Leak detection device and method for a connector assembly connecting two hydraulic elements conveying molten salts

Abstract

The invention relates to a leak detection device for characterizing a connector assembly (2) interconnecting two hydraulic elements, which has a test pipe (1) comprising a blind-end first portion (C1) and a second portion (C2) coupled to the first portion via the connector assembly, the second pipe portion being pressurized under light gas, the test pipe containing a predetermined quantity of molten salts (SF), the device comprising dynamics of movement of the test pipe, which is movable between a first position (P1) in which the connector zone (Z2) is immersed in the molten salts contained in the test pipe and a second position (P2) in which the connector zone is not immersed in the molten salts but is subjected to the light-gas pressure, the device comprising a sealed chamber (3) containing at least the connector.

Description

[0001] Device and method for leak detection for a fitting assembly connecting two hydraulic elements conveying molten salts

[0002]

[0001] The present invention relates to a leak detection device for a fitting connecting two hydraulic elements, such as, for example, hydraulic lines. Particular interest is given to cases where lines and / or pipes carry, in service, physico-chemically aggressive liquids, such as molten salts at high temperatures.

[0003]

[0002] The present invention also relates to a leak detection method for a fitting connecting two hydraulic lines, and more generally two hydraulic elements containing a liquid containing molten salts. The hydraulic elements may be lines, tanks, pumps, buffer vessels, filters, etc.

[0004]

[0003] The hydraulic lines of interest here are configured to convey a fluid, in particular a liquid, from one place to another in an installation that may be more or less complex. An example of an installation of interest here comprises one or more fluid circuits ensuring the transport of fluid in a nuclear power generation unit.

[0005]

[0004] According to a particular example, we are interested in pipes or conduits which transport a fluid of the molten salt type, at high temperatures which are typically in a range between 500°C and 950°C.

[0006]

[0005] When two pipes are connected to each other, a fitting with a sealing gasket is provided to prevent any leakage at that point.

[0007]

[0006] To properly compress the sealing gasket, a flanged assembly is usually used. A first flange presses against the back of a collar on a first pipe and a second flange presses against the back of a collar on a second pipe, the flanges being tightened together, one towards the other, by a plurality of tightening means such as bolts. This type of configuration is illustrated in Figure 1.

[0008]

[0007] It is not excluded to use other types of mounting with for example a clamping sleeve or a system of collars.

[0009]

[0008] It is known to perform basic fitting tests from documents CN217765405U or CN1 15962929.

[0010]

[0009] In the context of a nuclear energy-based installation, it is very important to ensure that the flanged connection system and the sealing gasket will be able to ensure the desired sealing performance throughout the life of the installation, without the possibility of dismantling the assembly thus formed.

[0011]

[0010] The present inventors are developing new solutions for so-called fourth-generation nuclear reactors based on molten salts, and they have designed a device and a method for being able to test a connection configuration joining two hydraulic elements, in particular two coupled pipes intended to convey a flow of molten salt liquid.

[0012]

[0011] To this end, a leak detection device is proposed for characterizing a fitting assembly connecting two hydraulic elements together, the device comprising a test pipeline including a first dead-end pipeline section and a second pipeline section coupled to the first section via the fitting assembly, the second pipeline section being connected to a light gas pressurization system by a light gas inlet, the test pipeline containing a predetermined quantity of molten salts, the device including a kinematic for the movement of the test pipeline, movable between a first position in which the area of ​​the fitting is bathed by the molten salts contained in the test pipeline and a second position in which the area of ​​the fitting is not bathed by the molten salts, but subjected to a light gas pressure,with a continuous passage of gas from the light gas inlet to the connection area, the device comprising a hermetically sealed enclosure containing at least the connection.

[0013]

[0012] If there is a leak at the fitting, while the test pipe is in the second position, light gas will spread into the hermetically sealed enclosure, which has been previously evacuated, and the light gas can be detected, even in minute quantities, by means of a spectrometer such as is known per se.

[0014]

[0013] Thanks to these provisions, it is possible to detect insufficient sealing performance at the connection, while keeping the assembly intact, i.e. without dismantling it.

[0015]

[0014] The detection device allows for tests, including cycling tests, to be carried out, representing and simulating the service life of the fitting assembly. If a leak is detected, the proposed solution is modified, a new design is proposed, and a new test sequence is performed with the new design, and so on until the solution is fully satisfactory.

[0016]

[0015] Advantageously, the light gas can be helium, which is a readily available gas.

[0017]

[0016] Put another way, the leak detection device allows for the characterization of the fitting's sealing performance. A helium leak is detected using a mass spectrometer, which makes it possible to detect even a minute quantity of helium that has leaked through the fitting. The proposed test allows for a very precise characterization of the high sealing performance required for the fitting assembly of interest here.

[0018]

[0017] The molten salts referred to here can be of any nature. It should be noted that the displacement method according to the invention proposed here can even work for any type of liquid and any type of fitting assembly.

[0019]

[0018] It should be noted that in the first position, the connection area is entirely immersed in molten salts at the test pressure. The entire periphery of the seal and the connection assembly is subjected to the physicochemical stresses imposed in particular by contact with the molten salts, which prove to be aggressive from a physicochemical point of view in practice.

[0020]

[0019] According to one embodiment, the two hydraulic elements are respectively two hydraulic pipes.

[0021]

[0020] Many configurations for connecting two hydraulic pipes end to end are found in a power plant type installation, particularly one based on nuclear reaction.

[0022]

[0021] It should be noted that the material of the first hydraulic line may differ from the material of the second hydraulic line, and their thermal expansions may also differ. This can lead to shear stresses on the seal, in addition to compressive stresses. The static and variable stresses on the seal can be quite significant. Differential expansion between the clamping screws and the flanges, particularly along the screw axis (since the screws, flanges, and lines are made of different materials), can cause variations in the clamping force and displacements of the contact surfaces, leading to a risk of poor sealing.

[0023]

[0022] For example, materials such as special steels, nickel-based alloys, ceramics like silicon carbide, or ceramic matrix composites can be considered for the conduits.

[0024]

[0023] According to one embodiment, the fitting is a flanged fitting.

[0025]

[0024] This type of fitting is mentioned and described in the first paragraphs of this document. This type of fitting usually includes a fairly large number of tightening bolts; the tightening order and method can be optimized based on the results obtained from the leak tests proposed herein.

[0026]

[0025] Wherefore, the proposed detection device makes it possible to optimize the geometric configuration of the flanged connection as well as the tightening method of the clamping bolts.

[0027]

[0026] According to one embodiment, the displacement kinematics is formed by a rotation.

[0028]

[0027] A rotating assembly is relatively simple to design and easy to implement.

[0029]

[0028] According to one embodiment, the angular stroke separating the first position from the second position is preferably chosen between 30° and 180°.

[0030]

[0029] According to a particular embodiment, the angular stroke separating the first position from the second position can be between 90° and 120°.

[0031]

[0030] According to one embodiment, the hermetic enclosure pivots with the test pipe.

[0032]

[0031] Consequently, it is not necessary to provide a rotating seal at the boundary between the evacuated volume and the outside. A hermetic enclosure with good sealing can thus be obtained, which can be evacuated to a very high vacuum, e.g., a few hundredths of an atmosphere.

[0033]

[0032] According to one embodiment, one or more pressure probes are provided, the pressure in the test pipeline being controlled by control means. The pressure is controlled in the positive pressurization range of the pipeline during the simulation phase of normal operation of the test pipeline. The pressure is also controlled in the vacuum range within the hermetically sealed chamber for the leak detection phase.

[0034]

[0033] According to one embodiment, one or more heating resistors and one or more temperature probes are provided, the temperature being controlled in the test pipe and / or the hermetically sealed enclosure via control means.

[0035]

[0034] According to one embodiment, the leak detection device includes a vacuum pump to carry out a vacuuming of the hermetically sealed enclosure in order to detect any possible presence of light gas by spectrometry.

[0036]

[0035] According to one embodiment, nitrogen is injected into the hermetically sealed chamber outside of the vacuum-pulling sequences. Repressurizing with nitrogen enables heat exchange between the wall of the hermetically sealed chamber and the flanged fitting assembly, thus contributing to temperature control. Indeed, radiative heat transfer, the only heat transfer vector in a vacuum, is much less efficient.

[0037]

[0036] According to one embodiment, the first portion includes a reservoir volume to house the molten salts when the test pipe is in the second position.

[0038]

[0037] This allows us to minimize the dimensions of the test pipeline for a given volume of molten salts. In other words, we propose a compact solution compared to a linear pipeline solution.

[0039]

[0038] According to one embodiment, the temperature of the molten salts is between 600°C and 950°C. The materials of the test pipe, the fitting assembly and the hermetic enclosure are chosen so that they can withstand such high temperatures.

[0040]

[0039] According to a second aspect, the present invention also relates to a leak detection method for characterizing, particularly in terms of sealing performance, a fitting assembly connecting two hydraulic elements, the device comprising a test pipe including a first dead-end portion and a second portion coupled to the first portion via the fitting assembly, the second pipe portion being connected to a light gas pressurization system by a light gas inlet, the test pipe containing a predetermined quantity of molten salts, the device comprising a hermetically sealed enclosure containing at least the fitting, the method comprising: a- bringing the test pipe, via a kinematic movement of the test pipe, into a first position in which the area of ​​the fitting is bathed by the molten salts contained in the test pipe,c1- Move the test pipe into a second position in which the connection area is not bathed in molten salts, but subjected to light gas pressure, with a continuous flow from the light gas inlet to the connection area, c2- Draw the airtight chamber into a vacuum, c3- Monitor for the possible appearance of light gas molecules in the airtight chamber using a mass spectrometer.

[0041]

[0040] The proposed method is simple, repeatable, and reliable. The sealing performance over the expected service life of the fitting assembly can thus be evaluated.

[0042]

[0041] The process may include a step b- of heating and pressurizing the test pipeline to achieve the physico-chemical stress conditions simulating service conditions.

[0043]

[0042] According to one embodiment, the temperature of the molten salts simulating normal service is between 450°C and 950°C, and the pressure in the test pipeline is between 1 bar and 10 bar.

[0044]

[0043] According to one embodiment, the hermetic enclosure pivots with the test pipeline.

[0045]

[0044] Wherefore, it is not necessary to provide a rotating seal at the boundary between the vacuum-sealed volume and the outside, and a high level of airtightness can be obtained.

[0046]

[0045] In one embodiment, one or more temperature and / or pressure cycles are performed. This allows for a fairly accurate simulation of the stresses experienced in a typical application of a thermal transport circuit using molten salts.

[0047]

[0046] The invention will be further detailed by describing non-limiting embodiments, and based on the accompanying figures illustrating variants of the invention, in which:

[0048] - [Fig.1] illustrates a cross-sectional view of a fitting assembly between two hydraulic pipes, according to two embodiment variants, with or without specific flanges;

[0049] - [Fig.2] schematically represents an example of a leak detection device according to one embodiment;

[0050] - [Fig.3] shows a first example of test piping, according to three different positions, in particular according to the first position of interest, and according to the second position of interest;

[0051] - [Fig.4] shows a second example of test piping, according to the first position of interest;

[0052] - [Fig.5] shows the second example of test piping, according to the second position of interest;

[0053] - [Fig.6] illustrates a third example of test channeling, according to the first position of interest and the second position of interest;

[0054] - [Fig.7] illustrates a flowchart of an example of the process steps;

[0055] - [Fig.8] shows a functional diagram of the gas system and part of the control system.

[0056]

[0047] In the various figures, the same reference numerals designate identical or similar elements. For the sake of clarity, some elements are not necessarily shown to scale.

[0057]

[0048] With reference to Figure 1, a coupling assembly 2 between a first pipe B1 and a second pipe B2 is now described. The pipes are generally of revolution about an axis W. The two pipes are aligned on the same axis W for the purpose of coupling them in an end-to-end position.

[0058]

[0049] A sealing gasket 23 is interposed between the front edges of the pipes. The sealing gasket 23 can, for example, be made from a high-performance elastomer, synthetic or natural.

[0059]

[0050] In the example shown on the left, see Figure 1 (a), each pipe comprises a fairly wide annular flange 25, 26 in which holes 24 are provided. A plurality of holes 24 are distributed around the flange all around the axis W. The two flanges 25, 26 extend radially outwards from the main section of the pipe. The two flanges 25, 26 are joined by bolts 7 received in the holes 24. The number of bolts can range from 8 to 16 without these values ​​being limiting.

[0060]

[0051] In the example shown on the right, see Figure 1(b), each pipe includes an annular flange 29 of smaller radial extension. In this configuration, the flanged assembly 2 comprises a first annular flange 21, which presses against the back of the flange 29 of the first pipe B1, and a second annular flange 22, which presses against the back of the flange 29 of the second pipe B2. The flanges 21 and 22 are clamped together, one in the direction of the other, by a plurality of clamping means, such as bolts. Here too, the bolts, numbering from 8 to 16, are distributed around the flange all around the axis W.

[0061]

[0052] Although a pipe-to-pipe connection has been shown, the coupling assemblies described above can be used to couple a pipe to a tank or to couple a pipe to a pump. In general terms, we are interested in a coupling assembly 2 that allows two hydraulic elements to be coupled together.

[0062]

[0053] We are interested in hydraulic elements, pipes, conduits or tanks which contain and / or transport a fluid of the molten salt type.

[0063]

[0054] The molten salts can be, for example, chlorinated salts or fluorinated salts.

[0064]

[0055] In the illustrated example, molten salts are used as a thermal transport medium in a primary circuit in a 4th generation nuclear reactor. However, molten salt pipes can be used in other applications.

[0065]

[0056] The molten salts are in the liquid phase in the configuration used. However, it should be noted that the molten salts, at room temperature, are in a granular solid state. They must therefore be heated to become liquid.

[0066]

[0057] Molten salts are at high temperatures, typically in the range of 450°C to 950°C. In one application example, the operating temperature of molten salts is in the range of 550°C to 750°C. In another application example, the operating temperature of molten salts can be in the range of 700°C to 850°C.

[0067]

[0058] The operating pressure in the molten salt pipelines is between 1 bar and 10 bar.

[0068]

[0059] Under these conditions, it is very important to ensure that the connection system and the sealing joint which connect the two hydraulic elements concerned will be able to ensure a desired sealing performance throughout the life of the installation, without having the possibility of dismantling the assembly thus formed.

[0069]

[0060] Advantageously, a leak detection device 4, schematically represented in Figure 2 and Figures 3 to 6, is used for this purpose.

[0070]

[0061] The proposed leak detection device includes a test pipe 1.

[0071]

[0062] The test line 1 comprises a first portion C1 and a second portion C2 coupled to the first portion via the fitting assembly. The first portion C1 is a dead end. The second portion C2 is in fluid communication with a light gas pressure source GL. The light gas can be, as in the illustrated example, helium. Of course, another light gas such as argon or another could be used instead of helium.

[0072]

[0063] In the illustrated example, the test pipe 1 contains a predetermined quantity of molten SF salts, which were introduced in the form of solid granules and then heated to liquefy them.

[0073]

[0064] The detection device includes means for heating the second section of the pipeline, particularly where the molten salts are typically located.

[0065] For this purpose, a heating roller 11 is used, which surrounds the second section of the pipeline. In the illustrated example, the detection device is equipped with at least one temperature probe that allows the temperature of the molten salts to be regulated within a desired temperature range.

[0074]

[0066] More specifically, a first temperature probe 18 is planned in thermal coupling with the second portion C2 of the test pipeline 1.

[0075]

[0067] In addition, a second temperature probe 19 can be provided in thermal coupling with the hermetic enclosure 3.

[0076]

[0068] In the illustrated example, the detection device is supported by a frame 6. Bearings 13 are provided to receive a rotation shaft A which serves as the basis for the pivoting kinematics which will be detailed later.

[0077]

[0069] In general, the device is intended to include a kinematic mechanism for moving the test pipe. More specifically, the test pipe can be moved between a first position P1 in which the area of ​​the fitting Z2 is immersed in the molten salts contained in the test pipe and a second position P2 in which the area of ​​the fitting Z2 is not immersed in the molten salts.

[0078]

[0070] Three examples of a pivoting kinematic arrangement are illustrated in figures 3 to 6. Of course, it is not excluded to use other displacement configurations that are not strict rotations.

[0079]

[0071] The first position P1 corresponds to the normal operating position of the fitting assembly. In the first position P1, the fitting assembly 2 is completely immersed in the liquid phase of the molten salts. The area of ​​the fitting Z2 is pressurized by the pressurization provided by the light gas.

[0080]

[0072] The second position P2 allows testing the sealing performance of the fitting assembly, particularly but not exclusively, with regard to the sealing gasket 23.

[0081]

[0073] In the second position P2 the test pipe 1 is subjected to the pressure of light gas GL, with a continuous passage of gas from the light gas inlet 12 to the connection area Z2.

[0082]

[0074] In general, the angular stroke separating the first and second positions P1, P2 can be between 30° and 180°.

[0083]

[0075] The detection device includes a hermetically sealed enclosure 3 containing at least the fitting 2.

[0084]

[0076] The hermetic enclosure 3 pivots with the test conduit.

[0085]

[0077] In the illustrated example, one or more pressure probes are provided. More specifically, a first pressure sensor 44 is provided upstream of the fitting, on the second section of the test pipeline.

[0086]

[0078] The pressure is controlled in the test pipeline.

[0087]

[0079] It is noted that the vacuum line and the pressurization line connected to the second section of the pipeline are flexible lines, which can be deformed by torsion along their axis of extension or by bending, without being damaged and without losing their fluid conductivity. The angle of torsion undergone depends on the angular difference between the first position P1 and the second position P2.

[0088]

[0080] Figure 3 illustrates a configuration where the angular stroke is 180°. In the second position P2, a continuous, free passage GL is created from the gas inlet 12 to the connection zone 2, without the molten salts preventing the pressurized gas from reaching the connection zone Z2 and the sealing gasket. If there is a leak, however small, light gas molecules will escape and enter the hermetically sealed enclosure 3, which has been previously evacuated by the vacuum pump 63.

[0089]

[0081] Figures 4 and 5 illustrate a second configuration where the angular stroke is approximately 45°. In this configuration, the angular stroke is much smaller and the deformation caused on the flexible pipes, the one that supplies the test line with light gas as well as the one that allows the airtight enclosure to be evacuated, is also much smaller.

[0090]

[0082] Figure 6 illustrates a third configuration where the angular stroke is approximately 100°.

[0091]

[0083] Figure 6 also illustrates the trick of using a reservoir-forming volume identified as 42 which makes it possible to reduce the overall dimensions and increase the overall compactness of the arrangement at the same quantity of molten salts and the same geometry of the connection assembly 2.

[0092]

[0084] The operation is identical or similar for the 3 examples of geometric configuration shown in figures 3 to 6.

[0093]

[0085] With reference to Figure 8, the detection device is supported by a support frame 6, here a tubular frame. A rotating shaft 46, which serves as the basis for the pivoting movement around the axis A, is received in two bearings 13 which are fixed to the support frame.

[0094]

[0086] The detection device includes a rotating assembly consisting of the test pipe 1, the hermetic enclosure 3, the temperature probe 19 and heating resistors 14 which can be attached to or integrated into the hermetic enclosure 3.

[0095]

[0087] In the example shown in Figure 8, the test pipe 1 has an L-shaped form with the long branch aligned with the horizontal axis A, and perpendicularly there is the short branch carrying the second portion C2. The position P1 with the short branch downwards is shown in dashed line, while the position P2 with the short branch upwards is shown in solid line.

[0096]

[0088] The detection device includes a control unit designated 5. The control unit 5 is part of an assembly generically called 'control means' which are used to implement the proposed method.

[0097]

[0089] As can be seen in figure 2, the detection device 4 is located with respect to an orthogonal frame of reference as follows: the vertical direction is noted Z, the horizontal direction called longitudinal is noted X, the horizontal direction called transverse is noted Y. The axis A is parallel to X.

[0098]

[0090] It is noted that the rotation of the crew rotating around axis A can be done manually or can be motorized.

[0099]

[0091] The detection device includes a helium reservoir R1, e.g., more generally, a light gas reservoir. Helium is injected into the test line 1 via a connecting pipe 16 and via the light gas inlet 12. The connecting pipe 16 is flexible, i.e., it allows bending and / or torsion. The pipe length is chosen to be sufficiently generous to allow deformation induced by a 180° rotation. The flexible pipe can be formed as a coil or a spiral.

[0092] It is noted that the inlet 12 is in a position close to the axis.

[0100]

[0093] Depending on the pressure available in the helium tank R1, a pressure reduction and regulation device may be used. In the illustrated example, a pump 61 controlled by the control unit 5 is used instead.

[0101]

[0094] The control of the helium pump 61 allows the pressure in the test pipe 1 to be adjusted, in conjunction with the information returned by the pressure probe 44.

[0102]

[0095] The helium pressure dictates the molten salt pressure. Preferably, the pressure used is consistent with the pressure expected under normal operating conditions of the molten salt pipeline. For example, the pressure may be between 1 bar and 10 bar.

[0103]

[0096] At the end of the pressure test sequence in the first position P1, a leak detection sequence is planned.

[0104]

[0097] The presence of light gas is detected by spectrometry, using a mass spectrometer 8.

[0105]

[0098] To do this, the hermetic enclosure 3 is evacuated via the pipe 17 which fluidly connects the internal volume of the hermetic enclosure 3 to the mass spectrometer 8, and to a vacuum pump 63 via an isolation solenoid valve 64.

[0106]

[0099] The vacuum hose 17 is flexible; in practice, it allows for bending and / or twisting. The hose length is chosen to be sufficiently generous to allow for deformation induced by a 180° rotation.

[0107]

[0100] A second pressure probe 45 is provided which measures the pressure in the vacuum draw pipe 17. This second pressure probe can be located in the mass spectrometer apparatus 8.

[0108]

[0101] It is noted that the tapping 17a is in a position close to the axis, the rotation of the rotating assembly essentially causes a deformation of the flexible vacuum pulling hose 17.

[0109]

[0102] According to an optional feature, outside of the leak detection phases, the vacuum of the hermetic enclosure 3 is not allowed to continue. In practice, nitrogen is introduced into the hermetic enclosure in order to promote heat exchange between the wall of the hermetic enclosure and the fitting assembly under test, in order to contribute to the control of the temperature of the fitting assembly under test.

[0110]

[0103] For this purpose, a nitrogen reservoir, labeled R2, is provided. Here too, a pressure regulator can be used if the pressure in the nitrogen cylinder is sufficient. However, in the illustrated example, a pump 62 controlled by the control unit 5 is used instead.

[0111]

[0104] A flexible pipe, designated 47, is provided to connect the nitrogen supply to the internal volume of the hermetically sealed enclosure.

[0112]

[0105] A manual valve or a solenoid valve 67 is provided on this flexible pipe 47 which allows the internal volume of the hermetic enclosure 3 to be properly isolated in order to be able to pull it under vacuum.

[0113]

[0106] The flexible tube 47 is fluidly connected to the hermetically sealed enclosure via a port 48 which is located for example near the axis of rotation.

[0114]

[0107] Regarding the pressure in the test line 1, it is noted that a manual valve or a solenoid valve 65 is provided to selectively supply light gas to the test line 1.

[0108] The temperature in the test line 1 is controlled by the control unit 5.

[0115]

[0109] The second portion C2 of the test pipe 1 is equipped with heating resistors 11 in the form of a coil or winding which follows the outside of the second portion C2 of the pipe.

[0116]

[0110] The hermetic enclosure 3 is equipped with heating elements 14.

[0117]

[0111] These heating resistors 11, 14 are preferably controlled by the control unit 5, which allows the temperature of the test pipe 1 to be regulated within a prescribed temperature range or according to a predetermined temperature cycling.

[0118]

[0112] With reference to Figure 7, the proposed method comprises the following steps, carried out partially or totally by means of the control unit 5: a- bringing the test pipe (rotating assembly), via the kinematics of movement of the test pipe, into the first position P1, b- heating and pressurizing the test pipe 1 to reach the physico-chemical stress conditions simulating the service conditions, (steps a- and b- can be carried out in any order), c1- bringing the test pipe (rotating assembly), into the second position P2, c2- pulling the hermetic enclosure 3 into a vacuum, via the vacuum pump, then if necessary close the isolation valve 64, c3- monitoring for any appearance of light gas molecules in the hermetic enclosure 3 by means of a mass spectrometer 8.

[0119]

[0113] According to another aspect, from a thermal point of view, it may be provided that the flexible pipes 16,17 (and optionally 47) have low thermal conductivity, so that when the test pipeline is brought to temperatures of several hundred degrees, the auxiliary equipment outside the support frame 6 is not overheated and remains at reasonable temperatures.

[0120]

[0114] The same applies to the bearings 13 which support the rotation of the shaft 46 with regard to the rotation kinematics, said bearings 13 and / or the shaft 46 having a low thermal conductivity.

[0121]

[0115] The isolation valves 65 and 67, respectively on the light gas supply pipe 16 and the nitrogen supply pipe 47, can each be supplemented by a non-return valve.

[0122]

[0116] According to one example, the volume of the hermetically sealed enclosure is small, a few tens of cm³ 3 , or even a few litres, although these values ​​are not limiting.

[0123]

[0117] The diameter of the pipes can typically be between 00 mm and 400 mm, without these values ​​being limiting.

Claims

DEMANDS 1. Leak detection device (4) for characterizing a fitting assembly (2) connecting two hydraulic elements together, the device comprising a test pipe (1) comprising a first dead-end portion (C1) and a second portion (C2) coupled to the first portion via the fitting assembly, the second pipe portion being configured to be connected to a light gas (GL) pressurization system by a light gas inlet (12), the test pipe containing a predetermined quantity of molten salts (SF), the device comprising a kinematic for the movement of the test pipe, movable between a first position (P1) in which the fitting area (Z2) is bathed by the molten salts contained in the test pipe and a second position (P2) in which the fitting area is not bathed by the molten salts, but subjected to a light gas pressure,with a continuous passage of gas from the light gas inlet (12) to the connection zone (Z2), the device comprising a hermetically sealed enclosure (3) containing at least the connection (2).

2. Detection device according to claim 1, in which the two hydraulic elements are respectively two hydraulic lines (B1, B2).

3. Detection device according to any one of claims 1 to 2, wherein the fitting is a flanged fitting (21, 22).

4. Detection device according to any one of claims 1 to 3, wherein the displacement kinematics is formed by a rotation, preferably with an angular stroke between 30° and 180° separating the first and second positions (P1, P2).

5. Detection device according to any one of claims 1 to 4, wherein the hermetic enclosure (3) pivots with the test channel (1).

6. Detection device according to any one of claims 1 to 5, wherein one or more pressure probes (44,45) are provided, the pressure in the test pipeline being controlled by control means (5).

7. Detection device according to any one of claims 1 to 6, wherein one or more heating resistors (11, 14) and one or more temperature probes (18, 19) are provided, the temperature being controlled in the test pipe and / or the hermetically sealed enclosure via control means (5).

8. A detection device according to any one of claims 1 to 7, wherein the leak detection device comprises a vacuum pump (63) for evacuating the hermetically sealed enclosure (3) in order to detect a possible presence of light gas by spectrometry.

9. Detection device according to any one of claims 1 to 8, wherein the leak detection device further comprises a nitrogen reservoir (R2) and nitrogen is injected into the hermetically sealed enclosure outside of vacuum-pulling sequences.

10. Detection device according to any one of claims 1 to 9, wherein the first portion comprises a reservoir-forming volume (42) for housing the molten salts when the test pipe is in the second position (P2).

11. Detection device according to any one of claims 1 to 10, wherein the temperature of the molten salts is between 450°C and 950°C.

12. Leak detection method for characterizing a fitting assembly (2) connecting two hydraulic elements together in a leak detection device (4), the device comprising a test pipe (1) including a first dead-end portion (C1) and a second portion (C2) coupled to the first portion via the fitting assembly, the second pipe portion being connected to a light gas (GL) pressurization system by a light gas inlet (12), the test pipe containing a predetermined quantity of molten salts (SF), the device comprising a hermetically sealed enclosure (3) containing at least the fitting, the method comprising: a- bringing the test pipe, via a kinematic movement of the test pipe, into a first position (P1) in which the area of ​​the fitting is bathed by the molten salts contained in the test pipe,c1 - bring the test pipe into a second position (P2) in which the connection area is not bathed in molten salts, but subjected to light gas pressure, with a continuous flow from the light gas inlet to the connection area, c2 - draw the airtight chamber into a vacuum, c3 - monitor for the possible appearance of light gas molecules in the airtight chamber using a mass spectrometer.

13. Detection method according to claim 12, wherein the temperature of the molten salts simulating normal service is between 450°C and 950°C, and the pressure in the test pipe (1) is between 1 bar and 10 bar.

14. A detection method according to any one of claims 12 to 13, wherein the hermetic enclosure (3) pivots with the test channel.

15. A detection method according to any one of claims 12 to 14, wherein one or more temperature and / or pressure cycles are carried out.

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