US PATENT SUBCLASS 166 / 322
.~.~.~ Retrievable

Current as of: June, 1999
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166 /   HD   WELLS

316  DF  VALVES, CLOSURES OR CHANGEABLE RESTRICTORS {5}
319  DF  .~ Fluid operated {4}
321  DF  .~.~ Fluid pressure biased to open position position {3}
322.~.~.~ Retrievable

DEFINITION

Classification: 166/322

(under subclass 321) Devices in which the valve is insertable and retrievable from the flow line, seats in position in the flow line and is usually held in position by a latch means.