| 摘要 |
An air ventilation pipe for a well casing cover is comprised of a cylindrical externally screw-threaded socket which has a cylindrical externally screw-threaded portion projecting downwardly through the aperture in a well casing cover. An enlarged head at its inner part for the engagement of a wrench. A nut for securing a cylindrical tube within the socket. The socket and nut compress between them a metallic deformable ring into sealing relationship with the cylindrical tube.
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