Tubing drain valve

A tubing drain valve suitable for use in a borehole pipe string, comprising:

• a sub suitable for incorporating within a borehole pipe string;
• a port between the interior and the exterior of said sub;
• and
• valve means for opening and closing said port wherein said valve means comprises
• a tubular piston movable within said sub and having an exterior adapted for sealing cooperation with the interior of said sub and having working surfaces in pressure communication with the interior of said pipe string;
• means for communicating fluid from the interior to the exterior of said piston to permit fluid communication through said port from the interior to the exterior of said sub when said valve means is in its open position;
• means for biassing said piston to its closed position;
• means for actuating said valve means to its open position in response to a pressure force developed across said working surfaces by the pressure in the interior of said sub;
• and
• lever means for actuating said valve means to its closed position in response to an actuating device movable through said pipe string, wherein said lever means comprises
• a dog having first and second arms pivotally mounted at a rotation/fulcrum point on said piston;
• said dog engageable on said first arm by said actuating device;
• and
• said dog engageable on said second arm with a surface of said sub to urge said valve means to its closed position.

A sub including a tubing drain valve suitable for use in a borehole pipe string, comprising:

• a tubular member adapted to be incorporated in a pipe string;
• a fluid passage through the wall of said tubular member;
• valve means to open and close said passage, comprising:
• a tubular piston having an exterior adjusted for sealing cooperation with the interior of said tubular member and having working surfaces in pressure communcation with the interior of said sub;
• means for communicating fluid from the interior to the exterior of said piston to permit fluid communication through said passage from the interior to the exterior of said tubular member when said valve means is in its open position;
• means for biassing said tubular piston to its closed position;
• means for actuating said valve means to its open position in response to a pressure force developed across said working surfaces by the pressure in the interior of said sub;
• and
• lever means for actuating said valve means to its closed position in response to an actuating device movable through said pipe string, wherein said lever means comprises
• a dog having first and second arms pivotally mounted at a rotation/fulcrum point on said piston;
• said dog engageable on said first arm by said actuating device;
• said dog engageable on said second arm with a surface of said sub to urge said valve means to its closed position.

A pipe string system suitable for use in a borehole, comprising:

• a plurality of tubular members interconnected to form a pipe string;
• a sub incorporated in said pipe string;
• a port between the interior and the exterior of said sub;
• valve means for opening and closing said port wherein said valve means comprises
• a tubular piston movable within said sub having an exterior adapted for sealing cooperation with the interior of said sub and having working surfaces in pressure communication with the interior of said pipe string;
• means for communicating fluid from the interior to the exterior of said piston to permit fluid communication through said port from the interior to the exterior of said sub when said valve means is in its open position;
• means for biasing said piston to its closed position;
• means for actuating said valve means to its open position in response to a pressure force developed across said working surfaces by the pressure in the interior of said sub;
• and
• lever means for actuating said valve means to its closed position in response to an actuating device movable through said pipe string, wherein said lever means comprises
• a dog having first and second arms pivotally mounted at a rotation/fulcrum point on said piston;
• said dog engageable on said first arm by said actuating device;
• and
• said dog engageable on said second arm with a surface of said sub to urge said valve means to its closed position;
• means for pressurizing the interior of said sub to a pressure sufficient to develop the force necessary to actuate the valve to its open position;
• and
• means insertable through said pipe string to mechanically actuate said valve to its closed position.