NO833724L - BALL VALVE. - Google Patents

Description

The invention relates to ball valves, in particular fire-resistant or fire-proof ball valves.

The term "fireproof" in connection with valves means a valve which satisfies certain requirements when subjected to

a fire, see Arant, Fire Safe Valves—An Overview, Proceedings, Thirty-Six Annual Symposium on Instrumentation for the Process Industries (Texas A&M University, 1981). Regrettably, the various organizations highlight different requirements and criteria,

and within the valve industry it has therefore not yet arrived^

to a common standard. According to one of the standards used (American Petroleum Institute 607), a valve can be certified as "fireproof" if it is still tight in the closed state after the valve body has had a temperature of at least 593°C for at least 10 minutes. Valves that are designed in such a way that they

are leak resistant when exposed to fire, but

do not meet the latter standard, are usually referred to as "fire resistant".

The invention relates in particular to a new and improved fireproof ball valve with soft seats, of the type that has a so-called floating valve ball, and the invention will be described below with reference to such ball valves. A person skilled in the art will, however, understand that the invention can have a wider field of application and can be adapted to other types and designs of valves.

Ball valves are usually provided with annular seats or seats made of a compliant and deformable plastic material, for example Teflon (trademark), which seals against the valve ball.

A pair of such seat rings are placed respectively around the valve inlet and around the valve outlet. The ball valve is fitted

so that it can move slightly axially in the seats under the fluid pressure conditions that prevail when the ball is in the closed position. Such a displacement of the ball causes it to rest against and bend and deform the seating arranged on the downstream side, whereby the sealing cooperation between this seating

ring and the orb is reinforced. The ring deflection will vary in accordance with the applied fluid pressure.

In the event of a fire, the soft ring seat in an ordinary ball valve will

with floating ball is damaged under the influence of the heat from the fire, so that the leakage through the valve may become unacceptable. On the downstream side of the ball, the seat destruction will usually be such that the plastic material first softens and then begins to flow out or squeeze out through the valve barrel. Continued strong heat exposure will eventually cause the seat to char and sublimate or evaporate. The destruction of the plastic seat means that the ball can move further axially under the influence of pressure, until the ball collides with a secondary seat. Such a secondary seat usually includes one made of metal or a non-combustible, or radially inwardly projecting projection in the valve housing, for example a support shoulder for the plastic seat. Usually, such a surface will not be specially designed to achieve a good sealing cooperation with the ball, and significant leaks will therefore occur here.

Another problem arises when the plastic seat is only partially destroyed during a fire. If, for example, a valve is only exposed to radiant heat from one side, or the fire is only of low intensity, then only the part of the valve seat that is closest to the source of the fire will soften and be squeezed into the valve barrel. - The ball can then shift under the fluid pressure towards the area that becomes available as a result of the squeezing, and the ball will then not make smooth contact with the secondary seat. As a result, a strong leakage path occurs.

Alternatively, the bullet can be held back and not made contact with

the secondary seat, the ball being held by the rest, i.

no broken parts of the plastic seat. Even in such a case, you will therefore get a significant leak. In all cases, fluid can pass through the valve and produce an extinguishing effect in the valve. This extinguishing effect will prevent further

destruction of the seat, with the result that a heavy leak is maintained through the valve.

A problem that occurs during a fire, and which one often does not

is aware of, is that the fluid pressure can be greatly increased when the fluid trapped between the inlet and the outlet is heated. The fire can heat up and even cause evaporation of the fluid centrally inside the valve, between the valve seats. Often the fire will be so intense that the fluid evaporates so quickly that it cannot escape quickly enough past the seats and thus prevent a too strong increase in pressure in the valve. Such a pressure increase can easily exceed the valve's certification value and can cause wear and tear of the gaskets around the spindle and in the valve joints, possibly rupture of the valve housing itself.

Another practical problem arises when straightening a fire hose

against a valve in a pipe system for volatile liquids, after the pipe system has been heated as a result of the influence of fire. The water from the fire hose will cause a rapid cooling which can cause a strong condensation of heated steam in the valve, with accompanying displacement of the ball and grinding of charred parts, waste and contaminants that can get stuck between the ball and the sealing rafts and thus cause further leaks.

A main requirement for a fire-resistant or fire-proof ball valve is therefore that the valve must be able to be tight when using normal valve seat materials under normal operating conditions, and must also be tight when exposed to a fire. Various shapes and types of ball valves have been proposed to achieve a fire-proof or fire-resistant ball valve, with varying degrees of success. It has been found that the defects in most previously known fire-proof or fire-resistant ball valves are so great that the devices themselves have limited economic and practical value.

In a conventionally known fire-resistant ball valve is used

a soft primary seat of a plastic material, such as Teflon (trademark), and a secondary seat of metal or a high-temperature composite material, designed to seal when the primary seat is destroyed during a fire. The secondary seat usually includes a metal disc sandwiched between the soft primary seat and a support shoulder in the valve body. This construction has the disadvantages that all metal-to-metal seals suffer from. Because the ball is never perfectly spherical, and because the secondary metal seat is never perfectly circular, the leakage through the secondary seal after the primary seal is broken during a fire will usually be large, because the ball does not make complete annular contact with the metal seat. In order for a metal-to-metal seal to be virtually leak-proof in a fire-proof version or in another version of a valve, the sealing flanges must be matched

by lapping or polishing. However, such surface treatment methods are very expensive, and matching patching is therefore economically unacceptable in connection with the production of fire-proof or fire-resistant ball valves. In addition, even a well-matched ball-secondary seat will be exposed to stresses and wear during normal valve operation, e.g. corrosion, pitting, shelling, erosion and the like, and such effects can be so powerful that in the event of a fire, the matching surface treatment will no longer have any effect. Ball valves where secondary metal seats or high-temperature composite seats are used also do not solve the problems of partial destruction of the primary seat, with the associated problems in connection with loose and blocking carbonized residues and waste materials that arise during rapid cooling.

A proposal to improve the performance of the secondary metal seat has been to add a secondary seat of a heat-resistant material that is more deformable and compliant than metal. Usually carbon or graphite rings are used. Such constructive designs can provide improved operating conditions when the equipment is new, but it has been found that these designs are particularly susceptible to damage during normal use. Normal wear and tear when operating the valve, erosion during the opening, or wear under the influence of foreign objects can easily damage the material in the secondary seats, because these are materials that are typically brittle and have low strength compared to a normal plastic seat. Such designs are therefore usually designed with a metal lip or edge as a final or tertiary seat in order to limit the leakage if the secondary seat is damaged. Such a larger number of seats naturally increases the size of the valve, makes it more complicated and increases the costs, without actually providing a more reliable emergency seal. Wear, erosion or foreign objects that can damage one of the seats will probably also damage all the seats, because they are all equally exposed to such influences during normal operation.

One alternative proposal for a fireproof valve has been to wrap an ordinary valve in sufficient insulation material, so that the valve is insulated for a sufficient period of time and can thus be described as fireproof. Another suggestion is to arrange a sprinkler system near the valve, for overspraying the valve during a fire. These latter proposals are unsuitable for practical cost reasons, because they require expensive installations and are costly in the case of equalization. In addition, an insulated valve will be an unsafe design, because you can never be sure whether the insulation has been properly attached or installed after each maintenance of the valve.

There is therefore a clear need for a fireproof ball valve which will be able to function satisfactorily under normal operating conditions and will also be tight, in the valve's closed position, in the event of a fire. The construction must not require the use of expensive sprinkler systems or

insulating gaskets to protect the valve.

According to the invention, the aim is therefore to provide

a new and improved ball valve that can overcome some or all of the above-mentioned disadvantages. The invention must also be able to utilize a wide range of sealing materials and allow for different seat designs.

According to the present invention, a ball valve is proposed

with a house with a central passage. A valve ball is placed in the passage, which has a continuous fluid flow opening. The valve ball is mounted so that it can be rotated between an open and a closed position with respect to the fluid flow through the valve. A pair of radially inwardly projecting shoulders in the central passage are placed around the barrel on opposite sides of the valve ball, and between these shoulders and the valve ball a pair of seat units are arranged. Each of these seat units includes an elastic seat ring stored in the valve barrel for fluid-tight interaction with the valve ball. Furthermore, each valve unit includes a deformable, heat-resistant secondary seat ring element which is placed between the elastic seat ring and the respective shoulder. This secondary seat ring element is essentially isolated with regard to normal operating contact with the valve ball and the fluid passing through the valve. When the elastic seating ring is damaged by being exposed to high temperatures, the secondary seating ring element will come into contact with the valve ball for sealing cooperation with it.

The invention aims to provide a new and improved bullet-proof ball valve which has improved fluid sealing properties when the valve is exposed to fire or heat.

The invention also aims to provide a ball valve where metal-metal seals are avoided.

Another purpose of the invention is to provide a ball valve where the fluid seal will be able to be maintained even after a partial or complete fire destruction of a primary seat element made of soft plastic.

Another purpose of the invention is to provide a ball valve which will prevent pinched-out residues of primary seats or charred residues and contaminants from settling between the valve ball and the sealing surfaces interacting with it.

Another purpose is to provide a secondary seat in a ball valve which will work even when the ball valve is exposed to fire damage, regardless of the design and the material used in the primary seat in the ball valve.

Another purpose is to provide a secondary seat that will not age and deteriorate during normal operation.

Another purpose is to provide a fireproof ball valve where the occurrence of a destructively high pressure inside the valve housing is prevented when the valve is exposed to high temperatures.

Yet another object is to provide a ball valve that includes a secondary seat that is isolated from destructive and abrasive forces from the fluid flow passing through the valve during normal operation.

More specifically, the invention relates to a fireproof ball valve which includes a valve housing with a central barrel. A valve ball with a through fluid flow opening is located in the valve housing barrel and can be rotated between an open and closed position with respect to the fluid flow through the valve.

In the barrel, it is arranged on opposite sides of the valve ball

a pair of radially inward projecting shoulders, and in the barrel a pair of radially inward projecting counterbores are also arranged on opposite sides of the valve ball. In the barrel, a pair of composite seat units are placed on the two opposite sides of the valve ball be-

calculated for fluid-sealing cooperation with the valve ball. Each of these seat units includes a reinforcing ring with a central opening and abutting against an inner end wall in the respective extended bore. A seating ring rests against the reinforcement ring and is designed so that it can be deflected elastically in the main towards and from the reinforcement ring. The seating ring has a central opening and a surface intended for installation cooperation with the valve ball. A secondary seating is inserted between the flexible seating and the respective shoulder. This secondary seating includes a disc spring having a central opening and a substantially frustoconical shape in the untensioned state. At least one ring-shaped disk of expanded carbonaceous material is placed on a number-known spring surface. The valve ball and the aforementioned pair of composite seat units are so dimensioned and adapted that in the event of damage to the seat ring as a result of the valve out-

set to high temperatures, the secondary seats will not be pressed into sealing engagement with the valve ball.

In a preferred embodiment of the invention, the secondary seat ring includes a disk spring in combination with a disk of expanded carbonaceous material. The plate spring has a mainly muteconic shape in its untensioned state. The ring of expanded carbonaceous material extends essentially radially to the same extent as the disc spring and is inserted at least between the spring and the primary seating made of soft plastic material. The disk spring acts to constantly press the carbon ring and the soft seater against the valve ball. When the primary seat is damaged in a fire, the carbonaceous material will come into contact with the valve ball and seal against it.

In yet another preferred embodiment of the invention, the secondary seat ring includes a pair of annular discs of expanded carbonaceous material. These washers are located on either side of the disc spring and essentially extend radially to the same extent as this. A first ring disc faces the valve ball and is only intended to cooperate with this in the event of damage to the primary soft seating. The second ring disc faces the respective shoulder for sealing cooperation with this in the event of damage to the primary seating.

Advantageously, a wear ring can be included in the primary seating and be placed in the main body between the primary seating and the secondary seating element.

The valve ball can advantageously have a second opening at right angles

on the main opening or barrel of the valve ball. This second opening faces the valve inlet when the valve ball is in the closed position.

ing and enables communication between the central area of the valve and the inlet.

The invention shall be described in more detail with reference to the drawings, where: Fig. 1 shows a longitudinal section through a ball valve according to the invention,

fig. 2 shows an enlarged section of part of the seat design

in the valve in fig. 1, and shows the seat design on the downstream side just before the valve components are assembled together,

as the valve ball is omitted to facilitate the overview,

fig. 3 shows an enlarged section of the same part as in fig. 2,

and shows the valve in a closed position and under influence

of an increased fluid system pressure,

fig. 4 shows a section as in fig. 3, but after the valve has been exposed to a fire and is so hot that the seat made of soft plastic has started to flow outwards,

through the valve stem,

fig. 5 shows a section as in fig. 4, in a condition where the valve ball has made contact with the secondary seat,

fig. 6 shows a section as in fig. 4 and 5, where the seat made of soft plastic is completely destroyed,

fig. 7 shows a diagram of the valve along line 7-7 in fig. 1,

with part of the valve body cut through,

fig. 8 shows an enlarged section of a seat design according to an alternative embodiment,

fig. 9 shows a section of yet another alternative embodiment, fig. 10 shows yet another alternative embodiment, and fig. 11 shows yet another alternative embodiment according to the invention,

fig. 12 shows a perspective view of the seat design in fig. 10

after a partial destruction as a result of fire, ie

the seat design is removed from the valve housing, and

fig. 13 shows a perspective view of the seat design in fig. 1,

after a partial destruction as a result of a fire, as the seat cover has also been removed from the valve housing, so that the damage can be seen more easily.

As mentioned, Fig. 1 shows a ball valve A where valve seat units B are arranged on each side of a floating valve ball C.

The ball valve has a valve housing 10 with a central part 12 and

two end parts 14, 16. The seat units B and the valve ball C are mounted inside the main part 12 and the valve ball is arranged so that it can be turned by means of a spindle with an operating handle. This turning device is denoted in its entirety by 18. The valve ball C has a first or main flow opening 15 which forms part of the valve path in the valve's open position. The valve ball C also has a second opening 17 which runs at right angles to the passage 15 and faces the valve inlet when the valve is in a closed position. Thereby, the fluid and fluid pressure inside the valve's central part connect with the fluid in the valve inlet. In the main case, all details of the one in fig. The valve shown in 1, with the exception of the seat ring units, is modified as needed for adaptation to different types or designs of ball valves.

In the embodiment shown, an essentially cylindrical opening 20 is arranged in the valve housing, the diameter of which is slightly larger than the diameter of the valve ball. Each of the end parts 14, 16 is releasably attached to the central part 12 by means of several bolts 22. These bolts pass through bores 24 in the end parts 14 and 16 and are screwed into threaded bores in the main part 12

(Fig. 7). It has been found advantageous to use several such bolts 22 which are screwed into the main part 12, because the problems which can arise with long joining bolts are thereby avoided. During a fire, the metal components of the valve will heat up and expand. When you possibly spray water on such a heated valve, the circumference of the valve and also the connecting bolts will cool and will contract faster than the rest of the valve housing. Such rapid cooling and contraction can result in the bolts 22 stretching or breaking. If you use several shorter bolts as shown, you reduce these problems. The end parts 14, 16 are provided with threaded runs 26, 28 or

other suitable means, for connecting the valve to a fluid system or a wiring network.

The turning device 18 includes a spindle 30 whose lower

end 32 is slidably engaged in a groove 34 in the upper end of the ball C. This arrangement enables the ball to rotate between open and closed positions while the ball has some freedom to move axially in the valve body when the valve is in a closed position and the ball is affected by the fluid pressure.

The spindle 30 extends through an opening 36 therein

central valve housing part 12. Sealing rings 38, 40, 42 which are intended for high temperatures, are placed in the opening 36 and seal the spindle passage no. A lower sealing ring 42

rests against an inwardly projecting flange 44 in the opening 36.

A pressure washer 46, which can also withstand high temperatures, is placed under the flange 44 and clamped against it by a projecting shoulder or flange 48 on the lower part of the spindle 30. The spindle is held in place by a packing eyelet 50 and a packing nut 52. As shown in fig. 1, the nut 52 will exert a compression force on the sealing ring 38, 40, 42 so that these expand radially and provide a fluid seal around the spindle.

Although it is possible to influence the valve spindle with many types of activators, including manual, mechanical or automatic ones, in the design example a simple handle 54 is shown. This handle is releasably attached to the spindle 30 by means of a nut 56 which clamps the handle against the top of the packing nut 52. A flattened part 58 is advantageously designed on the spindle which cooperates with a flattened part not shown in the opening in the handle, so that proper positioning of the handle on the spindle is thereby ensured. The swinging movement of the handle and thus also the swinging movement of the valve ball is limited by stops 62, 64 on the handle 54. These stops will engage suitable surfaces on the middle housing part 12 which form fixed stops for open and closed valve positions respectively.

As mentioned, a pair of seating ring units B are arranged on opposite sides of the valve ball C. These seating ring units are held firmly in place on each side of the valve ball at each end of the opening 20 through the valve housing part 12.

These seat ring units are placed essentially equidistant from and up diametrically opposite sides of the valve ball's axis of rotation, and the valve seats include central openings 66, 68. These seat ring units can be held in place by many possible means, but here they are shown locally -sert by means of shoulders 70, 72 which are formed in the end surfaces 74, 76 of the end parts. The inward movement is limited by a pair of shoulders or steps 78, 80 formed at the inner end walls of the respective extended bores at each end of the opening 20.

Between the central housing part 12 and the end parts 14, 16, there are arranged sealing rings 82, 84, placed in extended bores or counterbores 86, 88. Each such sealing ring is placed around the outer circumference of part of the associated seating unit B. The sealing rings 82, 84 is preferably made of a deformable, yielding, heat-resistant and thermally stable material, for example expanded carbonaceous material and wire mesh in order to thereby avoid problems in connection with sublimation and charring which can occur when e.g. a normal thermoplastic O-ring is exposed to fire or other high temperatures. In the preferred embodiment, Grafoil (trademark) is advantageously used as a deformable and heat-resistant material. However, it will be understood that other materials, for example asbestos or ceramic composite materials, will be able to be used. When the housing part 12 and the end parts 14, 16 expand and contract during heating and cooling during and after a fire, the sealing rings 82, 84 will always provide a satisfactory seal between the central housing part and the housing end parts.

The seat units B will now be explained in more detail with special reference to fig. 2-6 and 13. Fig. 2 shows a seat unit on the downstream side, at the housing end part 14, during the assembly of the valve components. Fig. 3 shows the seat unit in fig. 2

when the valve is fully assembled and the valve is closed and is subjected to an increased fluid system pressure. Fig. 4, 5 and 6 show the seat unit B in successive stages when exposed to fire. Fig.

4 shows a primary setter made of soft plastic material which has begun to flow and is being pushed out through the valve barrel. Fig. 5 shows the valve after the valve ball has made contact with the secondary seat. Fig. 6 shows the valve after the primary seat is completely destroyed and squeezed out or vaporized. Fig. 13 shows the seat unit B after a partial destruction, for example when the valve has been exposed to a fire or a radiant heat effect only on one side. Line 3-3,

4-4, 5-5 and 6-6 in fig. 13 corresponds to the cross sections shown in fig. 3, 4, 5 and 6.

As shown in fig. 2 and 3, each seat unit B consists of three components, namely a reinforcement or carrier 100, a primary seat ring 102 in the form of a ring element made of soft plastic material, and a secondary seat ring 104 in the form of a deformable, non-heat-flowing seat element. Although only part of the seat unit is shown in these figures, it should be clear that the other seat unit is identical, unless otherwise specifically highlighted, Reinforcement ring 100 is annular, with a central opening and is made of a rigid material, for example steel or another suitable metal. A first end surface 106 of the ring 100 faces the shoulder surface 100 of the end part 14. A second end surface 108 faces and rests against the end wall or step 78 in the barrel 20 of the main housing part, whereby the reinforcement ring 100 is fixed in the housing. A third annular surface 110 mainly faces the valve ball, but is dimensioned such that it has a distance therefrom, so that it does not abut against or interfere with the valve ball and prevents a deformation and displacement of the primary seating ring 102 between the third annular surface 110 and the valve ball. The outer ring surface 112 of the ring 100 rests against the wall in the race 20. This outer surface 112

and the other end surface 108 may optionally have a flange or a step and be dimensioned to abut against the shoulder 78, the ring 100 then being able to extend axially inside the race 20, should the valve design require it. However, such an additional flange is not included in the embodiment shown, because such a flange would require additional machining.

The seat ring 102 has a central opening 118. This opening

is smaller than the central opening in the reinforcement ring 100. The primary seat ring 102 can be deflected mainly towards and from the reinforcement ring 100. The seat ring 102 is designed so that it exerts a spring-like mechanical elasticity against the valve ball.

A first surface 120 faces the shoulder surface 70. A second surface 122 on the seat ring 102 faces the ring 100 and rests against the end surface 106 of the reinforcement ring 100. A third surface 124 on the seat ring 102 faces the valve ball C and is intended for fluid-sealing cooperation with this. A flange or a lip 126 extends axially from the first surface 120 of the seat ring 102 at the circumferential surface 128 of the ring. The lip 126 is preferably made continuous around the seat ring 102 and is positioned so that its radially inner surface essentially corresponds to the outer diameter of the secondary seats none 104. The lip 126 is chamfered at the outermost and is rolled slightly over the outer edge of secondary seats no 104, as shown in the drawing. Although it is not necessary, such an embodiment will advantageously result in the primary seating and the secondary seating being held together as a unit. Preferably, the seat ring 102 is made of a soft flexible plastic material, for example Teflon or polyethylene. Naturally, many other materials can be used here, for example acetal resins and the like, and even soft metals and ceramic composite materials can be used. Which material is chosen will to some extent depend on the normal operating conditions to which the valve is exposed.

In primary seats no 102 a blocking ing 130 is included. This ring

is engaged in an undercut groove 132 in the seating ring 102 and is isolated from the valve stem. The ring 13 can, however, be completely embedded in the seat ring 102 or be arranged outside the seat ring, for example in the form of an axially sealed lip on the secondary seat ring 104, in the direction towards the valve ball, at the inner diameter of the primary seat ring 102. Preferably, however, the ring 130 is arranged radially within the seat the annular body 102 and between secondary seats none 104 and the valve ball. In this preferred location, the locking ring 130 will be isolated and will not be exposed to the same stresses with regard to wear and damage as the primary seating ring 102 will be in normal operation. The barrier ring is of a thermally stable, non-heat-fluid material, preferably a Grafoil wire mesh composite material, in a similar manner to the sealing rings 82, 84, but it may optionally be entirely of Grafoil, wire mesh or of a ceramic or even metallic material.

The ring 104 is constructed with a central frustoconical plate spring 134 which lies between a first ring disc 136, which faces the shoulder 70, and a second ring disc 138, which faces the primary seating ring 102. These ring discs 136, 138 are preferred by Grafoil and have a radial extent which essentially corresponds to the radial extent of the disc spring 134, but it is within the scope of the invention that the rings 136, 138 possibly only extend over a part of the disc spring, for example so that the first ring disc 136 only extends over a part of the disc spring 134 near the outer diameter of the spring, while the second ring disc 138 extends over the part which is located near the inner diameter of the spring.

Such an embodiment can be particularly economical and advantageous

in larger ball valves.

It has also been found advantageous to leave the surface 74 of the shoulder 70 roughened or serrated, so that it makes better contact with the ring disc 136. When the valve is exposed to a fire, this improved contact will prevent the ring disc and disc spring from sliding, floating or pinching out . At high temperatures, the material Grafoil can become slightly fluid. The roughened or serrated surface will prevent such floating and help to maintain the sealing effect.

The outer diameter of the secondary seating ring 104 is such that the ring can be accommodated in the cylindrical cavity which is limited by the inner wall of the flange 126 and the surface 120 of the seating ring 102.

The inner diameter of the secondary ring is slightly larger than the diameter of the central opening 118 in the seating ring 102, thereby achieving that the secondary seats are not completely isolated from contact with the valve ball during normal valve operation, so that the ring is thus not exposed to wear and damage.

The disc spring 134 is selected so that its force will be sufficient, when the spring is partially compressed, to continuously press the seat ring 102 against the valve ball. The spring must be able to be compressed to a flattened state, to enable the valve ball's displacement movement and abutment against the third surface 124 of the seat ring 102 under normal operating conditions. From fig. 3, it appears that a good fluid seal is achieved, with the primary seat ring 102 held between the valve ball C, the reinforcement ring 100, the valve body main part 12 and the end body part shoulder 70. Under normal operating conditions, the secondary seat ring 104 will primarily act to press and hold the primary seat ring 102, and will not have some sealing function in itself.

When the valve components are handled together, as shown in fig.

1, 2 and 3, each of the primary seating rings 102 is deflected slightly in the direction of the other, with an axis of deflection approximately at the outer circumference, the primary seating none being pressed against the secondary seating ring 104 as a result of its interaction with the valve ball. Thereby, the associated plate spring 134 is slightly compressed. In addition to the spring contributing to the positioning of the valve ball, the spring deflection will also provide a sealing force between the two seating rings and the valve ball at the sealing ring surface 124, regardless of how low the system pressure may be. The secondary opening 17 in the valve ball faces the inlet when the valve is closed, thereby ensuring that the seat ring on the inlet side does not clog. Fluid that may be located centrally in the valve can freely expand by heating or evaporation and be relieved through the opening 17, without risk of pressure increase inside the valve.

With particular reference to fig. 4. 5. 6. 12 and 13 will now explain the operation of the above-described embodiment in more detail in connection with an assumed destruction of the primary seat in the event of a fire.

Fig. 4 shows how the seat ring 102 has been heated so that it flows or is pushed out through the opening 66 in the secondary seat ring 4 under the influence of the fluid pressure forces in the valve. When the seating ring 102 softens, the disk spring 134 will bend and maintain the seal against the valve ball C and against the end surface 74.

In fig. 5, the valve ball is displaced axially downstream in the valve and has pressed the secondary seat no 104 together, and now rests against the locking ring 130. The ring disc 138 is clamped between the plate spring 134 and the seat ring 102 and is in contact with the valve ball and closes to it. Because the ring disc 138 is preferably made of a heat-resistant, deformable material, such as Grafoil, the ring disc will adapt to the valve ball surface, thereby avoiding the problems known from earlier fireproof ball valves where metal-metal secondary seals are used. At the same time, the ring disc 136 rests against the shoulder 70 at its outer part and seals against it. The ring washer 136's deformation properties enable it to adapt to irregularities in the surface 74 and in the outermost region of the disc spring 134.

Secondary seats no 104 can optionally be made without the rings 136, 138, because it has been found that the disk spring 134, as a result of its circumferential elasticity, will form a suitable metal-metal seal against the valve ball C, without the problems that arise in connection with valve balls that are not perfectly spherical or not patched together- with secondary seats none.

The disk spring 134 has a circumferential elasticity as well as an axial elasticity, and by softening the seating ring 102, the secondary seats will not deflect and maintain the fluid seal between the valve ball and the surface 74. By circumferential elasticity is meant here the ability of the secondary seats to deflect axially more in one segment than in another.

Because the valve ball C is not here exactly spherical and because the central opening 66 in the disk spring 134 is not perfectly round, the ball and the spring will only have contact with each other in a few prominent places. The circumferential elasticity of the plate spring 134, however, enables a deflection at these prominent places, so that the ball will be able to make essentially continuous contact with the radially inner edge of the plate spring. Similarly, the outermost edge of the disc spring 134 will only contact the surface 74 in a few places. Here too, the circumferential elasticity of the disc spring will make it possible for the spring to be deflected to varying degrees around the circumference, so that an essentially continuous linear contact can be provided between the disc spring and the surface 74. The circumferential elasticity of the disc spring 134 will thus compensate for inaccuracies with regard to roundness at the inner and outer edges of the disc spring, inaccuracies with regard to the spherical shape of the valve ball C, and deviations from the completely flat surface 74.

The locking ring 130 acts as a locking device that prevents the soft plastic material in the seat ring 102 from being too forcefully squeezed out between the valve ball C and the secondary seat ring 104. Generally, a fire will not always heat the surface of a fireproof valve evenly, especially when the fire is a jet fire close to the valve and the heating of the valve therefore mainly takes place on the nearest side of the valve. In the event of a fire, one can therefore usually assume that the seat ring 102 will soften only in a first section along the circumference before the other areas soften. Without the barrier 130, the material in this first softened part could be pressed too strongly into the valve stem under the influence of the system pressure, so that the valve ball would then be able to move radially or laterally, i.e. perpendicular to the valve stem. When the valve ball moves downstream and presses through the soft plastic to contact the secondary seat ring 104, the valve ball will in that case be able to shift too much to one side and make uneven contact with the secondary seat ring 104. Large openings and leakage paths where melted plastic can then form and system fluid can be blown through. It has been possible to observe that such leakage paths and gaps occur in places which mainly have an angular distance of 90° from the direction vector of the radial displacement. At a point with an angular distance of 180° from the vector to the radial displacement, a fluid seal is maintained as a result of there being contact with the rest of the seat ring 102. System fluid that flows quickly through can then cool down the plastic seat ring 102 and prevent further melting of this . A larger leak can thereby form which does not change no matter how strongly the fire continues to act on the valve.

How a partial seat destruction takes place is shown in fig. 12. There is a seat design without a locking ring. The seat design has been exposed to a fire which has caused only a portion 141 to be pressed into the valve barrel. As a result, a larger leakage path 143 has occurred, because the valve ball has not been able to make contact with the secondary seat ring 104. The valve ball is prevented by the remaining parts of the seat ring 102 from moving radially or axially into the extruded area. The effect that the leakage fluid exerts on the seat ring is of such a nature that the seat ring is prevented from being destroyed or pushed out further, despite a continued intensive fire effect.

If a locking ring 130 is used, see fig. 5, then this will prevent the softened and melting plastic material from flowing regardless of where the plastic material first softens along the circumference of the seat ring. The locking ring 130 is placed in the seat ring 102 in such a way that only a narrow annular portion 144 can be pressed into the valve barrel. The main part 146 of the seating ring 102 is prevented from flowing past the blocking ring 130. The relatively small part 144 that will be able to be pushed out is of minor importance and with such pushing out the associated displacement area into which the valve ball can move will be insufficient to form of a lacquer strip. It is preferred that the locking ring 130 is placed in the seating ring 102 in such a way that the valve ball will make contact with the locking ring 130 at the same time as it makes contact with the secondary seating ring 104. The locking ring 130 can thus further contribute to the achievement of an effective secondary seal in the event of a destruction of the primary seating ring 102.

In fig. 6, the primary seat ring 102 is completely destroyed and a substantial part 146 (Fig. 5) of the soft piast seat ring has sublimated or evaporated out through the valve barrel. Between the valve ball C and secondary seats no 104 there is now a seal because the valve ball has contact with the ring disc 138, as well as deforming in accordance with the surface of the valve ball. The first ring disc 136 rests against the wall 74 and seals between the ring 104 and this wall. In addition, it is advantageous if the blocking ring 130 is dimensioned so that it can cooperate with the valve ball after the primary seating has been destroyed and the valve ball has shifted in the downstream direction. Such contact cooperation will provide the desired fluid seal.

From fig. 13 it appears that along the line 6-6 the valve ball has come into contact with the blocking ring 130 after the primary seat has been destroyed, and it has also come into contact with the secondary seat to maintain a fluid seal (fig. 6). Along the line 5-5, the squeeze-out of the essential part of the primary seat is blocked by the blocking ring 130, so that a formation of a leakage path is prevented as in fig. 12.

Fig. 8 shows an alternative embodiment. The same reference number is used here, with the addition of an apostrophe. New components are given new reference numbers. The secondary seating ring 104 is designed with a uniform ring disc 150 of a heat-resistant, deformable material, for example Grafoil or a composite material consisting of Grafoil

and wire mesh. When the primary seat no 102' is damaged in a fire, the valve ball C' can shift axially under the influence of the fluid pressure and move towards the radially innermost part of the secondary seat no 104', for sealing together with this. The wall 74' is preferably roughened or serrated and rests against

the end surface 152 of the secondary seat none and in fluid seal between the secondary seat ring and the shoulder 70'. Secondary seats no 104' can thereby adapt to the cooperating assault on the valve ball C and the wall 74'.

Another embodiment is shown in fig. 9. Secondary seat no 104" is designed with a disc spring 134" and an annular disc 156 of a heat-resistant, deformable material, for example Grafoil or a composite material of Grafoil and wire mesh. When the primary seat ring 102" is destroyed by a fire, the valve ball in its closed position and under the influence of the system pressure will move towards the secondary seat ring 104" and will deform the ring disc 156 so that a seal is formed. As the fire progresses, the disc spring 134" will be annealed. The softened disc spring, which is deformed by the valve ball, will thereby adapt more easily to the surface 74" and a better metal-metal seal behind the spring is thereby achieved. Yet another embodiment of the invention is one where a single ring disc is used on the plate spring surface facing the shoulder surface. A similar design will provide a metal-metal shoulder seal against the ball, while the washer faces the shoulder surface and seals against it. It is preferred to use a roughened or serrated surface for contact with the ring disc.

Fig. 10 shows an embodiment with a reinforcement ring 100''',

a primary seater 102'<11>, a secondary seater 104''', including a disc spring 134a first washer 136'''

and a second ring disc 138'<11>. The ring discs 136'', 138''

is made of Grafoil or another heat-resistant, deformable material. A blocking is not used here. When the seat ring 102'<11> is destroyed by a fire, the valve ball will shift axially and seal against the ring disc 138'<1>'. Ring disc 136''

will go against the roughened end wall 74'<11> to maintain the seal.

Fig. 11 shows another embodiment. The secondary seat element

104"" here consists of a simple plate spring, but a single heat-flowable deformable disk of, for example, Grafoil or a combination of wire mesh and Grafoil, or a combination of a plate spring and an annular disk of Grafoil, can also be used, in the same way as in fig. 9 (the secondary seat element 104"). A blocking ring 130"", preferably of Grafoil and wire mesh, is included in the primary seat 102"" for contact with the valve ball in the event of partial or total destruction of the primary seat, and for blocking the extrusion of a significant portion 146"" of seat ring 102"".

Claims (35)

1. Ball valve with a housing (10) with a central barrel (20), a valve ball (C) with a continuous fluid passage (15) and located in the valve body's central passage (20) and mounted for rotary movement between the open and closed position to control the flow of fluid through the valve, a pair of radially inwardly projecting shoulders (70, 72) in the central barrel (20), on opposite sides of the valve ball, and a pair of seat units (B) arranged axially between the shoulders (70, 72) and the valve ball (C), characterized in that each of the aforementioned seat units (B) includes an elastic seat ring (102) ) stored in the central barrel (20) for fluid-sealing cooperation with the valve ball (C), and a deformable, heat-resistant secondary seat ring element (138, 150) placed between the elastic seat ring (102) and the respective shoulder (70 or 72), as the secondary seat ring element (138, 150) is mainly isolated from normal operating contact with the valve ball (C) and the system fluid, but in case of damage to the elastic seat ring (102) at high temperatures can be brought into cooperation with the valve ball (C) to thereby seal the valve. 2. Ball valve according to claim 1, characterized in that the secondary seat ring element (138, 150) is made of expanded carbonaceous material. 3. Ball valve according to claim 1 or 2, characterized in that the seat unit (B) further includes a disc spring (13a) placed between the secondary seat ring (138, 150) and the respective shoulder (70 or 72) for pressing the elastic seat ring (102 ) and the secondary seat ring member (138, 150) to cooperate with the valve ball (C). 4. Ball valve according to claim 3, characterized in that the disk spring (13a) and the secondary seat ring element (138. 150) in the main case extends radially to the same extent. 5. Fireproof ball valve including a housing (10) with a central barrel (20), a valve ball (C) with a fluid passage (15) and located in the central barrel (20) and mounted for rotary movement between open and closed positions for control of the fluid flow through the valve, and a pair of seat units (B) placed axially in the central barrel (20) on opposite sides of the valve ball (C) for fluid-sealing cooperation with the valve ball, each seat unit (B) being placed between a respective radially inwardly projecting annular shoulder (70 or 72) in the central passage (20) and an inner wall (78 or 80) in a respective extended bore portion in the central passage, characterized in that each of the seat units (B) is a composite seat unit which includes a reinforcement ring ( 100) with a central opening and bearing against the respective inner end wall (78 or 80) in the extended bore part, a seat ring (102) which abuts against the reinforcement ring (100) and is designed for elastic deflection mainly against and from the reinforcement ring, which seat ring has a central opening and a surface (124) facing the valve ball (C) for sealing engagement with the valve ball, and a secondary seat ring (104) located between the flexible seat ring (102) and the respective shoulder (70 or 72 ). (134), in which the valve ball (C) and the aforementioned pair of seat units (B) are dimensioned in such a way that in the event of damage to the seat ring (102) as a result of the valve being exposed to high temperatures, the secondary seat ring (104) will be pressed into sealing engagement with the valve ball (C ). 6. Ball valve according to claim 5, characterized in that the valve ball (C) and the aforementioned pair of seat units (B) are dimensioned so that in the assembled state the flexible seat ring (102) and the secondary seat ring (104) in each unit (B) will be deflected and tensioned to press the flexible seating (102) into contact with the valve ball (C). 7. Ball valve according to claim 5 or 6, characterized by first and second rings (136, 138) arranged on opposite surfaces of the disc spring (134). 8. Ball valve according to claim 7, characterized in that the rings (136, 138) both extend radially to the same extent as the plate spring (134). 9. Ball valve according to claim 7 or 8, characterized in that an annular disc (136) of expanded carbonaceous material is placed at a respective shoulder (70 or 72), while the other ring disc (138) is placed against the flexible seating (102). 10. Ball valve according to claim 9, characterized in that if the flexible seat ring (102) is damaged by being exposed to high temperatures, the second ring disc (138) will come into contact with the valve ball (C) for sealing cooperation with it. 11. Ball valve according to claim 9 or 10, characterized in that the aforementioned one ring disc (136) makes contact with the respective shoulder (70 or 72) for fluid sealing cooperation. 12. Ball valve according to one of claims 5-11, characterized in that the ring disc (136 or 138) of expanded carbonaceous material is placed in at least one of the seat units (B) and is mainly isolated from the central opening in the associated flexible seating (102) thereby preventing the ring disc from being exposed to the normal operating wear and tear in the valve. 13. Ball valve according to claim 12, characterized in that the ring disc (138) of expanded carbonaceous material is placed between the flexible seat ring (102) and the plate spring (134). 14. Ball valve according to claim 12, characterized in that the ring disc (136) of expanded carbonaceous material is placed between the plate spring (134) and the respective shoulder (70 or 72). 15. Ball valve according to one of the preceding claims, characterized in that the radially inwardly projecting shoulders (70, 72) has roughened or serrated surfaces (74, 76) for cooperation with secondary seats none or the element (104 or 150). 16. A ball valve according to one of the preceding claims, characterized in that the valve's main housing part (12) contains several fastening means (22) for holding housing parts (14, 16) where the aforementioned shoulders (70, 72) are designed. 17. Ball valve according to one of the preceding claims, characterized in that the valve ball (C) includes a device for relieving pressure increases in the valve housing due to fluid heating and evaporation when the valve is exposed to high temperatures. 18. Ball valve according to claim 17, characterized in that the relief device includes a relief opening (17) arranged at right angles to the fluid passage (15) in the valve ball, which relief opening faces a fluid inlet opening (26) in the valve when the valve is closed. 19. Ball valve according to one of the preceding claims, characterized by a locking ring (130) in at least one of the aforementioned pair of seat units (B) to thereby prevent the flexible seat ring (102) from being squeezed out when the valve is exposed to high temperatures. 20. Ball valve according to claim 19, characterized in that the blocking ring (130) is placed in the seat unit (B) mainly isolated from the central opening in the associated flexible seating ring (102), thereby preventing the blocking from being exposed to the normal operational wear and tear and the like in the valve. 21. Ball valve according to claim 20, characterized in that the locking ring (130) is embedded in the flexible seating ring (102). 22. Ball valve including a valve housing (10) with a mainly cylindrical passage (20), a valve ball (C) arranged in the passage (20) and mounted for turning movement between open and closed position, the valve ball being able to be displaced mainly axially in the passage under influence of the fluid pressure, at least when the valve is closed, and with a pair of seat rings (102) arranged in the passage (20) on opposite sides of the valve ball (C) between the valve ball and a pair of shoulders (70, 72) in the valve housing (10), characterized by a blocking ring (130) which is associated with at least one of the aforementioned seat rings (102) and is designed to prevent the seat ring (102) from being squeezed out when the valve is exposed to high temperatures. 23. Ball valve according to claim 22, characterized in that the locking ring (130) is mainly arranged within the radial extent of the seating ring (102). 24. Ball valve according to claim 23, characterized in that the locking ring (130) is engaged in an annular groove (132) in the seating ring (102). 25. Ball valve according to claim 24, characterized in that the annular groove (132) is arranged in the seat ring (102) in such a way that it is isolated from the passage, so that the locking ring (130) is thereby not exposed to the usual operating wear and the like in the valve. 26. Ball valve according to claim 23, 24 or 25, characterized in that the blocking ring (130) is embedded in the seating ring (102). 27. Ball valve according to one of the claims 22-26, characterized in that a pair of disk springs (134) are inserted between each seating ring (102) and the respective shoulder (70 or 72) to continuously press the seating ring (102) into sealing cooperation with the valve ball (C), and in that the disc spring (134) includes an annular disc (136 or 138) of a heat-resistant material. 28. Ball valve according to claim 27, characterized in that the locking ring (130) is mainly inserted between the seating ring (102) and the respective plate spring (134). 29. Ball valve according to claim 27 or 28, characterized in that the heat-resistant material includes expanded carbonaceous material. 30. Ball valve according to claim 27, 28 or 29, characterized in that the said annular discs (136, 138) are arranged on each of the opposing surfaces of the disk spring (134) and are in the form of a first annular disc that extends over part of a first surface of the disc spring near its outer diameter on the side facing the respective shoulder £70 or 72) and a second washer extending over a portion of a second surface of the disc spring near its inner diameter, on the side facing the valve ball ( C). 31. Ball valve according to claim 22, characterized in that a pair of disc springs is inserted between each seat ring (102) and the respective shoulder (70 or 72) to continuously press the seat rings into sealing cooperation with the valve ball (C), and in that the blocking ring includes a axially directed lip of one of the disc springs and extends towards the valve ball at the inner diameter of the respective seating (102). 32. Ball valve according to one of the claims 22-31, characterized in that the locking ring (130) is dimensioned for contact with the valve ball (C) in the event of destruction of the respective seating (102). 33. Ball valve according to claim 32, characterized in that the locking ring (130) is dimensioned for contact with the respective shoulder (70 or 72) in the event of destruction of the seating ring (102) at higher temperatures, for the formation of a fluid seal between the valve ball and the respective shoulder ( 70 or 72). 34. Ball valve including a valve housing (10) with a central passage (20), a valve ball (C) with a fluid passage (15) and placed in the central passage (20) and mounted for rotary movement between open and closed positions for control of the fluid flow through the valve, and a flexible seat ring (102) stored in the passage (20) for fluid sealing cooperation with the valve ball (C), characterized in that a deformable, heat-resistant secondary seat element (130) is embedded in the primary seat ring (102) for isolation of the secondary seat element (130) with regard to normal operating contact with the valve ball (C) and the system fluid, and so that in the event of damage to the flexible seat (102) at high temperatures, the secondary seat element (130) will cooperate with the valve ball (C) to seal the valve. 35. Ball valve according to claim 34, characterized in that the secondary seat element (130) is arranged within the radial extent of the seat ring (102) and is dimensioned to prevent the flexible seat ring from being squeezed out through the central passage (20) when the valve is exposed to high temperatures.