| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a pipe whose strength is improved while suppressing a marked increase in manufacturing cost. SOLUTION: A large-sized pipe 4 has a corrugated form composed of projections 2 and recessions 3 formed on its outer surface alternatively in a pipe axial direction. In the pipe 4, the projections 2 and the recessions 3 are spirally formed in the axial direction. Straight or curved line connecting projection side outer edges of the recessions 3 adjacently to each other across the projection 2 is a width D of the projection 2 on the bottom side. The height H from the straight or curved line to the top of the projection is set larger than the bottom side width D.</p> |
