A Universal Expansion Joint is one containing two bellows joined with a spool piece for the purpose of absorbing any combination of the three basic movements: Axial movement, Lateral deflection and Angular rotation.
The primary purpose of Universal Bellows is to accept large amount of lateral deflections which in fact is a function of the amount of angulations each bellows can absorb and the distance between the two bellows. The length of the center spool piece can be adjusted so as to increase or decrease the lateral deflection capability.
Flexican also designs and supplies Universal Bellows with or without tie rods, which connects the ends of the unit to each other and restrains the pressure thrust load. The number of tie rods to be provided around the circumference of the expansion joint depends on the application, for instance two tie rods are provided 180 degrees apart which enables the expansion joint to bend or deflect angularly and laterally. Similarly three or more tie rods are provided equally by pressure thrust and in such cases only lateral deflections are possible without any significant forces being applied by the adjacent piping.
Universal Bellows Expansion Joints are usually long and are designed such that the thermal expansion of the entire unit's length is accepted as compression by the two bellow elements and as a result the overall length of the unit does not change when the piping is heated.