The invention relates to a valve unit including a flange housing and at least 2 valves placed in the flange housing, which valves include at least a first valve and a second valve, which first and second valves each have a spindle, which first valve is designed to shut off a flow through the valve unit when the spindle of the first valve is placed in a first position, and is designed to release a flow when the spindle of the first valve is placed in a second position, which second valve is designed to blow off a pressure when the spindle of the second valve is placed in a third position, which valves each have a spindle placed in a valve housing, which valve housing has a first end, in which area for the first end the spindle is operated to close and open the valve concerned, and an opposing lower part where each lower part belonging to a valve faces an outer surface of the flange housing into which the valves are built, which lower parts each have a first surface with at least one part of the surface essentially plane-parallel with the outer surface.

Valves of the SDBB type (Slimline Double Block & Bleed Valve) are used extensively for sealing measuring instruments in offshore installations, where they enable the measuring instrument to be replaced without the pressure being removed from the sealed system. The SDBB valve preferably consists of 3 needle valves integrated in a flange according to the standard ASME B16.5, arranged as 2 shutoff valves in series with an intermediate valve for blowing off the pressure. The demands on the components are very high and include demands relating to pressure, temperature, materials, dimensions and tolerances for flange fitting between valves/pipes and the flange itself.

In the current designs of SDBB valves with flanged-on needle valves, the seal against external influences consists of only one metal corner seal between the flange of the needle valve and the ASME flange body. However, it has been shown in practice that salt deposits from infiltrating seawater in the space of a relatively short time are capable of harming the function of the valve, unless expensive, difficultly machinable materials with a particularly high corrosion resistance are used.

From US471 1268 a valve unit is known as indicated in the introduction. However, the seals between the flange housing and the valve housings are also inadequate here, presenting a risk of infiltration of corrosive fluids. It is therefore the objective of the present invention to produce a valve unit which does not suffer from the aforementioned drawbacks or which provides at least a useful alternative to the state of the art.

This is achieved with a valve of the type indicated in the introduction, and where a first seal is arranged between the first surface of each lower part and the outer surface of the flange housing, and where, laterally to the first seal, there is a second seal having an annular sealing edge/contact edge on its upper free surface, which first seal is produced in a polymer material, and which second seal is a metal seal.

The present design therefore overcomes the problem of the infiltration of corrosive fluids by using at least one 2-stage seal (a 3-stage seal is preferably used), consisting of a first seal inside in the form of an O-ring between the flange of the valve housing and the flange of the flange housing, and outside the O-ring a metal-to-metal seal designed as a projecting sharp edge, preferably arranged on the surface of the valve housing facing the outer surface of the flange housing. The metal seal is an integral part of the surface of the valve housing and not a separate unit. The surface of the flange housing against which it is pressed is a flat surface. This area is particularly sensitive to fluid infiltration and the established sealing, which is provided here both by a metal seal and by a polymer seal, has proved effective in resisting the infiltration of fluids such as saline mists. The polymer seal is characterised in that it is resistant to chemical attacks, is relatively elastic and retains its sealing qualities even at very low temperatures. This ensures that the valve unit repels the infiltration of corrosive fluids to the inside of the unit where the spindle is located. Corrosion of the inner parts and of joint areas is therefore avoided. A further seal is advantageously arranged laterally to the metal seal, which is an elastic, annular, thin flat gasket which encloses the metal seal.

Moreover, all the threads are protected from the infiltration of seawater and include the following seals: the spindle thread with a scraper seal against the outermost part of the spindle. The screwed-in valve top comprises a polymer cap and the structure also has a seal under a lock nut. There are also gaskets between the screws securing the valve flange. The gaskets are arranged between the screw heads and the individual valve housings. Since temperatures down to -101 °C (-150°F) have been observed in some cases on the SDBB valves, the polymer seals are produced in a material that is able to resist these temperatures yet permanently retain the material properties to a certain degree. These materials include flour plastic (PTFE or PCTFE).

In the salt mist test, the structure has proved superior to prior art SDBB valves of other makes.

The first sealing package prevents fluid/the medium from escaping from the valve housing, whilst the second seal prevents salt mist from infiltrating the thread of the spindle.

It is noted that the second position for valve 1 and the third position for valve 2 are the same in principle since these are positions in which the spindles of the respective valves are in a position where flow is possible through the valve. In a further advantageous embodiment according to Claim 2, the metal seal is an integral part of the valve unit, and the annular sealing edge/contact edge has an annular, acute angled elevation in the area of contact between the lower part and the outer surface of the flange, and departing from one of them, which annular elevation gives rise to a metal seal between the lower part and the outer surface.

The annular elevation is preferably arranged on the surface of the lower part so that the contact surface between the lowest surface and the surface of the flange is formed when the top point of the annular elevation is pressed against the outer surface of the flange and deformed to produce a seal which is able to resist fluid infiltration when interacting with the remaining sealing arrangements. The annular elevation is an integral part of the surface of the lower part. The outer surface of the flange is flat.

In a further advantageous embodiment according to Claim 3, the annular sealing edge/contact edge is produced by an annular sharp sealing edge arranged on a top point line on the sealing edge/contact edge, and the metal second seal departs from the surface of the lower part facing the outer surface.

This is an advantageous design.

In a further advantageous embodiment according to Claim 4, the lowest part has an annular recess placed in the first surface, which faces the outer surface of the flange, in which recess the first seal is arranged.

This ensures that the gasket, when exposed to the joint pressure, floats and seals in an advantageous, regulated manner so that the seal is tight. In a further advantageous embodiment according to Claim 5, the valve unit includes a third seal arranged laterally to the second seal, which third seal is produced in a polymer material and which third seal is placed between the outer surface of the flange facing the lower part and the first surface of the lower part facing the flange housing, where the third seal encloses the second seal.

This ensures increased protection against the infiltration of fluid, including salt mist. The gasket is a flat gasket and includes an annular flat part on the inside and a flat network of polymer packing material on the outside.

In a further advantageous embodiment according to Claim 6, the valve unit has a thread, including threaded joints, which threaded joints have polymer seals.

Since essentially all threads/threaded joints have a polymer seal, this both provides against fluid infiltration and, which is also important, prevents the fluid inside the valve unit from escaping.

In a further advantageous embodiment according to Claim 7, the polymer seals have at least one polymer gasket which is situated between the upper surface of the of the valve housing, which opposes the lower part, and the radial surface of the spindle situated in the area in front of the upper surface of the valve housing.

These gaskets help prevent the medium from escaping from the valve housing and salt mist from infiltrating the valve housing. The specifically indicated gasket prevents salt mist from infiltrating the thread of the spindle. In a further advantageous embodiment according to Claim 8, the valve unit has a spindle gasket, which spindle gasket encloses a radial surface of the spindle and is situated, viewed in the axial direction, in the area between the first seal and the first end.

This gasket helps prevent the medium from escaping from the valve housing. In a further advantageous embodiment according to Claim 9, the valve unit includes 3 valves, which valves include 2 first valves and one second valve. The valves are preferably needle valves. In a further advantageous embodiment according to Claim 10, the polymer seals are produced in a polymer sealing material selected from materials which are able to preserve their sealing qualities at least partially down to a temperature of at least minus 101 degrees C, which materials include PTFE and PCTFE.

In a further advantageous embodiment, the valve unit includes 3 needle valves, two first valves and one second valve.

In a further advantageous embodiment, the valve unit includes more than 3 valves.

In a further advantageous embodiment, PTFE is mixed with carbon up to 30% by weight to produce polymer seals.

In a further advantageous embodiment, the valve unit is a block and bleed valve.

In a further advantageous embodiment, the polymer seals have an annular closed part which surrounds a part of the valve unit situated in the mesial direction relative to the annular closed part.

Mesial direction includes the axial direction.

In a further advantageous embodiment, the first sealing ring is an O-ring. In a further advantageous embodiment, the valve housing has a flange which is bolted to the flange of the flange housing, which flange includes the first surface.

In a further advantageous embodiment, the valve housing has a metal top piece.

The invention will be explained in further detail below with reference to the drawing, in which

Fig. 1 shows a valve unit according to the invention that includes 3 valves placed in a flange housing.

Fig. 2 shows a section along line ll-ll in Figure 1 and shows the section in a second valve. Fig. 3 shows a section along line Ill-Ill in Figure 1 and shows the section in a first valve.

Fig. 4 shows a detailed illustration in the area for a first and a second seal. Fig. 5 shows a flow diagram for a valve unit - a block and bleed valve according to the invention, as shown in Fig. 1 .

Fig. 1 shows a valve unit 1 , which here includes 3 valves placed in a flange housing 2, where three valves are a first valve 3', an identical further first valve 3" and a second valve 4, which in principle is of an identical design to the first two valves, which differs from them in that it is not manually operated but is operated by a key. The one first valve 3' of the valve unit 1 is connected to the process in which the valve unit is included, whilst the second first valve 3" of the valve unit is connected to an instrument. The second valve 4 is a shutoff valve. Valve unit 1 is therefore a Slimline Block and Bleed valve. As mentioned, there can also be only two valves, namely a first valve 3' and a second valve 4.

The invention will be explained in more detail with further reference to Figure 2 and Figure 3. Each valve has a spindle 5 for regulating a flow of a fluid through the valve. The valves shown are all needle valves. The first valves 3', 3", of which there are two, are designed to shut off a flow through valve unit 1 when spindle 5 is placed in a first position, and are designed to release a flow when spindle 5 is placed in a second position, an open position. The second valve 4 is designed to blow off a pressure when spindle 5 is placed in a third position. Each spindle 5 is placed in a valve housing 6. Valve housing 6 has a first end 7, where spindle 5 is operated for closing and opening the valve in question. Opposite this end is situated a lower part 8, where lower part 8 belonging to a valve 3', 3", 4 faces a second surface 9 - a flange - of flange housing 2 in which valves 3', 3", 4 are integrated. Each of lower parts 8 has a first surface 24 - a flange - with at least one surface part which is essentially plane-parallel with the outer surface 9.

Between the first surface 24 of each lower part 8 and the outer surface 9 of flange housing 2 is arranged a first seal 10, which encloses spindle 5. Laterally to first seal 10 is arranged a second seal 1 1 having annular sealing edge/contact edge 12 on its upper free surface. First seal 10 is produced in a polymer material, and second seal 1 1 is a metal seal.

The design of the seal is explained in greater detail with reference to Figure 4.

The lowest part 8 has an annular recess 17 placed in first surface 24, which faces outer surface 9 of the flange. First seal 10 is arranged in this recess 17. Seal 10 is a polymer oval to round in cross-section - an O-ring - preferably produced in a PTFE material (Polytetrafluoroethylene). When valve housing 6 is assembled in flange housing 2, first valve 10 will be deformed and recess 17 will exert a counter pressure. Laterally to this first seal 10 is placed metal seal 1 1 . This departs from/is an integral part of first surface 24/lower part 8 of the valve housing, and has an upper sharp edge (acute angled) 12, whose top point is pressed against outer surface 9 of the flange housing 2. In this case, a plastic deformation of the metal takes place, producing a seal between the two parts. The metal seal could in principle also depart from flange housing 2. The metal seal is not therefore a separate unit that is placed, but formed from one of the surfaces from which it departs.

Annular sealing edge/contact edge 12 is produced by an annular sharp sealing edge arranged on a top point line on sealing edge/contact edge 12. The metal second seal 1 1 departs from the surface of lower part 8 facing outer surface 9.

Valve unit 1 includes a third seal 18 arranged laterally to second seal 1 1 . Third seal 18 is produced in a polymer material and is placed between outer surface 9 of the flange facing lower part 8 and first surface 24 of lower part 8 facing flange housing 2. Third seal 18 encloses second seal 1 1 , and is a flat flange gasket. Spindle 5 comprises the opposite end, where it is operated, a cone 29 which, in the closed position, shuts off a flow. Cone 29 is secured to spindle 5 by a deformation of the lower tubular end of the spindle.

First valves 3', 3" and second valves 4 have a spindle gasket 22 which encloses a radial surface 28 of spindle 5 and is situated in the area between first seal 10 and the area facing away from outer surface 9 of the flange. The gasket prevents the medium from escaping from the valve housing.

Valve unit 1 comprises several threads 19, including threaded joints 20, all of which have polymer seals. The threaded joints in question include, for example, the joint between the flange of the valve housing and the flange housing, and include screws. Similarly, the joint will have lock nuts 30 placed between the top of the valve housing and the flange housing. Valve unit 1 also has, as far as first valves 3', 3" are concerned, a polymer cap 16 placed under the spindle handle and constituting part of upper part

7, and is included in a top piece 21 . It prevents salt mist from infiltrating the thread of spindle 5. Valve unit 1 also has a polymer gasket 14 in the area between the flange of top piece 21 and a lock nut 30, which encloses parts of spindle 5 and valve housing 6.

The polymer seals have, among other things, a polymer gasket 26, which is situated between upper surface 27 of valve housing 6 opposing lower part

8, and radial surface 28 of spindle 5 situated in the area in front of upper surface 27 of the valve housing.

The polymer seals are gaskets which are separate units which are advantageously placed.

The polymer material which is selected must have good mechanical and chemical properties, including a low friction value. It could be used in the area between just under minus 200 degrees and plus 250 degrees, and have a tendency toward cold flowing under load, which helps improve the sealing property. It should be chemically resistant to acids, solvents and base materials, and could be machined with conventional tools. It could not be attacked by microorganisms and should be not be absorbed whilst moist. Materials which have these properties include materials which belong to flour plastic, including PTFE.

Fig. 5 shows a flow diagram of a valve unit which is a block and bleed valve as shown in Fig. 1 .

It includes two first valves 3', 3, and a second valve 4. A shows the flow for the process, whilst B shows an output of a measuring instrument. Output C is the venting path for valve unit 1 and through second valve 4. Valve unit 1 , which is of the SDBB type, is therefore used for sealing measuring instruments in offshore installations, where it enables the measuring instrument to be replaced without removing the pressure from the sealed system. SDBB valves consist here of 3 needle valves integrated in a flange housing having 2 shutoff valves in series, namely first valves 3', 3", with an intermediate valve, namely second valve 4 for blowing off the pressure.

Reference numbers

1 . valve unit

2. flange housing

3. first valve

4. second valve

5. spindle

6. valve housing

7. first end

8. lower part

9. outer surface of the flange

10. first seal (enclosing the spindle)

1 1 . second seal

12. annular elevation

14. sealing ring

16. polymer cap

17. annular recess

18. third seal

19. thread

20. threaded joints

21 . top piece

22. spindle gasket

23. the area between the first seal and the area facing away

24. first surface on the valve housing

25. angled elevation

26. polymer gasket

27. upper surface of the valve housing

28. radial surface of the spindle

29. cone

30. lock nut