PREVENTER Russian patent published in 2003 - IPC

FIELD: equipment used for underground repair of oil and gas wells. SUBSTANCE: preventer is employed for wellhead sealing when emergency situation develops in well and for long outage. Preventer includes body with axial conduit for passage of pipes with technological equipment. It carries dies with drive and sealing elements to seal pipes located in well. Mobile gate plate with drive is intended to overlap hole remaining between sealing elements of shifted dies while there is no pipes in well. Mobile plug is located inside gate plate. This plug, when inoperative, is positioned inside gate plate. In working position plug is placed under action of pressure from below between sealing elements of dies. To shift plug into non-working position it is forced to sink inside gate plate. EFFECT: development of doubled die preventer with minimal values of height, mass and number of control wheels. 14 dwg