Rubber Joint

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Rubber Joint

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Rubber Joint

Rubber Joint

A rubber expansion joint is a flexible connector made of natural and/or synthetic elastomers and fabrics. If necessary, internal metal reinforcements are designed to reduce the stress caused by thermal movement and mechanical vibration in the piping system. Flanged single sphere expansion rubber joint can greatly reduce pipeline system vibration and noise, can solve the problem of joint displacement, axial expansion, etc.


According to the use area of rubber expansion joints, there are a variety of materials to choose from. In addition, rubber expansion joints also have advantages and disadvantages between metal expansion joints. Rubber expansion joints can absorb large movements in a short distance. They provide movement in all directions, such as axial, angular, lateral, and torsion that may occur due to external conditions. It can also reduce wind, impact loads and seismic motion.

Rubber Joint Features

According to different materials manufacture, flexible rubber joint can be made into many kinds: acid resistance, alkali resistance, corrosive resistance, oil resistance, heat resistance, adapt to many mediums and different environment.

Material is polar rubber, good sealing, light weight, easy installation, long service life, avoid contacting with sharp metal device.

Rubber Joint Application

• Heating and cooling equipment

• Material handling technology

• Water pipe

• Desalination plant

• Compressor

• Blower and fan

• Cement industry

• Chemical industry

• Glass industry

• Wood processing industry

• Pulp and paper industry

• Rail vehicles

• Refinery

• Shipbuilding

• Steel plant

• Sugar industry

Rubber Joint Matters needing attention

If use overhead, can match with elastic support, when installation, bolt with diagonal method to tighten up.

If pipeline pressure is high, use bolt connect the flange both ends.

Comparison with metal expansion joints

Temperature: The upper limit of temperature for rubber joints of standard structure and material is 110°C. Special structures up to 200°C are available. Metal expansion joints do provide a larger range, from -250°C to +950°C.

Pressure: The rubber joint depends on the diameter and can withstand pressures up to 15 bar under full vacuum rating. Metal fittings can be designed for pressures up to 100 bar.

Movement: Rubber and metal expansion joints have similar movement capabilities in the axial plane (compression and extension). However, rubber joints can of course absorb greater lateral movement than metal joints of similar length to face-to-face.

Spring stiffness: For standard face-to-face dimensions, rubber and metal joints do have similar characteristics in the axial plane. Metal joints are much harder to withstand lateral movement and generally have lower lateral movement capabilities.

Acoustic impedance: Although well-designed (multilayer) metal joints can reduce the transmission of visible vibration, they will continue to transmit distracting and/or destructive noise. Rubber joints can significantly reduce poor transmission in the piping system. The elastic component of the joint acts as a damper, absorbing the maximum percentage of perceivable noise and vibration.

Wear/corrosion resistance: The wall thickness of metal joints is usually between 0.15 mm and 2 mm. Rubber joints are much thicker, from 12 mm to more than 25 mm. The thin structure of metal joints makes them susceptible to corrosive chemicals and abrasive liquids and slurries. Rubber joints are highly resistant to all types of wear and erosion, and are superior to metal joints in applications where these conditions prevail.

Fatigue/cycle life: The fatigue life of metal joints is affected by many factors, such as temperature, pressure, motion, vibration, and the way the joint was originally designed. Generally, metal joints have a defined cycle or fatigue life, which can be calculated by various formulas (EJMA). Metal joints often fail due to fatigue due to excessive cycling/movement. On the other hand, rubber joints are composed of elastic elastomers, and the joint itself acts as a shock absorber and is not susceptible to fatigue/cyclic failure.

Installation/Maintenance: Rubber joints do not require additional gaskets. In many cases, they can be installed without using special processing equipment. The metal joints must be repaired from time to time to ensure that the flange gasket is still intact and will not deteriorate

Types of rubber expansion joints

Arch type:

The full-face integral flange design can be used for single-arch and multi-arch types.

Single narrow arch type:

The structure is made of fabric and rubber and reinforced with metal rings or wires. The full face flange is integrated with the main body of the joint, and drilled to match the bolt pattern of the pipe-matching metal flange.

This type of rubber-faced flange has enough thickness to form a tight seal on the metal flange without the use of gaskets.

Multiple narrow arches:

Joints with two or more arches can be made to accommodate larger movements than can be withstood by a single arch type joint.

 Most manufacturers' multi-arch joints are composite materials of standard-size arches that can move a single arch multiplied by the number of arches.

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