Circular preventer, also known as multi effect preventer. During operation, the annular rubber core is evenly squeezed towards the center of the wellbore, with good pressure resistance, good sealing, easy operation, and rapid opening and closing. Especially suitable for sealing various types and sizes of pipe columns, and can also seal all wellheads. When the blowout preventer is turned off, high-pressure oil rushes from the oil port on one side of the housing to the opening and closing chamber under the piston, moving the piston upwards, and the conical surface of the piston presses the rubber core
What should be paid attention to when using a circular blowout preventer to shut in the well and lifting the drilling tools (1) Only 18 degree butt welding is allowed for drill pipe joints (2) During drilling, there may be a small amount of leakage between the rubber core and the drill pipe, which is not only allowed but also necessary. A small amount of leaked drilling fluid can lubricate and cool the rubber core, extending its service life. If necessary, add lubricant to the top of the rubber core to lubricate it (3) The drilling speed must be slow, especially when passing through joints The annular blowout preventer is operated by a hydraulic control system. Due to the limitation of the top cover, the rubber core cannot rise and can only be squeezed to the center of the wellhead until the drilling tool is tightly held or the wellhead is completely closed, thus achieving the purpose of sealing the well When it is necessary to open the well, operate the directional valve of the hydraulic control system to allow high-pressure oil to flow from the oil port on the housing to the opening and closing chamber on the piston, move the piston downwards, close the chamber to release pressure, counteract the pushing force acting on the cone surface of the rubber core, and gradually reset the rubber core under its own elastic force, opening the wellhead