Helium leak test jig and helium leak test method using same

Abstract

This helium leak test jig comprises a plate, a first seal disposed so as to protrude from a first surface of the plate so as to surround the periphery of a predetermined first region on the first surface, and a second seal disposed so as to protrude from the first surface so as to surround the periphery of a predetermined second region set so as to surround the first region on the first surface of the plate. In a state in which the first seal and the second seal are in contact with the surface of a test object, a space defined by the first region of the plate, the inner surface of the first seal, and the surface of the test object is configured as a pressurized space to which helium gas is supplied, and a space defined by the second region of the plate, the outer surface of the first seal, the inner surface of the second seal, and the surface of the test object is configured as a decompression space for adhering to the test object.

Description

Helium leak test jig and helium leak test method using the same

[0001] The present disclosure relates to a helium leak test jig and a helium leak test method using the same.

[0002] Leak testing methods using helium are known for conducting leak tests on welds, etc. For example, in leak testing of storage tanks such as liquefied hydrogen tanks, the sniffer method is used, in which the inside of the tank is pressurized by filling it with helium gas, and a detector that detects helium gas leaking from the tank is brought close to the outer surface of the tank to conduct the leak test.

[0003] Furthermore, Patent Document 1 below shows an example in which a jig including a plate and a seal rubber is used for leak testing of a workpiece such as an engine cylinder block. By using such a jig, an airtight space can be created even if there is no airtight space filled with helium gas inside the workpiece.

[0004] Japanese Patent Application Laid-Open No. 2019-219216

[0005] However, the conventional sniffer method has a problem in that a large amount of helium is required to fill a sealed space such as the inside of a tank. Helium is difficult to obtain and expensive. Even in leak tests using a jig such as that described in Patent Document 1, the volume of the sealed space depends on the shape of the workpiece, so there is room for improvement in reducing the amount of helium used.

[0006] Therefore, an object of the present disclosure is to provide a helium leak test jig that can reduce the amount of helium used in a leak test using helium, and a helium leak test method using the same.

[0007] A helium leak test jig according to one aspect of the present disclosure comprises a plate, a first seal protruding from the first surface of the plate so as to surround a predetermined first region on the first surface, and a second seal protruding from the first surface of the plate so as to surround a predetermined second region on the first surface of the plate that is set to surround the first region, wherein when the first seal and the second seal are in contact with the surface of a test object, the space defined by the first region of the plate, the inner surface of the first seal, and the surface of the test object is configured as a pressurized space into which helium gas is supplied, and the space defined by the second region of the plate, the outer surface of the first seal, the inner surface of the second seal, and the surface of the test object is configured as a depressurized space that brings the plate into close contact with the test object via the first seal and the second seal.

[0008] A helium leak test method according to another aspect of the present disclosure is a helium leak test method for testing whether or not there is an unacceptable leak at a welded portion of a test object having a welded portion, the method including: placing a test jig including a plate, a first seal arranged to protrude from the first surface of the plate so as to surround a periphery of a predetermined first region on the first surface of the plate, and a second seal arranged to protrude from the first surface of the plate so as to surround a periphery of a predetermined second region set to surround the first region on the first surface of the plate, and positioning the first seal and the second seal so that the welded portion of the test object is positioned opposite the first region. The test jig is installed by abutting the second seal against the surface of the test object, and air is sucked out from within a reduced pressure space defined by the second region of the plate, the outer surface of the first seal, the inner surface of the second seal, and the surface of the test object to bring the test jig into close contact with the test object, and helium gas is supplied to the pressurized space defined by the first region of the plate, the inner surface of the first seal, and the surface of the test object to pressurize the pressurized space, and a helium detector that detects helium gas is brought close to the back side of the test object to perform a leak test on the region of the test object facing the pressurized space based on the detected amount of helium gas.

[0009] According to the present disclosure, the amount of helium used in a leak test using helium can be reduced.

[0010] Fig. 1 is a diagram showing a schematic configuration of a test jig used in a helium leak test method according to an embodiment of the present disclosure. Fig. 2 is a diagram showing a cross-sectional view of the test jig shown in Fig. 1 taken along line II-II. Fig. 3 is a diagram showing a schematic configuration of a helium leak test system using the test jig shown in Fig. 1. Fig. 4 is a flowchart showing the procedure for a helium leak test using the helium leak test system shown in Fig. 3. Fig. 5 is a diagram showing the test jig shown in Fig. 2 before and after decompression.

[0011] A helium leak test method according to an embodiment of the present disclosure will be described below. Fig. 1 is a diagram showing a schematic configuration of a test jig used in the helium leak test method according to an embodiment of the present disclosure.

[0012] As shown in FIG. 1 , the test jig 1 includes a plate 10, a first seal 11, and a second seal 12. The plate 10 is a plate-shaped member made of a metal such as aluminum or a resin such as acrylic. As described below, the surface PO of the test object 2 is not necessarily flat, so it is desirable for the plate 10 to be flexible so as to conform to the shape of the surface PO of the test object 2 to some extent. When the plate 10 is made of resin, the resin may be transparent. Because the plate 10 is transparent, as described below, when the test jig 1 is brought into close contact with the test object 2, it is possible to visually check whether there are any areas where the first seal 11 and the second seal 12 are not properly airtight. The first seal 11 and the second seal 12 are made of a resin such as a polyolefin-based thermoplastic resin.

[0013] The plate 10 has a rectangular first surface P1 and a second surface P2 opposite to the first surface P1. The first surface P1 is shown in Fig. 1. The shape of the plate 10 may be various shapes such as a square, a polygon, or a circle.

[0014] The first surface P1 of the plate 10 includes a central first region A1 and a second region A2 surrounding the periphery of the first region A1. The first region A1 is set as a rectangular region with rounded corners. The first seal 11 is arranged to surround the periphery of the first region A1. The second seal 12 is arranged to surround the periphery of the second region A2. The second seal 12 is arranged at the end of the plate 10. In this way, the first region A1 is the region surrounded by the first seal 11 on the first surface P1 of the plate 10, and the second region A2 is the region between the first seal 11 and the second seal 12 on the first surface P1 of the plate 10.

[0015] In this embodiment, the plate 10 has seal guides 13a, 13b, 13c, and 13d arranged on both widthwise sides of the first seal 11 and the second seal 12. The seal guides include an inner first seal guide 13a protruding from the first surface P1 on the inside of the first seal 11, an outer first seal guide 13b protruding from the first surface P1 on the outside of the first seal 11, an inner second seal guide 13c protruding from the first surface P1 on the inside of the second seal 12, and an outer second seal guide 13d protruding from the first surface P1 on the outside of the second seal 12. That is, the first seal 11 is arranged between the inner first seal guide 13a and the outer first seal guide 13b, and the second seal 12 is arranged between the inner second seal guide 13c and the outer second seal guide 13d. The first seal 11 and the second seal 12 are fixed to the first surface P1 of the plate 10, for example, with an adhesive or the like. These seal guides 13a, 13b, 13c, and 13d are formed in a rectangular shape with rounded corners. Therefore, the first seal 11 and the second seal 12 arranged along the seal guides 13a, 13b, 13c, and 13d are also arranged in a rectangular shape with rounded corners. The position of the first seal 11 is guided by the seal guides 13a and 13b, and the position of the second seal 12 is guided by the seal guides 13c and 13d.

[0016] FIG. 2 is a cross-sectional view taken along the line II-II of the test jig shown in FIG. 1 . FIG. 2 shows the test jig 1 installed on the test object 2. The test object 2 includes, for example, a tank inner shell member including a welded portion. For example, the inner shell of a spherical liquefied hydrogen tank is formed by welding multiple inner shell plates together into a ring shape and then welding multiple ring-shaped inner shell members together in the vertical direction. The helium leak test of this embodiment can be performed on any of these welds. That is, the helium leak test of this embodiment can be performed in any of the following states: two inner shell plates are welded together; a ring-shaped inner shell member is formed; and the inner shell of the liquefied hydrogen tank is integrally formed. Note that, although the surface PO of the test object 2 is shown as a flat surface in FIG. 2 , it may have a curved surface depending on the test object 2.

[0017] The first surface P1 of the plate 10 is the surface that faces the surface PO of the test object 2 when the test jig 1 is placed on the test object 2. The first seal 11 and the second seal 12 are disposed to protrude from the first surface P1 in a direction perpendicular to the first surface P1. More specifically, the seal guides 13a, 13b, 13c, and 13d protrude from the first surface P1 of the plate 10, and the first seal 11 and the second seal 12 protrude from end surfaces P3 of the seal guides 13a, 13b, 13c, and 13d that face the surface PO of the test object 2. As a result, when the test jig 1 is placed on the test object 2, the protruding tip ends 11a and 12a of the first seal 11 and the second seal 12 come into contact with the surface PO of the test jig 1.

[0018] When the test jig 1 is placed on the test object 2 and the first seal 11 and the second seal 12 are in contact with the surface PO of the test object 2, two spaces are defined by the plate 10, the first seal 11, the second seal 12, and the surface PO of the test object 2. The two spaces include a pressurized space V1 and a depressurized space V2.

[0019] The pressurized space V1 is defined by the first region A1 of the plate 10, the inner surface of the first seal 11, and the surface PO of the test object 2. The depressurized space V2 is defined by the second region A2 of the plate 10, the outer surface of the first seal 11, the inner surface of the second seal 12, and the surface PO of the test object 2. The depressurized space V2 surrounds the periphery of the pressurized space V1 in a plan view.

[0020] Furthermore, the plate 10 has a first hole H1 and a second hole H2. The first hole H1 penetrates the first surface P1 and the second surface P2 in the first region A1. The second hole H2 penetrates the first surface P1 and the second surface P2 in the second region A2.

[0021] Fig. 3 is a diagram showing a schematic configuration of a helium leak test system using the test jig shown in Fig. 1. As shown in Fig. 3, the helium leak test system 100 includes a test jig 1, a pressurization system 3, and a depressurization system 4.

[0022] A pressurization line L1 included in the pressurization system 3 is connected to the first hole H1. A pressurization source 22, which is a helium supply source, is connected to the pressurization line L1. For example, the pressurization source 22 includes a cylinder that stores helium and a regulator that adjusts the supply pressure. An on-off valve 23 and an air release valve 24 are connected to the pressurization line L1 between the pressurization source 22 and a connection portion to the first hole H1. The on-off valve 23 may function as a pressure adjustment valve that adjusts the pressure of the helium supplied from the pressurization source 22.

[0023] A decompression line L2 included in the decompression system 4 is connected to the second hole H2. A decompression source 25 is connected to the decompression line L2. For example, the decompression source 25 includes a vacuum pump or the like. A pressure adjustment valve 26 and an atmosphere release valve 27 are connected to the decompression line L2 between the decompression source 25 and the connection portion to the second hole H2. The configurations of the pressurization system 3 and the decompression system 4 can be changed based on various requirements.

[0024] In this embodiment, the plate 10 has a third hole H3 and a fourth hole H4. A first pressure gauge 28 that measures the pressure in the pressurized space V1 is connected to the third hole H3. A second pressure gauge 29 that measures the pressure in the depressurized space V2 is connected to the fourth hole H4.

[0025] Fig. 4 is a flowchart showing the procedure for a helium leak test using the helium leak test system shown in Fig. 3. First, the test jig 1 is placed on the surface PO of the test object 2 (step S1). At this time, the test jig 1 is placed so that the first area A1 of the plate 10 of the test jig 1 faces the area of ​​the test object 2 where the leak test is to be performed. As described above, when performing a leak test on a welded portion of a test object having a welded portion, the test jig 1 is placed by abutting the first seal 11 and the second seal 12 against the surface PO of the test object 2 so that the welded portion of the test object 2 is located in a position facing the first area A1.

[0026] Next, a pressurization line L1, which connects a pressurization source 22 from the second surface P2 side, is connected to the first hole H1 (step S2). A decompression line L2, which connects a decompression source 25 from the second surface P2 side, is connected to the second hole H2 (step S3). Furthermore, pressure gauges 28 and 29 are connected to the third hole H3 and the fourth hole H4, respectively. Note that the order of steps S2 and S3 may be reversed, or step S1 may be performed after steps S2 and S3.

[0027] Next, with the test jig 1 placed on the test object 2, the reduced pressure source 25 is activated to suction the air in the reduced pressure space V2, thereby reducing the pressure in the reduced pressure space V2 (step S4). Figure 5 shows the test jig shown in Figure 2 before and after decompression. The reduced pressure in the reduced pressure space V2 is reduced by suctioning the air in the reduced pressure space V2, and the test jig 1 is brought into close contact with the surface PO of the test object 2. At this time, the first seal 11 and the second seal 12 are deformed so as to be compressed between the plate 10 and the test object 2. This increases the airtightness of the pressurized space V1 and the reduced pressure space V2. The pressure in the reduced pressure space V2 can be adjusted by the pressure control valve 26 to maintain it at or below a predetermined reference value.

[0028] Next, the second pressure gauge 29 is used to check whether the pressure in the decompression space V2 has fallen below a predetermined reference value (step S5). If the pressure in the decompression space V2 has fallen below the predetermined reference value (Yes in step S5), the pressurization source 22 is activated to supply helium gas to the pressurized space V1, thereby pressurizing the pressurized space (step S6). Then, the first pressure gauge 28 is used to check whether the pressure in the pressurized space V1 has risen to a predetermined test pressure or higher (step S7).

[0029] In this manner, in the present embodiment, as a result of the decompression of the decompression space V2 and the pressurization of the pressurization space V1, pressure is applied to the first seal 11 from the inside, the pressurization space V1 side, to the outside, the decompression space V2. In order to maintain airtightness against such lateral pressure applied to the first seal 11, the protruding direction tip 11a of the first seal 11, i.e., the surface that contacts the surface PO of the test object 2, is flat. This makes it possible to prevent deterioration of airtightness due to the lateral pressure when lateral pressure is applied to the first seal 11 while the protruding direction tip 11a of the first seal 11 is in contact with the surface PO of the test object 2 and compressed in the protruding direction.

[0030] Furthermore, in this embodiment, an outer first seal guide 13b is disposed on the outside of the first seal 11. Therefore, when the above-described lateral pressure is applied to the first seal 11, it is possible to suppress displacement or deformation of the first seal 11 due to the pressure.

[0031] Furthermore, as the decompression space V2 is decompressed, lateral pressure is applied to the second seal 12 from the outside to the inside of the decompression space V2. To maintain airtightness against such lateral pressure applied to the second seal 12, the protruding direction tip 12a of the second seal 12, i.e., the surface that contacts the surface PO of the test object 2, is flat. This prevents deterioration of airtightness due to lateral pressure when the protruding direction tip 12a of the second seal 12 contacts the surface PO of the test object 2 and is compressed in the protruding direction. Furthermore, in this embodiment, an inner second seal guide 13c is disposed inside the second seal 12. Therefore, when the above-mentioned lateral pressure is applied to the second seal 12, displacement or deformation of the second seal 12 due to the pressure can be suppressed.

[0032] When the pressure in the pressurized space V1 reaches or exceeds the predetermined test pressure (Yes in step S7), the detection probe 30a of the helium detector 30, which detects helium gas, is brought close to the rear surface PI of the test object 2 to measure the detected amount of helium gas (step S8), as shown in Fig. 5. At this time, the on-off valve 23 may be closed to shut off the pressurized line L1. This maintains the pressure in the pressurized space V1 within the set pressure range.

[0033] If the amount of helium gas detected by the helium detector 30 is equal to or greater than a predetermined threshold, it is determined that there is an unacceptable leak in the area of ​​the test object 2 facing the pressurized space V1. After the leak test of that area of ​​the test object 2 is completed, the pressure relief valves 24, 27 are opened to return the pressure in the pressurized line L1 and the depressurized line L2 to atmospheric pressure. As the pressure in the depressurized line L2 returns to atmospheric pressure, the pressure in the depressurized space V2 also returns to atmospheric pressure, and the test jig 1 is released from tight contact with the test object 2.

[0034] By repeatedly performing such a leak test by changing the installation position of the test jig 1 relative to the test object 2, a leak test can be performed on the entire test object 2.

[0035] According to the helium leak test method using the test jig 1 of this embodiment, a helium leak test can be performed on a partial area of ​​the test object 2 that faces the first area A1 of the plate 10 by pressurizing that area. In this case, helium only needs to be supplied to the pressurized space V1 defined by the plate 10, the first seal 11, and the surface PO of the test object 2, so the amount of helium used can be reduced regardless of the shape of the test object 2.

[0036] Furthermore, since a pressurized space V1 is formed by the test jig 1 being tightly attached to the test object 2, a leak test can be performed even if the test object 2 itself does not have an airtight space that can be pressurized with helium.

[0037] In this embodiment, the first pressure gauge 28 is connected to the third hole H3, so that the pressurized state of the pressurized space V1 can be easily confirmed. Similarly, the second pressure gauge 29 is connected to the fourth hole H4, so that the depressurized state of the depressurized space V2 can be easily confirmed.

[0038] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various improvements, changes, and modifications are possible within the scope of the spirit of the present disclosure.

[0039] [Other Embodiments] For example, in the above embodiment, the cross-sectional shapes of the first seal 11 and the second seal 12 are rectangular, but this is not limiting. For example, the cross-sectional shape of the first seal 11 may be triangular or pentagonal or more. However, even in this case, it is preferable that the tip end in the protruding direction is flat. The cross-sectional shape may also be a trapezoid whose tip end in the protruding direction is wider than its base end. The cross-sectional shape may also be an inverted T-shape. The cross-sectional shape of the second seal 12 may be the same as or different from the cross-sectional shape of the first seal 11. The tip end in the protruding direction of the second seal 12 does not have to be flat.

[0040] Furthermore, methods other than adhesive fixing can be used to fix the first seal 11 and the second seal 12 to the plate 10. For example, the plate 10 and the seals 11, 12 may each have a fitting structure, and the seals 11, 12 may be joined by fitting into the plate 10. Note that the first seal 11 and the second seal 12 do not have to be fixed to the plate 10.

[0041] The shapes of the first seal 11 and the second seal 12 can be determined based on the pressure applied to each seal 11, 12. 2 ] is the force Fv2 [kgf] that attracts the test jig 1 to the test object 2 due to the decompression of the decompression space V2, the force Fv1 [kgf] that moves the test jig 1 away from the test object 2 due to the pressurization of the pressurization space V1, and the installation area S [cm ] of the seals 11 and 12 on the test object 2. 2 ], it can be expressed as P = (Fv2 - Fv1) / S. The shapes of the seals 11 and 12 can be determined so that P at this time is equal to or greater than a predetermined value.

[0042] In the above embodiment, the plate 10 has the holes H3 and H4 to which the pressure gauges 28 and 29 are connected, but this is not limiting. For example, if a pressure gauge is connected to the pressurized line L1, the third hole H3 may be omitted. Similarly, if the reduced pressure source has a pressure gauge or if a pressure gauge is connected to the reduced pressure line L2, the fourth hole H4 may be omitted.

[0043] However, even if the reduced pressure source 25 has a pressure gauge, by separately connecting a second pressure gauge 29 to the third hole H3 and the fourth hole H4 as in the above embodiment, the second pressure gauge 29 can be placed in a position that is easy for the operator to see without being restricted by the installation position of the reduced pressure source 25.

[0044] For example, if the test area of ​​the test object 2 is large, a helium leak test is performed at multiple locations while changing the installation position of the test jig 1 on the test object 2. If the installation position of the test jig 1 is changed without changing the installation positions of the pressurized line L1 and the reduced pressure source 25, when a helium leak test is performed at a location away from the installation positions of the pressurized line L1 and the reduced pressure source 25, the pressure gauges attached to the pressurized line L1 and the reduced pressure source 25 may be difficult to see from the installation position of the test jig 1, which is the work location. Even in such cases, by connecting pressure gauges 28 and 29, which can be moved independently of the pressurized line L1 and the reduced pressure source 25, to the third hole H3 and the fourth hole H4, each pressure can be easily grasped from the installation position of the test jig 1, which is the work location, even if the installation position of the test jig 1 is moved.

[0045] In the above embodiment, the seal guides 13a, 13b, 13c, and 13d are provided on the inside and outside of the first seal 11 and the inside and outside of the second seal 12, respectively. However, these seal guides 13a, 13b, 13c, and 13d may be omitted. Furthermore, when lateral pressure is applied to the first seal 11 from the pressurized space V1 to the depressurized space V2, the inner first seal guide 13a located on the inside of the first seal 11 and the seal guides 13c and 13d located on both sides of the second seal 12 may be omitted as seal guides for suppressing displacement or deformation of the first seal 11 due to the pressure. Furthermore, the seal guide 13d located on the outside of the second seal 12 may be omitted as a seal guide for suppressing displacement or deformation of the second seal 12 due to the lateral pressure acting inward on the second seal 12.

[0046] In the above embodiment, the plate 10 has one first hole H1 and one second hole H2, but the plate 10 may have a plurality of first holes H1 and a plurality of second holes H2. That is, helium may be supplied to the pressurized space V1 from a plurality of locations by one or a plurality of pressurization sources 22, or air may be sucked from the depressurized space V2 from a plurality of locations by one or a plurality of depressurization sources 25.

[0047] [Summary of the present disclosure] [Item 1] A helium leak test jig according to one aspect of the present disclosure comprises a plate, a first seal arranged to protrude from the first surface of the plate so as to surround the periphery of a predetermined first region on the first surface, and a second seal arranged to protrude from the first surface of the plate so as to surround the periphery of a predetermined second region on the first surface of the plate that is set to surround the first region, wherein when the first seal and the second seal are in contact with the surface of a test object, a space defined by the first region of the plate, the inner surface of the first seal, and the surface of the test object is configured as a pressurized space to which helium gas is supplied, and a space defined by the second region of the plate, the outer surface of the first seal, the inner surface of the second seal, and the surface of the test object is configured as a depressurized space that brings the plate into close contact with the test object via the first seal and the second seal.

[0048] According to the above configuration, a helium leak test can be performed on a portion of the test object that faces the first region of the plate by pressurizing that portion. In this case, helium only needs to be supplied to the pressurized space defined by the plate, the first seal, and the surface of the test object, which reduces the amount of helium used regardless of the shape of the test object.

[0049] [Item 2] In the helium leak test jig of Item 1, the first seal may have a flat tip in the protruding direction. This prevents deterioration of airtightness due to lateral pressure applied to the first seal from the pressurized space to the depressurized space when the tip in the protruding direction of the first seal contacts the surface of the test object and is compressed in the protruding direction.

[0050] [Item 3] In the helium leak test jig according to Item 1 or 2, the plate may have, in the first region, a first hole that penetrates the first surface and a second surface opposite the first surface, for supplying helium gas to the pressurized space from the second surface side and connecting a pressurization source that pressurizes the pressurized space to the second surface side, and a second hole that penetrates the first surface and the second surface in the second region and connects a decompression source that decompresses the decompressed space to the second surface side.

[0051] [Item 4] In the helium leak test fixture according to any one of Items 1 to 3, the plate may have an outer first seal guide protruding from the first surface outside the first seal, and the first seal and the second seal may protrude from an end face of the outer first seal guide. This makes it possible to suppress displacement or deformation of the first seal due to lateral pressure applied to the first seal from the pressurized space toward the depressurized space.

[0052] [Item 5] In the helium leak test jig of any one of Items 1 to 4, the plate may have an inner second seal guide protruding from the first surface inside the second seal, and the first seal and the second seal may protrude from an end face of the inner second seal guide. This makes it possible to suppress displacement or deformation of the second seal due to pressure acting inwardly across the second seal due to decompression of the decompression space.

[0053] [Item 6] In the helium leak test jig of Item 3, the plate may have a third hole in the first region that penetrates the first surface and the second surface and is connected to a first pressure gauge on the second surface side, thereby making it possible to easily check the pressurized state of the pressurized space.

[0054] [Item 7] In the helium leak test jig of Item 3 or 6, the plate may have a fourth hole in the second region that penetrates the first surface and the second surface and is connected to a second pressure gauge on the second surface side, thereby making it possible to easily check the decompression status of the decompression space.

[0055] [Item 8] A helium leak test method according to another aspect of the present disclosure is a helium leak test method for testing whether or not there is an unacceptable leak at a welded portion of a test object having a welded portion, the method including: a test jig including a plate; a first seal disposed protruding from a first surface of the plate so as to surround a periphery of a predetermined first region on the first surface of the plate; and a second seal disposed protruding from the first surface of the plate so as to surround a periphery of a predetermined second region on the first surface of the plate that is set to surround the first region; and the first seal and the second seal are attached to the test object so that the welded portion of the test object is positioned opposite the first region. The test jig is installed by abutting it against the surface of the test object, and the air is sucked out from within a reduced pressure space defined by the second region of the plate, the outer surface of the first seal, the inner surface of the second seal, and the surface of the test object to bring the test jig into close contact with the test object. With the test jig in close contact with the test object, helium gas is supplied to the pressurized space defined by the first region of the plate, the inner surface of the first seal, and the surface of the test object to pressurize the pressurized space. A helium detector that detects helium gas is brought close to the back side of the test object, and a leak test is performed on the region of the test object facing the pressurized space based on the detected amount of helium gas.

[0056] REFERENCE SIGNS LIST 1 Test jig 2 Test object 10 Plate 11 First seal 11a Protruding tip of first seal 12 Second seal 13a Inner first seal guide 13b Outer first seal guide 13c Inner second seal guide 22 Pressurized source 25 Reduced pressure source 28 First pressure gauge 29 Second pressure gauge 30 Helium detector A1 First region A2 Second region H1 First hole H2 Second hole H3 Third hole H4 Fourth hole P1 First surface of plate P2 Second surface of plate PO Surface of test object V1 Pressurized space V2 Reduced pressure space

Claims

1. A helium leak test jig comprising: a plate; a first seal arranged to protrude from a first surface of the plate so as to surround the periphery of a predetermined first region on the first surface of the plate; and a second seal arranged to protrude from the first surface of the plate so as to surround the periphery of a predetermined second region on the first surface of the plate which is set to surround the first region, wherein, when the first seal and the second seal are in contact with the surface of a test object, the space defined by the first region of the plate, the inner surface of the first seal, and the surface of the test object is configured as a pressurized space into which helium gas is supplied, and the space defined by the second region of the plate, the outer surface of the first seal, the inner surface of the second seal, and the surface of the test object is configured as a depressurized space which brings the plate into close contact with the test object via the first seal and the second seal.

2. A helium leak test jig as set forth in claim 1, wherein the tip of the first seal in the protruding direction is flat.

3. A helium leak test jig as described in claim 1 or 2, wherein the plate has: in the first region, a first hole that penetrates the first surface and a second surface opposite the first surface, for supplying helium gas from the second surface side to the pressurized space and connecting a pressure source that pressurizes the pressurized space to the second surface side; and in the second region, a second hole that penetrates the first surface and the second surface, for connecting a pressure reduction source that depressurizes the depressurized space to the second surface side.

4. A helium leak test jig as described in claim 1 or 2, wherein the plate has an outer first seal guide that protrudes from the first surface outside the first seal, and the first seal and the second seal protrude from the end face of the outer first seal guide.

5. A helium leak test jig as described in claim 1 or 2, wherein the plate has an inner second seal guide that protrudes from the first surface inside the second seal, and the first seal and the second seal protrude from the end face of the inner second seal guide.

6. A helium leak test jig as described in claim 3, wherein the plate has a third hole in the first region that penetrates through the first surface and the second surface and to which a first pressure gauge is connected on the second surface side.

7. A helium leak test jig as described in claim 3, wherein the plate has a fourth hole in the second region that penetrates through the first surface and the second surface and to which a second pressure gauge is connected on the second surface side.

8. A helium leak test method for testing whether there is an unacceptable leak at a welded portion of a test object having a weld, comprising: a test jig comprising a plate, a first seal disposed protruding from the first surface of the plate so as to surround a predetermined first region on the first surface of the plate, and a second seal disposed protruding from the first surface of the plate so as to surround a predetermined second region on the first surface of the plate so as to surround the first region; a test jig is installed by abutting the first seal and the second seal on the surface of the test object so that the welded portion of the test object is positioned opposite the first region; air is sucked from a decompressed space defined by the second region of the plate, the outer surface of the first seal, the inner surface of the second seal, and the surface of the test object, to bring the test jig into close contact with the test object; and helium gas is supplied to a pressurized space defined by the first region of the plate, the inner surface of the first seal, and the surface of the test object while the test jig is in close contact with the test object, thereby pressurizing the pressurized space; A helium leak testing method comprising: bringing a helium detector that detects helium gas close to the back side of the test object and performing a leak test on a region of the test object that faces the pressurized space based on the detected amount of helium gas.

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