JP2008224307A - Leakage inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a leakage inspection device using air-tight chamber forming structure capable of forming an air-tight chamber in a part to be inspected of a pipe directly from a side face of the pipe, in which the air-tight chamber can attain air-tightness enough to carry out an air-tightness test of high detection sensitivity. <P>SOLUTION: This leakage inspection device 10 is a leakage inspection device for detecting the leakage of gas in a cylindrical pipe 11 to an outside via the part to be inspected of the pipe, and is provided with the air-tight chamber forming structure having the air-tight chamber constituted to surround the part to be inspected of the pipe by a casing 12, and having at least the first sealing members 21, 22 and the second sealing member 41 of different degrees of softness arranged between the pipe and the casing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a leakage inspection apparatus, and more particularly, to a leakage inspection apparatus that can measure an inspected portion of a pipe with high sensitivity using a highly airtight airtight chamber.

  In an airtightness test of a cylindrical tube formed by connecting a plurality of cylindrical tube parts, an airtightness test is performed using a welded part connecting two cylindrical tube parts as an inspected part. In an airtightness test using a leakage inspection device, an airtight chamber forming structure is provided around the part to be inspected, gas (for example, helium gas or argon gas) is supplied into the cylindrical tube, and the cylindrical tube is passed through the part to be inspected. It is detected whether or not gas leaks into the outer airtight chamber forming structure. The gas used for such a purpose is hereinafter referred to as “search gas”. In the case of a cylindrical tube formed by connecting a plurality of cylindrical tube parts and having a plurality of welded portions, the hermetic chamber forming structure is moved in the axial direction of the cylindrical tube in order to perform an airtightness test of each welded portion. It will be necessary. For this purpose, it is not easy because the seal portion between the hermetic chamber forming structure and the cylindrical tube needs to be moved in the axial direction on the outer peripheral portion of the cylindrical tube. When the moving distance is long, it is not particularly easy. Moreover, in the inspection of the pipes that have already been laid, it is very difficult for the support fittings and the like to get in the way.

  In addition, if there is a part with a large diameter on the way from the end of the cylindrical tube to the part to be inspected, the airtight chamber forming structure cannot be moved over it, so the airtightness test could not be performed. .

  As a prior art regarding the problem of the above-mentioned airtightness test, there is a pipe leakage measuring instrument described in Patent Document 1. This leakage measuring instrument is provided with a casing that surrounds a weld line (welded part) portion of a pipe with two box members so as to be sandwiched from outside and forms a chamber around the weld line. The chamber portion in the casing communicates with the outside air through a communication pipe and is at atmospheric pressure, and the tip portion of the suction probe of the helium detector is provided in the chamber portion in the casing. The position of the suction probe with respect to the housing is set in advance, and when the housing is attached to the tube, the tip of the suction probe is arranged at a certain angle and a certain distance with respect to the weld line. By rotating the casing attached to the tube around the tube, the tip of the suction probe makes a round while being held in a fixed positional relationship with respect to the weld line. A search gas is supplied into the tube at a predetermined pressure, and the presence or absence of the search gas leaking from the weld line is measured by the suction probe and the helium detector. In this way, the inspection of helium leakage in the weld line of the pipe is performed. This method is called a sniffer method and is mainly used for inspection of a leak amount larger than 1 × 10 −6 Pa · m 3 / s. However, it is necessary to conduct an air tightness test for inspecting a smaller amount of leakage. In this case, the confidentiality of the leakage inspection instrument described in Patent Document 1 is insufficient and cannot be applied. .

As another conventional technique, there is an airtight formation structure described in Patent Document 2. In this airtightness test apparatus, a block-shaped cylindrical tube sealing portion formed of an elastic body such as silicon rubber is formed on the welded portion of two cylindrical tubes to be measured. Open and attach directly from the outer side surface of the cylindrical tube, so that even if the cylindrical tube, which is the object to be measured, has a large-diameter cylindrical tube end, An airtight chamber forming structure can be provided so that an airtightness test of the part to be inspected can be performed.
Japanese Utility Model Publication No. 7-18235 Japanese Patent Laid-Open No. 9-318483

  In order to increase the detection sensitivity of the leakage inspection apparatus, a conventional structure that forms an airtight chamber is insufficient. For example, according to the instrument for measuring leakage of a pipe according to Patent Document 1 described above, a portion to be measured of the pipe is surrounded by two box members so as to be sandwiched from the outside, and a seal portion between the pipe and the two box members is provided with rubber. An elastic body such as a sheet is sandwiched between them to form an airtight chamber. However, since a minute gap connecting the airtight chamber and the outside is formed at the portion where the two ends of the rubber sheet and the tube are abutted, the airtightness of the airtight chamber is high in order to obtain high detection sensitivity. It is extremely inadequate for the required tightness. Moreover, in the airtight formation structure by patent document 2, there exists a problem in the sealing performance in the notch part of a cylindrical tube sealing part.

  With reference to FIG. 13 and FIG. 14, the problem of the sealing property of the conventional leak measurement instrument will be specifically described. FIG. 13 is an end view of a conventional airtight chamber forming structure. An upper box member 102 and a lower box member 103 are arranged so as to sandwich the pipe 101 to be inspected, and a casing 105 that forms an airtight chamber around the welded portion is formed using the upper and lower box members 102 and 103. A search gas having a required pressure is supplied into the tube 101 by a search gas supply device (not shown). If a leak location exists in the welded portion of the tube 101, the search gas inside the tube 101 leaks from the leak location and flows out into the hermetic chamber in the housing 105. The leaked search gas is detected by the helium detector. The airtight chamber 103 in the housing 105 is exhausted by a vacuum device (not shown). As a result, the airtight chamber is maintained at a high required vacuum state, and the leaked search gas is guided to the helium detector.

  In the hermetic chamber forming structure in which the hermetic chamber can be formed directly on the measured portion of the pipe from the side surface of the pipe, the conventional hermetic chamber forming structure includes an upper box member 102 and a lower box member 103 as shown in FIG. Sealing materials 106 and 107 are provided on the contact surface to enhance the airtightness of the contact between the upper box member 102 and the lower box member 103 and to increase the airtightness of the airtight chamber 104 in the housing 105.

  However, the structure forming the hermetic chamber 104 has the following problems regarding the sealing performance. The range 108 shown in FIG. 13 is enlarged and shown in FIG. A sealing material 106 is attached to the contact surface of the upper box member 102, and a sealing material 107 is attached to the contact surface of the lower box member 103. Therefore, when forming the housing 105, the seal members 106 and 107 of the upper and lower box members 102 and 103 are in contact with each other in the portion facing each other, and in the portion facing the cylindrical tube 101, Touching the surface. Therefore, in principle, high sealing performance is realized by the sealing materials 106 and 107.

  However, a gap 109 is formed along the surface of the cylindrical tube 101 in the axial direction of the cylindrical tube 101 at the boundary between the portion in contact with the cylindrical tube 101 and the portion in which the sealing materials 106 and 107 are in contact with each other. It is formed. The gap 109 is a small gap. However, when an airtight test with high detection sensitivity is required, the air flowing into the airtight chamber 104 through the gap 109 exceeds an allowable amount. That is, in the hermetic chamber forming structure in which the hermetic chamber can be formed directly on the measured portion of the pipe from the side surface of the pipe, the conventional hermetic chamber forming structure shown in FIGS. 13 and 14 requires an airtightness test with high detection sensitivity. In such a case, there was a problem that the confidentiality of the airtight room was insufficient.

  In view of the above problems, an object of the present invention is a hermetic chamber forming structure capable of forming a hermetic chamber directly on the inspected portion of the tube from the side surface of the tube, and the hermetic chamber performs a hermeticity test with high detection sensitivity. An object of the present invention is to provide a leakage inspection apparatus using a hermetic chamber forming structure capable of realizing sufficient hermeticity to be performed.

  In order to achieve the above object, a leak inspection apparatus according to the present invention is configured as follows.

  A first leakage inspection device (corresponding to claim 1) is a leakage inspection device that detects that gas inside a tube leaks outside through the portion to be inspected of the tube. An airtight chamber forming structure having at least first and second seal members having different softnesses, which are arranged between a pipe and the housing, is configured by forming an airtight chamber so as to be surrounded by the housing. Configured to provide.

  In the above leakage inspection apparatus, the airtightness of the airtight chamber is ensured by the first seal member, and sealing is performed with high airtightness by the second soft and highly soft second seal member. The first and second sealing members made of preferably two rubber materials having different softnesses can improve the airtightness of the airtight chamber and perform highly sensitive gas detection.

  In the second leakage inspection apparatus (corresponding to claim 2), in the above-mentioned configuration, the housing is preferably composed of two half parts, and the two half parts are arranged on both sides of the inspected part of the tube. It is characterized by forming a housing.

  In the third leakage inspection apparatus (corresponding to claim 3), in the above configuration, preferably, the first seal member forms a closed ring surrounding the entire circumference of the pipe by the ends abutting each other. The second seal member is disposed so as to contact the first seal member and the pipe.

  In the above-described configuration, the fourth leakage inspection apparatus (corresponding to claim 4) is preferably characterized in that the softness of the second seal member is higher than the softness of the first seal member.

  In the fifth leakage inspection apparatus (corresponding to claim 5), preferably, the hermetic chamber surrounds a main hermetic chamber surrounding the part to be inspected and a seal portion between the pipe and the main hermetic chamber. An airtight chamber forming structure including a secondary airtight chamber configured outside the main airtight chamber is provided.

  In the sixth leakage inspection apparatus (corresponding to claim 6), in the above structure, preferably, the second seal member is disposed in a seal portion between the pipe separating the outside and the sub-airtight chamber and the sub-airtight chamber. Characterized.

  The seventh leak inspection apparatus (corresponding to claim 7) is preferably characterized in that, in the above configuration, the second seal member is an ultra-soft rubber or sponge.

  According to the present invention, at least the first and second sealing members having different softnesses with respect to the airtight chamber forming structure for forming the airtight chamber around the portion to be inspected of the pipe in the leakage inspection apparatus are provided, Since the airtightness is increased, highly sensitive search gas leakage detection can be performed.

  DESCRIPTION OF EMBODIMENTS Preferred embodiments (examples) of the present invention will be described below with reference to the accompanying drawings.

  First, the external shape and internal structure of the leakage inspection apparatus according to the embodiment of the present invention will be described with reference to FIGS. 1 is a perspective view of the appearance of the leakage inspection apparatus, FIG. 2 is an end view of the leakage inspection apparatus (a view taken in the direction of arrow A in FIG. 1), and FIG. 3 is a sectional view taken along line BB in FIG. FIG. 4 shows the main structure of the inside of the leakage inspection apparatus.

  The leak inspection apparatus 10 inspects whether a search gas such as helium gas is contained in a portion of the casing 12 attached to the cylindrical tube 11 and forming an airtight chamber, and a gas exhausted from the casing 12. And a mass spectrometer type leak detector 13. The casing 12 of the leakage inspection apparatus 10 is attached to the site of the welded portion 11A of the cylindrical tube 11 that is the inspection target. The cylindrical tube 11 has a relatively long shape in the axial direction. The leakage inspection apparatus 10 is directly attached from the outer side surface side of the cylindrical tube 11.

  In addition, the detection apparatus used with the leak inspection apparatus 10 according to the present invention is not limited to the mass spectrometer type leak detector 13 described above, and any detection apparatus can be used.

  The casing 12 of the leakage inspection apparatus 10 is configured by a casing upper part 12A and a casing lower part 12B coupled by a hinge 14. The casing 12 of the leakage inspection apparatus 10 is attached to the cylindrical tube 11 so as to be sandwiched between a casing upper part 12A and a casing lower part 12B that form a half of the casing 12. The internal space of the housing 12 is formed as a main hermetic chamber (main chamber) R1. The overall shape of the housing 12 is a substantially rectangular parallelepiped shape. In the above structure, the coupling means is not limited to the hinge 14, and the overall shape is not limited to a rectangular parallelepiped shape. The housing 12 is described as “housing upper portion 12 </ b> A” and “housing lower portion 12 </ b> B” based on FIG. 1, but these two portions (half-body portions) are the upper portion or the lower portion of the housing 12. It is not limited to the part.

  Cylindrical protrusions 15 are provided on the end surface portions on both sides of the housing 12. The cylindrical protrusion 15 is based on a semi-cylindrical protrusion 15A formed on both end faces of the housing upper part 12A and a semi-cylindrical protrusion 15B formed on both end faces of the housing lower part 12B. It is formed. By the cylindrical protrusions 15 on both sides, a sub airtight chamber (subchamber) R2 located on both sides of the main airtight chamber R1 in the housing 12 is formed. The casing 12 and the semi-cylindrical protrusion 15 are formed so as to be integrated. An airtight chamber forming structure is formed by the housing 12 and the semicylindrical protrusions 15A and 15B. In the above structure, elements such as the cylindrical protrusion 15, the semicylindrical protrusions 15A and 15B, and the auxiliary airtight chamber R2 are not essential conditions of the present invention.

  The housing upper part 12 </ b> A and the housing lower part 12 </ b> B attached to the cylindrical tube 11 so as to be sandwiched are coupled by a connector 16 and fixed as the housing 12 to the cylindrical tube 11.

  As shown in FIGS. 1 to 3, at least the upper gasket 21, which will be described later, is provided on the entire surface of the casing upper portion 12 </ b> A and the portion between the semicylindrical protrusion 15 </ b> A and the cylindrical tube 11. Is disposed, and a lower gasket 22 to be described later is disposed on the entire surface of the casing lower portion 12B and the semi-cylindrical protrusion 15B and the portion of the cylindrical tube 11 in contact with each other. More precisely, the upper gasket 21 and the lower gasket 21 are formed in a contact portion between the housing upper portion 12A and the housing lower portion 12B and a contact portion between the semicylindrical protrusions 15A and 15B. Are also arranged throughout. The upper gasket 21 and the lower gasket 22 have a function as a sealing member.

  As a result, as shown in FIGS. 3 and 4, the main airtight chamber R1 is formed inside the casing 12 located at the center, and the secondary air is formed inside the cylindrical projections 15 located on both sides. A closed chamber R2 is formed. The inside of the main hermetic chamber R1 is connected to the mass spectrometer type leak detector 13 through the hole 23 and the exhaust pipe 24, and is exhausted by the main vacuum pump incorporated therein. The auxiliary airtight chambers R2 on both sides are exhausted by the auxiliary vacuum pump 28 through the hole 26 and the exhaust pipe 27.

  The shape of the upper gasket 21 and the lower gasket 22 is shown in the perspective exploded view of FIG. In FIG. 5, the housing upper part 12A and the housing lower part 12B that form the housing 12, and the semicylindrical protrusions 15A and 15B that form the cylindrical protrusions 15 on both sides are shown separately. The housing upper part 12A and the semicylindrical protrusions 15A on both sides, and the housing lower part 12B and the semicylindrical protrusions 15B on both sides are integrally formed. The upper gasket 21 is disposed between the housing upper portion 12A and the semicylindrical protrusions 15A on both sides and the cylindrical tube 11, and the lower gasket 22 is disposed on the housing lower portion 12B and the semicylindrical protrusions 15B on both sides and the cylindrical tube 11. Arranged between. The linear portion indicated by reference numeral 11A in the cylindrical tube 11 means a welded portion. This welded part 11A becomes the part to be inspected.

  The upper gasket 21 and the lower gasket 22 are preferably formed so as to have the same shape using the same material, and are disposed so as to have a symmetrical relationship at the upper and lower positions of the cylindrical tube 11. The However, it is not essential that the material and shape of the upper gasket 21 and the lower gasket 22 are the same. The upper gasket 21 and the lower gasket 22 correspond to a first seal member.

  The material and shape of the gasket will be described with reference to the lower gasket 22. The lower gasket 22 is formed of a medium soft material that does not contain a large amount of plasticizer and can be shaped and held so as to have a shape as shown in FIG. This medium soft material is an elastic material such as rubber that exhibits high sealing performance. An example of this material is silicon rubber, for example. At the center of the lower gasket 22, there are linear frame bodies 31, 32 on both axial sides that form a space S 1 for forming the main airtight chamber R 1, and inner curved frame bodies 33, 34 on both circumferential sides. . Further, on both sides of the lower gasket 22, there are linear frame bodies 35, 36 on both sides in the axial direction that form a space S 2 for forming the auxiliary airtight chamber R 2, and an outer curved frame body 37 in the circumferential direction. The straight frame bodies 31 and 32 are located between the housing upper part 12A and the housing lower part 12B. The straight frame bodies 35 and 36 located on both the left and right sides are located between the cylindrical protrusions 15A and 15B. The inner curved frame bodies 33 and 34 and the outer curved frame body 37 are located between the cylindrical tube 11 and the semicylindrical protrusion 15B.

  Since the upper gasket 21 also has the same frame as the lower gasket 22, the corresponding parts are given the same reference numerals. Corresponding linear frame portions in the lower gasket 22 and the upper gasket 21 are in a positional relationship in contact during assembly.

  In the lower gasket 22, an ultra-soft gasket 41 is attached to a connecting portion between each of the straight frame bodies 35, 36 located on both the left and right sides in FIG. 5 and the outer curved frame body 37. The super soft gasket 41 is provided at a total of four locations in the lower gasket 22. The super soft gasket 41 is connected to the inner side of the bent portion from the linear frame 35, 36 to the outer curved frame 37 at the connecting portion between each of the linear frames 35, 36 and the outer curved frame 37. Attached in a slightly protruding shape. The super soft gasket 41 corresponds to a second seal member.

  The ultra-soft gasket 41 is a material having elasticity such as rubber, and contains a lot of plasticizers, and has a very soft elasticity that fits without making a gap in the surrounding shape. The material of the super soft gasket 41 is super soft rubber or sponge. The ultra-soft rubber has a rubber hardness (JIS K 6253) of 20 or less, preferably 10 or less. The super-soft sponge has a sponge hardness (JIS S 6050) of 20 or less, preferably 10 or less. The ultra-soft rubber is preferably an ultra-soft rubber (jull-like rubber) having both solid and liquid (GEL) properties. The super-soft sponge is preferably a single-cell sponge (single-foam sponge). As described above, the softness of the super soft gasket 41 is higher than the softness of the lower gasket 22.

  Next, the shape and mounting method of the super soft gasket 41 will be described in detail with reference to FIGS. FIG. 6 is an enlarged view of the area C in FIG. FIG. 7 is a longitudinal sectional view of the main part in FIG. 5, and FIG. 8 shows only the super soft gasket 41. As shown in FIG. 8, the super soft gasket 41 is composed of an outer portion 41a located on the semicylindrical protrusion 15B side and an inner portion 41b located on the cylindrical tube 11 side. The super soft gasket 41 has a block shape as a whole. In order to attach the super soft gasket 41 to the lower gasket 22, a hole 42 is formed between the straight frame body 35 and the outer curved frame body 37, and the super soft gasket 41 is attached to the hole 42 as indicated by an arrow D. The bottom gasket 22 is pushed in from the outside and attached. As a result, as shown in FIGS. 6 and 7, the outer portion 41 a of the super soft gasket 41 abuts on the linear frame body 35 and the outer curved frame body 37, and the inner portion 41 b protrudes inward from the hole 42. Placed in.

  As described above, since the upper and lower gaskets 21 and 22 are provided with the ultra-soft gaskets 41 at predetermined four locations, based on the arrangement relationship shown in FIG. 5, the cylindrical tube 11 which is an object to be inspected as shown in FIGS. When the housing 12 and the like are assembled to each other, each of the four super soft gaskets 41 of the upper and lower gaskets 21 and 22 comes into contact with the inner cylindrical tube 11 and the outer semicylindrical protrusion 15B, and is pressed against each other. . As a result, the super soft gasket 41 is deformed, and thereby, a small gap portion connecting the hermetic chamber and the outside can be sealed. For this reason, it is possible to prevent the gap 109 described with reference to FIG. 13 from occurring.

  According to the leakage inspection apparatus 10 having the above-described configuration, the hermetic chamber forming structure (the casing 12 and the cylindrical protrusion 15) can be provided directly from the outer side surface with respect to the inspection target portion of the cylindrical tube 11, Furthermore, in addition to the upper and lower gaskets 21 and 22 as the sealing member for maintaining the internal airtightness, the super soft gasket 41 is provided at the predetermined position described above, so that a narrow gap generated between the upper and lower gaskets 21 and 22 is formed. The gap portion can also be completely sealed. For this reason, the degree of vacuum in the main hermetic chamber R1 and the sub hermetic chamber R2 formed inside the housing 12 or the like can be made smaller than 5 Pa, and an extremely high desired detection sensitivity (for example, 1 × 10 −9 Pa · m3 / s) can be achieved. Furthermore, since it is not necessary to increase the softness of the upper and lower gaskets 21 and 22 themselves, the influence of the plasticizer can be minimized.

  Moreover, according to the attachment structure of the ultra-soft gasket 41 according to the above-described embodiment, the holes 42 are used for placement, so that positioning can be performed accurately.

  FIG. 9 shows a modification of the super soft gasket. FIG. 9 is a view similar to FIG. The ultra-soft gasket shown in this embodiment is formed in a sheet shape, not a block shape. No hole is formed in the bent portion between the straight frame body 35 and the outer curved frame body 37 of the lower gasket 22, and sheet-like super soft gaskets 51 and 52 are respectively formed on the outer surface and the inner surface of the bent portion. Affixed. The super soft gasket 51 on the outer surface can be omitted.

  FIG. 10 shows another embodiment of the leakage inspection apparatus according to the present invention, which is the same as FIG. In this embodiment, for example, a casing 12 of a leakage inspection apparatus used for leakage inspection of the rectangular tube 61 is shown. The same reference numerals are given to the elements substantially the same as those described in the above-described embodiment. In this casing 12, in order to perform a leak test on the rectangular tube 61, the protrusions 62 formed on both sides of the casing 12 become rectangular tube-shaped protrusions 62 so as to fit the rectangular tube 61. Yes. The square cylindrical projection 62 is composed of half-square cylindrical projections 62A and 62B. The frame in the circumferential direction of the upper and lower gaskets 21 and 22 is formed as a bent frame that is bent at approximately 90 degrees so as to fit the rectangular tube 61. Other configurations are the same as those of the above-described embodiment. Thus, the same action and effect as the above-described embodiment can be exerted on the rectangular tube 61 as well.

  Although the cross section of the rectangular tube 61 in the other embodiments described above is substantially square, the rectangular tube 61 is not limited to this. Generally, the leakage inspection apparatus according to the present invention can be used for leakage inspection of a polygonal tube. In this case, the shape of the protrusions on both sides of the housing 12 and the shape of the upper and lower gaskets are formed so as to have a shape corresponding to the shape of the tube to be inspected.

  11 and 12 show still another embodiment of the leakage inspection apparatus according to the present invention. FIG. 11 is substantially the same as FIG. 2, and FIG. 12 is a cross-sectional view taken along the line EE in FIG. FIG. In this embodiment, the casing 12 described in each of the above embodiments and a portion (airtight chamber forming structure) corresponding to the cylindrical protrusion 15 or the like are formed in, for example, a rubber-like block 71 having medium flexibility. . This rubber-like block 71 has a rectangular parallelepiped shape as a whole, and has a hole 72 for accommodating the cylindrical tube 11 as an object to be inspected as shown in FIG. A notch 73 is provided over the entire length, and a hole 74 is formed at the center of the lower surface. In the rubber block 71, an airtight chamber corresponding to the above-described main airtight chamber R <b> 1 is formed as a part of the hole 72 inside the hole 74. Further, the diameters of both sides of the hermetic chamber R1 in the hole 72 are formed to be substantially equal to the outer diameter of the cylindrical tube 11.

  When the rubber block 71 is attached to, for example, the cylindrical tube 11 that is an object to be inspected, the lower cut portion 73 of the rubber block 71 is pushed to the left and right, and the cylinder is formed through a gap formed by the cut portion 73. The tube 11 is press-fitted and accommodated in the hole 72. At this time, the welded portion 11A is located in the airtight chamber R1. 11 and 12 show this state. 11 and 12, the rubber block 71 is pressed from the outside by an arbitrary fixing member (not shown), so that the cut portion 73 is brought into close contact and the cut portion 73 is fixed so as not to open. The The hole portions on both sides of the hermetic chamber R 1 in the hole 72 are in close contact with the outer surface of the cylindrical tube 11. The inside of the airtight chamber R1 is evacuated through the hole 74.

  In FIG. 12, the upper portion of the rubber block 71 is shown as a cross section, while the lower portion shows one contact surface of the cut portion 73. When the cylindrical tube 11 is narrowed by the rubber block 71, the super soft gasket 41 is connected to the cylindrical tube 11 in the cut portion 74 so that gas does not leak through a narrow gap as described in the above embodiment. It is attached to the part of the contact surface and the mutual contact surface. As a result, narrow gaps can be sealed.

  The configurations, shapes, sizes, and arrangement relationships described in the above embodiments are merely shown to the extent that the present invention can be understood and implemented, and the numerical values and the compositions (materials) of the respective configurations are as follows. It is only an example. Therefore, the present invention is not limited to the described embodiments, and can be variously modified without departing from the scope of the technical idea shown in the claims.

  INDUSTRIAL APPLICABILITY The present invention is used for realizing a high airtightness with respect to a welded portion such as a cylindrical tube and performing a leak inspection with high sensitivity.

It is a perspective view which shows the external appearance of the leak inspection apparatus which concerns on embodiment of this invention. FIG. 2 is an end view (a view in the direction of arrow A in FIG. 1) of the leakage inspection apparatus of the present embodiment. It is the BB sectional view taken on the line in FIG. It is a figure which shows the principal part structure inside the leakage inspection apparatus which concerns on this embodiment. It is a disassembled perspective view of the leak inspection apparatus concerning this embodiment. It is the elements on larger scale of the range C in FIG. It is a longitudinal cross-sectional view of the super soft gasket shown in FIG. It is an external appearance perspective view which shows only the super soft gasket shown in FIG. It is a longitudinal cross-sectional view which shows the other attachment method of a super soft gasket. It is a figure similar to FIG. 2 regarding the leakage inspection apparatus of other this embodiment. It is a figure similar to FIG. 2 which shows the end surface of the airtight chamber formation structure of the leak test | inspection apparatus of further another embodiment. It is the EE sectional view taken on the line in FIG. It is an end view of the conventional airtight chamber forming structure. FIG. 14 is an enlarged view of a range 108 in FIG. 13.

Explanation of symbols

10 Leakage inspection device 11 Cylindrical tube 11A Welded part (inspected part)
12 Housing 13 Mass spectrometer type leak detector 15 Cylindrical protrusion 21 Upper gasket 22 Lower gasket 41 Super soft gasket 51 Super soft gasket 61 Square tube 71 Rubber block 72 Hole 73 Cut section R1 Main airtight chamber R2 Secondary airtight chamber

Claims (7)

A leak inspection apparatus for detecting a search gas inside a pipe leaking outside through an inspected portion of the pipe,
An airtight chamber is formed so as to surround the inspected part of the tube with a casing,
A leakage inspection apparatus comprising an airtight chamber forming structure having at least first and second sealing members, which are disposed between the tube and the casing and have different softnesses.   The said housing | casing consists of two half-body parts, and arrange | positions the said two half-body parts on the both sides of the said to-be-inspected part of the said pipe | tube, The said housing | casing is formed. Leakage inspection device.   The first seal member is disposed so as to form a closed ring surrounding the entire circumference of the tube when the end portions abut against each other, and the second seal member is in contact with the first seal member and the tube. The leakage inspection apparatus according to claim 1, wherein the leakage inspection apparatus is arranged.   The leak inspection apparatus according to claim 3, wherein the softness of the second seal member is higher than the softness of the first seal member.   The airtight chamber includes a main airtight chamber that surrounds the part to be inspected, and a secondary airtight chamber that is configured outside the main airtight chamber so as to surround a seal portion between the pipe and the main airtight chamber. The leak inspection apparatus according to any one of claims 1 to 4, further comprising:   6. The leak inspection apparatus according to claim 5, wherein the second seal member is disposed at a seal portion between the tube and the sub-airtight chamber separating the outside and the sub-airtight chamber.   The leakage inspection apparatus according to claim 1, wherein the second seal member is an ultra-soft rubber or a sponge.

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