Series B50 & B55 are welded metal bellow seals used in chemical, petrochemical and refinery process pumps for moderate temperature/pressure application and for process services requiring corrosion resistance. These bellow seals are constructed by welding a series of diaphragms together at the edges to form a bellows unit. The bellows unit eliminates the need for springs, dynamic secondary seal and provides flexibility to the seal face in addition to compensating for seal face wear.