FI13345Y1 - Flange joint - Google Patents

Abstract

Flange coupling for connection between two pipes made of different materials, which materials are difficult to weld to each other, which flange coupling comprises - a first flange (1), which is equipped with an inlet nozzle (10) and which is made of a first material, which is part of the same material group as the first pipe, and – a second flange (2), which is equipped with an outlet nozzle (11) and which is made of a second material, which is part of the same material group as the second pipe, and both flanges ( 1, 2) are equipped with fasteners for securing the joining of the two flanges (1, 2), characterized in that the first flange (1) or the second flange (2) is equipped with bearing edge (14), and the second of the flanges (2, 1) is equipped with a bearing surface (9), which is arranged opposite to the bearing edge (14), in which bearing edge (14) there is the primary seal (3) chamber (12) which is closer to the center of the flange (1, 2) in the secondary flow and the edge that is further away from the center, the chamber (13) of the plane seal (4) is in the secondary flow, and the first flange (1) and the second flange (2) are intended to be arranged to the area of the bearing edge (14) of the first or second flange (1, 2) against the other of these two flanges against the bearing surface (9), by which it is ensured that forces and torques are transferred between both flanges, and in the remaining area of the flanges there is a gap (15), which ensures the deformation of the flanges and enables the prestressing required for the flanges to be connected.

Description

FLANGE JOINT

The technical solution concerns a heterogeneous flange joint, which preferably replaces the heterogeneous weld joint of two pipes made of different materials, in which case, for example, a corrosion-resistant steel pressure pipe can be connected to a carbon steel pipe, and thus a material transition is achieved without using the standard solution implemented with a heterogeneous weld joint. The device according to this technical solution is particularly advantageously used to form a connection between the nozzle of a steam generator jacket made of pearlitic-ferritic steel or another, for example, carbon steel application, and a pipe made of a different material, such as austenitic corrosion-resistant chromium nickel steel, which are difficult to weld together.

Background of the invention

In some technical applications, large carbon steel equipment is used, but many of the pipes connected to them must be made of corrosion-resistant steel materials due to the relatively high corrosion loss of the materials. Usually, the material transition is carried out at the nozzle immediately next to the carbon steel component with a so-called heterogeneous

N with welded joint. The assembly is rather complicated (in terms of inspections during manufacturing, installation, planning and use), because first a so-called diffusion layer of pearlitic-ferritic steel or bainite must be installed.

E tice to the part made of steel, which prevents itself

S heterogeneous joint deterioration and carbon diffusion hit-

S to silicification and the subsequent formation of carbides due to thermal

N 30 to the area under the callus. However, the solution in question is only used in pipes with a large wall thickness, i.e. more than 9 mm on average. In pipes with a smaller wall thickness, a so-called transition material is used directly in the heterogeneous weld joint, which, however, does not form an equally effective diffusion layer. Normative technical documents of the Association of Mechanical Engineers (NTD

According to A.S.I.), heterogeneous weld joints may not be made in the weld joints of nuclear power plants directly at the installation sites, but only factory-made heterogeneous weld joints are allowed, but this requirement is not possible to comply with in certain cases. However, such a welded joint is exposed to very strong stress due to the different thermal expansion of the two materials and other wear mechanisms, and in the transition area (at the interface between carbon steel and stainless steel) there is also a depletion of alloying substances, and thus in areas under thermal influence damage may occur, especially at the grain boundaries due to different coefficients of thermal expansion and in addition to high loads caused by other wear mechanisms. Therefore, heterogeneous weld joints are very problematic, especially in components exposed to thermal stress, and they often show significant crack-type volume defects after only a few years of use, which is why such joints require renovation or even dismantling by removing the pipe at the weld.

One of several possibilities for heterogeneous weld joints

N of the applications is a weld joint made with a steam generator

A pipe © formed from a carbon steel nozzle in the jacket of N 25 (where the entire jacket of the steam generator is made of carbon steel) and a short corrosion-resistant pipe connected to it

E for the gap that connects both pipes to the condensing vessel, o which is used to measure the water level in the steam generator. = 30 Another typical application is the connection of an impulse pipe made of stainless steel to the pressure take-off points of several components or to large carbon steel pipes.

Flanged joints are available that connect two pipes made of different materials and are equipped with primary flow seals, but they are only used to connect two straight pipe sections. However, such flange connections are not suitable for applications exposed to thermal and pressure stress, such as the aforementioned steam generators. The weakness of such a connection is that the primary flow is exposed to "relaxation", because the steam generator must be alternately started and stopped due to regular maintenance breaks for refueling the reactor, which is why the tightening of the flange connections with a certain torque must be checked regularly. In addition, the seals must be changed at the maintenance intervals specified by the manufacturer. Otherwise, the tightness of the flange joint may suddenly weaken during the operation of the plant, which endangers the safety of the operation of the nuclear power plant.

In the document W02016/066659 published by ALSTOM Technology Itd on 27.10.2015, a direct flange connection is described, which is used to connect two pipes made of heterogeneous materials with two flanges, each of which is made of a different material, which is identical to the pipe attached to that flange, where the shape of the flanges at the inner end forms the first seal when the flanges are placed relative to each other

N and tightened with screws, which gasket is available in an affordable so-

N 25 in the form of vellum supplemented with a second seal surrounding the first seal ©, and said second seal is formed by a metal ring placed in two opposite

Into the two opposite grooves formed in the E side flange. This seal o is only used in a situation where both = 30 flanges are separated from each other, in which case the first seal ä breaks. In order to guarantee tightness, the flange connection in question is preferably equipped with a third seal, which is arranged outside the flanges.

Heterogeneous welded joints have only rarely been replaced by flanged joints, because such joints used in high-pressure pipes, which are exposed to temperatures above 200 *C, are subject to enormous, variable stresses from the connected pipes (both thermal expansion and potential dynamic loads), which would lead very quickly to the deterioration of the sealing properties of standard graphite seals in the primary flow.

The subject of a technical solution

In accordance with the technical solution, a flange connection has been designed that connects two pipes made of different materials, which are difficult to weld together. The connection can be located, for example, directly in one pipe, such as behind the pressure outlet point of an equipment discharge channel made of one material, such as carbon steel, towards a connected branch pipe made of another material, such as corrosion-resistant steel, which materials are difficult to weld together. In this application, pipe means, in addition to the commonly used meaning, any tubular outlet channel of the equipment that enables connection to the nozzle of the flange connection to which another pipe is connected. The flange joint is particularly advantageously connected to the above-mentioned pipes with the help of nozzles, hit-

By getting N. The flange connection is especially advantageously intended

N 25 to replace existing heterogeneous weld joints. 2 The subject of the technical solution is a flange connection according to definition 2 of protection requirement 1, which consists of two flanges with

E manufacturing materials are difficult to weld together. The materials of the individual flanges of the flange joint according to the technical 3 30 decision have been selected from the same material group as one and the other

O the materials of the pipes on the side where the nozzle of each flange > can be welded to the pipe it is connected to.

According to the description of the technical solution, the shape of the two flanges is adapted for use in the primary seal of the secondary flow, which is designed to be especially tight, and in the secondary seal, whose task is to prevent leaks in case of possible damage to the primary seal. In addition, this combination enables the effective detection of potential damage to the 5 primary seal at an early stage (when the leak is very small) by taking out the pressure from the space between the primary seal and the secondary seal. When both seals are arranged in the described way for secondary flow, the flange connection is able to transfer large forces and torques without cyclic loading being applied to the seals, which significantly improves the reliability of the heterogeneous connection.

The flange connection according to the technical solution can be used in systems containing any medium. It is also suitable for all flange materials required by the media in question.

The flange connection according to the technical solution comprises in particular the following parts, which are arranged as a functional unit to guarantee the required operation of the entire system, namely: - the first flange, which is made of a material belonging to the same material group as the material of the first connection of the first pipe;

N - the second flange arranged on the first flange

O 25 opposite to join them together and which is

O made of the same material group as the material of another tube o (for example, an impulse tube); z - secondary flow primary seal; > - secondary flow secondary seal; = 30 - fasteners (bolts and nuts).

N The flange connection according to the technical solution includes special

Preferably between the primary and secondary seals, a leak chamber that collects any leaks that have passed through the primary seal and is equipped with an outlet opening that indicates the deterioration of the tightness of the primary seal. Deterioration of the tightness of the primary seal is indicated by an increase in the pressure in the leakage chamber and then by the detection of a leak in the primary seal. Even more advantageously, the flange joint includes a built-in device integral to the joint, which indicates leaks in the primary seal.

The device is particularly advantageously designed to be connected with the first flange to the pressure outlet of the device, such as a steam generator. The flange of the first one is especially cheaply made of carbon steel.

On the inside of the nozzle, i.e. viewed from the bearing rim to the center, there is a gap in the flange connection that is large enough to ensure that the bearing rim sits securely on the bearing surface between the primary and secondary seals; it is also necessary to take into account the given manufacturing tolerances, so that the contact surface between the bearing edge and the bearing surface is the only contact surface between both flanges, which guarantees the transmission of external forces and torques. Correspondingly, a gap is formed between the flanges, i.e. the space between both flanges outwards from the bearing edge, i.e. towards the edges of the flanges, where the bearing edge meets the bearing surface. In this case, outside the edge of the bearing between the flanges, especially at the fasteners (preferably bolts and nuts),

N of the contact formed by the bearing edge in contact with the bearing surface

The N 25 foxing surface must be the only contact surface between the flanges and the © gap ensures proper pre-tensioning of the fasteners by allowing the flanges to deform as they are tightened

E with clamps. Fasteners can be, for example, bolts o and nuts, bolts with nuts or the like, = 30 which ensure the reliable connection of both flanges to the flange joint as required for such a flange joint.

The assembly of the flange connection according to the invention described above, which has a bearing edge and a bearing surface and a gap between the other surfaces of both opposite flanges, guarantees that after tightening the fasteners, such as bolts and nuts, during operation, the primary and secondary the chamber dimensions of pig seals, especially the height, change as little as possible during operation, because although the seals have a certain recovery ability, this ability weakens significantly as the number of compression and release cycles increases. When the contact stress on the surface of the seal is reduced, the sealing ability of the seal decreases in direct proportion. The higher the pressure of the medium, the stricter the requirements for the contact stress on the seal surfaces. At high pressures, the optimal specific pressure of the seal is about 80 MPa or even more.

In a particularly advantageous embodiment, the height of the chamber of the primary seal is the same as that of the chamber of the secondary seal, and if the thickness of the primary and secondary seals is the same, i.e. about 30 percent greater than the height of the chamber at the beginning of tightening, then the primary seal and secondary seal of the secondary flow are compressed in a controlled manner by tightening the flanges with seals. However, this requirement depends on the mechanical properties of the seals and may differ accordingly, and depending on the type of seal, deviations of about 30 percent from the above-mentioned value

N are possible.

N 25 According to another advantageous application form of the flange joint, the chamber of the primary seal and/or the chamber of the secondary seal is designed in a key and groove style, whereby the recess representing the groove

E is formed on one flange and on the other flange a shoulder representing key 2 is formed, which fits into the recess. Those skilled in the art 3 30 will appreciate that in such a case the height of the chamber is

O should be dimensioned in such a way that the height is increased by the height of the shoulder.

In a particularly advantageous form of application, the fasteners are placed near the secondary seal, or as close as technically possible to minimize unwanted deformations.

The flange connection according to the technical solution is especially suitable for steam generators of VVER-type nuclear power plants, because - the primary seal of the secondary flow is not subjected to varying loads due to varying forces and torques in different operating modes, but is only subjected to the load of the static specific pressure of the graphite ring, which occurs preferably in a key-and-groove type primary seal chamber and resulting from tightening of the joint at the contact surface, which transmits external forces and torques; - also in the secondary flow (preferably in a key and groove type chamber) there is a secondary seal to guarantee complete tightness even when the tightness of the primary seal weakens; - a take-out groove and a take-out opening are preferably formed between the primary and secondary seals to detect possible leaks of the primary seal, and

N thanks to this technical part, it is possible to detect a possible impaired function of the primary seal in time long before the loss of tightness > by using a secondary seal that is dimensioned

E for the same specific pressure (and thus also the

S delle) as a primary seal, formed by a second seal

N 30

O

S The flange connection according to the technical solution can be particularly advantageously installed in the pipe leading to the measuring vessel of the double chamber of the steam generator, where small tédysgraphite rings are especially advantageously installed as seals in both chambers instead of the current heterogeneous connections due to the small dimensions required for the flange connection. If in other applications the grooves are larger or wider in diameter, spiral or comb profile seals can still be used in the secondary flow instead of only full oraphite seals.

The flange joint can have nozzles on both flanges preferably arranged in the shape of the letter Z2, where the outlet opening of the flange joint is at a different level than the inlet channel in order to avoid inaccuracies in the nozzle gaps and to adjust the height of the double chamber measuring vessel during assembly.

Another advantage of the flange connection according to the technical solution is that it makes it possible to implement both flanges with different nozzle wall thicknesses, for example the flange on the side of the steam generator can have a clearly larger nozzle wall thickness to guarantee sufficient strength against significant corrosion of the inner surfaces, i.e. the wall thickness decrease, in case or if there is a need to transfer large forces or torques.

Thanks to the collection of possible leaks that have passed through the successive seals and the primary seal, the advantage of the flange connection according to the technical solution is the possibility of implementing a leak-

N already stated by doing when installing the flange joint

N 25 pressure test in the space between the primary and secondary seals. In this case, the risk of possible leaks is avoided in the entire system in which = the flange connection is installed, for example the steam in question

E in connection with commissioning of the power plant's power plant including the generator.

S 30 Another advantage is the possibility of monitoring possible primary sealing

I make leaks during the operation of a system containing a flange connection.

The final dimensioning of all functional surfaces and suggestions regarding suitable shapes are made based on information that depends, among other things, on the manufacturing material of the seals and information on the maximum forces and torques applied to both flanges of the joint, obtained through stress analysis.

However, for a first approximate estimate, the basic conditions for dimensioning can be drawn up as follows: - The diameter of the primary seals must be as small as possible, and the primary seal must 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 recovery ability of the seal is at least four times the thermal expansion of the joint in the seal chamber. - The width of both gaskets should be approximately the same as their height in the compressed state, but it should not be excessive to guarantee a sufficient specific pressure of the gasket.

The advantages of the flange connection according to the technical solution compared to the current level of technology are the following, when the following issues are especially taken into account: - The flange connection is very reliable, even if

N distends large forces and torques (which are ver-

Available for the load capacity of welded joints).

O m 25 - The secondary seal prevents medium leaks, even if the primary seal is damaged. j - In the advantageous application form of the flange connection, the chamber between the primary and 2 secondary seals enables the primary

N early detection of leaks through the seal.

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> 30 - The flange connection advantageously allows the inlet and outlet nozzles to be placed on different axes, so that the flange connection can be installed in pipes that are not on the same axis. - Both flanges are shaped in such a way that they can be manufactured using die forging technology and only a small part of their surfaces have to be machined. = During installation, the tightness of the flange connection can be tested from the outlet in the space between the primary and secondary seals, in which case leaks can be avoided and the power unit does not need to be switched off when starting normal operation. - Thanks to the secondary seal, the flange connection can be used safely without external leaks of the medium until the next maintenance break, even if the primary seal is damaged. - The possibility to check the tightness regularly during maintenance breaks of the power unit without emptying the steam generator where the flange connection is installed. - Thanks to the inexpensive application form, where the flange joint can be used in pipes that are not on the same axis, the flange joint according to the technical solution is also suitable for areas where there is little space and where until now heterogeneous weld joints have had to be used.

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S The flange connection according to the technical solution is particularly suitable

Preferably for connecting the double-chamber measuring vessel used for measuring the liquid level of the secondary circuit of the steam generator. z The flange joint according to the technical solution is mainly used > to improve the safety, service life and reliability of heterogeneous joints in nuclear power plants, where such

There are quite a lot of N toxins, but they can be used in all of them

S 30 in technical processes that require the joining of two different materials. A flange connection can be particularly advantageous to replace the connection between two pipes that are difficult to weld together, or to be used in areas where possible medium leaks need to be detected during operation before they become large.

Description of drawings

In order to illustrate the object of the technical solution more clearly, drawings are briefly described below, which show examples of application forms. It is obvious that the drawings describe only some, but not all, application forms of the presented utility model, and an expert in the field can prepare other application form examples and drawings without creative work. The patterns in the drawings show the following:

Figure 1 - a picture of a Z-shaped flange connection that enables the connection of non-concentric pipes

Figure 2 - cross-sectional view of the flange connection on the plane passing through its middle, perpendicular to the connection plane of both flanges

Figure 3 — a picture of an L-shaped flange joint that is installed in pipes that are at a 90 degree angle to each other

Figure 4 - a picture of a flange connection, which is installed in the same

N for central pipes &

O Examples of technical solution application forms 2 25 An example of a possible application form is described below

E dosta, which helps to understand 2 flanged joints built according to the technical solution. Although the technical solution 3 in question is described below with the help of certain application forms, it does not

O is in no way limited to the application forms described here. The protection requirements attached to Ai- > 30 limit the technical solution. Examples of the application forms of the flange connection according to the technical solution are shown in the pictures only as diagrams and are not limited to the described application forms of the flange connection. For illustration purposes, the size of certain parts of the embodiments shown in the drawings may have been enlarged or they are not to scale. Therefore, the dimensions and relative dimensions do not correspond to the actual sizes. In addition, the terms "first", "second" and similar terms appearing in the explanation and in the protective claims are used to distinguish similar parts from each other and their purpose is not necessarily to describe the sequence or temporal order, status or mutual order of superiority of the parts, unless otherwise stated or unless it is according to their intended use. Although certain forms of application of the technical solution described here contain certain parts but not others, which are nevertheless included in other forms of application, combinations of parts of different forms of application are possible, as they fall within the scope of the technical solution and form other than those described in this document application forms that are completely understandable to experts in the field. For example, in the following protection requirements, all application forms subject to the protection requirements can be used in all kinds of combinations. The expert understands that other applications of the flange connection according to the technical solution are also possible and some of them are described

N in examples and figures. The application form examples represent

O 25 therefore only a few possible forms of application, and not

This should be understood as limiting the technical solution to the described application forms. The expert can also add other parts to the aforementioned parts without changing the content of the invention. However, all these forms of application belong to the field of technical = 30 solutions, which are limited only by security requirements. > Figure 1 shows a flange connection according to one application form of the technical solution, which is designed for pressure system technology, for example for extracting pressure medium from a carbon steel pressure vessel of a steam generator through a connection opening to a corrosion-resistant pipe via a flange connection. In the example of the application form in Figure 1, one of the flanges is in the shape of a Z body, in which case the axis of the inlet nozzle of the flange connection is not identical to the axis of the outlet nozzle. This type of nozzle assembly of the flange connection enables the nozzle to be placed particularly advantageously at the required height by rotating the entire flange connection in the pipe to be connected during installation. The distance between the axes is arbitrary. For design reasons, it is not necessarily advantageous to place the discharge nozzle too far from the outer edge of the flange. Figure 1 shows the first flange 1, which is equipped with an inlet nozzle 10, and the connected second flange 2, which is equipped with an outlet nozzle 11, and both flanges 1,2 are connected with fasteners, represented here by bolts 7 and nuts 8. The flange connection also has adapted outlet 6, which indicates leaks of the primary seal. In the application form shown in Figure 1, the flange connection also includes a plug 16. In this example, the plug closes a hole made through the second flange 2 perpendicular to the discharge nozzle 11, which is used to create a cavity that connects the discharge nozzle 11 of the second flange 2 with the cavity of the first flange 1, which is connected to the inlet nozzle 10 to ensure the fluid connection from the inlet nozzle 10 of the flange connection to the outlet nozzle

N meen 11. The expert understands that the method in which another

A cavity is formed in the body of O 25 flange 2, it is only advantageous

O from the manufacturing point of view, but not the only possible method. According to the examples of the application form of the flange connection, which are not z described here, it is possible to form such connections, for example, with suitable forms of flanges, casting ai- = 30 or other methods of processing the material. In such a case

N sess, the desired cavity is formed outside the air flange

S opening hole, which makes the plug 16 unnecessary in the flange connection. The expert also understands that the described inlet nozzle of the flange can also function as an outlet nozzle and, accordingly, the outlet nozzle can be used as an inlet nozzle. Correspondingly, the expert understands that the fasteners can also be of other types, such as screws passing through the holes made through the second flange and the first flange, or other parts that guarantee a reliable connection of both flanges.

Figure 2 shows a cross-sectional view of the flange connection according to the technical solution shown in Figure 1. The parts of Figure 2 which are the same as in Figure 1 are marked with the same reference numbers. Thus, the flange connection includes the first flange 1 and the second flange 2, and the second flange 2 is equipped with a bearing rim 14, while the first flange 1 is equipped with an opposite bearing surface 9. A gap 15 is made in the flanges 1,2 outside the bearing rim 14 for the bearing rim in order to get the nut 14 properly in contact with the bearing surface 9 and to tighten the flanges 1,2 to each other, because deformations may occur in the flanges 1,2 when tightening with fasteners. The bearing surface 9 and the bearing edge 14 are designed to guarantee the transfer of forces and torques between the flanges 1,2. In the first flange 1 and/or in the second flange 2, next to the bearing edge 14 or the bearing surface 9, a primary seal chamber 12 is formed, in which the primary seal 3 is placed, and the primary seal chamber 12 is in this example of the application form of the flange connection according to the technical solution shaped

N dosted actually on the adjacent edges of both flanges

between O 25, so both flanges participate in its formation

Oh there. A person skilled in the art will understand that the primary seal chamber 12 o can be formed similarly to the secondary seal chamber 13 z in either flange, as described below. Fig. > part 2 shows the secondary seal 30 chamber 13 formed in the second flange 2 and the secondary seal 4 fitted to it.

A chamber 5 is formed in the area of the border 14 between the chamber 12 of the primary seal and the chamber 13 of the secondary seal 5 to collect leaks. This leak chamber 5 is connected to the outlet 6, which is used to measure possible leaks in case of possible damage to the primary seal 3. An appropriate sensor is included in the outlet 6, which indicates the increase in pressure in the leakage chamber 5. If the primary seal 3 is damaged, the pressure in the leakage chamber 5 rises, which registers on the sensor, thanks to which damage to the primary seal 3 is detected. The expert understands, however, that the leak collection chamber 5 can be formed in addition to the area of the bearing rim 14 also in the bearing surface 9, which is pressed against the surface of the bearing rim 14.

The advantage of the flange joint according to the technical solution is that in such a case, the secondary seal 4 starts to function as the primary seal 3 and continues to guarantee the tightness of the flange joint until the next maintenance break, when the flange joint is dismantled and the primary seal 3 is replaced. The flanges are tightened together with clamps.

Figure 3 shows a flange connection according to another possible application form of the technical solution, which is similar to Figure 1 but where the second flange 2 is in the shape of the letter L, thanks to which the flange is able to change the direction of the outlet nozzle 11 with respect to the inlet nozzle 10 of the first flange 1 usually by 90 degrees , and the angle can vary between 0 and 90 degrees. However, one or both flanges also have other possible applications for situations where the assembly requires that the direction of the discharge nozzle corresponds to

In the direction of the given pipe. The parts of Fig. 3 which are the same as

O 25 in figures 1 and 2, are marked with the same reference numbers.

O Figure 4 shows another example of the application form of the flange joint according to the technical solution o, where the nozzles of both z flanges are arranged on the same axis. Parts of Fig. 4 which are the same as in Figs. 1-3 are designated by the same = 30 reference numerals.

N In Figures 1-4, the flange connection according to the technical solution

Its fasteners consist of individual bolts 7, which are screwed into the second flange 2 and nuts 8. Another type of construction is also possible, for example one where both flanges have through holes, in which case, for example, mounting bolts and nuts can be used.

In Figures 1-4, the flange connection according to the technical solution is designed functionally as follows:

The medium from the first pipe arrives at the first flange 1 of the flange connection through the inlet nozzle 10. The primary seal of the secondary flow is compressed by both flanges (1,2), which are tightened together with fasteners, which forms a pressure barrier due to the effect of the specific pressure on the front surfaces of the seals. If the primary seal is damaged or a low specific pressure is applied to the seal, medium may leak into the chamber between the primary and secondary seals. The chamber in question has an outlet for a pressure sensor to detect leaks in the primary seal in time. Due to the high tightness of the secondary seal, the secondary seal prevents possible medium leaks sufficiently, even if the primary seal is damaged.

A person skilled in the art will understand that the terms "first flange" and "second flange" are only used to distinguish the parts from each other, so the first flange may comprise an outlet nozzle and the second flange may comprise an inlet nozzle, unlike in the embodiments described here. The expert also understands that, for example, the first flange can be fitted to the bearing surface and the second flange can be equipped with a bearing edge. Expert

N understands accordingly that the primary seal and the secondary seal

O 25 chambers can be formed in opposite flanges. All

However, these forms of application fall within the scope of this technical solution. = a

S Industrial applications

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N 30 Practical applications of the proposed solution are especially the replacement of existing heterogeneous weld joints, especially in nuclear power plants using pressurized water reactors. In such joints, after a few years of use, crack-type volumetric defects occur, which are caused by several physical reasons and which, as a rule, cannot be prevented. Structurally similar flange joints can be used in other technical systems where it is required to connect pipes made of different materials that are difficult to weld together. The proposed flange joint improves the safety and service life of the heterogeneous joint, as the risk of uncontrollable cracks occurring in current heterogeneous weld joints and media leaks due to damage to the primary seal can be prevented. However, the joint in question is designed to transfer large forces and torques comparable to welded joints.

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List of reference numbers: 1 First flange 2 Second flange 3 Primary seal 4 Secondary seal 5 Leakage chamber 6 Drain opening for measuring leaks in case of damage to the primary seal 7 Bolt 8 Nut 9 Bearing surface 10 Inlet nozzle 11 Outlet nozzle 12 Primary seal chamber 13 Secondary seal chamber

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& 15 14 Bearing flange — 15 Gap between flanges

I Jami o o 16 Tulppa o +

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Claims (11)

PROTECTION REQUIREMENTS 1. A flange joint for connecting two pipes made of different materials, which materials are difficult to weld together, where the flange joint includes - a first flange (1) equipped with an inlet nozzle (10) and made of a first material belonging to the same material group as the first pipe, and - a second flange (2) equipped with a discharge nozzle (11) and made of another material belonging to the same material group as the second pipe, both flanges (1,2) are equipped with fasteners to ensure the interconnection of both flanges (1,2), known that the first flange (1) or the second flange (2) is equipped with a bearing rim (14), and one of the flanges (2,1) is equipped with a bearing surface (9) arranged opposite the bearing rim (14), where in the bearing rim (14) is on the edge closer to the center of its flange (1,2) the chamber (12) of the primary seal (3) in the secondary flow and on the edge further from its center is the chamber (13) of the secondary seal (4) in the secondary flow, and the first flange (1) and the second flange ( 2) is intended to be fitted to the area of the bearing edge (14) of the first or second flange (1,2) against the bearing surface (9) O 25 of one of these two flanges, which ensures the transfer of forces and torques 5 between both flanges, and in the area left behind the flanges 0 there is a gap (15) which guarantees the deformation of the flanges and enables the formation of the required pre-tensioning of the flanges to be connected. 3 30 N 2. A flange connection according to protection claim 1, characterized in that in the area of the bearing rim (14) or bearing surface (9) between the primary seal (3) and the secondary seal (4) there is a leakage chamber (5) formed for the collection of leaks, and the leakage chamber (5) is equipped with an outlet (6), which gives a signal about the loss of tightness of the primary seal when the pressure in the space in question increases. 3. A flange connection according to protection claim 2, characterized in that the outlet opening (6) intended for indicating the loss of tightness of the primary seal is equipped with a pressure sensor that indicates the pressure increase in the leakage chamber (5) in order to detect a possible leak. 4. Flange connection according to protection requirement 2, characterized in that the outlet opening (6) intended for indicating the deterioration of the tightness of the primary seal is a separate pressure outlet. 5. A flange connection according to one of the protection requirements 1-3, characterized in that the fasteners are arranged near the chamber (13) of the secondary seal to minimize unwanted deformations. 6. A flange connection according to one of the protection requirements 1-3, characterized in that the inlet nozzle (10) of the first flange (1) and the outlet nozzle (11) of the second flange (2) are arranged on different axes to connect two pipes on different axes. No. 25 N 7. A flange connection according to one of the protection requirements 1-5, O characterized by the fact that the primary seal chamber (12) and S the secondary seal chamber (13) are formed in the flange (1,2), E which is equipped with the bearing edge (14). 2 30 3 8. A flange connection according to one of the protection requirements 1-5, O characterized in that the primary seal chamber (12) and > the secondary seal chamber (13) are formed in the flange (1,2), which is equipped with a bearing surface (9). 9. A flange connection according to one of the protection claims 1-5, characterized in that the primary seal chamber (12) is formed between the first flange (1) and the second flange (2), and the secondary seal chamber (13) is formed in the first flange (1) and/or to the second flange (2). 10. A flange connection according to one of the protection requirements 1-9, characterized in that the height of the primary seal chamber (12) and the secondary seal chamber (13) is 30% lower than the height of the corresponding seal (3,4) in the non-compressible state when fitted to that chamber (12,13). 11. A flange connection according to one of the protection requirements 1-8, characterized in that the flange (1,2), which is arranged against the flange (2,1) equipped with the chamber (13) of the secondary seal, is equipped with a shoulder that forms a key that fits into that chamber (13) forming a key and groove - joint where the height of the chamber (13) has been increased by the height of the shoulder. 0 N O N 5 LO O I Jami a o O 5 N N O N D