| 摘要 |
<p>A drainage pipe (1) wrapped in a strip (4) of non vegetable filtering material whose width is adequate to allow its side edges (5) and (6) in one case to overlap and be glued or soldered together, in another case to be glued to the pipe (1) along two lines (7) and (8).</p><p>The invention also comprises the method through which, immediately following the machine which manufactures the drainage pipe (1), the strip (4) of filtering material of indefinite length is first placed with a first side edge (5) over the first trace of glue poured along a first line (7) of the said pipe (1), it is then wrapped around the same pipe and a second trace of glue is poured, in one case over the first edge (5), in another case along a second line (8).</p><p>Finally, the filtering strip (4) is completely wrapped around by bringing the second edge (6) over the second trace of glue to achieve their joining.
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