall be provided which contain at least the following information.

— Chemical analysis

— Tensile testing (ISO 6892-1)

— Tube forming drift expanding testing (ISO 8493)

— Dimensional inspection

— Non-destructive testing for the verification of hydraulic leaktightness (ISO 10893-1)

— Non-destructive testing for the detection of longitudinal imperfections (ISO 10893-10)

— Plating information

7.3 Stainless steel tubes shall comply with ISO 1127.

7.3.1 Stainless steel tubes shall be cold-drawn, solution annealed, and scale-free. Tubes made of stainless steel shall be suitable for welding.

7.3.2 Mechanical properties after heat treatment at room temperature shall be as follows.

Yield strength: R_p0,2 min.: 245 MPa

Tensile strength: R_m: 500 to 730 MPa

Elongation after fracture: A_min.: 35 %

Hardness: max. 90 HRB

7.3.3 Inspection and testing documentation shall be provided which contain at least the following information:

— Chemical analysis

— Tensile testing (ISO 6892-1)

— Tube forming drift expanding testing (ISO 8493) or Ring-expanding test (ISO 8495)

— Resistance to intergranular corrosion (ISO 3651-2)

— Dimensional inspection

— Non-destructive testing for the verification of hydraulic leaktightness (ISO 10893-1)

— Non-destructive testing for the detection of longitudinal imperfections (ISO 10893-10)

Table 2 — Metric tube sizes

Table 3 — Inch tube sizes

8.1 The dimensions across flats of elbow, tee and cross connectors shall be as shown in the respective tables with minus tolerance only. For sizes up to and including 24 mm, tolerances for across flats dimensions for forgings shall be  mm, and for sizes larger than 24 mm, they shall be  mm. The basic forging size may be increased up to the maximum size shown for barstock, but the size selected shall be a metric across‑flat size with minus tolerance only.

8.2 Hex tolerances shall be in accordance with ISO 4759-1, product grade C. Minimum across corner hex dimensions are 1,092 times the nominal 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 15° to 30° to a diameter equal to the width across flats, with a tolerance of  mm.

The connectors shall conform to the requirements given in Figures 5 to 19 and Tables 6 to 20. They shall be designed so that resistance to flow is reduced to a minimum.

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).

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 passage.

Unless otherwise designated, the wall thickness at any point on the connectors shall not be less than the thickness established by the specified dimensions, tolerances, and eccentricities for inner and outer surfaces.

Angular tolerance on axes of end on elbows, tees, and crosses shall be ±2,5° for tube sizes up to and including 10 mm and ±1,5° for all larger sizes.

Details of contour shall be chosen by the manufacturer, provided the dimensions given in Tables 6 to 20 are maintained. Wrench flats on elbows, tees, and crosses 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.

The dimensions for the stud ends shall conform to those given in ISO 6149-3. Stud ends in accordance with ISO 1179‑3, ISO 9974‑2 and ISO 11926‑3 shall not be used for new designs in fluid power applications.

Dimension of reducing connectors shall be in accordance with Annex A.

The screw threads on the tube flared ends of the connectors shall be ISO inch screw threads in accordance with ISO 725. Straight threads shall be class 2A or 2B, except external threads which are plated or coated may exceed 2A diameters but shall not exceed maximum of 3A diameters. Internal threads of all classes shall be within specified limits after plating or coating.

When external threads are produced by thread rolling and the body is not undercut, the unthreaded area adjacent to the shoulder may be reduced to the minimum pitch diameter.

External threads shall be chamfered and internal threads shall be countersunk as specified.

The screw threads for stud ends of connectors shall be in accordance with the applicable defined stud end standard. The dimensions of the stud end connectors shall comply with the requirements given in this document.

Unless otherwise specified, connectors shall be made from carbon steel.

Stainless steel connectors shall be made from the material specified by the user and shall be passivated. Carbon steel and stainless steel connectors fabricated from multiple components must be bonded together with materials having a melting point of not less than 1 000 °C (1 832 °F).

Workmanship shall conform to the best commercial practice to produce high-quality connectors. Connectors shall be free from visual contaminants, all hanging burrs, loose scale and slivers which might be dislodged in use and any other defects that might affect the function of the parts. All machined surfaces shall have a surface roughness value of MRR Ramax 6,3, except where otherwise specified.

The external surfaces and threads of all carbon steel parts shall be plated or coated with a suitable material that passes a salt spray test in accordance with ISO 9227. The following requirements shall apply:

a. No appearance of corrosion products of the protective coating before 96 h.

b. No appearance of corrosion products of the base metal before 144 h.

The following exceptions shall apply

a. All internal fluid passages

b. 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.

c. Areas where there is mechanical deformation of the plating or coating caused by crimping, flaring bending and other post-plate metal forming operations.

d. Areas where the parts are suspended or affixed in the test chamber where condensate can accumulate.

Parts manufactured to this specification shall not be cadmium plated and shall not use hexavalent chromate coatings. Internal fluid passages shall be protected from corrosion during storage and shipping. Changes in plating or coating shall be re-qualified to ensure assemby torque is not affected.

By a method agreed between manufacturer and user, the face of the connectors and threads (both internal and external) shall be protected by the manufacturer from nicks and scratches that would be detrimental to the function of the connector. Passages shall be securely covered to prevent the entrance of dirt or other contaminants. Nuts and sleeves that are furnished separately from the connector shall be protected from rust, but do not require capping.

Unless otherwise noted, all sharp corners shall be broken to 0,15 mm maximum.

The assembly of the connectors with the connecting tubes shall be carried out without external loads. Upon request the manufacturer shall provide assembly instructions for the use of the connectors. These instructions should include the following information:

— 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 number of wrenching turns or assembly torque;

— recommendations regarding the tools to be used for assembly;

— torque values listed in Table 5 are for controlled testing to establish compliance to the performance requirements set forth in Table 4. Recommended assembly torques by manufacturers may vary from Table 5;

— smaller sizes (–2 through –8) of 37° flare connectors are less tolerant to overtightening than the larger sizes. Overtightening in these sizes causes deformation of 37° cone of the male end. Excessive deformation of the cone results in loss of clamping force and, hence, loss of seal. It can also reduce flow area.

The following information should be supplied by the user when making an inquiry or placing an order. Refer to the Designation of connectors in in Clause 6 for additional information:

— description of connector;

— material of connector;

— material and size of tube;

— fluid to be conveyed;

— working pressure;

— fluid working temperature range;

— ambient temperature range;

— seal material.

Connector bodies and nuts shall be permanently marked with the manufacturer's name, trademark or code identifier, unless otherwise agreed upon by the user and manufacturer. Nuts to be used with connectors used with 30 mm and 32 mm tubes shall be marked with the relevant tube outside diameter.

The following outlines the performance test requirements for standard 37° flared connectors. Connectors, Swivel nuts, and sleeves shall be tested in acccordance with ISO 19879, unless otherwise specified. In addition to the test requirements and procedures specified, all components must be able to pass the performance requirements in the as-shipped condition (e.g. annealed components, plating, coatings, rust preventative, etc.).

Working pressures for connectors, tube connections, cap nuts, and hose fittings shall be as listed in Table 4 or as specified in respective clause. Proof pressures shall be twice the working pressures and minimum burst pressures shall be four times the working pressures.

For each size, nine test assemblies in accordance with ISO 19879 shall be subjected to the proof test procedure specified in ISO 19879, prior to burst and cyclic endurance tests. They shall not leak at the respective proof pressures given in Table 4.

Table 4 — Test pressures for steel and stainless steel 37° flared connections

Three of the test assemblies that had been subjected to the proof test in 15.1.1 shall be used for the burst test. The test shall be conducted in accordance with the burst test procedure specified in ISO 19879 and at the minimum torque values given in Table 5. Test blocks and other mating test components for burst testing shall be unplated and hardened to 45 to 55 HRC. The test assemblies shall meet or exceed the minimum required burst pressures given in Table 4.

Table 5 — Qualification test torque requirements

The remaining six test assemblies that were subjected to the proof test in 15.1.1 shall be subjected to the cyclic endurance test procedure as specified in ISO 19879. The test shall be conducted at the torque values given in Table 5. Test blocks and other mating test components for Cyclic Endurance testing shall be unplated and hardened to 45 to 55 HRC. The test assemblies shall pass a cyclic endurance test for 1 000 000 cycles at the respective impulse pressures given in Table 4.

For each connector size, three samples each of the tube nut (N) and sleeve (SL) and the 90° swivel elbow (SWE) nut shall be subjected to the overtightening test as specified in ISO 19879. Test blocks and other mating test components for Overtightening testing shall be unplated and hardened to 45 to 55 HRC. Connector swivel nuts and sleeves shall be capable of withstanding the overtightening qualification test with no indication of failure when torqued to the overtightening values given in Table 5.

Repeated Assembly Test shall be conducted at the torque shown in Table 5 and pressures shown in Table 4. Test blocks and other mating test components for Repeated Assembly testing shall be unplated and hardened to 45 to 55 HRC. Samples shall be assembled and disassembled ten times. Proof test per 15.1.1 shall be conducted following the first and tenth assembly. The test shall be conducted as specified in ISO 19879. The leakage test per ISO 19879 test procedure is not required unless requested by the customer.

Definition of failure after repeated assembly testing:

a. Nut cannot be removed by hand after breakaway.

b. Nut cannot swivel freely by hand (nut and sleeve bonding is allowed).

c. Nut no longer conforms with the dimensional and Proof Test requirements.

d. Any visible cracks or breakage, or plastic deformation on the swivel nut.

Test data shall be reported on the test data form in ISO 19879.

For components that comply to this document, it is recommended to confirm this in test reports, catalogues and sales literature, e. g. “37° flare connector according to ISO 8434-2”.

Dimensions in millimetres
Surface roughness in micrometres

a Pitch diameter.

b Optional construction for shapes.

c Full thread.

d No axial tool marks are allowed on this surface; for spiral tool marks, a surface roughness value Ra ≤ 1,6 µm shall be used.

Figure 5 — 37° flared connection

Table 6 — Dimensions of 37° flared connections

Dimensions in millimetres

Dimensions in millimetres
Surface roughness in micrometres

a Slight flat permissible.

b No axial tool marks are allowed on this surface; for spiral tool marks, a surface roughness value Ra ≤ 1,6 µm shall be used.

Figure 6 — 37° single flare for tubes

Table 7 — Dimensions of 37° single flare for metric and inch tubes

Dimensions in millimetres

Figure 7 — Recommended chamfer for single 37° flares

Table 8 — Recommended chamfer dimensions for single 37° flares

Dimensions in millimetres
Surface roughness in micrometres

a Slight flat permissible.

b No axial tool marks are allowed on this surface; for spiral tool marks, a surface roughness value Ra ≤ 1,6 µm shall be used.

Figure 8 — 37° double flare for tubes

Table 9 — Dimensions of 37° double flare for metric and inch tubes

Dimensions in millimetres

Dimensions in millimetres
Surface roughness in micrometres

a Optional construction.

b Recommended identification for metric sleeves.

Figure  9 — Sleeves – MSL (for metric tubing) and ISL (for inch tubing)

Table  10 — Dimensions of sleeves for metric and inch tubing

Dimensions in millimetres

Dimensions in millimetres
Surface roughness in micrometres

a Both sides.

b Break corners, h₁ minimum both sides.

c Break corners.

d Full thread.

Figure  10 — Tube nut (N)

Table  11 — Dimensions of tube nuts<Tbl_--></Tbl_-->

Dimensions in millimetres

NOTE For details not shown here, see Figure 5 and Table 6.

Figure  11 — Union connectors

Table 12 — Dimensions of union connectors

Dimensions in millimetres

NOTE For details not shown here, see Figure 5 and Table 6.

Figure  12 — Stud connectors with ISO 1179-3 stud ends

Table 13 — Dimensions of stud connectors with ISO 1179-3 stud ends<Tbl_--></Tbl_-->

Dimensions in millimetres

NOTE For details not shown here, see Figure 5 and Table 6.

Figure 13 — Stud connectors with ISO 6149-3 stud ends

Table 14 — Dimensions of stud connectors with ISO 6149-3 stud ends<Tbl_--></Tbl_-->

Dimensions in millimetres

NOTE For details not shown here, see Figure 5 and Table 6.

Figure 14 — Stud connector with ISO 11926-3 stud ends

Table 15 — Dimensions of stud connectors with ISO 11926-3 stud ends<Tbl_--></Tbl_-->

Dimensions in millimetres

NOTE For details not shown here, see Figure 5 and Table 6.

Figure 15 — Stud connector (SDS) with ISO 9974-2 and ISO 1179-2 stud ends

Table 16 — Dimensions of stud connectors with ISO 9974-2 and ISO 1179-2 stud ends<Tbl_--></Tbl_-->

Dimensions in millimetres

NOTE For details not shown here, see Figure 5 and Table 6.

Figure 16 — Stud connector (SDS) with ISO 9974-3 and ISO 1179-4 stud ends

Table  17 — Dimensions of stud connectors with ISO 9974-3 and ISO 1179-4 stud ends<Tbl_--></Tbl_-->

Dimensions in millimetres

a Maximum bulkhead thickness: 10 mm.

b Distance from last full-form thread to bearing face.

c Optional construction.

NOTE For details not shown here, see Figure 5 and Table 6.

Figure 17 — Bulkhead connectors and corresponding bulkhead locknuts

Table 18 — Dimensions of bulkhead connectors and corresponding bulkhead locknuts<Tbl_--></Tbl_-->

Dimensions in millimetres

a Optional dual angle seat.

b Method of attachment of swivel nut is at the option of the manufacturer.

c No axial tool marks are allowed on this surface; for spiral tool marks, a surface roughness value Ra ≤ 1,6 µm shall be used.

NOTE For details not shown here, see Figure 5 and Table 6.

Figure 18 — Swivel connector

Table 19 — Dimensions of swivel connectors<Tbl_--></Tbl_-->

Dimensions in millimetres

a) Cap (CP)

b) Plug (PL)

Key

1 tube nut

2 insert

a For dimensions, see Figure 10 and Table 11 for details.

b Stake or flare to retain insert.

c Optional construction.

d No axial tool marks are allowed on this surface; for spiral tool marks, a surface roughness value Ra ≤ 1,6 µm shall be used.

e Optional dual angle seat

NOTE For details not shown here, see Figure 5 and Table 6.

Figure 19 — Cap and plug

Table 20 — Dimensions of caps and plugs<Tbl_--></Tbl_-->

Dimensions in millimetres