Selection of the expansion joint

The main function of Expansion Joints is to compensate the movements and vibrations in piping systems, machinery and equipment. The movements which the Expansion joint has to compensate are always movements from one part of the piping system relative to another. There is a wide variety of applications in which expansion joints can be used. To properly select the most suitable expansion joint for your application it is necessary to check all selection criteria.

 

1. Material of the bellow

The material of the expansion bellow depends on the medium that will flow through the piping system, the
working pressure of the system and the temperature and the kind of movement. The most common expansion bellow materials are Stainless steel, a variety of rubber grades, PTFE and fabric.

The standard stainless steel expansion joints are made out of AISI 316L (1.4404) material which covers a wide variety of media combined with a good pressure and temperature resistance. For the material resistance against the medium please check out our resistance chart at the end of this catalogue.

 2. Expansion joint type

 An important parameter for the selection of the most suitable type of expansion joint are the movements which the expansion joint will have to compensate.

 

This will be vibrations, axial movements, lateral movements, angular movements or a combination. Other important parameters are the nominal diameter, connections and built-in length of the expansion joint. Sometimes additional accessories will be required such as tie-rods, balancers or inner sleeves.

 3. Piping system

The piping system influences the selection of the expansion joint. The length of the pipes and temperature differences define the magnitude of movements. Also the restriction into terms of installation possibilities, the piping piping accessories, anchors and guides will be taken in account when calculating an expansion joint.

 

The system ‘s reliability is dependent of on good engineered anchors, guides and expansion joints. Unstable anchors can lead to dangerous situations.

4.  Pressure and temperature resistance

When the piping systems is working at elevated temperatures it is necessary to check if the bellow material resists these higher temperatures.

All pressures indicated in this catalogue are given at room temperature. For higher temperature it is necessary to take the derating of the material into account. When the temperature raises the materials will be less resistance to pressure forces. For stainless steel these derating factors are well-known:
°C 20

5. Technical Calculations

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BM Europe Expansion Joints Technical Cal
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