Rectangular metal expansion joints are designed to absorb movements in all three directions i.e. axial, lateral and angular. The rectangular bellows are mostly designed for very low pressure applications such as ducts, exhaust systems, ventilation systems etc.Rectangular metal pipe 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 pipe 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. Like circular pipe expansion joints, rectangular pipe 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.