U.S. Bellows custom designed these externally pressurized expansion joints for a pipeline in Kentucky. The bellows are fabricated from Inconel 625 LCF and all other components from carbon steel. The expansion joints are 4″ in diameter and 32″ OAL. They are designed for an operating pressure of 135 psig at 358°F with 3″ of compression. All expansion joints were hydro-tested prior to shipment. Externally pressurized expansion joints are suited for piping systems that require large amounts of axial compression or extension. In externally pressurized expansion joints, the bellows elements are arranged so that the media flow is on the external surface of the bellows. Externally pressurizing the bellows eliminates pressure instability as a limitation to the design and permits the absorption of large amounts of axial expansion.
