| 摘要 |
This is an improvement in Wellstein's U.S. Pat. No. 3,812,910 issued May 28, 1974 comprising generally: an improved shaped frustoconical seat for the saddle contoured gasket or seat in the washer or nut for better sealing the outside of the well casing with the outside of the nipple that extends through the hole therein for withstanding higher pressures; and/or the employment of a pair of gaskets inside and outside the casing surrounding the nipple and contoured to the interior and exterior walls of the casing, also for insuring better sealing.
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