A metal bellow, consisting one or more corrugations is the flexible element of an Expansion Joint. It is typically composed of a light gauge metal tube of one or more ply formed in to a series of corrugations. Bellows Systems expansion joints can be manufactured from any material which has the necessary drawing quality, and the corrosion resistance required by the operating conditions of the system in which they might be installed. The pitch and depth of draw of any bellows can be varied and the shape modified to meet special requirements.
Multi-ply bellows are primarily used on expansion compensators as standard equipment and also on other large diameter expansion joints where significant reduction is compressive forces (spring stiffness) are desired. Toroidal bellows are used often where extremely high-pressure applications are encountered.