A pipe extending from a first side toward a second side includes a side wall and a spool. The spool formed in the side wall is bent so as to protrude from an outer circumferential surface of the pipe, and extends to surround the outer circumferential surface. The spool includes a first portion located on the first side and a second portion located on the second side. There is a clearance between the first portion and the second portion in a top region of the spool, and the first portion and the second portion substantially abut each other in a base region.