| 摘要 |
A gate valve assembly 11 comprises a body 13, a gate 17, a stem 21, and a backseat 45 for sealing between the stem 21 and the body 13. The backseat 45 is an annular member (47, Fig. 2) with a complementary surface on its inside that fits over a spherically shaped section of the stem 21, thus allowing the backseat 45 to rotate and pivot with respect to the stem. An outer surface of the backseat is bevelled for sealingly engaging a stem passage 22 formed through the body 13. A flex element (67, Fig. 2) is provided for sealing a surface adjacent the backseat. The flex element forms a seal between the backseat member 47 and the stem 21or between an annular retainer (63, Fig. 2) and the backseat.
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