Thermal growth, equipment movement, vibration or pressure pulsation may generate movement in a piping system. When this movement is not absorbed by the piping system itself, an expansion joint is the perfect solution.
An expansion joint is a device primarily formed by flexible bellows used to absorb movements in a piping system while containing pressure and a medium running through it.
The most important part or main element of any expansion joint is the bellow. The bellow is a flexible element consisting of one or more corrugation and the end tangents.
The most standard types of connection parts are welding ends and flanges. Metal Expansion Joints are connected to pipes, machines and apparatus either by welding them to the pipes or by flanging them. In some cases, screwed nipples or clamps are used.
The basic advantages to be gained from using Expansion Joints are:
- Little space required for installation
- Absorption of movements in multiple directions due to their inherent flexibility
- They require no maintenance
- They reduce load and temperature loss to a minimum
There are three basic movements that can be absorbed by an Expansion Joint:
Axial Movement is the change in dimensional length of the bellows from its free length in a direction parallel to its longitudinal axis.
Angular Movement is the rotational displacement of the longitudinal axis of the bellows toward a point of rotation.
Lateral movement is the relative displacement of one end of the bellows to the other end in a direction perpendicular to its longitudinal axis.