NON-RETURN VALVE FOR DRILLING STRING Russian patent published in 1998 - IPC

FIELD: oil and gas production industry. SUBSTANCE: this relates to devices for shutting-off drilling pipes and can be used in drilling, replacement of tools, and repair of wells without their plugging. Body of non-return valve has nipple and adapter. Installed between them is sectional seat in the form of bush and resilient elastomeric member. Located at side of nipple and in contact with seat is disk-type shut-off member. It has rod going along axis of adapter. Spring is installed in tail part of rod and it presses shut-off member against seat. Through-passage of adapter has ribs. Rod is made in the form of central stem and shell, and ribs connect them to each other. Spring is located in cylindrical circular space between shell and adapter. Tail part of shell rod is provided with cylindrical circular protrusion. Catches are seated in slots of circular protrusion. Circular bore is made in inner surface of adapter to receive catches. Each of catches is made in the form of cam installed in slots of circular protrusion of shell countersunk on axle for possible deviation towards circular bore of adapter. Cam is additionally biased by spring from adapter to wall of shell slot. EFFECT: higher efficiency. 2 cl, 2 dwg