A safety valve for insertion into an oil-well production pipe for closing or opening the pipe, said valve comprising a generally tubular valve body,
- a movable shutter (11) located at the lower part of said valve body and biased toward a closed position,
- a tubular slide (9) arranged to slide longitudinally inside the valve body for causing by its descending motion the opening of the shutter,
- a return spring (10) located in an annular housing between the slide and the valve body so as to bias said slide upwardly toward an upper shutter closing position,
- hydraulic means for displacing said slide downwardly and comprising a control fluid intake (3a, 4a) through the valve body and a sealed volume between the slide and the body for receiving the control fluid, said slide having a differential cross-section subjected to the pressure of the fluid contained in said sealed volume so as to receive a downward force when said volume is pressurized;
- an anchoring system at the upper part of the valve body for securing the valve body into a receiving sleeve (1) in the production pipe, said anchoring system comprising radially movable dogs (54) capable of entering into an anchoring groove (1b) of the receiving sleeve, a tubular shuttle piston (58) slidingly mounted in the valve body and including a surface to be subjected to the pressure of the control fluid in such a manner as to be subjected to an upward force when said control fluid is under pressure;
- and a lock bushing (55) mounted so as to receive the upward force of said shuttle piston and to be forced upwardly thereby, said lock bushing having a peripheral cam (56) for forcing said dogs into said anchoring groove when said cam (56) reaches the level of said dogs during the travel thereof to an anchoring position;
- upper and lower seal means (15, 16) arranged around the valve body for sealing the interface between said valve body and the receiving sleeve above and below the control fluid intake;
- said shuttle piston (58) being slidingly displaceable in said valve body so as to be freely slidable in said valve body between a lower stop position and an upper stop position, said shuttle piston being only subjected to fluid pressure in the absence of any mechanical blockage along its displacement,
- said lock bushing (55) being slidingly mounted in said valve body independently of said shuttle piston in such a manner that said shuttle piston only exerts upward pressure on said lock bushing without driving said shuttle piston when said shuttle piston is in said upper stop position,
- said valve body having on the peripheral surface thereof a stop shoulder (51a) adapted to cooperate with said stop means (1bi) of said receiving sleeve in said anchoring position, said valve body having a diameter less than the portion of said valve body below said stop shoulder so as to permit the entry of said valve body into said receiving sleeve when said stop shoulder (51a) comes into contact against said stop means (1bi) of said receiving sleeve.