Rectangular metal expansion joints have a variety of applications in the power, petrochemical, refining, chemical, and steel industries. Since there are no standard duct sizes, and due to the wide range of pressure and temperature combinations, each rectangular metal expansion joint is custom-engineered to provide the most economical design that will absorb the thermal movements of the system in which it is installed.
General arrangement of rectangular expansion joints with supported sides
- Absorbs axial and lateral movements
- Variety of bellows geometry (for long straight sides)
- Normal guiding is required
- Manufactured for a wide variety of materials
Like circular expansion joints, rectangular expansion joints absorb three types of movement: axial, lateral and angular. For the purpose of designing rectangular bellows, it is critical to know in which direction the lateral and angular movements will occur, i.e. parallel to the long and/or short side of the bellows.
Unlike circular bellows where the pressure stress is a circumferential membrane (hoop) stress, the rectangular bellows must be designed for longitudinal (beam) bending stresses. Long unsupported lengths must frequently be supported to prevent excessive deflection and stresses of the bellows element. In certain applications, covers and liners can perform the function of pressure supports.