PURPOSE:A long resin pipe is molded reasonably and inserted easily into an existing pipe for traction. CONSTITUTION:A flat resin pipe 15 which is molded into the same diameter as the inside diameter of an existing pipe 3 or a little smaller outer diameter and processed so that a sectional area becomes small is bent gently along a pipe axis by a pair of uneven molding rollers 6 having the high radius of curvature in the vicinity of a pulling-out port of a heating and pressurizing vessel 4 and premolded. The flat resin pipe 15 is pulled down in the vicinity of the existing pipe, molding-processed gradually by a pair of molding rollers 7, 8 whose radii of curvature become smaller in order and bending of the flat resin pipe is made large. The flat resin pipe bent and molded large is bent by a recessed type roller 9 so that both ends of a widthwise direction are approached and introduced into the existing pipe by molding into a double wall cylindrical state.
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