Universal Expansion Joint
A Universal Type Expansion Joint is one which contains two bellows with a connecting pipe between them. It is usually furnished with limit rods or full thrust tie rods, depending upon the service conditions. Tie rods or limit rods stabilize the center pipe connection and distribute movement evenly between bellows. Tie rods are required where it is necessary to absorb full pressure thrust and other externally applied loads.
Universal Expansion Joints are normally designed to absorb any combination of axial and lateral movement and angular rotation in multi-plane piping arrangements. They are extremely well suited to the absorption of large amounts of lateral displacement. The magnitude of the lateral displacement can be varied considerably because any increase in the length of the center pipe nipple produces a corresponding increase in allowable lateral deflection. In installations involving large amounts of thermal change, where there is a change in elevation of the piping or where offsets exist, it is frequently possible to install Universal Type Expansion Joints in the offset or drop leg, which will absorb considerably more movement laterally than can be absorbed in compression by standard units. Installation of a Universal Expansion Joint in such instances will usually result in a considerably reduced construction cost.
Universal Expansion Joints are usually constructed with either two sets of short tie rods, one set over each bellows, or with overall tie rods. A unit with the two sets of short rods is designed primarily to limit movement and stabilize the connecting pipe section. A unit with overall tie rods is designed to absorb full pressure thrust, to stabilize the connecting pipe section, and to absorb all external loads which are present, such as wind loads and weight of center pipe nipple where unit is exceptionally long.