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Pressure Balanced Expansion Joints

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Pressure balanced expansion joints play a critical role in a variety of applications. They are used in piping systems to absorb thermal expansion, vibration, and other movements while maintaining the integrity of the pipeline by minimizing the forces imposed on the system by the expansion joint.

What are Pressure Balanced Expansion Joints?

A pressure-balanced expansion joint is capable of accommodating both axial and lateral movements while counteracting the bellows pressure thrust. To achieve this, an additional bellow is integrated into the unit and is exposed to the line pressure, generating a force that is equal and opposite to the main bellows. By connecting these two bellows, the pressure load on the unit is effectively neutralised.
Pressure balanced expansion joints are available in two different types, elbow pressure balanced expansion joints and in-line pressure expansion joints. The choice between in-line and elbow pressure balanced expansion joints depends on the specific requirements of the piping system.

Elbow Pressure Balanced Expansion Joints

Elbow pressure balanced expansion joints are designed for use in piping systems where changes in direction occur. They have a curved or angled shape that allows them to accommodate both axial and lateral movements as well as changes in direction.

When an ordinary axial expansion joint is installed in a pressurised pipe system, the pressure reaction force and the force required to move the pipe expansion joint are transmitted to the pipe system. The pressure thrust force can be substantial and can create high demands and stresses on the guides and fix points used for supporting or fixing the pipe system.

This can be alleviated somewhat if the pipe layout either supports the use of lateral/angular or gimbal expansion joints or can be altered to do so, however if this is not practicable then the use of pressure balanced inline or elbow expansion joint is advantageous.

Elbow pressure balanced expansion joints balance this pressure thrust force internally within the expansion joint.

Only the spring rate force that is needed to move the pipe expansion joint is transmitted to the pipe system. This decreased load acting on the guide reduces the need for supporting structures.

In-Line Pressure Balanced Expansion Joints

In-line pressure expansion joints are also designed to absorb axial and lateral movements resulting from thermal expansion, vibration or other mechanical stress. They are designed to handle axial movement and also counteract the pressure thrust force generated by the bellows.
An in-line pressure balanced expansion joint comprises of balancing bellows and line bellows. The balancing bellows have a larger effective area, which is always twice the area of the in-line bellows. These two types of bellows are connected through a series of tie-rods.

Where are Pressure Balanced Expansion Joints used?

Pressure balanced expansion joints are commonly used in piping systems that experience high pressure and high- temperature fluctuations. Typically, this will include industrial applications where the pipeline or ductwork is subjected to high-pressure changes, thermal expansion, or contraction.
Pressure balanced expansion joints can reduce the stresses and forces that are transmitted to the pipeline or ductwork, which can increase the overall lifespan of the system. The reduced pressure thrust can allow for the use of smaller and lighter anchors, which can lead to cost savings in terms of both materials and installation.

Why Choose Stourflex for Pressure Balanced Expansion Joints?

Stourflex is one of the UK’s leading suppliers of pipework expansion joints and pipeline equipment. With our wealth of experience, we can provide technical advice and sales support to ensure you obtain the right expansion joints for your needs. Contact us for further information, advice and support.