Fusion tube manufacturing method and fusion tube

摘要

PROBLEM TO BE SOLVED: To provide a fusion tube capable of reducing pressure loss and enhancing pressure resistance. A fusion tube manufacturing method according to the present invention comprises a step of connecting end portions of first and second resin tubes by fusion to obtain a fusion tube, and the first pipe before connection. The ratio of the maximum inner diameter at the end of the resin pipe to the maximum inner diameter at the end of the second resin pipe before connection is 1.02 or more and 1.15 or less, and the step of obtaining the fused tube In, the inner diameter of the first resin pipe at the maximum height position of the first convex portion formed on the inner peripheral surface of the first resin pipe is formed on the inner peripheral surface of the second resin pipe. A fused tube having a larger inner diameter than the second resin tube at the maximum height position of the second convex portion is obtained. [Selection diagram] Figure 1