ISO 8434-1 24°cone tube fittings dimensions

The 2018 PDF Version of DIN EN ISO 8434-1 fitting is the metallic tube connection for fluid power and general use with 24°cone connectors. It 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.

Content of ISO 8434-1 standard

• Material of ISO 8434-1 fittings

• Pressure/temperature requirements for 24°cone connectors for fluid power and general use

• Designation of ISO 8434-1 connectors

• Requirements for tubes

• Across-flats dimensions and tolerances

• Screw threads of ISO 1834-1 fittings

• Dimensions of 24 degree cone end, cutting ring and nuts

• Dimensions fo weld-on nipple, o-ring, weld-on reducing nipple

Material of ISO 8434-1 fittings

1 body  2 nut  3 cutting ring

Figure 1  Cross-section of typical 24°cone connector with cutting ring

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

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.

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.

Cutting rings

The ring material shall be compatible with the fluid to be conveyed and provide an effective joint.

Steel cutting rings are to be used in combination with other steel connector components and steel tubes.

Stainless steel cutting rings are to be used in combination with other stainless steel connector components and stainless steel tubes.

Brass cutting rings are to be used in combination with other brass connector components and copper tubes.

Other combinations of materials shall be agreed upon between the purchaser and supplier

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.

Pressure/temperature requirements for 24°cone connectors for fluid power and general use

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.

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.

The connector assembly shall meet or exceed all applicable performance requirements given in Clause 15. Testing shall be conducted at room temperature.

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.

According to different applications and different pressure ratings, there are three series of connector, designated by

LL, for extra light-duty

L, light-duty

S, heavy-duty

Designation of ISO 8434-1 connectors

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.

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.

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.

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

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.

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.

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.

If the connector has a tube union connection, it shall be designated first. Then the designation shall proceed clockwise.

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

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

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)

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)

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) Types of ISO 8434-1 Fittings.

Across-flats dimensions and tolerances

For sizes up to and including 24 mm, tolerances for across-flats dimensions for forgings shall be

0 to -0,8 mm, and for sizes larger than 24 mm, they shall be 0 to -1mm

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 0 to -0,4mm. The dimensions across flats for nuts and on the bodies of the connectors shall be those given in Table 5 and Tables 9 to 21.

Screw threads of ISO 1834-1 fittings

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 0 to -0.4mm.

Stud 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.

Dimensions of 24 degree cone end and cutting ring

Cutting ring (CR) and 24° cone end 

Assembly

Dimensions of cone end and cutting ring

Tube nut (N)

Dimensions of tube nut

Dimensions fo weld-on nipple, o-ring, weld-on reducing nipple