Threaded hydraulic pipe connectors (fittings) with 24° sealing cone and a cutting ring are popularly used in numerous industrial applications to join together or connect rigid pipe assemblies with outer diameters of 4 ÷ 42 mm, made of steel. They can also be used to connect flexible hose assemblies (as a body without nuts and cutting rings). They are suitable for hydraulic and pneumatic drives and controls, but also for general purpose applications. Compliant with DIN 2353 (PN-EN ISO 8434-1) standard.

Working principle of a cutting ring connector

Elements needed to connect a pipe to a hydraulic system: connector (1), cutting ring (2), nut (3) and hydraulic precision pipe (4). During installation the sharp edges of the cutting ring (5 and 6) slide down the cone (7) biting into the surface of the pipe and forming a visible shoulder (8). The pipe, cut square, must be pressed against the bottom of the seat in the connector body (9), otherwise the ring does not bite into the pipe deep enough.

before installation	after installation

The fittings manufactured according to DIN 2353, depending on application and pressure, are divided into the following series:

• LL (very light series) – suitable for small hydraulic and cooling devices, plastic pipe assemblies, compressed air, propane, etc.
• L (light series) – standard system applications within the working pressure range of that series
• S (heavy series) – suitable for higher pressure, high pressure hydraulic systems e.g. impact equipment applications, building ships and heavy machinery, mining, chemical industry.

Basic information

Material

DIN 2353 connectors are available in two material versions:

• carbon steel (zinc-plated or phosphated), standard sealing: NBR rubber
• stainless steel (AISI 316), standard sealing: Viton.

Working temperature

Allowable working temperature as determined by the material of the connector and sealing used:

• carbon steel: from -40°C to +120°C
• carbon steel + NBR: from -35°C to +100°C
• stainless steel: from -60°C to +400°C
• stainless steel + Viton: from -20°C to +200°C

Working pressure

The maximum working pressure (nominal pressure) of DIN 2353 connectors differs depending on series (light, heavy), size (pipe O.D.), type, material and manufacturer. The table below shows data for various types of connectors, from different manufacturers, made of carbon steel or stainless steel. It is intended for reference only, to enable initial selection. If the required working pressure exceeds the value given as minimum in the table, please contact Tubes International for proper selection.

The nominal pressure (maximum working pressure) given by a manufacturer is derived from calculations for static working conditions that take into account a safety factor of 4:1 for cutting ring connections and from 1.5 to 2.5 for connections screwed into a body or BANJO fittings. When choosing a connector, dynamic pressure load and vibrations must be also considered. For temperatures above +100°C, the maximum working pressure may require reduction (contact Tubes International).

Medium:

DIN 2353 connectors are suitable for a broad range of fluids and gases. However, always check if a medium is compatible with the material of the connector and sealing. For all applications different from standard hydraulic oils, please contact Tubes International.

Pipe assemblies used in hydraulic systems:

Pipes used for building hydraulic systems:

• seamless precision pipes made of steel, protected against corrosion (phosphated, zinc-plated), annealed
• precision pipes made of steel, cold-drawn, free of annealing scale, heat treated (annealed)

Pipe dimensions (outside diameter, wall thickness) must be selected according to the target value of working pressure and flow rate in the system.

Comparative test in a salt spray chamber for 720 hours
standard zinc coating	VOSS Coat zinc-nickel coating

Improved construction of DIN 2353 connections

All components of VOSS connection system are perfectly matched to each other. Thus it takes less effort to assemble them and the elements do not wear so much. Main advantages:

• reduction of a final assembly angle from 90° to 30°
• require significantly less effort during installation
• easy final assembly in confined spaces
• protection against excessive tightening during final assembly
• suitable for repeated assembly

There are both manual and fully automatic devices developed to assemble elements of DIN 2353 VOSS connections correctly. For proper selection of your solution, please contact Tubes International.

VOSS Ring^M cutting ring connections

VOSS RingM cutting ring allows for easy, quick and reliable connection. Improved cutting geometry ensures superb tightness. All parts exposed to high pressure impact are reinforced to increase stability and pressure resistance. A patented limit stop enables correct  pre-assembly, prevents over-tightening or under-tightening of the connector. The cutting ring, with a very thin, yet extremely hard surface created in the process of surface hardening, can be easily used  for stainless steel pipes. VOSS RingM rings are coated with VOSS Coat in black colour as standard.

Characteristics: extreme hardness to bite into pipe surface deep enough high dynamic load capacity optimum construction facilitates correct assembly minor spring-back after assembly suitable for use with carbon steel and stainless steel pipes

ES-4 cutting ring connections

A cutting ring with a  moulded seal  in the recess on the cone of the ring and an additional o-ring between the ring and pipe (stainless steel rings have labyrinth metal sealing). The seals stop all possible leaks that may sometimes occur  when metallic sealing loosens, e.g. during continuous full load operation or operation under dynamic loads. The rings are available in both carbon steel (coated with VOSS Coat, NBR sealing) and stainless steel (with FPM/FKM sealing).

Characteristics: additional elastomer sealing ideal for dynamic loads reinforced ring construction can be pressed harder against 24° cone slight spring-back after assemblycarbon steel and stainless steel versions available

Formed pipe connections – VOSSForm^SQR

A pipe end in VOSSForm^SQR system is plastically formed  to work with DIN 2353 connectors. To obtain a uniquely shaped shoulder on the pipe, the section of pipe material is formed with a specially designed VOSS device (available in Tubes International). This formed pipe end comes with an additional elastomer seal (FPM/FKM is a standard seal material).

VOSSForm^SQR connection combines the highest level of safety with exceptional quality. It withstands the most extreme dynamic loads, bending , temperature fluctuations ensuring durable and reliable connection.

VOSSForm^SQR system is available in carbon steel and stainless steel.

Characteristics: greatest resistance to dynamic loads noticeable increase in tightening torque prevents over-tightening or under-tightening of a connector connection forming process is very fast perfect solution for series production available in carbon steel and stainless steel

BV-10 stud connection

System suitable for operation under extreme loads. Resists bending moments, pressure variations, continuous maximum working pressure operation and temperature fluctuations. BV-10 stud is mounted in a pipe end by pushing it in with VOSS manual device. The surface of the stud is serrated on the pipe side to prevent it from sliding off and acts as metal sealing.  The flared end of the pipe is held by a clamping ring inside the nut.

Characteristics: outstanding resistance to dynamic loads easy assembly, even on thick-walled pipes compatible with all DIN 2353 connectors can be used with stainless steel pipes available in carbon steel and stainless steel

DIN2353 Eaton Walterscheid™ connectors with 24° sealing cone are designed to connect pipes in the most challenging applications. Eaton Walterscheid™ system ensures tightness of the connection up to 800 bar (for heavy series) and 500 bar (for light series).

DIN2353 Eaton Walterscheid™ DIN2353 connectors are made of carbon steel with nickel-free Guardian Seal™ coating to provide exceptional resistance to corrosion. The corrosion resistance of Guardian Seal™ coating exceeds the German VDMA24576 K5 standard (min. 720 hours in a salt spray chamber before red corrosion occurs), qualifying the connectors for operation in critical applications and toughest environments. Guardian Seal™ is also a more eco-friendly plating technology. The coating is free of nickel and solvents. It meets global requirements of such EU directives as RoHS (Restriction of Hazardous Substances), ELV (End-of-Life Vehicle) and REACH (Regulation for Registration, Evaluation, Authorization and Restriction for Chemicals).

DIN2353 Eaton Walterscheid™ connector with corrosion resistant Guardian Seal™ coating is a popular solution in offshore and marine industry, for heavy duty application in agriculture, mining, railway and construction.

Three options of Eaton Walterscheid™ system are available depending on operating conditions:

WalPro – static operation

A nut with a cutting ring. The ring is specially shaped for uniform cut penetration and clamp evenly distributed around the pipe diameter. During assembly, the cutting ring bites into the pipe surface and is pressed against 24° cone in the seat of a nut sealing the connection. Stainless steel version is also available. A complete system with cutting rings and nuts is available only as a set marked with a code HD-MWP…

WalRing –  system prone to vibration

A nut with a double-edge cutting ring integrated with a hardened, support ring coated with rubber and a special WALFORMplus system elastomer (Viton) seal  for even more support. The support ring ensures that the cutting ring properly bites into the pipe. The connection is sealed when an elastomer seal is pressed between the pipe, the ring and 24° cone in the seat of the nut during tightening.  A complete WalRing system with rings, seal and nut is available only as a set marked with a code HD-MWR…

WALFORMplus –  tightness even in highly dynamic operation conditions, pressure pulsation and mechanical loads.

A nut with an elastomer (Viton) seal. For the system to work, the end of a pipe must be reshaped in a special machine intended for this purpose (available at Tubes International). A shoulder formed from the pipe material in this way together with the elastomer seal do not require any additional elements such as rings to make perfectly tight connection. During  assembly, the elastomer seal is pressed between the shoulder formed on the pipe and 24° cone in the seat of a nut sealing the connection.   The elements of WALFORMplus system (seal and nut) are available only as a set, marked with a code HD-MWF…