FIELD: tubing string.
SUBSTANCE: invention relates to sealing. Valve for sealing the channel overlapping the annular space is installed in the lifting pipes string and comprises an internal pipe, a coupling, a top cover connected to the coupling, and a lower cover, made with possibility of being screwed on the coupling and retention of the internal pipe due to the bearing. Coupling is made with possibility of rotation on internal pipe and comprises ledge. Ledge at coupling rotation rests against the ripper, which is made with possibility of attachment to internal pipe by means of screws. First passage hole is made in the pipe. Second through hole is made in coupling. Holes in tube and coupling have substantially the same diameter. With aligned first and second through holes valve is in open position. At displacement of first through hole relative to second through hole by 180° due to the coupling rotation the valve is in the closed position and ensures tightness of connection of internal cavity of the internal pipe relative to external space of the valve.
EFFECT: reliable sealing and depressurization without additional lowering-lifting operations.
1 cl, 3 dwg
