Rectangular sheets of stainless steel are rolled along the long edge of the rectangular sheet in a tube and the tube is welded. The tube is then worked up into bellows using mechanic and hydraulic forming methods. Bellow units of expansion joins are produced from stainless steel of thickness 0,1 to 0,3 mm according to EJMA (Expansion Joint Manufacturers Association) standards. However specifi c applications can also be designed and produced using nonstandard and distinctly shaped bellows. Before the design phase all design conditions and constraints have to be determined accurately.
The diameter of the pipe where the expansion joint is to be mounted, the type of fluid coming in contact with, the maximum values of pressure and temperature to occur in the pipeline, the amount of expansion at the pipeline are the most important conditions of design. In addition to these lateral or angular designs for other specific systems can also be made.