Understanding Pressure Thrust in Bellows Design
Pressure thrust is the longitudinal force generated by the internal pressure acting on the effective area of a metal expansion joint (bellows) in a piping system. A bellows is a flexible, discontinuous component that cannot resist this force on its own. Therefore, the pressure thrust must be transferred to the system’s anchors or supports.
Why Pressure Thrust Matters in Bellows Design
- The magnitude of pressure thrust is calculated as the product of internal pressure and the bellows’ effective area, based on the mean diameter of the bellows convolutions.
- Proper management of pressure thrust is essential to prevent over-stressing anchors and connected equipment, which can otherwise lead to mechanical failure or system downtime.
- If adequate anchors or guides are not installed, the bellows will experience uncontrolled deformation caused by the pressure thrust, risking total failure of the expansion joint.
- When anchors cannot absorb the pressure thrust, tie rods are used to restrain the force. However, this comes at the cost of restricting the bellows’ ability to absorb axial movement.
- Failure to consider pressure thrust during design can lead to premature failure, costly repairs, and unsafe operating conditions
Additional Load Considerations
Wind loads and installation loads must be provided and considered During design to ensure a perfect, site-specific, and compliant expansion joint solution Accounting for these loads ensures overall system integrity and reliable long-term performance.
Did You Know?
At LSI-MECH, we carefully evaluate pressure thrust in every application and integrate it into the design of our metal expansion joints and bellows to ensure long-term reliability, structural safety, and performance even under the most demanding conditions. Pressure thrust design considerations comply with international standards including: ASME, EN, JIS, GOST, and EJMA