UNIVERSAL EXPANSION JOINTS

Universal expansion joints consist of two multi-convoluted bellows connected with an intermediate pipe into one assembly.

Belman has developed a series of universal expansion joints that allows all three movements: axial, lateral and angular simultaneously.
The universal expansion joints can be equipped with all kinds of end connections, like welding ends, welded or loose flanges, and an endless number of accessories such as inner sleeves, cover and movement controls.

Belman designs and manufactures a wide range of universal expansion joints.

Customised solutions
As customised solutions universal expansion joints are available in all sizes up to DN 12.000, all designs and all materials.

Standard solutions
As standard solutions universal expansion joints are available in size range DN 50 – 2200.

The universal expansion joints allow a large amount of lateral offset in multiple planes, and the lateral deflection can be increased or decreased by changing the length of the intermediate pipe. Universal expansion joints do not use tie rods, and are therefore suitable only for low pressure applications. Fix points and guides must be sufficiently designed to withstand the full pressure thrust forces and other loads. Universal expansion joints is not to be confused with lateral expansion joints.

Definitions
Movement is shown as AX (axial), LA (lateral), AN (angular) mm + deg. The parallel displacement is indicated as negative (-) and positive (+) respectively. It is very important to notice if the movements is stated in combination (universal), or as an alternatively combination of the different directions.

Example
The elongation of the bellow is +10 and the compression of the bellow is -20. This will be shown as: +10/-20 mm. Equal parallel displacement is shown as: +/-20 mm.

Universal expansion joints can absorb movements in all directions, and are used in uncritical, low pressure installations like ventilation ducts, exhaust gas systems, fresh air ventilation and process equipment.

What are the advantages of using Universal expansion joints?

• Absorb movements in all directions
• Absorption of large axial movements and lateral movements in one expansion joint (Universal expansion joints)
• Can be modified to suit existing installation gap

What are the requirements for using Universal expansion joints?

• Only for low pressure applications
• Fix points and good guides are required
• Many fix points and guides are needed for long pipe sections

Universal expansion joint to absorb lateral movement

Shows a tied universal expansion joint used to absorb lateral deflection in a single plane
“Z” bend. Where dimensionally feasible, the expansion joint should be designed to fill the entire offset leg so that its expansion is absorbed within the tie rods as axial movement.

The tie rod should be extended to the elbow centre line when practical. The thermal movement of the horizontal lines is absorbed as lateral deflection by the expansion joint.

Only directional guiding is required since the compressive loading on the pipe consists only of the force necessary to deflect the expansion joint. Any thermal expansion of the offset leg external to the tie rods, such as that part of the elbows at either end, must be absorbed by bending of the horizontal pipe legs.

Provisions should be made in the design of the guides to allow for both this deflection and the reduced length of the expansion joint in its deflected position.

Universal expansion joint in “Z” bend

Shows a typical application of a tied universal expansion joint in a three plane “Z” bend.
Since the universal expansion joint can absorb lateral deflection in any direction, the two horizontal piping legs may lie at any angle in the horizontal plane.