| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a pipe body such that the corner parts of a square cylinder part, which is low in pressure resisting deforming properties and by which breakage is easily caused, and especially the two corner part of the square part is reinforced to an extend that a given pressure resisting deformation strength is provided without being locally weakened. SOLUTION: In a pipe body P, cylinder parts 2 approximately in a square in cross section and cylinder parts 3 approximately in a circular shape in cross section are alternately disposed axially of the pipe body P to form a pipe wall 1. Thickness in a peripheral direction of the circular cylinder part 3 is formed not uniformly Namely, the thickness of parts 3a... equivalent to the corner parts 2a... of the square cylinder part 2 in increased to a value higher than the thickness of a part 3b equivalent to the central parts 2b... of the sides of the square cylinder part 2.</p> |
