FIELD OF THE INVENTION

The invention relates to ball valves, more particularly to a ball used in a ball valve and a manufacturing method of the ball. Furthermore the invention relates to valves in fluid piping systems.

BACKGROUND OF THE INVENTION

District heating and cooling systems require high pressure proof valves that can be used reliably for long periods. Ball valves are used to shut off the flow of water or other fluid in the system. In the prior art the ball of the ball valve has been constructed from cast iron, which has consumed a lot of raw material and resulted to a heavy ball. The durability of the cast iron ball has traditionally been very good compared to other solutions. In a regular cast iron ball the cavity inside the ball is not formed to a straight tube. In order to save material costs the cavity is usually larger than straight tube form, inducing turbulence in the flow of the fluids. Currently the cost of the cast iron material is about double the cost of the plate stainless steel.

It is also known to form cavities to the ball and fill those cavities with suitable filler material. This results to very expensive manufacturing method.

In another known ball type a hollow ball is manufactured from a tube blank being formed to shell sphere. These hollow balls can be difficult to machine after the ball shape has been formed. Hollow balls can also induce turbulence creating restriction in the flow of the fluids passing through the ball. PURPOSE OF THE INVENTION

The purpose of the invention is to overcome aforementioned problems or at least significantly alleviate them. Another purpose of the invention is to present a new type of ball to a ball valve that is suitable for large piping systems. Such ball valves are suitable for shut-off valves in e.g. district heating and cooling systems, pressured air pipelines and oil pipelines. Furthermore the invention discloses the method of manufacturing said ball.

SUMN[ARY

The invention discloses a ball member for a ball valve. The ball member comprises at least one portion for receiving stem assembly for rotating the ball member around the axis of rotation in the ball valve. The ball comprises also a passageway for fluids extending to apertures located at different sides of the spherical surface of the ball member.

According to the invention the ball member comprises a shell element forming said spherical surface of the ball member, the shell element having at least two apertures. A tubular element extends between the apertures, the ends of the tubular element being attached to the edges of the apertures. The tubular element forms the passageway. The passageway of this type does not create additional turbulence to the flow of the fluid. There is a hollow space between the shell element and the tubular element, and a supporting structure which is arranged inside the hollow space and attached to the shell and the tubular element. The hollow space in this context is to be understood as a space which does not have a function for receiving any structural forces applied to the ball member. A space filled with light foam or similar filler material is essentially hollow according to the present invention.

In a preferred embodiment of the invention said supporting structure comprises at least one spacer flange attached to the tubular element and to the shell element. The spacer flange is fitted around the tubular element parallel to the edge of the aperture. In an embodiment of the invention the attachments between the shell element, the supporting structure and the tubular element are welded or more preferably laser beam welded. The attachment between the supporting structure and the tubular element or the shell element comprises a welding point that is formed through a hole on the tubular element or the shell element wherein the hole is filled with a weld. In another embodiment the attachments may also be glued. The ball member may comprise only plate steel material yet improving the strength and durability compared to a plate steel based ball known in the prior art. The ball member is preferably made of stainless steel or titanium.

The invention discloses also a method for manufacturing a ball member for a ball valve, comprising the steps of forming a hollow ball, forming portions for receiving stem assembly for rotating the ball member around the axis of rotation in the ball valve, and forming a passageway for fluids extending to apertures located at different sides of the spherical surface of the ball member. The method also comprises a step of attaching the outer surface of at least one spacer flange to inside the spherical surface element of the ball member and forming a passageway by attaching the ends of a tubular element to the edges of the apertures and to the inner surface or the spacer flange.

In an embodiment according to the invention the spacer flange is attached to the spherical surface element in at least two portions thereby said spacer flange forming a circular shape parallel to the edges of the apertures. The spacer flange is larger than the circular aperture, the inner diameter of the spacer flange is similar to the diameter of the aperture; therefore it would be difficult to insert the spacer flange inside the ball member in one piece. In one embodiment jig pieces are attached to the first spacer flange and the second spacer flange is attached parallel to the first spacer flange to a distance defined by said jig pieces. Preferably the aperture and spacer flanges inside the ball member are all parallel to each other.

In an embodiment holes are formed to the tubular element to distances from the aperture similar to the position of the spacer flange attached inside the spherical surface element and welding the spacer flange to the tubular element by filling said holes. The inner diameter of the spacer flange fits around the tubular element enabling the welding method through filling a hole.

In an embodiment said spherical surface element is formed from two halves that may be identical. Said halves are attached together by a welding seam extending to middle of the stem assembly' s position and parallel to the apertures position on the spherical surface. This affects the durability of the ball member positively especially in the closed position.

In an embodiment the attachments between the surface element, the supporting structure and the tubular element are laser beam welded. Laser beam welding is an effective method resulting in small heat-affected zones and minimal structural distortions.

The invention introduces a plate material based ball for a ball valve that has improved strength combined with reasonable manufacturing costs. Using the plate material according to the invention reduces the manufacturing costs significantly. The structural durability is well achieved in relation to the pressure requirements. Large industrial valves are not usable in district heating or cooling applications because of the high cost. The flow characteristics are also improved compared to cast iron or traditional shell ball valve.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this specification, illustrate embodiments of the invention and together with the description help to explain the principles of the invention. In the drawings:

Fig. 1 is a simplified drawing of a ball valve,

Fig. 2 is a cross-sectional view of a ball member,

Fig. 3 shows two halves of the shell element during the manufacturing process,

Fig. 4 shows the inside of the ball member prior to attaching the tubular element during the manufacturing process,

Fig. 5 shows the tubular element prior to attaching it to the ball member during the manufacturing process,

Fig. 6 shows the ball member with the welding points and welding seams,

Fig. 7 shows the spacer flange structure during the manufacturing process, and

Fig. 8 shows spacer flange structures attached to ball member during the manufacturing process . DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

In figure 1 is shown a simplified drawing of a ball valve. The valve body 1 has a seat arranged for the ball member 3. An inlet 6 and an outlet 8 can be connected to piping to allow fluids flowing through the valve. Fluids may be either gasses or liquids. The ball member 3 has a spherical outer surface and includes a port extending through the ball member 3. The ball member 3 is rotatable between a closed position in which the flowing of the fluid from the inlet 6 to the outlet 8 trough the port is hindered, and an open position in which the flowing of the fluid from the inlet to the outlet is allowed through the port .

A stem 4 is attached to the ball member for rotating the ball member around an axis of rotation. The valve body comprises a stem bush 2 to support the stem. The stem can be rotated by turning a handle 7. The ball member inside the valve body rotates from closed to open position by turning the handle about 90 degrees. The valve comprises also ball seals 5.

In figure 2 is shown a cross-sectional view of the ball member. The passageway for fluids is shown as a tubular element 24. The tubular element 24 is attached to the edges of the apertures 21,22 of the substantially spherical shell element 23. The tubular element 24 is preferably at a right angle with the axis of rotation, but could also be at different angles still enabling the flow of fluids. It is also possible that the tubular element 24 comprises more than one outlet or inlet. The tubular element 24 may be for example T-shaped with one inlet and two outlets. The portion for receiving stem assembly 20 for rotating the ball member around the axis of rotation in the ball valve comprises preferably also a corresponding portion 25 at the opposite side of the ball member 23, which enables the rotating movement. Another embodiment comprises a floating arrangement without the portion at the opposite side.

Spacer flanges 29 are located inside the ball member, in the hollow space 27 between the tubular element 24 and the shell element 23. The number of spacer flanges 29 may vary, there may be just one spacer flange 29 as a supporting structure 28, but preferably there are six spacer flanges 29 positioned symmetrically in relation to the axis of rotation, three on both ends of the tubular element 24 in a manner that enables the tubular element 24 to be fitted inside spacer flanges 29. Spacer flanges 29 are attached to outer surface of the tubular element 24 for example by welding through holes 30 that are manufactured to the locations of the spacer flange 29. The inner diameter surface of the spacer flange 29 is visible through the hole 30 prior to filling the hole 30 with welding filler material. The outer surface of the spacer flange 29 is attached to inner surface of the shell element 23. This creates a hollow space 27 inside the ball member. The spacer flange 29 has preferably circular shape fitting between the round inner surface of the shell element 23 and the round outer surface of the tubular element 24.

The manufacturing of the hollow ball comprises a step of forming a hollow ball, for example from a tube blank or a plate steel as is known in the prior art. In Figure 3 is shown how the hollow spherical surface element is formed from two halves 31, 32. As shown in Figure 6, the attachment is made along the line 62 that extends to middle of the position of the stem assembly 63 and middle of the surface element 23. Portions for receiving stem assembly 20 can be formed at the beginning or a later stage of the manufacturing process, when the supporting structure 28 is in place to prevent deformations of the spherical ball. In one embodiment the portion for receiving stem assembly may be attached also to the tubular element 24, thereby increasing the structural stability.

In hollow balls according to the prior art the passageway for fluids has been formed either by opening apertures to different sides of the spherical surface element or by welding a tube between the apertures. However, this has lead to a structurally weak ball that does not withstand high pressures that are present in the large scale piping systems.

In Figure 4 is shown a manufacturing stage of the ball member. The spacer flanges 29 are welded in position one at a time, beginning from the smallest one 44 that is closest to the aperture 21. The first spacer flange 44 is welded to the inner surface of the spherical surface 23 of the ball element in a position parallel to the aperture 21. The spacer flanges 29 are fitted inside the spherical surface 23 in two or more portions and the separate portions are welded together to form a solid spacer flange 29 inside the spherical surface 23.

To the first spacer flange 44 is welded one or more jig pieces 43 that guide the second spacer flange 45 to a predetermined distance from the first spacer flange 44. These predetermined distances are used also in defining the positions of the holes 51 in the tubular element 24, as shown in Figure 5. Holes 51 are formed to similar distance from each other than are distances between the spacer flanges 29 inside the surface element 23.

The second spacer flange 45 is fitted similarly as the first spacer flange 44 inside the spherical surface element 23, in two or more portions. The second spacer flange 45 is welded into the position determined by jig pieces 43, parallel to the first spacer flange 44. Welding of spacer flanges 29 and jig pieces 43 can be executed inside the spherical surface element 23 as welding instruments can be inserted to the spherical surface 23 from the aperture 21, 22.

Third spacer flange may be fitted utilizing the same method as with the second spacer flange 45. An effective arrangement of spacer flanges 29 comprises six spacer flanges 29 positioned three on both sides of the stem assembly 20. As the spacer flanges 29 are preferably circular, they are not positioned to the portions for receiving stem assembly 20 at the spherical surface element 23.

Figure 7 shows a manufacturing stage of another method for attaching spacer flanges 29 inside the spherical surface element 23. Parallel spacer flanges 29 are attached to jig pieces 43 prior to installing spacer flanges to the shell element 23. Spacer flanges 43 and jig pieces 43 form a spacer flange structure 71. The spacer flange structure 71 may comprise complete spacer flanges or just a portion as shown in Figure 7. The portion of spacer flange structure 71 can be constructed in an assembly jig enabling a specific fitting. Portions of spacer flange structure 71 can be combined to a whole spacer flange structure before attaching it to inner surface of the shell element 23. Each portion may also be attached separately. In this manner the complete spacer flange structure 71 is formed inside the shell element 23. Figure 8 shows a spacer flange structure attached inside the surface shell element 32. In this example the spacer flange structure has been formed in two similar portions.

The attachment method may be either gluing or preferably welding. Attachments between ball halves 31, 32 may be laser beam welded as well as attachments between the tubular element 24 and the shell element 23. As the surface contact point between the spacer flange 20 and the shell element 23 may be uneven at some points, this attachment can be made by MIG or TIG welding.

The ball valves are used in large piping systems that may produce high pressures or pulsations in the pressure. Such systems are usually an integral part supporting a larger installation, such as district heating or cooling centre. It is therefore very important that the valve is durable and requires as little maintenance as possible. The ball member's diameter may vary from 300 millimeters to 900 millimeters; a preferred embodiment is a ball member between 400 to 750 millimeters. The invention enables manufacturing a ball member that may withstand 37 bar pressure, where the thickness of the stainless steel material is 10 millimeters. The hollow space inside the ball member and the ability to use plate material leads to significant material savings. Another benefit is a lighter ball member that is easier to rotate.

It is obvious to a person skilled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways. The invention and its embodiments are thus not limited to the examples described above; instead they may vary within the scope of the claims.