FT 型投入式止回閥  

Drop-in Check Valve Type FT

FT型投入式止回閥是鉆柱內防噴器。該工具結構簡單，操縱方便，只要缷開方鉆桿的接頭螺紋便可以投入鉆桿的水眼內就位后就能達到內防噴的目的。投入式止回閥由凡爾接頭和止回閥總成兩部分構成。凡爾接頭與止動環用螺紋連接并上緊扣和鉆柱連接下入井內，在未投入止回閥總成時，作為鉆柱上的一個接頭。

FT type drop-in check valve is a kind of Insied 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 immdiately and back pressure valve sub is into the I.D. of drill pipe and then pumped downward to the required place.Thus the blowout accident can ba prevented.Drop-in check valve consists of back pressure sub and check valve assembly.Back pressure sub is connected with stop ring and tightened on and put into downhole with drill string.back pressure sub is used as a sub above drill string before check valve assewbly is run in downhole.