| 摘要 |
A port apparatus for well piping comprising a sleeve valve mounted in longitudinally slideable engagement with the bore of an outer housing, the sleeve valve having an open position, a pressure equalization position, and a closed position, the sleeve valve also having a first annular shoulder by which the sleeve valve is engaged for moving the sleeve valve from the closed to the pressure equalization position and a second annular shoulder by which the sleeve valve is engaged for moving the sleeve valve from the pressure equalization position to the open position, these first and second annular shoulders being longitudinally spaced by a distance equal to the longitudinal distance between successive sleeve valve positions, a mandrel housing adapted to be positioned in the bore of the outer housing and fixed in longitudinal position relative to the outer housing, a mandrel telescopically mounted in the mandrel housing and adapted for longitudinal travel within predetermined limits relative to the mandrel housing and having shifting keys thereon for engaging one of the sleeve valve annular shoulders when at its extended position and for releasing the sleeve valve annular shoulder when at its retracted position thereby shifting the sleeve valve from one longitudinal position to the next, the sleeve valve annular shoulder which is engaged depending upon which initial position the sleeve valve is in and therefore which annular shoulder the shifting keys encounter when the mandrel is extended.
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