SE543037C2 - Ball valve device and use of ball valve device - Google Patents

Abstract

The invention relates to a ball valve device (1) comprising a valve housing (2), a valve seat (3) arranged in the valve housing (2) and a ball element (4) rotatably mounted in the valve housing (2) about an axis of rotation (R) so that it can assume different angular positions. The ball element (4) has a surface (5) which is such that, when rotating the ball element (4), the surface (5) is completely smooth and continuous and without grooves over the entire area where it covers the valve seat (3). The valve seat (3) has one or more through openings through which liquid can flow when the ball element (4) is rotated to an open position and at least the part of the valve seat (3) which comes into contact with liquid flowing through the ball valve device (1) is made of reinforced polytetrafluoroethylene (PTFE). The invention also relates to the use of the ball valve device according to the invention.

Description

BALL VALVE DEVICE AND USE OF BALL VALVE DEVICE TECHNICAL FIELD The present invention relates to a ball valve device which comprises a valve body, a valve seat arranged in the valve body and has one or more through openings and a ball element which is rotatably arranged in the valve body.

BACKGROUND OF THE INVENTION Ball valve assemblies are previously known which comprise a valve seat with a through opening and a rotatable spherical member which is provided with a groove. Such ball valve devices can be used to control the flow of a liquid in an industrial process. Valve seats for such ball valve devices can be made of hard materials such as steel, but for applications where there are high demands on tightness, it has been shown that hard materials do not give a completely satisfactory result and in some applications the demand on tightness is simply higher than what hard materials can handle. When there are high demands on tightness, valve seats are therefore used in soft materials such as polymeric materials. However, it has been shown that even such ball valve devices that have valve seats in soft materials can suffer from leakage after a period of use so that liquid leaks through even when the ball valve device is in a completely closed position. It is the object of the present invention to provide a ball valve device designed to reduce the risk of leakage.

DESCRIPTION OF THE INVENTION The ball valve device according to the invention comprises a valve housing, a valve seat which is arranged in the valve housing and a ball element which is rotatably stored in the valve housing around a rotational axis so that it can assume different angular positions. The ball element is arranged to cooperate with the valve seat so that liquid cannot pass through the ball valve device when the ball element is in a first angular position but pass through the ball valve device when the ball element is turned to an angular position that differs from the first angular position. The ball element has a surface which in the first angular position completely covers the valve seat is such that when turning the ball element from the first angular position, the surface is completely smooth and continuous over the entire area where it covers the valve seat. The valve seat has one or more through openings through which liquid can flow when the ball element is turned to an angular position that differs from the first angular position. At least the portion of the valve seat that contacts fluid flowing through the ball valve assembly is made of reinforced polytetrafluoroethylene (PTFE).

Alternatively, the valve seat is made of a homogeneous steel quality or of metal with 60 - 70% cobalt, 20 - 30% chromium, and 0.5 - 12.0% molybdenum and a certain amount of nickel. The valve seat (3) has a through-flow part (6) which through-flow part ( 6) is extended in a direction perpendicular to the axis of rotation (R) of the ball element (4) so that rotation of the ball element (4) gradually allows increased flow through the ball valve device (1) as the ball element (4) is turned more away from its first angular position, as well as of the valve seat flow-through portion has a single through opening (7) and the valve seat has a groove (12) which groove (12) faces the smooth surface (5) of the ball element (4) when the valve seat (3) is mounted in the ball valve assembly (1), which groove ( 12) is extended in a direction perpendicular to the rotation axis (R) of the ball element (4) and has one end wide through the opening (7) so that rotation of the ball element (4) from the first angle position causes liquid to flow through the through opening (7) ) and in the groove (12) and then pass the ball element (4).

In advantageous embodiments, the entire valve seat can be made of reinforced polytetrafluoroethylene.

In embodiments of the invention, at least the part of the valve seat that comes into contact with liquid flowing through the valve device is made of polytetrafluoroethylene (PTFE) reinforced with 5 - 40 volume percent glass, preferably 10 - 25 volume percent glass.

In other embodiments, at least the part of the valve seat that comes into contact with liquid flowing through the valve device can be made of polytetrafluoroethylene (PTFE) reinforced with 5-35% carbon by volume, preferably 5-25% carbon by volume and most preferably 10-25% carbon by volume. The carbon is then preferably carbon powder/carbon black.

In yet other embodiments, at least the part of the valve seat that comes into contact with liquid flowing through the valve device can be made of polytetrafluoroethylene (PTFE) reinforced with 5-40 volume percent graphite and preferably 5-15 volume percent graphite.

One can also think of embodiments where at least the part of the valve seat that comes into contact with liquid flowing through the valve device is made of polytetrafluoroethylene (PTFE) which is reinforced with steel. You can then use austenitic steel, and preferably austenitic stainless steel, preferably austenitic acid-resistant stainless steel. You can also advantageously use superaustenitic, duplex or superduplex steels or nickel-based steel alloys (steel alloys that contain nickel to some extent). If non-austenitic steel is used as reinforcement material, this should preferably constitute 10 - 60% by weight of the material in the valve seat.

In embodiments of the invention, the valve seat has a flow-through portion with one or more through openings, which flow-through portion is extended in a direction that is perpendicular to the axis of rotation of the ball element so that rotation of the ball element gradually allows increased flow through the ball valve device as the ball element is turned more away from its first angular position.

In some embodiments, the valve seat may have a flow-through portion having a single-through opening that extends in a direction perpendicular to the axis of rotation of the ball member. The through opening can then have a width that increases in the direction that is perpendicular to the axis of rotation of the ball element or a width that decreases in the direction that is perpendicular to the axis of rotation of the ball element in such a way that the part of the through opening that has the largest width is first exposed when the ball element is turned from the first angular position.

In other embodiments, the valve seat has a flow-through portion with a plurality of through-openings distributed in the direction perpendicular to the axis of rotation of the ball element. The through-flow portion of the valve seat can then include one, two or more rows of through-flow openings that run parallel to each other. In yet other embodiments, the through-flow portion of the valve seat can have a single through opening at one end of the flow-through portion wherein the valve seat has a groove which groove faces the smooth surface of the ball element when the valve seat is mounted in the ball valve assembly. This groove then extends in a direction perpendicular to the axis of rotation of the ball element and has an end at the through opening so that rotation of the ball member from the first angular position allows fluid to flow through the through opening and into the groove and then pass the ball member. The groove may have a width that decreases in the direction away from the through opening.

In advantageous embodiments, a spring element can be placed in the valve housing and arranged to act against the valve seat so that the valve seat is pressed into contact with a support surface in the valve housing so that the position of the valve seat in the valve housing is fixed. A cover element can then be removably attached to the valve housing and positioned so that the cover element holds the retaining spring element when the cover element is attached to the valve housing. The cover element is then preferably (but not necessarily) arranged so that it is accessible from the outside of the valve device and thereby enables removal of the cover element and spring element so that the valve seat can be replaced with another valve seat.

The invention also relates to the use of the ball valve device according to the invention in an industrial process in connection with the regulation of a flow of, for example, water, steam, petroleum products or chemicals from the group of chlorine, chlorine dioxide, hypochlorite, sodium hydroxide, sodium sulfate, nitric acid, sulfuric acid, hydrogen peroxide, calcium chloride or hydrochloric acid which are allowed to pass through the ball valve device. Such use can also be understood in terms of a process where a flow of liquid or steam passes through a pipe in an industrial process where the flow is regulated by means of the ball valve according to the invention. It is understood that the flow through the ball valve device can consist of a mixture of liquid and steam and that liquid and/or steam passing through the ball valve device can be a mixture of different substances, for example a mixture of water and nitric acid; a mixture of water and one or more petroleum products or a mixture of one or more petroleum products and one or more chemicals.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a view of a known ball valve device in a closed position, Figure 2 shows a cross section along A-A in Figure 1.

Figure 3 shows a view corresponding to Figure 1 in an open position.

Figure 4a shows a cross section along A-A in Figure 3.

Figure 4b shows an enlargement of a part of Figure 4a. Figure 5 is a perspective view, partially seen through, of an embodiment of the ball valve device according to the invention. Figure 6 shows a commonly used ball element for ball valve devices today.

Figure 7 shows a ball element for use in the inventive ball valve device.

Figure 14 shows, in cross-section, an embodiment of the ball valve device according to the invention in a first position, which is a fully closed position.

Figure 15 shows, in cross-section, the same embodiment as Figure 14, but here the ball valve device is in a position which is not completely closed but allows some flow of liquid.

Figure 16 a - e shows a possible design of the valve seat for the ball valve device shown in Figure 14 and Figure 15. Figure 17a - e shows a variant of the valve seat shown in Figure 16 a - e.

Figure 18 a - e shows a further possible variant of the valve seat shown in Figure 16 a _65.

Figure 19 a - e shows a valve seat that differs from the valve seat of Figure 17 a - e primarily in that it exhibits two grooves instead of just one.

Figure 20 shows, in perspective, how the valve seat can be detached from the ball valve assembly.

DETAILED DESCRIPTION OF THE INVENTION With reference to Figure 1 and Figure 2, a known ball valve device is shown which includes a ball element 4 and a valve seat 3 with a through opening 14. In Figures 1 and 2, the ball valve device is in a fully closed position where liquid cannot flow through the ball valve device because the ball element 4 blocks the through opening 14 of the valve seat 3. As can be seen from Figure 1, the ball element 4 has a groove 13 in its surface. In Figure 3 and Figure 4b, the same ball valve device is shown in an open position, where the ball element 4 is rotated around an axis so that the groove 13 occupies a position that coincides with the through opening of the valve seat 3. Liquid can then flow through the ball valve device through the through opening 3 because the groove 13 then offers a one-through flow channel. Often the valve seat 3 is in contact with at least one spring element (not shown in Figure 4a and 4b) which presses the valve seat 3 into contact with a support surface which may be part of a valve housing. The force from the spring element (or spring elements) then presses the valve seat with a force marked with arrows Fi Figure 4a. When the ball valve device is partially open for a long time, the valve seat 3 can be pressed against the groove 13 of the ball element 4. As the valve seat 3 consists of a comparatively soft material such as, for example, polytrafluoroethylene (PTFE), the edges of the groove 13 of the ball element 4 can be pressed into the soft material in the valve seat 3 and partially deform the valve seat 3. Part of the valve seat 3 sinks into the groove 13.

In this patent application and in all patents that may be granted on the basis of this application, the term "ball element" shall be understood and understood as an element that includes a segment of a sphere such that a part of the ball element has a spherical shape as shown in, for example, Figure 7, Figure 8 and Figure 9. When the ball valve device is in a completely closed position as shown in, for example, Figure 8, the surface of the ball element that faces the valve seat is a curved surface with a radius of curvature and the surface that then faces the check valve seat is then identical to the surface that a fully spherical body with the same radius of curvature would exhibit against the valve seat. It is understood that the valve seat has a shape that corresponds to/mirrors the shape of the ball element so that the ball element can interact undisturbed with the valve seat.

In Figure 4a, a circled area is shown which is designated by the reference S. This area is shown enlarged in Figure 4b. The reference designation D denotes the indentation/indentation that the edges of the groove 13 have made in the valve seat 3. When the valve assembly is closed, the edge of the ball element can shear off part of it material sunk into the groove 13. Then leakage can occur when the valve device is closed. The present invention solves this problem in a manner described in the following.

Reference is now made to Figure 5 where a ball valve device according to the present invention is shown in perspective and partially in section. The ball valve device 1 according to the invention comprises a valve housing 2, a valve seat 3 which is arranged in the valve housing 2 and a ball element 4. The ball element 4 is rotatably stored in the valve housing 2 around the axis of rotation (axis of rotation) R so that it can assume different angular positions. Suitably, the ball element 4 then sits on a rotatable rod A so that rotation of the rod A causes the ball element to turn around the axis of rotation R. The ball element 4 is arranged to cooperate with the valve seat 3 so that liquid cannot pass through the ball valve device 1 when the ball element 4 is in a first angular position but passes the through ball valve device l when the ball element 4 is turned to an angular position that differs from the first angular position. As can be seen from Figure 5, a spring element 9 can be arranged to act against the valve seat 3 and the spring element 9 can consist of, for example, a spring washer. In many practical embodiments, a cover element such as for example a cover washer 11 can be fixed in the valve housing 2 in such a position that the spring element 9 and thus also the valve seat 3 is held in place. The cover washer 11 can be attached to the valve housing 2, for example by having threads in its periphery which cooperate with threads in the valve housing, but the person skilled in the art realizes that the cover washer 11 can be attached to the valve housing 2 in many other ways that do not need to be explained in detail. In principle, the cover washer 11 can be attached to the valve body in a permanent way, for example through welding, but in preferred embodiments the cover washer 11 is removably attached (for example by threading) so that the cover washer 11 can be easily removed in connection with, for example, the replacement of the valve seat 3 or repairs, maintenance work and the like.

With reference to Figure 6, a ball element 4 of a kind which is previously known in the technical field is now shown. As explained earlier with reference to Figure 1 - 3 and Figure 4a, this ball element 4 has a groove 13 into which the material of a soft valve seat can sink, which can cause damage to the valve seat. Figure 7 instead shows a ball element 4 intended to be used in the ball valve device according to the invention. This ball element 4 lacks such a groove 13 that the ball element in Figure 6 is provided with. Instead, the ball element 4 according to Figure 7 has a smooth surface 5 without grooves. The part of the ball element 4 which has a smooth surface 5 without grooves is so large that it can be made to cover the valve seat. Thereby the cancule element 4 is turned to an angular position where it exhibits a surface 5 facing the valve seat 3 which is completely smooth without grooves. The surface 5 of the ball element 4 is such that, when the ball element 4 is mounted in the ball valve device 1 and the ball valve device 1 is in a closed position, it completely covers the valve seat 3. The surface 5 is also such that when turning the ball element 4 from the first angular position, it is completely smooth and continuous over the entire area where it covers the valve seat 3. This is the position that the ball element must take when the ball valve device 1 is completely closed (the first angular position) so that no liquid can pass through the ball valve device 1. Hereinafter, the closed position of the ball valve device 1 will be referred to as "a first position" (first angular position) or "the first position". In order to allow the passage of liquid through the ball valve device 1, the valve seat 3 has one or more through openings through which liquid can flow when the ball element 4 is turned to an angular position that differs from the first angular position which will be explained in more detail later in this description.

The entire part of the ku1e1ementet 4 which moves over the valve seat 3 thus has a surface 5 which is completely smooth and continuous and without grooves over the entire area where this surface 5 covers the valve seat 3 (in whole or in part). Even when the surface 5 only partially covers the valve seat 3, there is thus no groove in the surface 5 into which parts of the material in the valve seat can sink. At least the part of the valve seat 3 that comes into contact with liquid flowing through the ball valve device 1 is made of reinforced polytetrafluoroethylene (PTFE ). Preferably, the entire valve seat 3 is made of reinforced polytetrafluorene, but embodiments are conceivable where only a part (or parts) of the valve seat is made of unreinforced PTFE.

Because the material in the venti1 seat3 is reinforced, the shape stability of the material is improved.

In some embodiments, the part of the valve seat 3 that comes into contact with liquid flowing through the ball valve device 1 can be made of polytetrafluoroethylene (PTFE) coated with 5-40% glass by volume, preferably 10-25% glass by volume. It is understood that the entire valve seat can be made of PTFE reinforced with 5 - 40% glass by volume.

In other embodiments, the part of the valve seat 3 that comes into contact with liquid flowing through the ball valve device 1 can be made of polytetrafluoroethylene (PTFE) reinforced with 5-35% carbon by volume, preferably 5-25% carbon by volume and most preferably 10-25% carbon by volume. It is understood that the entire valve seat can be made of PTFE reinforced with 5 - 35% carbon by volume. By carbon is meant here primarily carbon powder/carbon black, among other things because carbon powder/carbon black is well suited when you want to achieve an even distribution of the carbon in the PTFE material so that you obtain even material properties. Carbon black is a material that is advantageous when you want have low friction.

Glass is a reinforcing material which is advantageous when very cold media must pass through the ball valve device, for example liquid nitrogen. Valve seats with carbon become very brittle at low temperatures and glass is then more suitable as a reinforcing material. Reinforcement materials other than glass or carbon can also be used. In some possible embodiments, the valve seat 3 - or at least the part of it that comes into contact with liquid flowing through the ball valve device 1 - can be made of polytetrafluoroethylene (PTFE) reinforced with 5 - 40 volume percent graphite and preferably 5 - 15 volume percent graphite. The applicant has not currently tested graphite, but there are theoretical reasons to believe that graphite can give even lower friction than black smoke.

A further conceivable alternative could be to have at least the part of the valve seat 3 that comes into contact with liquid flowing through the ball valve device 1 be made of polytetrafluoroethylene (PTFE) reinforced with austenitic steel, preferably polytetrafluoroethylene (PTFE) reinforced with 10 - 60% by weight of austenitic steel. It is understood that the entire valve seat 3 can be made of PTFE reinforced with austenitic steel and the steel can advantageously be stainless austenitic steel. By stainless austenitic steel is understood here steel with an austenitic structure that contains chromium (12 - 30 percent) and nickel (7 - 30 percent and other metals, often molybdenum (2-3 percent). The carbon content of these steels is generally relatively low, usually below 0 .05 percent.

The steel in the reinforcing material can advantageously also be duplex steel, i.e. ferritic-austenitic stainless steel containing chromium, nickel, molybdenum, carbon and nitrogen. A duplex steel can contain, for example, 22 - 24.9 percent chromium, 5 - 8 percent nickel, 1 - 4 percent molybdenum, carbon below 0.03 percent (for example 0.01 - 0.029 percent carbon) and nitrogen 0.4 percent .

Super duplex steel can also be used for the reinforcement. By superduplex steel is meant duplex steel with a chromium content of 25 percent or more, for example 29 percent chromium.

Furthermore, the steel in the reinforcement can also be a super-austenitic steel and high-nickel-based steel alloys can also be advantageously used.

Stainless steel as reinforcement has proven to be more resistant to high surface pressures between the valve seat and ball element as well as flow media that are tougher against soft materials due to e.g. high mass concentrations, but above all a valve seat with stainless steel reinforcement can withstand higher temperatures than carbon black reinforcement because it is a more stable reinforcement .

An embodiment will now be explained with reference to Figure 14 and Figure 15.

In Figure 14, the ball valve device 1 according to the invention is shown in a closed position, the ball element 4 is thus in the first angular position and blocks the flow of liquid. As can be seen from Figure 14, the valve seat 3 has a single through opening 7 which leads to a groove 12 which, however, cannot let liquid through because the ball element 4 blocks the way. In Figure 14 you can also see how a spring element 9 (for example a spring washer) is placed in the valve housing 2 and arranged to act on the counter valve seat 3. The valve seat 3 is thereby pressed into contact with a support surface 10 in the valve housing 2 so that the position of the valve seat 3 in the valve housing 2 is fixed. A cover element 11 is removably attached to the valve housing 2 and positioned so that the cover element 11 holds the spring element 9 when the cover element 11 is attached to the valve housing 2 and the cover element 11 is preferably arranged so that it is accessible from the outside of the ball valve device 1 and thereby enables the removal of cover element 11 and spring element 9. By doing so, you can, among other things, get access to changing the valve seat 3 for another valve seat 3. This can be the case when you want a valve seat with different control properties or when a valve seat that has been damaged for some reason needs to be replaced with a new one.

Figure 15 shows how the ball element 4 is rotated around its axis of rotation R so that liquid can flow through the ball valve device 1 by passing through the groove 12. Even in the embodiment according to Figure 14 and Figure 15, the surface 5 of the ball element is such that when turning the ball element 4 from the the first angular position is completely smooth and continuous over the entire area where it covers the valve seat 3. This reduces the risk of wear on the valve seat 3.

With reference to Figure 16a - 16e, a possible design of the ball valve device 1 according to Figure 14 and Figure 15 will now be explained. In Figure 16a - 16e, similar views of the valve seat 3 are shown in a way that corresponds to the views according to Figure 10 a - e. As can be seen from the figures, the valve seat 3 in this embodiment has a through opening 7 at one end of the flow-through part 6. The through opening 7 is located so that it will be exposed only when the ball element 4 is turned away from its closed position. However, the through opening 7 is located only at one end of the through-flow part 6 and the rest of the through-flow part 6 consists of a groove 12 which is formed in the valve seat 3 on the surface facing the ball element 4 when the valve seat 3 is in place in the ball valve device 1. The groove 12 will thus be facing the smooth surface 5 of the ball element 4 when the valve seat 3 is mounted in the ball valve device 1. The groove 12 is extended in a direction perpendicular to the axis of rotation R of the ball element 4 and has an end at the through opening 7 so that rotation of the ball element 4 from the first angular position means that liquid can flow through the through opening 7 and in the groove 12 and then pass the ball element 4 As shown in Figure 16 a - 16 e, the groove 12 can have a width that decreases in the direction away from the through opening 7.

In Figure 17a - 17e, a variant of the valve seat 3 shown in Figure 16a - 16e is shown. The variant shown in Figure 17a - 17e has the groove 12 a width which is essentially constant along the extent of the groove 12 and the groove 12 is also significantly wider than the variant according to Figure 16a - 16e. The continuous opening 7 is also larger than the variant according to Figure 16 a - 16e and has also been given a more oval shape. It is understood that these differences result in different flow characteristics than is the case with the variant according to Figure 16 a - 16e.

Another variant is shown in Figure 18a - 18 e. This variant is similar to that shown in Figure 17a - 17 e but the through opening 7 has here been given a circular round shape and the groove 12 is not as wide.

Another variant is shown in Figure 19a - 19e. In this variant, the groove 12 is tapered away from the through opening 7 and the groove 12 is divided into two parts, 12a and 12b. The division is achieved by an edge 15 which extends along the groove 12.

The different variants according to Figure 16a - 16e; Figure 17a - 17e; Figure 18a - 18e; and Figure 19a - 19e work in basically the same way. When the ball element 4 is turned away from the first position (angle position), liquid can flow in through the continuous opening 7 and further into the groove 12 and thus flow between the valve seat 3 and the ball element 4 until the liquid reaches a point where the valve seat 3 is not covered by the ball element at all 4 and the liquid can then flow further through the ball valve device 1. Before the liquid has reached a point where the ball element 4 no longer covers the valve seat 3, the liquid is forced to flow through the groove 12 and thus cannot take any other path. It is understood that the design of the groove then becomes important for the flow characteristic/control properties of the ball valve device 1. 11 As shown in Figure 20, the valve seat 3 can be replaced by loosening the cover washer 11, removing the spring washer 9 and then lifting out the valve seat 3 so that it can be replaced with another valve seat, for example a valve seat with different control properties.

Because the ball element 4 has a smooth surface without grooves, wear on the valve seat can be reduced, which in turn reduces the risk of leakage.

The valve seat used in the ball valve device according to the invention can advantageously be manufactured with additive manufacturing, also known as 3D printing. By using additive manufacturing, complicated shapes can be manufactured more easily. Methods for additive manufacturing are described in, for example, US patent number 9,862,140 and US patent number 9,944,016.

The ball valve device according to the invention can be advantageously used in environments where corrosive chemicals must pass through the ball valve device and the choice of reinforced polytetrafluoroethylene (PTFE) means that the valve seat can better withstand exposure to such chemicals. The ball valve device according to the invention may in particular be suitable for use in the paper and pulp industry where corrosive chemicals are used. PTFE also has a low coefficient of friction, which is an advantage.

In some cases, the inventive construction can also be advantageously applied to a single ball valve device that does not use a valve seat made of reinforced PTFE and then enables good regulation of a flow, even if the tightness is not as good as with a valve seat unreinforced PTFE. This may be the case when the flow to pass through the ball valve device contains hard particles and the ball valve device must meet high requirements for resistance to abrasion. For such applications, a ball valve device may be used which has a valve seat made of a material with high abrasion resistance but which is otherwise designed in accordance with what is described above and with reference to the attached figures. For such applications where high abrasion resistance is a requirement, the valve seat can be made of a homogeneous steel quality or of metal with a high content of cobalt. In this context, "homogeneous" means that it is one and the same material throughout the detail. Steel grades particularly suitable for such applications can be austenitic stainless steel, duplex stainless steel or super austenitic stainless steel. A suitable steel grade can for example be SS 142328 which is a super duplex material containing 0.030% carbon (C), 0.8% silicon (Si), 1.2% manganese (Mn), 0.035% phosphorus (P), 0.020% Sulfur (S), 24% - 26% Chromium (Cr), 6.0% - 8.0% Nickel (Ni), 3.5% - 5.0% Molybdenum (Mo) and 0.24% - 0.32% nitrogen (N). Such materials have high resistance to abrasion. When there are very high demands on abrasion resistance and/or when the fluid passing through the ball valve device 12 is at a very high temperature, a metal with a high cobalt content can be used instead of steel. This can be suitable, for example, when the fluid passing through the ball valve device has a temperature of 400 OC or higher or when there are extremely high demands on abrasion resistance. The metal in the valve seat can then be made of a material which contains at least 60% cobalt and which also contains chromium, nickel and molybdenum. For example, the material may contain 60 - 70% cobalt, 20 - 30% chromium, and 0.5 - 12.0% molybdenum as well as a certain amount of nickel. Such materials have a very high abrasion resistance, higher than the above steel qualities and they can also withstand high temperatures. The applicant reserves the right to file patent claims also for such ball valve devices where the valve seat is made of a steel quality as stated above or of a metal with a high content of cobalt as stated above.

The invention also includes use of the ball valve device according to the invention, whereby the ball valve device is used in an industrial process where liquid containing chemicals from the group chlorine, chlorine dioxide, hypochlorite, sodium hydroxide, sodium sulfate, nitric acid, sulfuric acid, hydrogen peroxide, calcium chloride or hydrochloric acid is allowed to pass through the ball valve device 1. Such industrial processes can be found within, for example paper and pulp industry but can also be found in other areas, for example where you have to manage the flow of petroleum products.

Claims (1)

A ball valve device (1) comprising a valve housing (2), a valve seat (3) arranged in the valve housing (2) and a ball element (4) rotatably mounted in the valve housing (2) about an axis of rotation (R) so that it can assume different angular positions and which is arranged to cooperate with the valve seat (3) so that liquid can not pass through the ball valve device (1) when the ball element (4) is in a first angular position but pass through the ball valve device (1) when the ball element (4) is rotated to an angular position which differs from the first angular position, characterized in that the ball element (4) has a surface (5) which in the first angular position completely covers the valve seat and which is so shaped that when the ball element (4) is rotated from the first angular position, the surface (5) is completely smooth and continuous throughout the area where it covers the valve seat (3), in that the valve seat (3) has one or more through openings through which liquid can flow when the ball element (4) is rotated to an angular position which differs from n the first angular position and the valve seat is made of a homogeneous steel grade or of metal with 60 - 70% cobalt, 20 - 30% chromium, and 0.5 - 12.0% molybdenum and a certain amount of nickel or of at least that part of the valve seat (3) which comes into contact with liquid flowing through the ball valve device (1) is made of reinforced polytetra [urethane] (PTFE), in that the valve seat (3) has a through fl portion (6) which through fl portion (6) extends in a direction perpendicular to the axis of rotation ( (R) so that rotation of the ball element (4) gradually allows increased fate through the ball valve device (1) as the ball element (4) is rotated further away from its first angular position, and that the valve seat through the fate portion has a single through opening (7) and the valve seat has a groove ( 12) which groove (12) faces the smooth surface (5) of the ball element (4) the proximity valve seat (3) is mounted in the ball valve device (1), which groove (l2) extends in a direction perpendicular to the ball element (4) r shaft (R) and has one end at the through opening (7) so that rotation of the ball element (4) from the first angular position means that liquid can flow through the through opening (7) and into the groove (12) and then the passage ball element (4). A ball valve device (1) according to claim 1, wherein the groove (l2) has a width which decreases in the direction away from the through-opening (7). A ball valve device (1) according to claim 1, wherein the entire valve seat (3) is made of reinforced polytetra [urethane]. A ball valve device (1) according to claim 1, wherein at least the valve seat (3) which comes into contact with liquid flowing through the ball valve device (1) is made of polytetra [urethylene (PTFE) reinforced with 5 - 40% by volume glass, preferably 10 - 25% by volume of glass. A ball valve device (1) according to claim 1, wherein at least the part of the valve seat (3) which comes into contact with liquid flowing through the ball valve device (1) is made of polytetra [urethane] (PTFE) which is reinforced with 5 - 35 volume percent carbon, preferably 5 - 25 volume percent carbon and most preferably 10 to 25 volume percent carbon. A ball valve device (1) according to claim 1, wherein at least the part of the valve seat (3) which comes into contact with liquid flowing through the ball valve device (1) is made of polytetra [urethylene (PTFE) reinforced with 5 ~ 40% by volume graphite, preferably 5 - 15% by volume graphite . A ball valve device (1) according to claim 1, wherein at least the part of the valve seat (3) which comes into contact with liquid flowing through the ball valve device (1) is made of polytetra [urethane (PTFE) reinforced with stainless austenitic steel. A ball valve device (1) according to claim 1, wherein at least the part of the valve seat (3) which comes into contact with liquid flowing through the ball valve device (1) is made of polytetra [urtene] (PTFE) lined with stainless austenitic steel alloyed with nickel (Ni) or reinforced with a duplex steel, a super-duplex steel or with a high nickel-based steel alloy. A ball valve device (1) according to claim 1, wherein a spring element (9) is placed in the valve housing (2) and arranged to act against the valve seat (3) so that the valve seat (3) is pressed into abutment against a support surface in the valve housing (2) so that the valve seat (3) position in the valve housing (2) is fixed and wherein a cover element (11) is releasably fixed in the valve housing (2) and placed so that the cover element (11) holds the spring element (9) when the cover element (11) is fixed in the valve housing (2) and wherein the cover element ( 11) is arranged so that it is accessible from the outside of the ball valve device (1) and thereby enables removal of cover elements 10. (11) and spring elements (9) so that the valve seat (3) can be replaced by another valve seat (3). Use of a ball valve device (1) according to any one of claims 1 to 9, wherein the ball valve device is used in an industrial process in connection with regulation of a waste of, for example, water, steam, petroleum products or chemicals from the group chlorine, chlorine dioxide, hypochlorite, sodium hydroxide, sodium sulfate, nitric acid, sulfuric acid , hydrogen peroxide, calcium chloride or hydrochloric acid or mixtures of such media.