ELBOW/BEND PIPE, MANUFACTURE THEREOF, AND MANUFACTURING DEVICE THEREFOR

PROBLEM TO BE SOLVED: To lower a speed of internal fluid colliding against an inside surface wall in the outside radius part in a bent part of a bend pipe such as an elbow pipe so as to suppress generation of erosion or corrosion by forming a cross section shape of the bend pipe into a specific elliptic shape. SOLUTION: In an elbow/bend pipe 11 in a plant piping system, a cross section of the pipe 11 is formed into a shape in which an axis of a plane including the inside diameter and the outside diameter of the bend part serves as a major axis while an axis making an angle of 90 deg. with the major axis serves as a minor axis. Fluid 1 in a pipe flows inward from the lower side and flows outward to the right side through the bend pipe 11. In this case, an axis of the pipe cross section including the outside radius and the inside radius of the bent part in the bend pipe 11 corresponds to a major axis of an ellipse while an axis making an angle of 90 deg. with the major axis in the cross section corresponds to a minor axis of the ellipse. Since the pipe cross section is an elliptic shape, the fluid 11 is smoothly flows inside the pipe 11. Therefore, the fluid 1 is prevented from directly colliding against the pipe inside wall face in the bend outside radius part.