SK9761Y1 - Flange connection - Google Patents

Abstract

A flange connection for connecting two pipelines made of mutually difficult-to-weld materials comprising a first flange (1) equipped with an inlet port (10) made of a first material belonging to the same material group as the first pipe, and a second flange (2) equipped with an outlet port (11) made of from the second material, belonging to the same material group as the second pipe, these flanges (1,2) are equipped with connecting means to ensure mutual connection of both flanges (1,2). The first or second flange (1,2) is equipped with a fitting hem (14), while the second of these flanges (2,1) is equipped with a fitting surface (9) arranged opposite the fitting hem (14). At its edge closer to the center of the flange (1,2), the abutment hem (14) is equipped with a chamber (12) for the primary seal (3) in the secondary power flow, while at its edge further from the center it is equipped with a chamber (13) for the secondary seal (4) in the secondary power flow. The first flange (1) and the second flange (2) are designed to fit only in the surface of the bearing hem (14) of the first or second flange (1,2) with the bearing surface (9) of the second of these two flanges while ensuring the transmission of force and moment loads between both flanges with a gap (15) in the remaining area of the flanges to ensure the deformation of the flanges and to create the required prestressing of the connected flanges.

Description

The field of technology

The technical solution refers to a heterogeneous flange connection, advantageously replacing a heterogeneous welding connection of two pipelines made of mutually different materials, which enables the connection of, for example, a corrosion-resistant pressure pipeline to a carbon steel pipeline, and thus ensures a material transition, without using the standard solution realized by a heterogeneous welding connection. The device according to this technical solution serves especially advantageously to realize the connection between the sleeve of the steam generator casing, made of pearlitic-ferritic steel or other applications, for example carbon steel, and the connecting pipeline made of another material, for example austenitic corrosion-resistant chrome-nickel steel, which are mutually difficult to weld.

Current state of the art

In some technical applications, large equipment made of carbon steel is used, but the various connecting pipes must be made of corrosion-resistant steel due to the relatively large corrosion losses of the material. By default, this material transition is realized on the neck directly in the carbon apparatus - the so-called heterogeneous weld joint. It is a relatively complicated node (such as production, assembly, but also from the point of view of design and operational controls), when it is first necessary to weld the so-called a diffusion layer that prevents the degradation of the heterogeneous weld joint itself and the diffusion of carbon into the weld joint, and thus the subsequent formation of carbides in the heat-affected area. However, this solution is only used for pipes with a larger wall thickness, which is roughly over 9 mm. With smaller pipe wall thicknesses, the so-called transition material, which, however, does not create such an effective diffusion layer. According to the regulations of the normative technical documentation of the association of mechanical engineers NTD A.S.I. for welding in the nuclear power industry, it is forbidden to weld the own heterogeneous weld joints directly at the assembly, but only as a workshop heterogeneous weld joint, which is impossible in some cases. However, due to the different thermal expansion and other degradation mechanisms of both materials, this weld joint is a highly stressed place, and also in the transition area (at the carbon steel/corrosion-resistant steel interface) depletion of alloying elements occurs, and thus the possibility of indications in the heat-affected area especially at the grain boundaries - with the contribution of high stresses from different coefficients of thermal expansion and other degradation mechanisms. These heterogeneous welded joints are therefore very problematic, especially for thermally stressed parts, and to a high degree show significant volume defects of the crack type after only a few years, which often cause the necessity of reconstructing such a joint or can even cause an accident by tearing off the pipe at the weld point.

One of the many possible applications of heterogeneous weld joints is the weld between a pipe formed by a carbon steel neck on the steam generator shell (the entire steam generator shell is made of carbon steel) and a subsequent short corrosion-resistant pipe that connects the two pipes to the condensation vessel for measuring the water level in the steam generator. Another typical application is the connection of corrosion-resistant impulse pipes to pressure intakes from various apparatus or larger carbon pipes.

There are flange joints for connecting two pipes of mutually heterogeneous materials, which are equipped with a seal in the main power flow, but these only exist for connecting two straight pipe sections. However, such a flange joint is not suitable for thermal and pressure-stressed applications, such as to the aforementioned steam generator. The disadvantage of such a connection is that when sealing in the main power flow due to the start-up and shutdown of the steam generator due to regular shut-downs for the replacement of nuclear fuel in the reactor, it "relaxes", so it is necessary that the flange connection is regularly checked to see if it is tightened to the prescribed tightening torque. In addition, it is necessary to change the seal at the service intervals prescribed by the manufacturer. Otherwise, there may be a sudden failure of the tightness of the flange connection during the operation of the equipment, which may threaten the safety of the operation of the nuclear power plant.

Document WO2016/066659 of ALSTOM Technology Ltd. of 27/10/2015 describes a direct flange connection for connecting two pipes made of heterogeneous materials, which uses two flanges, each of a different material, the same as the pipe connected to the given flange, while the shape of the flanges at the inner end forms when they are placed on top of each other and pulling the screw flanges together the first seal, which in a preferred embodiment is complemented by a second seal surrounding the first seal, this second seal being formed by a metal ring inserted into two opposing grooves formed respectively in two opposing flanges. This seal is only used in a situation where the flanges would open and thereby disrupt the first seal. In order to ensure the tightness of this joint, this flanged joint preferably contains another third seal arranged on the outside of the flanges.

The reason for the small number of replacements of the heterogeneous weld joint with a flange joint is that on high-pressure pipes stressed by temperatures above 200 °C, these joints are enormously alternately stressed from the following pipe (both from thermal expansions and from possible dynamic loads) - which would very quickly lead to loss of the sealing ability of the standard graphite gasket in the main power flow.

The essence of the technical solution

According to this technical solution, a flange joint is provided for connecting pipes made of different mutually difficult-to-weld materials, which can, for example, be placed immediately on one pipe, for example behind the pressure take-off at the outlet of the device, made of one material, for example carbon steel, towards the subsequent take-off a pipe made of a second material, made of, for example, corrosion-resistant steel, which are difficult to weld to each other. For the purposes of this application, the term pipe means, in addition to its commonly used meaning, any tubular outlet from the device that allows connection to the neck of the flange connection and to which another pipe needs to be connected. The flange joint is particularly advantageously connected to the mentioned pipes by welding. The flange joint is especially advantageously intended as a replacement for the existing welded heterogeneous joint.

The essence of the technical solution is a flange joint containing a pair of flanges made of materials that are difficult to weld to each other, as defined in claim 1. The materials of the individual flanges of the flange joint according to this technical solution are selected from the same material groups as the pipe materials from one and the other side, so it is possible to weld the neck of the given flange with the pipe connected to it.

As is clear from the description of the technical solution, the pair of flanges is adapted in shape for the application of the primary seal in the secondary power flow, which is designed to achieve high tightness, and further for the application of the secondary seal serving to prevent leaks in the event of damage to the primary seal. This combination further enables an effective indication of possible damage to the primary seal in the initial phase (when the leakage is very small) by means of pressure extraction from the intermediate space between the primary and secondary seals. Thanks to the described arrangement of both seals in the secondary force flow, it is possible for the flange joint to transmit high force and moment effects without cyclic stressing of the seal, which results in a fundamental increase in the reliability of this heterogeneous flange joint.

The flange connection according to this technical solution can be used in systems with any media. It is also suitable for all material designs of flanges required by these media.

The flange joint according to this technical solution mainly contains the following parts, which are arranged as a functional unit ensuring the required functionality of the entire system, namely:

- the first flange made of material of the same material group as the material of the first connection to the first pipe,

- a second flange arranged against the first flange for their mutual connection made of material of the same material group as the material of the second (for example, impulse) pipe,

- primary seal in the secondary power flow,

- secondary seal in the secondary power flow a

- fasteners (bolts and nuts).

The flange connection according to this technical solution particularly advantageously contains a chamber between the primary and secondary seals for capturing potential leaks from the primary seal, equipped with an output for signaling the loss of the primary seal. Leakage of the primary seal is indicated by an increase in pressure in the leak detection chamber with a subsequent indication of a leak in the primary seal. Even more advantageously, the flange connection further contains an integrated device for signaling a possible leak of the primary seal, which is directly part of this connection.

The device is especially advantageously designed for connection with the first flange for pressure withdrawal from the device, such as a steam generator. The first flange is particularly advantageously made of carbon steel.

The flange joint on the inner side of the socket, i.e. from the mounting flange to the center, must contain a sufficient gap to ensure the correct seating of the mounting flange on the mounting surface between the primary and secondary seals, it is also necessary to take into account the given production tolerances so that the contact surface of the mounting flange with the mounting surface was the only contact surface between the two flanges, which will ensure the transmission of external force and moment effects. Similarly, a gap is created between the flanges when the mounting flange is placed on the mounting surface and in the space between both flanges from the mounting flange outwards, i.e. in the direction of the edge of the flanges, so on the outside of the mounting flange between the flanges, mainly in the place of the connecting elements (preferably bolts and nuts ), after placing the abutment flange on the abutment surface, this surface of their contact must be the only contact surface between the flanges of the gap, which will ensure the correct preload of the connecting elements due to the possible deformation of the flanges when they are pulled by the connecting elements. Therefore, connecting elements can be e.g. studs with nuts, bolts with nuts and similar fasteners to ensure reliable connection of both flanges of a flanged joint as required of that flanged joint.

Thanks to the described arrangement of the flange joint according to the invention with a bearing flange and a bearing surface and a gap between the remaining facing surfaces of both flanges, it is ensured that after tightening the connecting means, e.g. bolts and nuts, during operation there was as little as possible change in the dimensions, especially the height, of the chamber for the primary and secondary seals, because the seal does have the ability to cushion, but this ability decreases sharply with the number of cycles of its compression and relief. By reducing the contact stress on the surface of the seal, the sealing ability of the seal is directly proportionally reduced. The higher the pressure of the medium - the higher the requirement to achieve contact tension on the sealing surfaces. For high pressures, the optimal specific pressure in the seal is about 80 MPa, but even more.

It is particularly advantageous if the chamber for the primary seal is created with the same height as the chamber for the secondary seal and if the height of the primary and secondary seals is the same, while at the beginning of compression it is about 30% higher than the height of the chamber, so that after tightening the flanges with the connecting elements caused a controlled compression of the primary and secondary seals in the secondary power flow. However, this requirement depends on the mechanical properties of the seal and can vary accordingly, so deviations from the stated value of approx. 30% are possible, depending on the type of seal.

According to another preferred embodiment of the flange connection, the primary seal chamber and/or the secondary seal chamber is formed in a tongue-and-groove style, so that one flange has a groove-shaped chamber, while the other of the flanges has a tongue-shaped protrusion that fits into chambers-grooves. It is obvious to the expert that in such a case it is necessary to increase it by the height of the projection when calculating the height of the chamber.

It is particularly advantageous if the connecting elements are located near or as close as technically possible to the secondary seal to minimize undue deformation.

The flange joint provided by this technical solution is particularly suitable for use in steam generators of nuclear power plants of the VVER type, because

- the primary seal in the secondary power flow is not stressed by alternating forces and moments at different operating conditions, but is only loaded by the static specific pressure in the graphite ring developed in the chamber for the primary seal, preferably of the tongue/groove type, from the tightening of the connection to the contact surface , which ensures the transmission of external forces and moments;

- the secondary seal is also in the secondary power flow (preferably in the tongue/groove chamber) and will ensure full tightness even if the tightness of the primary seal is reduced;

- the advantageous creation of a sampling groove and a sampling bore between the primary and secondary seals for the identification of a possible leakage of the primary seal - this technical element enables the early identification of a possibly reduced function of the primary seal long before the loss of tightness would occur, because the second barrier created by the secondary seal is used , which is designed for the same specific pressure (thus also tightness) as the primary seal.

The flange connection according to this technical solution can be especially advantageously installed on the pipe to the two-chamber measuring vessel of the steam generator, while due to the small dimensions of the flange connection for installation, instead of the existing heterogeneous connection, small full graphite rings are especially advantageously installed as a seal in both chambers for sealing. If in another application the grooves would be on a larger diameter and would be wider - perhaps instead of a purely graphite seal, a spiral or comb seal could be applied - again in the secondary power flow.

The flange joint can advantageously have the throats of both flanges arranged in a "Z" shape, when the outlet from the flange joint is at a different level than the inlet, which helps to eliminate the inaccuracy of the throat spacing, and the height adjustment of the two-chamber measuring container during assembly.

Another advantage of the flange joint according to this technical solution is that it is possible to create both flanges with different thicknesses of the throat walls, e.g. flange on the side of the steam generator with a significantly greater thickness of the throat wall to ensure sufficient strength even in the case of massive corrosion (weakening) of the internal surfaces or in the case of transmission of high force or moment loads.

The advantage of the flange joint according to this technical solution is the possibility, thanks to the tandem seal with the removal of any leaks that have penetrated through the primary seal, to perform a leak test when the flange joint is installed at the destination, by performing a pressure test of the space between the primary and secondary seals, which enables the elimination of the risk possible leakage during start-up of the entire system on which the flange connection is installed, e.g. on the block of the nuclear power plant containing the given steam generator.

Another advantage is the possibility of monitoring possible leakage of the primary seal during the operation of the system containing this flange joint.

The final dimensioning and design of the appropriate shape of all functional surfaces is carried out on the basis of data depending, among other things, on the used sealing material and knowledge of the maximum force and moment effects acting on the joint of both flanges - using strength calculation.

But for a first approximation, the basic conditions for their dimensioning can be determined as follows:

- The primary seal should have the smallest possible diameter and be located in a closed chamber.

- The height of the primary and secondary seals should be approximately the same, but at least such that the springing of the seal is at least 4 times the thermal expansion of the joint in the place of the seal chamber.

- The width of both seals should be approximately the same as the height of the seal in the compressed state, but due to sufficient specific pressure in the seal, it must not be excessive.

The advantages of the flange connection according to this technical solution compared to the current state of the art are the following, especially when it is used:

- the flange joint is characterized by high reliability at high force and moment loads on this joint (which are comparable to the bearing capacity of welded joints),

- thanks to the secondary seal, media leaks are eliminated even if the primary seal is damaged,

- the chamber between the primary and secondary seals in the advantageous arrangement of the flange connection enables the early identification of a potential leak through the primary seal,

- the flange connection advantageously allows the placement of the inlet and outlet necks in different axes, so that it is possible to place the flange connection even on uneven axis pipelines,

- the shape of both flanges is suitable for production with die forging technology and requires a small proportion of machined surfaces,

- the possibility of testing the tightness of the flange joint during assembly using the sampling of the intermediate space between the primary and secondary seals to perform a pressure test, which enables the elimination of leakage and the need to shut down the energy block when the block starts up into normal operation,

- thanks to the presence of the secondary seal, it is possible to operate this flange joint safely even in case of damage to the primary seal, even until the next shutdown without external leakage of the medium,

- the possibility of regular checking of the tightness function during shutdown of the power unit without the need to drain the steam generator on which this flange joint is applied,

- thanks to its advantageous arrangement with the possibility of application to uneven axial pipelines, the flange joint according to this technical solution is also suitable for applications requiring small built-up spaces, which until now could only be realized using a heterogeneous weld joint.

The flange connection according to this technical solution is particularly suitable for connecting a two-chamber measuring container that measures the level of the medium of the secondary circuit in the steam generator. The flange connection according to this technical solution serves primarily to increase the safety, durability and reliability of the heterogeneous connection in nuclear power plants, where there are a relatively large number of these connections, but they can be used in all technological processes in which the connection of pipes from two different materials is used. Especially advantageously, it deals with the replacement of the joint of two pipelines made of different materials, which are difficult to connect by welding or where it is necessary to ensure a possible leakage of the medium before a major leak occurs during operation.

Overview of images behind the drawings

For a clearer illustration of the subject matter of the technical solution, the drawings that are used in the description of the exemplary embodiments will be briefly described. It is clear that the described drawings are only some, but not all, of the embodiments of the presented ÚV, and the expert can create other examples of embodiments and drawings without expending creative work. In these drawings they represent:

fig. 1 view of a flange joint with a Z-shaped body enabling connection to an off-axis pipe, fig. 2 view of the flange connection in a section guided by a plane passing through its center around to the plane of the connection of both flanges, fig. 3 a view of a flange connection with an L-shaped body for installation on a pipe forming a mutual angle of 90°;

fig. 4 then represents a view of a flange connection intended for installation on a coaxial pipe.

Implementation examples

For a better understanding of the flange connection according to this technical solution, an example of its possible implementation will now be described. Although the technical solution will be further described using specific embodiments, it is in no way limited to the embodiments described here. The technical solution is limited only by the attached protection claims. The examples of implementations of the flange connection according to this technical solution shown in the images are only schematic and are not intended as limiting the flange connection to the illustrated implementations. The embodiments shown in the drawings may have the size of some elements enlarged for illustrative reasons and may not be drawn to scale. Thus, dimensions and relative dimensions do not correspond to actual sizes. Further, the terms first, second and similar terms in the description and in the claims are used to distinguish between similar elements and do not necessarily describe the succession or temporality or space or superiority of one element over another unless expressly stated or implied by their functions. Moreover, although some embodiments of the technical solution described herein include only some elements but not other elements, while these are included in other embodiments, combinations of elements from different embodiments are possible so that they fall within the scope of the technical solution and form other embodiments, such as are described here, which will be fully understandable to persons orientated in the field. For example, in the following claims, all claimed embodiments may be used in any combination. It is clear to the expert that other versions of the flange connection according to this technical solution are also possible, some of which are shown in the examples and in the pictures. The examples of embodiments therefore represent only some possible embodiments and should not be used as limitations of the technical solution only to the depicted embodiments. The expert can also add others to the mentioned parts, but their presence will not change the essence of the invention. However, all these implementations still fall within the scope of this technical solution, which is limited only by the requirements for protection.

In fig. 1 shows a flange joint according to one embodiment of this technical solution, which is designed for pressure system technology, which is, for example, the removal of pressure medium from the pressure vessel of a steam generator made of carbon steel with an outlet for connecting, via this flange joint, a corrosion-resistant pipe. In the embodiment example in fig. 1 is one of the flanges in the form of a Z-piece, so the axis of the inlet neck of the flange joint is not identical to the axis of the outlet neck. This arrangement of the necks of the flange joint makes it particularly advantageous to place the neck at the desired height by turning the entire flange joint during its assembly on the pipes it connects. The distance between these axes can be arbitrary. For design reasons, it may be advantageous if the outlet is not too far from the outer edge of the flange. In fig. 1 shows the first flange 1 equipped with an inlet port 10, the adjacent second flange 2 equipped with an outlet port 11, while both flanges 1, 2 are connected by connecting elements, here represented by bolts 7 and nuts 8. The flange joint is also equipped with an output 6 for signaling primary seal leakage losses. The flange connection in its embodiment in fig. 1 also contains a plug 16. In this embodiment, it closes a borehole led by the second flange 2 perpendicular to the outlet port 11, while this borehole serves to create a cavity connecting the outlet port 11 of the second flange 2 with the cavity in the first flange 1 connected to the inlet port 10 to ensure of the fluid connection of the inlet port 10 of the flange connection with the outlet port 11. It is clear to the expert that this embodiment of the cavity in the body of the second flange 2 is only advantageous from the point of view of production, but not the only possible one. In the non-illustrated examples of the implementation of the flange joint, it is possible to make such a connection, e.g. suitable shape of flanges during casting or another way of mechanical material processing. In such a case, the corresponding cavity will be created without the presence on the outer side of the flange of the drilled hole, and thus the existence of the plug is not necessary for the proper function of the flange connection, so the plug 16 does not have to be present at all. It is also obvious to the expert that with the described flange connection, the inlet port can be the same as the outlet port, and conversely, the outlet port can be the inlet port. Likewise, it is clear to the expert that other implementations of the connecting means are also possible, e.g. screws that will pass through the corresponding holes in both the second flange and the first flange, and others that will ensure a reliable connection of both flanges.

In fig. 2 shows a section of a flange joint according to this technical solution from fig. 1. In fig. 2 are identical elements from fig. 1 marked with the same reference signs. The flange connection thus includes a first flange 1, a second flange 2, while the second flange 2 is equipped with a bearing flange 14, while the first flange 1 is equipped with a bearing surface 9 arranged against it. A gap 15 is arranged in the surface of the flanges 1, 2 outside the bearing flange 14 , which allows the fitting flange 14 to be properly fitted to the fitting surface 9 and the flanges 1, 2 to be pulled together and allows the possible deformation of the flanges 1, 2 when tightened by means of fasteners. The landing flange 14 with the landing surface 9 is designed to ensure the transmission of force and moment loads between the two flanges 1, 2. At the edge of the landing flange 14, resp. of the bearing surface 9, a primary sealing chamber 12 is provided in the first flange 1 and/or the second flange 2, in which the primary sealing 3 is arranged, while the primary sealing chamber 12 is in this case created in this example of the implementation of the flange connection according to this technical solution actually between the adjacent edges of both flanges, so both flanges contribute to its creation. It is clear to the expert that the chamber 12 for the primary seal can be created similarly to the chamber 13 for the secondary seal described below, in any of the flanges. In fig. 2, a secondary sealing chamber 13 is formed in the second flange 2, in which the secondary seal 4 is arranged. Between the primary sealing chamber 12 and the secondary sealing chamber 13, a chamber 5 is formed in the surface of the fitting flange 14 to catch leaks. This chamber 5 for capturing leaks is connected to output 6 for measuring possible leakage in the event of damage to the primary seal 3. Output 6 includes a corresponding sensor for recording the increase in pressure in chamber 5 for capturing leaks, but it can also be a remote pressure sensor. In the event of damage to the primary seal 3, the pressure rises in the chamber 5 for catching leaks, which is recorded by the sensor, and thus it is possible to detect a violation of the primary seal 3. However, it is clear to the expert that the chamber 5 for catching leaks can be the same as in the area of the abutment flange 14 also formed in the contact surface 9, which is pressed against the surface of the contact edge 14.

The advantage of the flange joint according to this technical solution is that the secondary seal 4 in such a situation takes over the role of the primary seal 3 and further ensures the tightness of the flange joint until the next shutdown, when the flange joint is disassembled and the primary seal 3 is replaced. The flanges are pulled together by fasteners.

In fig. 3 then shows a flange joint according to another possible embodiment of this technical solution, which is similar to the embodiment in fig. 1, but where the second flange 2 is in the form of an L-piece, that is, this flange also has the function of changing the direction of the outlet neck 11 compared to the inlet neck 10 of the first flange 1, usually by 90°, but the angle can vary from 0° to 90°. However, other versions of one or both flanges are also possible, where the requirement is that the assembly meets the requirements for adjusting the direction of the outlet pipe according to the connecting pipe. In fig. 3 are identical elements from fig. 1 or 2 marked with the same reference numerals.

fig. 4 represents another example of the implementation of a flange connection according to this technical solution with the necks of both flanges arranged on the same axis. In fig. 4 are identical elements from fig. 1 to 3 denoted by the same reference numerals.

In fig. 1 to 4 are the connecting elements of the flange joint according to this technical solution, formed by individual bolts 7, screwed into the second flange 2, and nuts 8. However, another design is also possible, e.g. as long as both flanges are equipped with through holes, it is possible to use screws with nuts, etc.

The flange joint according to this technical solution is shown in fig. 1 to 4 functionally created as follows:

The medium from the first pipeline enters the first flange 1 of the flange connection through the inlet port 10. The primary seal in the secondary power flow is compressed by both flanges (1, 2), pulled together by the connecting means, and by the effect of specific pressure on the front surfaces of the seal, it creates a pressure barrier. In the event of damage to this primary seal or due to a low specific pressure on the seal, media may leak into the chamber between the primary and secondary seals. From this chamber, a sampling is carried out to the pressure sensor, identifying in time a potential leak of the primary seal. Due to the high tightness of the secondary seal, this creates a sufficient barrier against possible leakage of the medium, despite the possibly damaged primary seal.

It is clear to the person skilled in the art that the terms first flange and second flange are used only to distinguish them from each other, and that the first flange may therefore include an outlet port, while the second flange may include an inlet port, in contrast to the described embodiments. Furthermore, it is clear to the expert that, e.g. the first flange can be equipped with a bearing surface, while the second flange is equipped with a bearing flange. It is also clear to the expert that it is possible to create chambers for primary and secondary sealing in the opposite flange as well. All these implementations still fall within the scope of this technical solution.

Industrial applicability

The practical use of the proposed solution is mainly considered for the replacement of current heterogeneous welded joints - primarily for power plants with pressurized water reactors, which show volume defects of the crack type after several years of operation - for several physical reasons, which in principle cannot be ruled out. A flange connection of a similar design can also be used in other technological systems in which the connection of pipes made of different materials with difficult weldability is required. The designed flange joint significantly increases the safety and service life of the heterogeneous joint, as it eliminates the risk of uncontrollable cracks in the current heterogeneous weld joints and at the same time eliminates possible media leaks even in case of damage to the primary seal. At the same time, this joint is created to transmit high force and moment effects comparable to a welded joint.

List of reference marks first flange second flange primary seal secondary seal chamber for catching leaks outlet for measuring possible leakage in case of damage to the primary seal bolt nut bearing surface inlet throat outlet throat chamber for primary seal chamber for secondary seal mounting flange gap between plug flanges

Claims (11)

CLAIMS FOR PROTECTION 1. A flange joint for connecting two pipelines made of mutually difficult-to-weld materials comprising a first flange (1) equipped with an inlet port (10) made of a first material belonging to the same material group as the first pipe and a second flange (2) equipped with an outlet port (11) made of from the second material, belonging to the same material group as the second pipe, these flanges (1, 2) are equipped with connecting means to ensure mutual connection of both flanges (1, 2), characterized in that the first or second flange (1, 2) is equipped with a mounting flange (14), while the other of these flanges (2, 1) is equipped with a mounting surface (9) arranged opposite the mounting flange (14), while the mounting flange (14) is closer to the center of the flange (1) , 2) equipped with a chamber (12) for the primary seal (3) in the side power flow, while at its edge further from the center it is equipped with a chamber (13) for the secondary seal (4) in the side power flow, while the first flange (1) and the second flange (2) are designed to fit only in the surface of the bearing edge (14) of the first or second flange (1, 2) with the bearing surface (9) of the second of these two flanges while ensuring the transfer of force and moment loads between both flanges with a gap (15) in the remaining area of the flanges to ensure deformation of the flanges and create the required prestressing of the connected flanges. 2. A flanged joint according to claim 1, characterized in that a chamber (5) is created in the area of the seating flange (14) or the seating surface (9) between the primary seal (3) and the secondary seal (4) for catching leaks, while this the chamber (5) for catching the leak is equipped with an output (6) for signaling the loss of the primary seal by increasing the pressure in this space. 3. Flange joint according to claim 2, characterized by the fact that the output (6) for signaling the leakage of the primary seal is equipped with a pressure sensor for signaling the increase in pressure in the chamber (5) for capturing leaks to identify any leakage. 4. A flange connection according to claim 2, characterized in that the output (6) for signaling the loss of a primary seal leak is a remote pressure tap. 5. Flange joint according to one of claims 1 to 3, characterized in that the connecting means are arranged near the chamber (13) for secondary sealing. 6. A flange connection according to one of claims 1 to 3, characterized in that the inlet port (10) of the first flange (1) and the outlet port (11) of the second flange (2) are arranged in different axes to enable the connection of two non-aligned pipelines . 7. Flange connection according to one of claims 1 to 5, characterized in that the chamber (12) for the primary seal and the chamber (13) for the secondary seal are formed in the flange (1, 2) equipped with a fitting flange (14). 8. Flange connection according to one of claims 1 to 5, characterized in that the chamber (12) for the primary seal and the chamber (13) for the secondary seal are formed in the flange (1, 2) equipped with a bearing surface (9). 9. Flange connection according to one of claims 1 to 5, characterized in that the primary sealing chamber (12) is formed between the first flange (1) and the second flange (2), while the secondary sealing chamber (13) is formed in the first flange (1) and/or in the second flange (2). 10. A flange joint according to one of claims 1 to 9, characterized in that the chamber (12) for the primary seal and the chamber (13) for the secondary seals are created with a height 30% lower than the height of the respective seal (3, 4 ) in the uncompressed state, arranged in the given chamber (12, 13). 11. Flange joint according to one of claims 1 to 8, characterized in that the flange (1, 2) arranged opposite the flange (2, 1) by the chamber (13) for secondary sealing is equipped with a projection forming a tongue, which extends into this chamber ( 13) to create a tongue-groove connection, while the height of the chamber (13) is increased by the height of the protrusion.