Expansion Joints

About Expansion Joints

Expansion Joints also called compensators or bellows expansion joints are flexible devices installed in piping systems ducts and vessels to absorb dimensional changes caused by thermal expansion contraction vibration or movement without inducing excessive stress on the system

What Are Expansion Joints Made Of

Expansion joints typically consist of the following elements

Bellows Element

The core flexible component usually made of stainless steel or other alloys

Formed with corrugations convolutions to provide flexibility and absorb movement

End Connections

Weld Ends Flanges or Threaded Ends for connecting to the pipeline

Accessories Optional

Inner Sleeve Flow Liner Protects bellows from turbulence and erosion

Outer Cover Shroud Shields bellows from mechanical damage and environment

Tie Rods Limit Rods Controls pressure thrust and movement limits

Hinges Gimbals For angular movement control in special designs

Insulation Layer For hightemperature applications

Functions of Expansion Joints

Absorb Thermal Expansion Contraction Compensate for length changes due to temperature variations

Reduce Vibration Dampen vibrations from pumps turbines or compressors

Correct Misalignment Compensate for minor installation or settlement deviations

Relieve Stress Prevent excessive loads on pipes anchors and equipment

Types of Expansion Joints

Axial Expansion Joint Single Bellows

Handles axial movement along the pipeline

Universal Expansion Joint

Two bellows with a center spool for lateral movement

Hinged Expansion Joint

Allows angular rotation in one plane only resists pressure thrust

Gimbal Expansion Joint

Allows angular movement in multiple planes

Pressure Balanced Expansion Joint

Neutralizes pressure thrust while absorbing axiallateral movements

Rubber Fabric Expansion Joints

For lowpressure lowtemperature ducting systems eg HVAC

Summary Table

Type Movement Absorbed Pressure Thrust Restraint

Axial Axial only No

Universal Lateral some axial No unless tied

Hinged Angular single plane Yes

Gimbal Angular multiplane Yes

Pressure Balanced Axial lateral Yes