Contraction: 
A metal expansion joint is fabricated item to be fitted into a pipeline to absorb movements in and
Forces exerted on the pipeline. A sheet of metal rolled into a cylinder and seam welded using the
GTAW(TIG) welding process. Convolution(corrugations) are formed into the wall of the elements. 
The elements may be single ply or multi-ply. The joint consist of a metal expansion joint element
With flanges or pipe weld ends fitted to facilitate the bolting or welding of the joint into a pipeline. 
Control devices commonly called hardware in the industry, can be attached to control the direction
And amounts of movement that the bellows achieves.