Expansion Joint Design, Manufacture and Testing for Large Capacity Steam Turbines

The rapidly growing trend for higher capacity steam turbines with large steam flows demand the use of long lengths and large size pipes. Thermal expansions of up-to 50mm and pipe diameters up-to 2600mm are required to be dealt with calling for the use of Expansion Joints to control the stresses in both the pipes as well as the end equipment. The bellows in the Expansion Joints used for the steam turbine application are stretched to their limiting values of the stresses in order to make them as flexible as possible with the aim of limiting the pipe and end equipment operational stresses. Three fundamental types of loading are presented to provide insight into the way bellows convolutions are stressed during operation. The optimization of the bellows profile geometry is discussed briefly. A comparison of the resulsts obtainied by proven computational methods as well as by using international EJMA standard is made to highlight the safety built in the well established methods used.