ASEISMATIC PIPE INSERTION PORT FORMING METHOD

PROBLEM TO BE SOLVED: To form a projection on an outer periphery of an insertion port of an aseismatic pipe easily.SOLUTION: Provided is a forming method of an insertion port projection of an aseismatic pipe formed by a centrifugal casting process. As the forming method, an insertion port end side is casted so as to become thicker than a straight part of the pipe, and an outer periphery of the insertion port end is cut by a predetermined width for reducing a diameter, and the projection is cut on an outer face of the insertion port. Thereby weldment of a metal ring or the like to the outer face of the insertion port is not required for forming the projection on the insertion port outer face, so that weldment work and processing work related to the weldment work are eliminated, resulting in significant reduction of work load.