INTRA-FLANGE CHECK VALVE FOR INJECTION WELLHEAD FITTINGS Russian patent published in 2008 - IPC E21B34/02 

FIELD: oil production equipment for reservoir pressure keeping systems and to be included in injection well wellhead fittings.

SUBSTANCE: check valve comprises reel-like body with central orifice for check valve receiving. The orifice has end annular sealing extensions to be inserted in corresponding grooves. The grooves are made in front and rear connection flanges of wellhead injection fitting pipeline. The check valve is valve pair of downhole sucker-rod pump. Valve pair position is within positive magnitude of angle of valve pair inclination with respect to horizontal line. Valve pair includes seat and ball arranged in valve cage with central and peripheral through channels so that the ball may move in longitudinal direction for distance equal to valve stroke. Seat is retained by seat holder from the side of front connection flange included in injection wellhead fittings pipeline provided with groove for disc filter receiving. The disc filter has inner annular bead formed from the side of wellhead fitting pipeline flange connection.

EFFECT: increased operational reliability of check valve.

2 dwg