WO2001042695A1

WO2001042695A1 - A ball valve device

Info

Publication number: WO2001042695A1
Application number: PCT/NO2000/000417
Authority: WO
Inventors: Finn RØED
Original assignee: RING-O-VALVE NORGE AS
Current assignee: RING-O-VALVE NORGE AS
Priority date: 1999-12-08
Filing date: 2000-12-06
Publication date: 2001-06-14
Anticipated expiration: 2002-06-08
Also published as: NO310578B1; AU1743601A; NO996062D0; NO996062L

Abstract

The invention relates to an internal force-transmitting ring (44), flange or plate in connection with an axle (32) of a ball valve (8) used preferably in a high pressure pipe connection, for example a landing string between a floating rig and an underwater well. The ring (44), flange or plate is fixedly arranged on each of the separate axles (32) of the valve ball (22) and projects beyond the spline ridges (34) or similar securing means of the axles (32). The ring (44), flange or plate is placed in a force-transmitting manner against an abutment surface (42) or seat in the axle bore (26) of the ball (22). By well pressure, the axles (32) are subjected to outward and piston-like pressure forces, which are absorbed by the valve ball (22) through the ring (44), flange or plate, and thus are not transmitted to bearings and seals in the pertaining valve housing (10), creating great friction and wear therein.

Description

A BALL VALVE DEVICE

Field of the Invention

This invention relates to a force-transmitting ring or plate in connection with an axle of a valve ball in a high pressure valve, preferably for use in a high pressure pipe connection between a floating rig and an underwater well.

Background of the Invention

The above-mentioned high pressure pipe connection, within the art often called a landing string, is necessary to allow downhole well work to be carried out when a well is under pressure, for example in order to perform tests or completions in the well. The landing string is normally provided with varying types of hydraulically activated valves. In addition, well head equipment at the bottom of the landing string often requires the supply of hydraulic fluid, electricity and/or control signals. This is achieved in that the supply pipes, cables and similar are preferably placed externally to the landing string. Normally both the landing string, supply pipes, cables and similar are enclosed by a so-called riser, which is also a tubular connection between a floating rig and an underwater well. Under normal circumstances the annulus between the riser and the landing string is filled with water, which exerts a hydrostatic pressure in the annulus.

The tubing and pertaining equipment for its hanging in the wellhead of the underwater well are secured during installation below the landing string, and are passed through the riser and hung, for instance, in the wellhead on the sea floor. A condition of this operations is, among other things, that the landing string with external supply pipes, cables and similar must be allowed to pass freely through the riser. In addition, the landing string and pertaining valves must have a sufficiently large internal bore diameter to allow passing of downhole tools and equipment for use in, among other things, testing and completion. This restricts the space available in the riser for building in possible high pressure valves and pertaining actuators.

Known technique

Limited space available in the riser for the building in of high pressure valves and pertaining actuators in practice assumes the use of ball valves. Such a valve consists internally of a tubular passage and a valve ball, both with a tubular and longitudinal bore extending therethrough and of sufficient diameter for downhole tools and equipment to pass. The outer circumferential edge of the ball bore constitutes, at the same time, a cutting edge, which should be capable, in an emergency, when the ball is rotated, of cutting a wire, coiled tubing or similar equipment, which might be present in the ball bore. This presupposes the application of a sufficiently great tcrque to the ball.

The valve ball is provided with two separate and concentric axles, one on either side of the ball, each axle extending radially outwards from the central bore of the ball and projecting from the ball. The axles are rotationally supported in an annular part of a tubular pressurised valve housing enclosing the ball. The end of each axle is formed with a diametrical groove, the grooves of the axles being of the same configuration, dimensioned and positioned relative to one another. In addition the valve is provided with one or more hydraulically activated annular actuator pistons, which may move in an annular actuator cylinder belonging thereto. The piston and cylinder are formed externally to the axles, but internally to the valve housing, the piston and cylinder being built in concentrically about the longitudinal axis of the valve and transmitting a hydraulic force in the direction of the longitudinal axis of the valve. On either side, the actuator piston is provided with a torque-transmitting pin and a pertaining shoe, arranged to each axle, so that the shoe can glide in the diametric groove mentioned above. The torque-transmitting pin and a pertaining shoe are positioned eccentrically to the longitudinal axis of the axle, so that a short torque arm is formed. By means of the above-mentioned assembly, a torque is thereby transmitted to the axles of the ball, thereby rotating them, said shoe gliding in the groove at the end of each axle.

Drawbacks of Known Technique

Limited space within the landing string makes it, among other things, little convenient to weld or in another manner fixedly arrange axles externally on the valve ball. The valve ball is rotatably supported in the valve housing by means of two separate axles inserted through axle bores in the ball wall into the valve housing. Well pressure within the landing string and the well bore applies a radial, outward, piston- like pressure force to each axle, which force is transmitted to the valve housing. On rotation of the valve ball, the pressure force results in great friction and wear in the support devices and seals of the valve housing. The torque for the rotation of the valve ball is supposed, among other things, to overcome support friction in both the axial and radial directions of the axles, and friction between the valve ball and seat rings. In case of an emergency the actuator device of the valve should also be capable of applying a sufficient torque to the ball for the cutting of a wire, coiled tubing or similar equipment that might be present in the ball bore. In addition, it is often desirable or necessary to assign a safety factor to the ball valve, in the form of extra torque capacity.

In order to satisfy the requirements made on the ball valve, it is often necessary to have a great torque available. In known technique and when the above-mentioned short torque arm is used, it involves the use of hydraulic actuator pressures of up to 700 bar. This causes a great degree of stress on pipes, pipe connections, other valves, seals, pistons and any other parts in the hydraulic system. The necessity of a great torque also entails great loads and severe wear, possibly deformations, in all connections and parts which participate in the transmission of the torque. For example, severe wear and deformations in high-stress shoes and grooves at the ends of the axles, could cause insufficient opening or closing of the ball valve, possibly incomplete cutting of a wire or coiled tubing in an emergency, or downhole tools and equipment to snag or be prevented from passing the ball valve.

It is common for an actuator piston to be subjected to high hydraulic pressure on the one side and full well pressure on the other side. In addition, temperature differences and/or pressure conditions in the well will cause different expansion or contraction in, among other things, pistons and cylinder walls, which will make a gap between them vary in size. Such conditions make great demands on, among other things, the physical configuration, size, number and sealing properties of piston seals. In practice it is often difficult to fulfil these requirements, and leaks are often experienced, which will, for one thing, lead to contamination of the hydraulic fluid of the valve. In a ball valve of the kind in question the degree of opening of the ball is normally determined by measuring the amount of hydraulic fluid used to rotate the ball. Hydraulic leaks will therefore lead to measurements providing incorrect readings of the degree of ball opening.

Transmission of well pressure to the valve housing and pertaining actuator device may also lead to so-called reversed well pressure on the hydraulic piston(s) of the actuator device. Pressure variations or pressure pulses in the well could thereby be transmitted to the hydraulic piston(s) of the actuator device, move it/them and thereby influence the degree of opening of the valve ball. This is particularly relevant when the hydraulic piston(s) is/are subjected only to hydrostatic pressure from the hydraulic fluid of the actuator device.

The above drawbacks may make critical situations occur, which often result in extensive and expensive maintenance work. Object of the Invention

The object of the invention is to provide a device, which, as compared to known technique and by a given well pressure, utilises a highly reduced torque to attain satisfactory performance in a ball valve. Thereby many of the above- mentioned drawbacks of known technique are reduced, possibly eliminated.

Realisation of the object(s)

The object is realised through the features specified in the description below and the subsequent Claims.

As mentioned, the main problem in known ball valves is that high pressure from the well is transmitted through the axles of the valve ball as radial, outward and piston-acting compressive forces to the respective support devices in the valve housing. Therefore, in this connection a great deal of the torque of the actuator device is used to overcome friction in the support devices .

According to the invention it is sought to avoid, possibly reduce to a great extent, said compressive forces, in that they are essentially transmitted to, and absorbed by, the valve ball. This is achieved in that preferably at that end, which is the nearest to the centre line of the valve, each axle is provided with a flange, ring or plate, fixedly arranged thereto and projecting sufficiently beyond the circumference of the axle and having an abutment surface, which bears in a force-transmitting manner on a complementary abutment surface or seat formed in the axle bore of the ball. Relative to the longitudinal axis of the axle, the flange, ring or plate is arranged perpendicularly and concentrically thereto. The pressure forces affect each axle to an equal extent, but in opposite directions, as each axle and the flange, ring or plate pertaining to it are of the same shape and dimension as compared to the other axle, the axles being concentric to one another. Thereby the pressure force on the one axle is balanced by a corresponding but opposite pressure force on the other axle. It is assumed that the valve ball is formed and sized to absorb these forces.

The above arrangement also presupposes that axles are separate and loose, and that they are inserted into the axle bores after the ball has been positioned in the valve. Otherwise, the invention presupposes axle supports, high pressure seals and an actuator device in order to apply a torque to the ball and its axles. This will be explained in further detail in the following example of an embodiment of the invention.

Advantages of the Invention

Most of the advantages of the invention appear from the text above. As compared to known technique and by a given well pressure, the invention involves that a highly reduced torque can be used to achieve sufficient rotation of a valve ball in a valve as described above, outward and piston-like pressure forces, acting on the axles of the ball, not being transmitted to the valve housing but being absorbed by the valve ball. The reduced torque is used, among other things, to overcome friction forces arising in the axle supports as a consequence of pressure differentials across the ball valve, said friction forces acting in the longitudinal direction of the valve and the landing string. The torque should also overcome friction between the valve ball and seat rings. A result of the invention is also that well pressure is not transmitted to the actuator device of the valve, whereby problems of reversed well pressure are avoided, hydrostatic pressure from the hydraulic fluid of the actuator device being higher in normal conditions than the hydrostatic pressure on the opposite side of the piston of the actuator device.

In a valve housing provided with so-called Scotch Yoke actuators, cf. the following exemplary embodiment, and in which the above-mentioned force-transmitting flange, ring or plate is used, necessary hydraulic actuator pressure can be reduced, for example, towards 200 bar. In known ball valves in the same well pressure conditions, actuator pressure of up to 700 bar must often be used. The result of reduced hydraulic actuator pressure is fewer and smaller leakages in the hydraulic system of the valve. On this basis, in ball valves, in which the degree of opening of the ball is determined by measuring the applied amount of hydraulic fluid, a more accurate reading of the degree of opening of the ball can be achieved than by the use of higher actuator pressure.

The application of a highly reduced torque involves, among other things, that the hydraulic system and devices of the valve, relating to torque transmission, can be sized for considerably smaller loads, and that such equipment thereby requires less space, less maintenance and that it costs less. It is also obvious that such equipment can be provided with extra torque or hydraulic pressure capacity without the physical dimensions of equipment used in corresponding known equipment being exceeded. A reduced torque will also be of advantage in ball valves, where possibly no hydraulic actuator devices are used.

Application of the invention may thus allow known technique to be used in connections where that has hitherto not been possible, or where it has been little convenient to use such technique, reduced torque conceivably being a precondition for the application of for example electrically driven actuator devices or other types of torque-transmitting devices, which have hitherto been unsuitable or insufficient in the conditions mentioned above.

A brief Description of the Figures in the Drawings

In the following part of the description, and referring to the set of figures, an exemplary embodiment of the invention will be shown. One specific reference numeral refers to the same detail in all the drawings where this detail is indicated, and

Fig. 1 shows a vertical section through an open ball valve, in which the actuators of the ball valve are hidden in the valve housing behind the axle bore, due to the position of the section;

Fig. 2 shows a circumferential cross-section of the ball valve in its open position, and through the axle bores of the valve ball, the left-hand half of the section showing an axle and an actuator positioned in the valve, the right-hand half of the section showing bores and recesses in the valve ball and the valve housing;

Fig. 3 shows a partial section of the same circumferential cross-section as that shown in Fig. 2, the assembly of the axle with pertaining force-transmitting ring within the axle bore of the valve ball being shown; and

Fig. 4 shows a vertical section through a Scotch Yoke type actuator in the valve housing, seen from the side of the valve.

Description of an Exemplary Embodiment

Fig. 1 shows a known configuration of a ball valve 8. The valve 8 consists of an outer tubular valve housing 10 being provided at either end with a support 12 for a valve seat ring 14. Further, each support 12 at the end of the valve is provided with a threaded portion 16 for connection to coaxial pipes. Externally the support 12 consist of a circumferentially threaded portion 18, which is screwed into a portion 20 of the valve housing 10 with corresponding internal threads. Internally in the valve 8 each support 12 rests resiliently on, and retains in position, a valve seat ring 14. The ball valve 8 is provided with two valve seat rings 14, facing in opposite directions, each bearing on the external surface of a valve ball 22 positioned centrally. The valve ball 22 has a through-going bore 24 for the passage of well equipment to be used, for example, in the testing and completing of a well. To allow opening or closing of the valve 8, either side of the ball 22 and the valve housing 10 have a through-going axle bore 26. The opposite axle bores 26 are positioned concentrically and diametrically relative to one another. On the surface abutting the support 12, each valve seat ring 14 is provided with a series of pre-loading springs 28, which ensure contact and tightening between the ball 22 and the valve seat rings 14. In its closed position and pressurised upstream, the valve 8 can be subjected to relative longitudinal-axial movements of the ball 22 and the valve seat rings 14 end leaks in connection therewith, which is compensated for b} means of said arrangement with preloading springs 28. Otherwise the support 12 is provided with several pressure-sealing seals 30.

Fig. 2 shows the axles 32 provided with axial spline ridges 34 and spline grooves 36, engaging corresponding spline grooves 38 and spline ridges 40 in both the axle bore 26 of the valve ball and in the actuator 41 of the valve housing 10. In its end portion nearest to the central line of the ball 22, the axle bore 26 is widened, so that an abutment surface 42 is formed immediately in front of the spline grooves 38 and spline ridges 40. To each axle 32 there is secured, in this axle bore area, for example by machining or welding, a flange-like ring 44, which projects beyond the diameter of the spline ridges 34 and spline grooves 36 of the axle 32. Thereby an abutment surface 46 is provided, bearing, in the assembled state, on the abutment surface 42. By well pressure the axles 32 are subjected to outward and pistonlike pressure forces which are absorbed through the ring 44 into the valve ball 22, and thus are not transmitted to the support devices of the valve housing 10, causing great friction and wear therein. The ring 44 may for example be laser or electron welded to the axle 32 after the latter has been formed with the spline ridges 34 and spline grooves 36.

Figs. 2 and 4 show Scotch Yoke actuators 41 built into a valve housing 10. For each axle 32 the valve housing 10 is provided with two axial actuator bores 48 extending parallel to the longitudinal axis of the valve housing 10. Each actuator bore 48 is provided with two hydraulic cylinders 50, one at either end of the bore 48, the cylinders 50 being connected by means of a piston rod 52 of a rectangular cross- section, provided with a hydraulic piston 54 at either end. In addition, either end is provided with an end piece 56 with a threaded opening 58 for the inlet/outlet of hydraulic fluid. The axle 32 is placed centrally between, and perpendicularly to, two co-operating piston rods 52. Further,

5 each axle 32 is secured by means of said spline ridges 34 and 38 and spline grooves 36 and 40 to a sleeve 60, which is provided with two parallel flange-like actuator discs 62 and 62' of the same diameter, projecting radially from said sleeve 60. Relative to the longitudinal axis of the axle 32, o the piston rod 52, of rectangular cross-section, is secured eccentrically between the actuator discs 62 and 62", whereby the actuator 41 is assigned a torque arm to which it can transmit the hydraulic forces. The piston rod 52 is secured between the actuator discs 62 and 62" by means of a through- 5 going torque-transmitting pin 64, which may move, when the actuators 41 are activated, in a radial gliding shoe 66 in each of the discs 62 and 62". In the gliding shoe 66 each torque-transmitting pin 64 is provided with a surrounding bushing 68 or similar. Otherwise, the actuator 41 is provided o with an external cover plate 70 with pertaining axial bearing 72. In the valve housing 10 the axles 32 are provided with main bearings 74 and pertaining high pressure seal(s) 76.

The ball valve 8 opens or closes when the actuator 41 on either side of the valve ball 22 is subjected to hydraulic 5 pressure, which drives co-operating pistons 54 so that the ball 22 receives a required torque through the discs 62 and 62" and axles 32. For the rest, the actuator disc 62 is provided with a circumferential recess 78 with abutment surfaces 80, bearing, after a full turn, on a stopper 82 0 limiting the angle of rotation of the discs 62 and 62" and valve ball 22 to 90° preferably. As described in this exemplary embodiment, each of the axles 32 of the valve 8 extends outward to an actuator device in the external face of the valve housing 10, so that the actuator device and the ends of the axles 32 are easily accessible and can be made visible. Thereby the axle(s) 32 and the actuator disc(s) 62 can have, for example, a positioning device arranged thereto, not shown in the figures of the drawings, which can easily be made visible from the outside of the valve 8. The positioning device will at any time accurately indicate the degree of opening of the axles 32 and thereby of the valve ball 22. On testing or downhole operation of the valve 8, it will therefore be easy to check the degree of opening of the valve ball 22 and otherwise inspect the actuator device.

Claims

C l a i m s

1. A ball valve device (8) of the kind preferably used in a high pressure pipe connection, wherein the ball valve (8) is provided with one or more actuators (41) in a valve housing (10), the actuator(s) (41) applying a torque to a valve ball (22) and its axles (32), opening or closing the ball valve (8), and the actuator(s) (41) being activated preferably hydraulically through the supply of hydraulic fluid through pipes and connections o pertaining thereto, c h a r ac t e r i s e d i n that for the ball (22) each axle (32) is provided with an internal ring (44), flange or plate, the ring (44), flange or plate being formed with an abutment surface (46) which abuts a complementary abutment surface (42) s or seat formed in the axle bore (26) of the ball (22).

2. A device according to claim 1, c h ar ac t e r i s e d i n that relative to the longitudinal axis of the axle (32), the ring (44), flange or plate is arranged perpendicular and concentric to the axle (32).

o 3. A device according to claim 1 or 2 , c h a r a c te r i s ed i n that the ring (44), flange or plate is placed in a force-transmitting manner against the abutment surface (42) or seat formed in the axle bore (26) of the ball (22).

5 4. A device according to one or more of the preceding claims, c h a r ac t e r i s ed i n that the outer diameter or outer measurement of the ring (44), flange or plate projects beyond corresponding measurement of the spline ridges (34) or similar securing means of the axle (32).

5. A device according to one or more of the preceding claims, c h a r a ct eri s ed i n that the ring (44), flange or plate is preferably arranged to the end portion of the axle (32), nearest to the central line of the ball (22) .