Ball valve assembly

1. A ball valve assembly comprising:

a pipe section having an axial bore for enabling fluid flow therethrough in use;

a valve ball having an internal conduit, the valve ball being mounted within the pipe section and being for rotation with respect to the pipe section between an open position in which fluid within the axial bore may flow through the internal conduit and a closed position in which the internal conduit is inaccessible to fluid within the axial bore;

a device configured to rotate the valve ball, the device being located radially outside the axial bore;

an encapsulation positioned to receive the valve ball and having portions located radially between the pipe bore and the device configured to rotate the valve ball, such that the encapsulation prevents fluid within the axial bore from accessing the device configured to rotate the valve ball; and

a hydraulic fluid line,

wherein the device comprises a piston actuated by hydraulic fluid pressure within the hydraulic fluid line; and

wherein the pipe section comprises a failsafe fluid path in fluid connection with the bore, such that in the event of a loss of hydraulic fluid pressure within the hydraulic fluid line, fluid flows from the bore through the failsafe fluid path to force one or more crossheads to move towards the valve ball causing the valve ball to rotate into the closed position.

2. The bail valve assembly according to claim 1 , wherein the valve ball comprises first and second diametrically opposed trunnions, and the valve ball is mounted via respective trunnion plates, wherein each trunnion plate receives a respective trunnion.

3. The ball valve assembly according to claim 2 , wherein the trunnion plates are carried by the encapsulation.

4. The ball valve assembly according to claim 2 , wherein seals are provided between each trunnion plate and the encapsulation to prevent fluid flow therethrough.

5. The ball valve assembly according to claim 1 , wherein the encapsulation defines a wall of the axial bore.

6. The ball valve assembly according to claim 1 , wherein the encapsulation carries an insert, the insert defining a wall of the bore.

7. The ball valve assembly according to claim 1 , wherein the device configured to rotate the valve ball comprises a crank attached to the valve ball.

8. An underwater well facility comprising a valve assembly in accordance with claim 1 .

9. A ball valve assembly comprising:

a pipe section having an axial bore for enabling fluid flow therethrough in use;

a valve ball having an internal conduit, the valve ball being mounted within the pipe section and being for rotation with respect to the pipe section between an open position in which fluid within the axial bore may flow through the internal conduit and a closed position in which the internal conduit is inaccessible to fluid within the axial bore; and

a device configured to rotate the valve ball, the device being located radially outside the axial bore;

wherein the device configured to rotate the valve ball comprises a first piston and a second piston located on opposed sides of the valve ball in the direction a the bore axis, the first piston and second piston being configured to be actuated by a common hydraulic fluid line, such that application of hydraulic fluid pressure at the common hydraulic fluid line causes the first piston and second piston to be subjected to linear actuating forces of substantially equal magnitude in opposite directions; and

wherein the pipe section comprises a failsafe fluid path in fluid connection with the bore, such that in the event of a loss of hydraulic fluid pressure within the common hydraulic fluid line, fluid flows from the bore through the failsafe fluid path to force one or more crossheads to move towards the valve ball causing the valve ball to rotate into the closed position.

10. The ball valve assembly according to claim 9 , wherein application of hydraulic fluid pressure at the common fluid line causes the valve ball to rotate to an open position, and wherein a second common hydraulic fluid line is provided, such that applying hydraulic fluid pressure to the second common hydraulic fluid line causes the first piston and second piston to be subjected to linear actuating forces of substantially equal magnitude in opposite directions, causing the valve ball to rotate to a closed position.

11. The ball valve assembly according to claim 9 , wherein each piston is connected to the valve ball via a respective crank arm, such that linear motion of the piston causes rotation of the valve ball.

12. The ball valve assembly according to claim 11 , wherein each piston is connected to the valve ball via an additional respective crank arm at a diametrically opposite position to the first respective crank arm.

13. The ball valve assembly according to claim 12 , wherein the valve ball comprises a first and a second diametrically opposed trunnion, and wherein the crank arms are connected to respective trunnions.

14. An underwater well facility comprising a valve assembly in accordance with claim 9 .

15. A ball valve assembly comprising:

a pipe section having an axial bore for enabling fluid flow therethrough in use;

a valve ball having an internal conduit, the valve ball being mounted within the pipe section and being for rotation with respect to the pipe section between an open position in which fluid within the axial bore may flow through the internal conduit and a closed position in which the internal conduit is inaccessible to fluid within the axial bore;

a device configured to rotate the valve ball, the device being located radially outside the axial bore; and

an encapsulation positioned to receive the valve ball and having portions located radially between the pipe bore and the device configured to rotate the valve ball, such that the encapsulation prevents fluid within the axial bore from accessing the device configured to rotate the valve ball;

wherein the device configured to rotate the valve ball comprises a first piston and a second piston located on opposed sides of the valve ball in the direction of the bore axis, the first piston and the second piston being configured to be actuated by a common hydraulic fluid line, such that application of hydraulic fluid pressure at the common hydraulic fluid line causes the first piston and the second piston to be subjected to linear actuating forces of substantially equal magnitude in opposite directions;

wherein the pipe section comprises a failsafe fluid path in fluid connection with the bore, such that in the event of a loss of hydraulic fluid pressure within the common hydraulic fluid line, fluid flows from the bore through the failsafe fluid path to force one or more crossheads to move towards the valve ball causing the valve ball to rotate into the closed position.

16. The ball valve assembly according to claim 15 , wherein application of hydraulic, fluid pressure at the common fluid line causes the valve ball to rotate to an open position, and wherein a second common hydraulic fluid line is provided, such that applying hydraulic fluid pressure to the second common hydraulic fluid line causes the first piston and the second piston to be subjected to linear actuating forces of substantially equal magnitude in opposite directions, causing the valve ball to rotate to a closed position.

17. An underwater well facility comprising a valve assembly in accordance with claim 15 .