Tianhe - Model FT Type - Drop-in Check Valve
FT type Drop-in Check Valve is kind of drill stem internal blowout preventing tools. The check valve consists of top landing sub and check in valve. Landing sub is connected with stop ring with thread connection, it worked as a sub before check in valve assembly had been dropped. When a blowout is about to happen, the thread connections of the Kelly is screwed out immediately and a check valve is placed into the drill pipe and then pumped downward to the required place. Thus the blowout can be prevented.