Untied Expansion Joints
Untied Metal Expansion Joints (MEJs) or bellows, are designed to allow free axial movement without internal restraints like tie rods. This flexibility makes them ideal for handling thermal expansion, vibration, and pipe movement.
Since these joints are untied, the pressure thrust load is transferred directly to the anchors. As a result, anchors must be engineered to withstand both pressure thrust and spring forces from supports like hangers.
Key Highlights
- Pressure thrust acts on external anchors
- Anchors must be designed for both pressure thrust and spring forces
- Untied MEJs are commonly used in high-temperature and high-pressure systems such as power plants, refineries, and HVAC systems.
Untied-Single Expansion Joints
- Contains a single bellows element
- Allows axial movement
- Transfers pressure thrust to pipe anchors
- Used in systems with thermal expansion and space constraints
Untied Universal Expansion Joints
- Two bellows connected by a centre spool
- Accommodates large lateral movement and some axial motion
- Also transfers pressure thrust to anchors
- Ideal for longer runs needing high flexibility.
Key Consideration
- Since there are no tie rods, the anchors must be designed to handle pressure thrust and spring forces.
At LSI-MECH, we specialize in the detailed engineering and design of untied expansion joint systems. Our in-house team ensures that all pressure thrust loads are accurately calculated and that anchors, guides, and spring supports are optimally designed to safely handle these forces. For these metal Expansion Joints, we offer complete in-house services including blasting and painting, along with the provision of shipping brackets that support the joint during transport and must be removed after installation. We also have the expertise to internally line metal expansion joints with rubber or PTFE for special service conditions.