SYNTHETIC RESIN PIPE

PROBLEM TO BE SOLVED: To provide a synthetic resin pipe capable of strengthening welding strength in a curved part, even when a curving degree is large in the curved part, in a cylindrical member for forming a passage inside by welding two members. SOLUTION: The cylindrical member 10 having the passage 18 inside is formed by welding a first member 12 forming a first recess part 28 and a first joining part 22 and a second member 14 forming a second recess part 40 and a second joining part 34. A pair of first plane parts 28 having a maximum width in the first recess part 28 is formed in the first member 12, and a pair of second plane parts 38 having a maximum width in the second recess part 40 is formed in the second member 14. By forming a welding place 44 of the first member 12 and the second member 14 as a joining place of the first plane part 28 and the second plane part 38, a curving angle β in the curved part of the welding place 44 can be enlarged more than a curving angle α in the curved part of the cylindrical member 10, and the welding strength in the curved part of the welding place 44 can be strengthened. COPYRIGHT: (C)2009,JPO&INPIT