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