The Proco Series 251/BT PTFE & FEP Lined Expansion Joints are designed for tough, demanding, corrosive chemical applications such as chemical and petrochemical process facilities and highly corrosive industrial piping and pollution control systems. Use of the Series 251/BT expansion joints is especially prevalent in the paper industry, where their ability to resist corrosive attack at elevated temperature and pressure is unrivaled by other competitive metal or plastic expansion joints.