BELLOWS - TYPES OF MOVEMENTS

TYPES OF MOVEMENTS

Expansion joint is defined as an assembly containing one or more bellows used to absorb dimensional changes caused by thermal or mechanical movement in a pipeline or duct.

Expansion joints assembly consist of Bellow (Flexible Element) and end connections (Pipe, Flange or any special fittings as per requirements). As per design requirements Limit Rods(Tie Rods), Internal Sleeve(Liner), Shroud (External Cover) are also provided.

Three basic types of movements absorbed by Expansion Joints.

A	AXIAL
	A-1 Axial Extension
	It is Lengthening of an expansion joint parallel to its longitudinal axis.
	A-2 Axial Compression
	It is Shortening of an Expansion joint parallel to its longitudinal axis.

B	Lateral Deflection
	The relative displacement of the end connections of an Expansion joint perpendicular to its longitudinal axis. This movement has also been referred to as lateral offset, lateral movement or parallel misalignment.


C	Angular Rotation
	The angular displacement between longitudinal axis of the end connections of an expansion joint.

Vibration

Vibration is always undesirable in a piping system and often bellows type Expansion joints are used to dampen vibration. It is essential to know the magnitude of movements and the frequency of the vibration in the system.

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