The basic element of a Metallic Expansion Joint (MEJ) is the bellows - a flexible, corrugated tubular metal element to absorb movements in a piping system. In the operating environment the crictical stresses and movements may actinaxial,lateralorangulardirections and the bellows must therefore be designed and dimensioned to accommodate these movements. Metallic Expansion Joints are broadly broken into Unrestrained Assemblies and Restrained Assemblies.