FLAP FOR CASING STRING Russian patent published in 2008 - IPC E21B34/06 

FIELD: boring.

SUBSTANCE: invention is referred to boring field. The flap contains a thrust ring with axled openings. Under a valve seat the plate with a working surface is placed. At the top with a thrust ring, and in bottom with a plate the spring-biased double-end bolt is connected with a through hole. In a spring-biased double-end bolt through hole a shear lock is placed. The flap is furnished by the cylindrical body. In the top of shank bore of the body the conical bore with formation of an annular platform for interplay with a thrust ring is executed. In bottom of shank bore of the body the cylindrical bore, furnished with a thread is executed. The valve seat is executed in the form of the hollow step sleeve. On an outboard surface of a saddle the thread is placed. In the top the saddle is furnished with internal bore. In the bottom of an outboard surface of a saddle the gouge for the screen is executed, connected with shank bore of the flap by means of some through holes. In the body the baffle plate is placed. The baffle plate is furnished by axled smooth-bore openings, and on the centre - by a threaded opening. In a threaded opening the hollow stopper is installed, on side surfaces of which two oval openings for movement possibility of a shear lock are executed. At the upper end of a hollow stopper the recess with a conical surface for the seal installation which have been drawn in by a spring through a washer, is executed. Between the bottom end of a hollow stopper and a baffle plate an o-ring is installed. The plate is executed with a bilateral wedge-shaped track in which the seal is placed.

EFFECT: increase of reliability of device operation.

1 dwg