| 摘要 |
A stem tip seal for a shutoff valve includes a valve member having an axial recess at the outer end that operatively receives a retaining sleeve. The retaining sleeve includes a flange portion engaging a shoulder formed by a circumferential groove in the valve member to effectively limit relative movement between these two components. A tapered surface at one end of the retaining sleeve cooperates with a tapered surface formed on the valve member for confining a seal ring. The seal ring is under compression and biases the retaining sleeve toward a first or outer limit position. Initial contact between the retaining sleeve and valve seat prevents nibbling or chipping of the seal ring during valve closure, and extended contact between the retaining sleeve and valve seat provides support during valve opening to prevent seal blow out.
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