Description and application
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.
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.
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
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.
|series||pipe O.D. |
|maximum working pressure [bar]|
|for complete connectors|
by different manufacturers
|LL||4 ÷ 8||100||–||–|
|L||6 ÷ 15||250||160||400|
|18 ÷ 22||160||100||315|
|28 ÷ 42||100||100||250|
|S||6 ÷ 12 (14)||630||400||630|
|16 ÷ 25||400||250||400|
|30 ÷ 38||250||250||315|
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).
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.