伊人久久大香线蕉成人网,老司机午夜福利18,69精品人人人妻人人玩痴汉,国产成人久久一区二区影院,国产黄视频在线观看,久久国产精品99久久人妖人妖,另类天堂一区二区三区视频

    It is an inside BOP(blowout preventer) in the drill string . It is simple in structure and easy to operate . When blowout is going to be happened , the thread connections of the kelly are screwed out immediately and the back pressure valve is put into the I.D. of drill pipe and then pumped downward to the required place. Thus the blowout accident can be prevented. The tool is consisting of landing sub and check valve assembly . The landing sub is thread connected with stop ring and tightened on and put into downhole with drill string . The landing sub is used as a sub above drill string before check valve is run in downhole .

Technical parameters and specifications