| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a flexible underground pipe having reasonable flexibility allowing bent piping work but suppressed from bending extremely and facilitat ing inserting work of a cable. SOLUTION: The flexible underground pipe is composed of an external layer formed by spirally winding a hard band like body made of hard synthetic resin, and an internal layer made of hard synthetic resin attached to an inner circumferential face of the external layer. The external layer is formed by spirally winding the hard band like body with an S-shaped cross section comprising a linear bottom wall part, an upward facing side rim part erected from the bottom wall part in one side rim, and a rising part, an upper wall part and a downward facing side rim part sequentially connected from the bottom wall part toward another side rim, and engaging and connecting the upward facing side rim part and the downward facing side rim part in adjacent side rims. A hard spiral part is attached to an inner circumferential face of the internal layer by spirally winding tape made of hard synthetic resin at predetermined intervals.</p> |
