FLAP VALVE SEALING ARRANGEMENT

Abstract

Flap valves include a valve housing and a flap disc in a flow channel of the valve housing. The flap disc can be pivoted between an open position and a closed position. The flow channel on its outer circumference includes a sealing lip arrangement, which has two elastic sealing lips arranged at a distance from each other in the direction of flow. With the valve disc in the closed position, the sealing lips bear under elastic prestress against the sealing surface of the valve disc to form a seal and thereby form an annular cavity surrounding the sealing surface of the valve disc. Further, with the flap disc in the closed position, the passage of fluid from the high-pressure side in the flow channel to the low-pressure side of the flow channel prevented due to the cross-sectional areas of the two sealing lips of the sealing lip arrangement being inclined or bent towards the inside of the annular cavity.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of PCT/EP2020/068397 filed Jun. 30, 2020, the contents of which are hereby incorporated by reference in the entirety and for all purposes.

FILED OF THE INVENTION

The present technology relates to flap valves, also known in the English-speaking world as “butterfly valves”.

BACKGROUND OF THE INVENTION

A flap valve comprises a valve body defining a flow channel for the flow of a liquid or gaseous fluid and a flap valve disc mounted on the valve body and pivoting about a pivot axis. The dimensions and shape of the flap valve disc correspond to the cross-section of the flow channel. The valve disc can be swiveled about a swivel axis between a closed position and an open position. In the closed position, the valve disc rests with a sealing surface on the outer circumference of the flap valve disc against an annular sealing lip assembly located on the inner circumference of the flow channel and in the closed position blocks the flow of liquid or gaseous fluid through the flow channel. In the open position, the fluid flows around the flap valve disc and can pass through the flow channel.

Publication DE 43 43 562 A1 describes a flap valve including: a valve body designed for installation between two sections of a pipeline and provided with a flow channel for the flow of a fluid, a valve disc arranged in the flow channel and pivotable between a closed position and an open position and mounted on the valve body, this valve disc shutting off the flow of the fluid in the closed position and opening the passage of the fluid in the open position, and an annular sealing lip arrangement which is fastened to the inner circumference of the flow channel, surrounds the flow channel and has two annular sealing lips which consist of elastic material. The two annular sealing lips are arranged at a distance from one another in the direction of flow, bear with their inner sealing edges under elastic prestress against a sealing surface located on the outer circumference of the valve disc when the valve disc is in the closed position, thereby forming an annular cavity surrounding the sealing surface of the valve disc.

Sealing lip arrangements with elastically yielding sealing lips have the advantage over non-elastic seals that the drive torques required to open and close the valve disc remain relatively low. Similarly constructed flap valves are described in DE 28 29 066 C2, EP 0 412 229 B1 and DE 195 15 014 A1. In the flap valves described in these publications, the cross-sectional areas of the two sealing lips of the sealing lip arrangement are inclined or bent outwards in relation to an annular cavity defined between the two sealing lips, i.e. against the direction of flow of the fluid, for example as shown in FIG. 5. As a result, the fluid flowing to the flap valve in the direction of the pressure drop from the high-pressure side to the low-pressure side attempts, when the flap disc is in the closed position, to press these outwardly inclined or bent sealing lips back into the annular cavity lying between them, whereby the contact pressure with which the inner sealing edges of the sealing lips are pressed against the sealing surface of the flap disc increases due to the special cross-sectional shape of these sealing lips.

If uncontrollable pressure increases occur on the high-pressure side of a sealing lip arrangement as shown in FIG. 5, this increase in contact pressure, as explained above, continues until the sealing lip on the high-pressure side gives way or is destroyed, so that the fluid enters the annular cavity between the two sealing lips at high pressure, pushes back the second sealing lip on the low-pressure side in the opening direction and passes through largely uncontrolled towards the low-pressure side.

There is therefore a need for a flap valve to prevent uncontrolled passage of fluid from the high-pressure side to the low-pressure side as discussed above.

BRIEF SUMMARY

The present technology relates to a flap valve wherein the cross-sectional areas of the two sealing lips of the sealing lip arrangement are inclined and/or bent towards the interior of the annular cavity.

In the flap valve in accordance with the present technology, the pressure increases on the respective high-pressure side of the flap valve as explained above lead to the sealing lip of the sealing lip arrangement on the high-pressure side being pressed down towards the interior of the annular cavity by the action of pressure. With this depressing force being greater than the elastic restoring force of the sealing lip on the high pressure side, the fluid may enter the annular cavity between the two sealing lips slowly and without destroying the sealing lip on the high pressure side. The fluid entering the annular cavity builds up a counter-pressure within the annular cavity which supports the sealing lip on the high pressure side from its interior side, so that the sealing lip on the high pressure side is protected against the uncontrolled passage of fluid or destruction. With the pressure in the annular cavity corresponding to the pressure of the fluid on the high pressure side, the sealing edge of this sealing lip on the high pressure side contacts with the sealing edge of the sealing surface of the valve disc with the sealing effect predetermined by the elastic pretension of the sealing lip.

Due to the cross-sectional shape and alignment of the low-pressure side sealing lip of the sealing lip arrangement, fluid that has penetrated into the annular cavity cannot leave the annular cavity in the direction of the low-pressure side either, due to the sealing lip on the low-pressure side increasing its sealing effect when pressurized from the annular cavity due to the inclination and/or curvature of this sealing lip directed against the direction of the pressure drop. The sealing lip on the high-pressure side and thus the entire sealing lip arrangement is thus considerably less sensitive to uncontrollable pressure increases that sometimes occur.

In embodiments, in order to be able to easily replace the sealing lip assembly together with the two sealing lips when necessary, the two sealing lips of the sealing lip assembly may be attached to a support ring which is insertable into a matching annular recess on the inner circumference of the flow channel of the valve body. The sealing lips, which may be made of stainless steel, may be welded to the support ring.

In embodiments, the two sealing lips and/or the back-up ring are manufactured in an additive process from metallic materials with elasticity and hardness adapted to local requirements. This makes it possible to adapt the sealing lip arrangements to the requirements with regard to their dimensions and their shape and material properties. In order to be able to use the annular cavity located between the two sealing lips for improving the sealing effect and/or further functions, in embodiments the annular cavity located between the sealing lips may be connected to a pressure fluid channel leading out of the valve housing. This pressure medium channel leading out of the valve body may be connected to a pressure medium source. This makes it possible to influence the pressure prevailing in the annular cavity between the sealing lips and thus the sealing effect of the sealing lips in a targeted manner by pressurizing or reducing the pressure, for example depending on the pressure difference across the flap valve.

In embodiments, as an alternative or in addition to the above-mentioned pressure medium source, the pressure medium channel leading out of the valve housing may be connected to a lockable collecting device for leakages. This is beneficial in removing residual medium from the annular cavity.

In embodiments, as an alternative or in addition to the measures discussed above, the pressure medium duct leading out of the valve housing may be provided with a supply device for providing a setting and/or hardening sealing agent. Such sealing agents, which may be used in an emergency, may permanently block the flap valve in the closed position and subsequently make it necessary to remove the entire sealing lip arrangement. According to the present technology, this emergency use is particularly promising for the flap valve because the sealing agent can be filled in at particularly high pressure due to the special design and arrangement of the sealing lips.

Embodiments of the present technology relate to methods of using embodiments of the flap valves as disclosed herein. In embodiments, the present technology relates to a method for increasing the sealing effect of a flap valve, in which the pressure medium channel leading out of the valve housing is connected to a pressure medium source, this method being characterized in that, after the flap disc has reached the closed position, the annular cavity located between the sealing lips is pressurized by means of the pressure medium source via the pressure medium channel. In embodiments, the present technology relates to a method for observing and/or monitoring leaks on a flap valve, in which the pressure medium channel leading out of the valve housing is connected to a collectors device which can be shut off, this method being characterized in that, when the flap disc is in the closed position, the annular cavity located between the sealing lips is connected to the collector device via the pressure medium channel and is kept under observation. In embodiments, the present technology relates to a method for the emergency shut-off of a flap valve, in which the pressure medium channel leading out of the valve housing is connected to a supply for a setting and/or hardenable sealing agent, this method being characterized in that, when the flap disc is in the closed position, the annular cavity located between the sealing lips is acted upon by the setting and/or hardenable sealing agent via the pressure medium channel, the filling pressure of the sealing agent being greater than the pressure of the fluid flowing through the flap valve at the flap valve.

In embodiments, the sealing lip arrangement according to the present technology, as disclosed above, may be coupled to the outer circumference of the valve disc additionally or alternatively to the valve body.

In embodiments, the present technology relates to a flap valve including a valve body designed for installation between two sections of a pipeline and provided with a flow channel for the flow of a fluid. The flap valve further may comprise a valve disc arranged in the flow channel and pivotable between a closed position and an open position and mounted on the valve housing, this valve disc shutting off the flow of the fluid in the closed position and opening the passage of the fluid in the open position. The flap valve further may comprise an annular sealing surface which is arranged on the inner circumference of the flow channel of the valve housing and against which, when the valve disc is in the closed position, a sealing lip arrangement arranged on the outer circumference of the valve disc rests, which sealing lip arrangement has two elastic sealing lips which are arranged at a distance from one another in the direction of flow and which, when the valve disc is closed, rest with their outer sealing edges under elastic prestress against the sealing surface of the housing, thereby forming an annular cavity surrounding the valve disc. This flap valve may be characterized by the cross-sectional surfaces of the two sealing lips of the sealing lip arrangement being inclined and/or curved towards the interior of the annular cavity.

In embodiments, the two sealing lips of the sealing lip arrangement may be attached to a support ring, which in this case can be inserted into a suitable annular recess on the outer circumference of the valve disc so that the sealing lip arrangement is replaceable.

In embodiments, in order to achieve sealing effects the sealing lips and/or the support ring are manufactured in an additive process from metallic materials with elasticity and hardness adapted to local requirements.

In the following, the invention is further explained by means of a detailed description in connection with the attached drawings, in which the same reference signs indicate identical structural elements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross-section of a flap valve in the closed position with a sealing arrangement according to embodiments of the present technology.

FIG. 2 shows an enlarged detail A from FIG. 1.

FIG. 3 shows a cross-section of a first design of the back-up ring and the sealing lips attached thereto according to embodiments of the present technology.

FIG. 4 shows a cross-section of a second design of the back-up ring with the sealing lips attached thereto according to embodiments of the present technology.

FIG. 5 shows schematically the pressurization of a double lip arrangement according to the state of the art.

FIG. 6 shows schematically the pressurization of a double lip arrangement according to embodiments of the present technology.

FIG. 7 schematically shows the arrangement of a flap valve according to embodiments of the present technology in a pipeline together with the connectable additional units.

FIG. 8 shows a flap valve similar to FIG. 2, in which the sealing lip arrangement is located on the outer circumference of the valve disc according to embodiments of the present technology.

DETAILED DESCRIPTION

For the purpose of explanation, some specific details are given in the following description to allow a thorough understanding of the many aspects and embodiments of the technology disclosed herein. Different aspects and embodiments of the technology can be practiced independently. In some cases, known structures and devices are only shown schematically in order to avoid obscuring the underlying principles, aspects and embodiments of the invention. Identical reference signs and designations in the different figures indicate identical elements.

FIG. 1 shows an embodiment of a flap valve according to the present technology, which is designated in its entirety by the reference sign 100. The flap valve 100 has a valve body 1 surrounding a flow channel 200 through which a liquid and/or gaseous fluid can flow.

Valve body 1 is also provided at both ends with connecting flanges 2 and 3, which can be used to connect it to a pipeline 300 (see FIG. 7). In this way the flap valve 100 is connected to the pipeline 300 and controls the flow of gaseous or liquid fluid through this pipeline 300.

In the flow channel 200 of the valve body 1 there is a circular disc 4, whose dimensions and shape are adapted to the cross-section of the flow channel 200. This valve disc 4 is attached to a swivel axis 5 running parallel to a plane of extension of the valve disc 4 and supported in the valve body 1 and can be swiveled between an open position and a closed position by means of this swivel axis 5. In the open position, the plane of the flap disc 4 runs essentially parallel to the axis of the flow channel 200, so that the fluid flowing to the flap valve 100 can pass around the flap disc 4 through the flow channel 200. In the closed position shown in FIG. 1, the flap disc 4, in contrast, rests with a sealing surface 6 on its outer circumference against an annular sealing lip arrangement 7,8 located on the inner circumference of the flow channel 200 and thus blocks the flow of fluid through the flow channel 200. In the design example shown in FIG. 1, the sealing surface 6 of the flap disc 4 is conical in shape, because the flap disc 4 is mounted here in multiple eccentricity.

As further shown in FIGS. 1 and 2, the annular sealing lip arrangement 7,8 has two annular sealing lips 7 and 8. These sealing lips are made of a resilient material, such as stainless steel or other suitable elastic material, and are fixed to the inner circumference of the flow channel 200 of valve body 1, spaced apart in the direction of flow. The two sealing lips 7 and 8 each have an inner sealing edge 7a and 8a, respectively, with which they rest under elastic pretension against their sealing surface 6 when the valve disc 4 is in the closed position, and an outer fixing edge 7b and 8b, respectively, with which they are fixed to the inner circumference of the flow channel 200 of the valve body 1. When the valve disc 4 is in the closed position, the two sealing lips 7 and 8 form a closed, annular cavity 9 between them in cooperation with the sealing surface 6 of the valve disc 4.

The cross-sectional surfaces of the two sealing lips 7 and 8 of the sealing lip arrangement 7,8 are inclined and/or bent towards the interior of this annular cavity 9, as can be seen particularly well in FIGS. 3 and 4. This particular inclination and/or bending of these sealing lips 7 and 8 has surprisingly beneficial effects on the sealing behavior, as will be explained below.

There are various possibilities for an easy to handle, replaceable attachment of the sealing lips 7 and 8 to the inner circumference of the passage channel 200 of valve body 1.

In embodiments, for example as shown in FIG. 2, an annular recess 10 is provided on the inner circumference of the passage channel 200, into which a support ring 11 for the sealing lips 7 and 8 can be inserted. In this case the sealing lips 7 and 8 are clamped in the area of their outer fixing edges 7b and 8b in the annular recess 10 with the aid of this support ring 11.

In embodiments, for example as shown in FIG. 3, the two stainless steel sealing lips 7 and 8 may be welded to the support ring 11 in the area of their fixing edges 7b and 8b. In embodiments, stainless materials, other than stainless steel, may also be used.

In embodiments, for example as shown in FIG. 4, the sealing lips 7 and 8 and/or the back-up ring 11 are manufactured in an additive process from metallic materials with elasticity and hardness adapted to local requirements. For example, by appropriate cross-sectional shape and choice of material, the sealing lips 7 and 8 can be made relatively stiff in the area of their outer fixing edges 7b and 8b, relatively hard in the area of their inner sealing edges 7a and 8a and relatively elastic in the areas in between. When using this additive process, numerous other adaptations to local requirements are envisioned.

The above mentioned, surprisingly advantageous effect of the design of the sealing lip arrangement according to the present technology on the sealing behavior is explained in the following by means of a comparison between a sealing lip arrangement known according to the state of the prior art as shown in FIG. 5, and a sealing lip arrangement according to the technology, as shown in FIG. 6.

For the sealing lip arrangement shown in FIG. 5 in the closed position according to the state of the art (see DE 28 29 066 C2), the valve body is marked with a. Two sealing lips b and c are attached to this valve body at which, in the closed position shown, touch a sealing surface e located on a valve disc d. As can also be seen from FIG. 5, the two sealing lips b and c are inclined or bent outwards in relation to the annular cavity f between them.

With this sealing lip arrangement known according to the state of the art as shown in FIG. 5, the pressure on the high pressure side HP in the direction of arrows 12 increases to such an extent that the sealing lip b becomes permeable in the direction of the annular cavity f, i.e. leaks or is destroyed, or a relatively high pressure quickly builds up in the annular cavity f between the two sealing lips b and c, which is sufficient to bend the outwardly inclined or bent sealing lip c located on the low-pressure side LP in the opening direction, so that the fluid that has penetrated into the annular cavity g can pass through to the low-pressure side LP largely unhindered.

With the sealing lip arrangement according to the present technology shown in FIG. 6, the pressure on the high pressure side HP in the direction of arrows 12 becomes so great that the sealing lip 7, which is under elastic prestress, becomes permeable in the direction of the annular cavity 9, the fluid which penetrates into the annular cavity 9 cannot readily leave this annular cavity and builds up an increased pressure in the annular cavity 9 which supports both sealing lips 7 and 8 in the closing/sealing direction. This supporting effect is indicated in FIG. 6 by arrows 13. With the supporting pressure in the annular cavity increased to correspond to the pressure on the high pressure side HP, the sealing lip 7 on the high pressure side is again in contact with the sealing surface 6 of the disc 4 with its original elastic pretension due to the supporting pressure from the annular cavity 9. The sealing lip 8 on the low pressure side remains absolutely tightly sealed due to its inclination and/or bending in the direction of the annular cavity 9.

The annular cavity 9, arranged between the two sealing lips 7 and 8, in combination with the shape and arrangement of the sealing lips 7 and 8 according to present technology, may be used alone or in combination with additional elements of the flap valve in order to further improve the sealing behavior of the flap valve according to the present technology. For this purpose, as shown in FIGS. 1, 2 and 3, the annular cavity 9 may be connected to a pressure fluid channel 14 leading out of the valve body 1.

In embodiments, the pressure medium channel 14 leading out of valve body 1 may be used for various purposes, for example as shown in FIG. 7. As shown there—but only schematically—the pressure medium channel 14 leading out of valve body 1 can be connected individually or in any combination to: a source of pressure medium 15, a lockable collecting device 16 for leakages, and/or a feeding device 17 a sealant.

With the aid of the pressure medium source 15, the pressure prevailing in the annular cavity 9 between the sealing lips 7 and 8 may be influenced/controlled and thus the sealing effect of these sealing lips may be controlled in a targeted manner by applying or reducing pressure, for example as a function of the pressure difference at the flap valve 1.

With the leakage collecting device 16 connected to the pressure medium channel 14, the sealing effect of the flap valve may be permanently monitored. For example, as soon as leaks occur, the leaks can be detected by the amount of fluid accumulating in the collecting device 16.

For a total shut-off of the flap valve, for example in an emergency, the annular cavity 9 between the two sealing lips 7 and 8 can be pressurized with a setting and/or hardening sealant via the pressure fluid channel 14 with the aid of the sealant supply device 17. Due to the special design and inclination of the sealing lips 7 and 8 according to the invention, this sealing agent can be introduced into the annular cavity 9 at particularly high pressure, so that an absolutely safe and tight emergency seal can be guaranteed.

FIG. 8 shows, in a similar representation to FIG. 2, an arrangement of a sealing lip arrangement according to the present technology on the outer circumference of the disc of a flap valve.

In FIG. 8 the body of the flap valve is marked with the reference mark 1001 and provided with connecting flanges 1002 and 1003 for connection of a pipe not shown. In the flow passage 1200 of the valve body 1001 there is a flap disc 1004, which can be pivoted about an unshown pivot axis between a closed position and an open position and is shown in the closed position in FIG. 8, and which is provided with a sealing lip arrangement 1007,1008 on its outer circumference. The sealing lips 1007 and 1008 of this sealing lip arrangement, which are made of elastic material, are in contact under elastic prestress with a conical, annular sealing surface 1006, which is located on the inner circumference of the flow channel of the 1200 of the valve body 1001, in the illustrated closed position of the flap valve.

The two sealing lips 1007 and 1008 of the sealing lip arrangement are also here arranged at a distance from each other in the flow direction of the flap valve and form an annular cavity 1009 together with the conical sealing surface 1006 of the valve housing 1001 when the flap disc 1004 is in the closed position. The special feature of this sealing lip arrangement is also here that the cross-sectional surfaces of the two sealing lips 1007 and 1008 of this sealing lip arrangement are inclined and/or curved in the direction of the interior of the annular cavity 1009.

The effect of the sealing lip arrangement connected to the flap disc is the same as for the sealing lip arrangement disclosed above regarding a sealing lip arrangement connected to the valve body, as shown in FIGS. 1-3.

For easy replacement, the two sealing lips 1007 and 1008 of the flap valve explained in FIG. 8 may be attached to a support ring 1011, which can be inserted into a matching annular recess 1010 on the outer circumference of the flap disc 1004.

In order to be able to better adapt the sealing effect to the local requirements in terms of shape, elasticity and hardness in this case as well, the back-up ring 1011 and/or the sealing lips 1007 and 1008 are also manufactured in an additive process.

In embodiments, with regard to the bearing of the valve disc, different arrangements may be used, for example different types of valves including: a centric design in which the swivel axis of the disc passes through the center of the seal assembly which is centered around the axis of the flow channel, a single eccentric design, in which the swivel axis of the disc is axially displaced in the flow direction along the axis of the flow channel, a double-eccentric design, in which, in addition to the single-eccentric design, the swivel axis of the valve disc is displaced perpendicular to the axis of the flow channel, and a triple-eccentric design, in which, in addition to the double-eccentric design, the plane of the annular sealing arrangement is no longer perpendicular to the axis of the flow channel. The present technology relates to flap valves of all designs.

Different aspects, designs, implementations or features of the described design examples can be used separately in any combination. In particular, it should be noted that the various elements of FIGS. 1-4,6 and 7 belonging to the concept of the invention can be combined in different ways without deviating from the meaning or scope of the invention.

The indefinite articles “one” or certain articles “the”, “the” or “the” or similar expressions used shall, in the context of the description of the invention and in particular in the context of subsequent patent claims, be interpreted as covering both the singular and the plural, unless such interpretation clearly contradicts the context. The terms “comprising”, “having”, “including” and “contained” shall be interpreted as open terms (i.e. “including but not limited to”) unless otherwise indicated. The indication of ranges of values is essentially an abbreviation and refers in individual cases to each individual value falling within that range, or gradients thereof, unless otherwise indicated in the description. Each value disclosed in this way is treated as if it were individually mentioned in the description. All the steps of the procedure described here may be performed in any appropriate order unless otherwise indicated or the context clearly contradicts. Examples or indications in exemplary language (e.g. “as is”) are included in the description to better explain embodiments of the invention and do not imply any limitation of the scope of protection of the invention, unless otherwise claimed. No linguistic formulation in the description should be interpreted as indicating that an unclaimed element is important for the execution of the invention.

The term “essentially” used in the description refers to the complete or almost complete extent or degree of an action, characteristic, property, state, structure, object or event. For example, an object that is “substantially” enclosed would mean that the object is either completely or almost completely enclosed. The exact degree of deviation from absolute completeness allowed may depend on the specific context in some cases. In general, however, the closeness to realization will be such that the same overall result is achieved as if an absolute and complete realization had been achieved.

The preferred embodiments of the invention described here include the best way of implementing the invention known to the inventor. The invention is open to various modifications and alternative constructions. Certain exemplary embodiments of these are shown in the drawing and have been described in detail above. Variants of these preferred embodiments in the sense of the invention may become obvious to the average person reading this description. Inventors expect experienced skilled persons to be able to use such variants as required and to be able to realize the invention in ways other than those specifically described here. Accordingly, it is understood that there is no intention to limit the invention to the special form or the disclosed forms. On the contrary, the invention comprises all modifications and equivalents of the subject matter of the invention claimed in the attached claims, as permitted by applicable law. Furthermore, the invention comprises any combination of the elements described above in all possible variations unless otherwise indicated in the description or unless the context clearly contradicts it. The above description uses a specific nomenclature for explanatory purposes in order to provide a thorough understanding of the embodiments described. However, it is clear to the professional that certain details are not necessary to perform the described embodiments. Thus, the above descriptions of specific embodiments are presented for illustrative and descriptive purposes only. They are not intended to be exhaustive or to limit the described embodiments to those which are individually disclosed. It is obvious to the average expert that many modifications and variations are possible with respect to the above teachings.

Claims

1. A flap valve, comprising:

a valve body configured to be coupled between two sections of pipe, wherein the valve body defines a flow channel configured for a fluid to flow through;

a flap disc pivotably coupled to the valve body within the flow channel, wherein the flap disc is configured to rotate between a closed position wherein the flap disc blocks a flow of the fluid through the flow channel and an open position wherein the flap disc does not block the flow of the fluid through the flow channel; and

a pair of elastic sealing lips coupled to an inner circumference of the flow channel of the valve body within the flow channel,

wherein the pair of elastic sealing lips comprise a first sealing lip and a second sealing lip,

wherein each of the first and second sealing lips define an inner surface and an outer surface;

wherein in the closed position the outer surface under elastic prestress contacts and forms a seal with a sealing surface on an outer periphery of the flap disc, and an annular cavity is defined between the inner surface of the first sealing lip, the inner surface of the second sealing lip, and the sealing surface of the flap disc, and

wherein the first sealing lip and the second lip are inclined and/or bent toward each other to define the annular cavity.

2. The flap valve of claim 1, wherein the first and second sealing lips are each attached to a support ring,

wherein the support ring is configured to be inserted into a matching annular recess on the inner circumference of the flow channel of the valve body.

3. The flap valve of claim 2, wherein in the first and second sealing lips and/or the support ring are produced in an additive process from metallic materials with at least one of elasticity and hardness of different portions of the first and second sealing lips and/or the support ring being different from other portions.

4. The flap valve of claim 1, wherein the annular cavity defined between the sealing lips is fluidically connected to a pressure medium channel leading out of the valve body.

5. The flap valve of claim 4, wherein the pressure medium channel leading out of the valve body is connected to a pressure medium source.

6. The flap valve of claim 4, wherein the pressure medium channel leading out of the valve body is connected to a collecting device configured for detecting leakages.

7. The flap valve of claim 4, wherein the pressure medium channel leading out of the valve body is connected to a supply configured for delivering a setting and/or curable sealing agent.

8. A method for operating the flap valve according to claim 5, comprising:

positioning the flap disc in the closed positioned; and

pressurizing the annular cavity defined between the first and second sealing lips with the pressure medium source in order to increase a sealing force of the outer surfaces against the sealing surface on the outer periphery of the flap disc.

9. A method for observing and/or monitoring leakages of the flap valve according to claim 6, comprising:

positioning the flap disc in the closed positioned;

collecting fluid from the annular cavity in the collecting device.

10. A method for sealing the flap valve according to claim 7, comprising:

positioning the flap disc in the closed positioned; filling the annular cavity with the setting and/or hardenable sealing agent through the pressure medium channel.

11. The flap valve of claim 1, wherein each of the first and second sealing lips define an arcuate profile wherein the outer surfaces are convex and the inner surfaces are concave,

wherein the outer convex surfaces of the first sealing lip and the second sealing lip face away from each other, and the inner concave surfaces of the first sealing lip and the second sealing lip face toward each other to define the annular cavity.

12. A flap valve, comprising: a pair of elastic sealing lips coupled to an outer circumference of the flap disc, wherein the pair of elastic sealing lips comprise a first sealing lip and a second sealing lip, wherein each of the first and second sealing lips define an inner surface and an outer surface;

a valve body configured to be coupled between two sections of pipe, wherein the valve body defines a flow channel configured for a fluid to flow through;

a flap disc pivotably coupled to the valve body within the flow channel, wherein the flap disc is configured to rotate between a closed position wherein the flap disc blocks a flow of the fluid through the flow channel and an open position wherein the flap disc does not block the flow of the fluid through the flow channel; and

wherein in the closed position the outer surface under elastic prestress contacts and forms a seal with a sealing surface on an inner circumference the flow channel of the valve body, and an annular cavity is defined between the inner surface of the first sealing lip, the inner surface of the second sealing lip, and the sealing surface of the flow channel, and

wherein the first sealing lip and the second lip are inclined and/or bent toward each other to define the annular cavity.

13. The flap valve of claim 12, wherein the first and second sealing lips are each attached to a support ring,

wherein the support ring is configured to be inserted into a matching annular recess on the outer circumference of the flap disc.

14. The flap valve of claim 13, wherein in the first and second sealing lips and/or the support ring are produced in an additive process from metallic materials with at least one of elasticity and hardness of different portions of the first and second sealing lips and/or the support ring being different from other portions.

15. The flap valve of claim 12, wherein the annular cavity defined between the sealing lips is fluidically connected to a pressure medium channel leading out of the valve body.