JP4644100B2 - Helium leak test method and apparatus - Google Patents

Description

  The present invention relates to a helium leak test method and an apparatus therefor, and more particularly to a helium leak test method and a helium leak test unit for testing the airtightness of a welded portion of a pipe, and a helium leak test apparatus using the same.

Conventionally, as a leak test method for testing the airtightness of a welded portion of a pipe, an annular groove constituent portion is provided at both ends of a cylindrical member by annular flanges projecting to the outer peripheral side, and the annular groove formed in the annular groove constituent portion is O A ring or seal ring is attached, and a pressurized fluid supply port for sealing is provided in the cylindrical member to supply pressurized fluid toward the inner peripheral side of the O-ring or the seal ring in the annular groove, and the cylinder A pressurized leak test unit is prepared in which a pressurized fluid supply port for test for supplying pressurized air from the inside toward the outer peripheral side is provided at the center of the member. Then, during the leak test, the pressurized leak test unit is inserted into the pipe so that the pair of O-rings or seal rings are located on both sides of the welded part of the pipe, and then is annularly formed from the pressurized fluid supply port for sealing. A pressurized fluid is supplied to the inner peripheral side of the groove, the outer peripheral side of the O-ring or seal ring is pressed against the inner peripheral surface of the pipe, and the inner peripheral surface of the pipe in the welded portion and the outer peripheral surface of the cylindrical member The enclosed annular space is sealed, and then, a predetermined inspection pressure is applied by supplying a pressurized fluid from the test pressurized fluid supply port into the annular space, and a change in the inspection pressure or welding of a pipe is performed. What is known to test hermeticity by a change in the state of soapy water applied around the part (see, for example, Patent Document 1 and Patent Document 2).
JP 2003-214972 A Japanese Utility Model Publication No. 2-27543

However, in the leak test method, in the case of checking the airtightness by the pressure change of the test pressurized fluid added to the annular space between the pressurized leak test unit and the pipe, in the case of a minute leak from the welded part of the pipe Has a problem in that it cannot accurately capture a minute pressure change due to this, and takes a long time for the inspection. In addition, leakage from the welded portion of the pressurized test fluid applied to the annular space between the pressurized leak test unit and the pipe is applied by soapy water around the welded portion and airtight due to changes in the state of the soapy water. In the case of inspecting the property, since the state of the soapy water is visually observed, in the case of a minute leak, it is still impossible to inspect quickly and accurately.
Therefore, the periphery of the welded portion of the pipe is masked with vinyl or the like, helium gas is supplied to the pressurized fluid supply port for testing of the pressurized leak test unit, and leaks from the welded portion by the pressurized sniffer method. A leak test can also be performed by sucking helium gas with a vacuum pump and detecting it with a helium detector. However, in this case, since the annular space between the pressurized leak test unit and the pipe is wide, the consumption of helium gas is increased, and the inside of the masking is sealed to obtain the required sensitivity, and the atmosphere inside There is a problem that it takes time to prevent the presence of helium in the inside and the workability is not good.

  The present invention has been made in view of the above circumstances, and can detect even a minute leak in a welded portion of a pipe quickly and reliably, and consume as little helium as a test gas as much as possible. An object of the present invention is to provide a helium leak test method, a helium leak test unit, and a helium leak test apparatus that can perform a leak test easily and efficiently.

The present invention is characterized by the following points in order to solve the above problems.
In other words, the helium leak test method according to claim 1 includes a vacuum vessel and a pressurizing unit, and the vacuum vessel includes a cylindrical member in which flanges provided with pipe insertion holes are fixed to both ends, and each of the flanges. A first annular packing made of an elastic member disposed in an annular groove provided in the inner peripheral portion, and the pressure unit is provided on the outer periphery of the shaft-shaped member and both ends of the shaft-shaped member. is a second annular packing made of arranged elastic member in the annular groove has, a helium leak test method using a helium leak test unit having a, in each pipe insertion hole of the vacuum vessel, the a pipe having a welded portion which is a test specimen, a step of the weld portion is inserted until positioned therebetween of each flange, from said pressurized gas introducing hole provided in the shaft-like member and each of the flanges, the each annular Pressurized gas inside the groove And pressing the second annular gasket between said first annular packing by introducing an inner periphery and between the pipe and the inner periphery of the outer peripheral of the pipe flange and the outer periphery of the shaft-like member a step of sealing between said from the test gas introduction hole provided in the shaft-like member, the annular gap between the outer peripheral surface of the inner peripheral surface and the shaft member of the pipe which is sealed by a second annular packing And a step of evacuating the annular space between the inside of the cylindrical member sealed by the first annular packing and the outer periphery of the pipe.

The helium leak test method according to claim 2 is the helium leak test method according to claim 1, wherein the pressurized gas introduction hole provided in the shaft-shaped member is provided along an axial direction of the shaft-shaped member. The test gas provided in the shaft-shaped member, and a communication hole provided in the radial direction of the shaft-shaped member communicating with the pressurized gas introduction hole. The introduction hole includes a test gas introduction hole provided along the axial direction of the shaft-shaped member, and a communication hole provided in the radial direction of the shaft-shaped member communicating with the test gas introduction hole. The first annular packing and the second annular packing are formed in a U-shaped cross section.

The helium leak test unit according to claim 3 is a helium leak test unit comprising a vacuum vessel and a pressurizing unit, wherein the vacuum vessel is provided with flanges provided with pipe insertion holes fixed at both ends in an airtight manner. a tubular member forming an annular space between the pipe having a weld which has been inserted into the pipe insertion hole, the first consisting of an elastic member disposed within an annular groove provided the the inner periphery of each flange an annular packing, the provided in each flange, said the inside first annular packing pressurized gas introduction hole for introducing a pressurized gas that presses the outer peripheral surface of the pipe in each annular groove, the tubular member A vacuum exhaust port for exhausting the gas in the annular space, and the pressurizing unit is provided with an annular groove on the outer periphery of both ends , and an axial member inserted into the pipe ; The shaft member A second annular packing made of an elastic member disposed in the annular groove, provided in the shaft-like member, presses the second annular gasket on the inner circumferential surface of the pipe within the annular groove of the shaft-like member a pressurized gas inlet for introducing a pressurized gas, provided in the shaft-like member, the annular gap between the outer peripheral surface and the inner peripheral surface of the pipe shaft-like member between each other the second annular packing A test gas introduction hole for introducing helium gas, and the pressurized gas introduction hole provided in the shaft-shaped member includes a pressurized gas introduction hole provided along the axial direction of the shaft-shaped member; A communication hole provided in the radial direction of the shaft-shaped member that communicates with the pressurized gas introduction hole portion, and the test gas introduction hole provided in the shaft-shaped member is formed of the shaft-shaped member. A test gas introduction hole provided along the axial direction, and the test gas introduction hole Characterized in that the communicating holes provided in the radial direction of the shaft-like member which communicates, are composed of, the first annular packing and the second annular packing is formed to have a U-shaped cross section It is said.

The helium leak test unit according to claim 4 is the helium leak test unit according to claim 3 , wherein the tip of the rolling part is in contact with the outer peripheral surface of the pipe at the axial end of the vacuum vessel. A plurality of casters for guiding the vacuum vessel in the axial direction of the pipe in a state where the axis of the pipe insertion hole of the flange is aligned with the axial center of the pipe are provided at intervals in the circumferential direction of the pipe insertion hole. It is characterized by that.

  The helium leak test unit according to claim 5 is the helium leak test unit according to claim 3, wherein the end of the axial member of the shaft-like member is contacted with the tip of the rolling portion against the inner peripheral surface of the pipe. A plurality of casters for guiding the shaft member in the axial direction of the pipe in contact with the shaft center of the shaft in alignment with the shaft center of the pipe are provided at intervals in the circumferential direction of the shaft member. It is characterized by that.

A helium leak test apparatus according to claim 6 is configured to supply pressurized gas to each pressurized gas introduction hole of the vacuum vessel and the pressurizing unit in the helium leak test unit according to any one of claims 3 to 5. A pressurized gas supply unit to be supplied is connected via a pipe, and a helium gas supply unit for supplying helium gas to a test gas introduction hole of the pressurizing unit is connected via a pipe and connected to the shaft-like member. The piping for supplying pressurized gas and the piping for supplying helium gas are arranged inside the support tube, and a roughing exhaust pump and a helium leak detector are connected to the vacuum exhaust port of the vacuum vessel via the piping. It is characterized by being.

  The helium leak test apparatus according to claim 7 is the helium leak test apparatus according to claim 6, wherein a sorption pump is provided in a pipe connecting the vacuum exhaust port and the helium leak detector. .

  A helium leak test apparatus according to claim 8 is the helium leak test apparatus according to claim 6 or 7, wherein a standard leak unit is connected to the annular space of the vacuum vessel via a pipe. .

The helium leak test apparatus according to claim 9 is the helium leak test apparatus according to any one of claims 6 to 8 , wherein the helium leak test apparatus is arranged at a predetermined distance in an axial direction of the pressurizing unit, and is a connecting member. and a one frame and the other frame connected by a helium leak test unit, helium leak detectors, crude引排air pump is mounted on one of the stand, the pressurized gas supply unit and a helium gas supply unit and the other frame And the support tube is fixed to the other frame .

  The helium leak test apparatus according to claim 10 is the helium leak test apparatus according to claim 9, wherein the one base and the other base are supported by a guide member and are movable in the axial direction with respect to the pipe. It is characterized by being provided.

The present invention has the following excellent effects.
That is, according to the helium test method according to claim 1, an airtight annular gap and an annular space are easily and reliably formed on the inner and outer peripheral portions of the welded portion of the pipe as a test object by the pressurizing unit and the vacuum vessel. When the helium gas supplied to the annular gap inside the pipe leaks from the weld into the annular space outside the pipe, the leakage of the helium gas is evacuated by evacuating the annular space. The detector can reliably detect the leak, and the leak test of the welded portion of the pipe by the pressure sniffer method can be easily and reliably performed.

According to the helium leak test unit of the third aspect, the pipe having the welded part to be tested can be surrounded by the vacuum vessel, and an airtight space can be easily formed around the welded part. When performing the helium leak test by the pressure sniffer method, it is not necessary to perform the troublesome work of masking the periphery of the welded portion of the pipe with vinyl or the like, and the workability is extremely good. In addition, an airtight space surrounding the welded portion of the pipe can be formed by a vacuum vessel equipped with an annular packing that is pressed against the outer peripheral surface of the pipe by supplying pressurized gas inside the flange at the end of the cylindrical member. An annular airtight space for introducing helium gas is formed in the inner peripheral portion of the pipe by a pressurizing unit having annular packings that are pressed against the inner peripheral surface of the pipe by supplying pressurized gas to the outer periphery of both ends. Can do. Therefore, if the helium gas supplied to the airtight space inside the pipe leaks outside through the welded portion of the pipe from the airtight space, even if the leaked helium gas is minute, the inside of the airtight space of the vacuum vessel The helium leak test method according to claim 1 or 2 can be accurately performed by evacuating the gas in the airtight space and inspecting with a helium leak detector.

  According to the helium leak test unit of the fourth aspect, since the caster is brought into a state where the axis of the pipe insertion hole of the flange of the vacuum vessel is aligned with the axis of the pipe, the inner peripheral surface of the pipe insertion hole and the pipe An annular gap that is uniform in the diametrical direction is formed between the outer circumferential surface of the pipe and the annular gap can be surely sealed by the first annular packing. A space can be easily formed. Further, when the vacuum vessel and the pipe move relative to each other in the axial direction, it is possible to prevent the first annular packing in a restored state by releasing the seal from abnormally contacting and damaging the outer peripheral surface of the pipe.

  According to the helium leak test unit according to the fifth aspect, the shaft center of the shaft-shaped member of the pressurizing unit is aligned with the shaft center of the pipe by the caster. An annular gap that is uniform in the diametrical direction is opened between the circumferential surface and the annular gap can be reliably sealed by the second annular packing, and the pipe is interposed between the second annular packings. An annular airtight space for introducing the pressurized gas can be easily formed. Also, when the pressurizing unit and the pipe move relative to each other in the axial direction, the second annular packing in a restored state by releasing the seal is prevented from abnormally contacting the inner peripheral surface of the pipe and being damaged. Can do.

  According to the helium leak test apparatus according to claim 6, after inserting the pipe having the welded portion between the vacuum vessel and the pressurizing unit, the pressurized gas introduction hole of the vacuum vessel and the pressurizing unit from the pressurized gas supply unit. After forming the annular airtight space formed outside the pipe inside the vacuum vessel and the airtight annular space formed outside the pressurizing unit inside the pipe by supplying pressurized gas to The helium gas is supplied from the helium gas supply unit to the test gas introduction hole of the pressurizing unit, and leaks from the welded portion of the pipe by evacuating the airtight space of the vacuum vessel from the vacuum exhaust port by the roughing exhaust pump. The presence or absence of minute helium gas can be detected quickly and reliably with a helium leak detector so that leak tests can be performed easily and efficiently. Kill.

According to the helium leak test apparatus of the seventh aspect, even if the gas sucked from the inside of the vacuum vessel contains an impure gas, the impure gas can be easily removed by increasing the suction exhaust speed by the sorption pump. In addition, a leak test using a helium leak detector can be performed with higher accuracy and reliability.
According to the helium leak test apparatus according to claim 8, the sensitivity of the vacuum suction system of the vacuum vessel as equipment for performing the leak test is confirmed, the sensitivity calibration of the helium leak test unit is performed, and the leak by the helium leak test unit The test can be performed accurately.

According to the helium leak test apparatus according to claim 9, the devices constituting the helium leak test apparatus can be compactly mounted on the gantry, and in particular, the helium leak detection side device is a helium leak test unit. Since the equipment on one side that supplies pressurized gas and helium gas is installed on the other base, the pressurized gas and helium gas in the helium leak test unit are It can be opened at a position away from the helium leak detection side, and the adverse effects of these gases on the helium leak test can be reduced.
According to the helium leak test apparatus according to claim 10, by moving each gantry along the guide member, the helium leak test unit can be accurately moved to the weld portion of the pipe, and there are a plurality of weld portions. Leak tests can be performed efficiently even with pipes.

Hereinafter, a helium leak test unit according to an embodiment of the present invention will be described with reference to FIGS.
In FIG. 1, reference numeral 1 denotes a helium leak test unit according to an embodiment of the present invention. The helium leak test unit 1 includes a cylindrical member 4 in which flanges 3 and 3 having a pipe insertion hole 2 at the center are fixed in an airtight manner at both ends, and the pipe insertion holes 2 of the flanges 3 and 3. A vacuum vessel 8 provided with an annular packing (first annular packing) 7 disposed in an annular groove 6 provided in the peripheral portion is provided.

  Projections 10 are provided on the outer end surfaces of the flanges 3, 3, and a plurality of casters 11 (three in the illustrated example) 11 are provided inside the protrusions 10 at predetermined intervals in the circumferential direction of the pipe insertion hole 2. Is provided. Each caster 11 is supported by the protruding portion 10 via a shaft 11a oriented in the diameter direction of the pipe insertion hole 2 inside the protruding portion 10, and rotates around the shaft 11a. The ball holder 11b has a ball (rolling portion) 11c that is rotatably held at the tip, and the tip of the ball 11c protruding from the ball holder 11b is inserted into the pipe insertion hole 2. A minute annular gap e1 is formed between the outer peripheral surface of the pipe P and the inner peripheral surface of the pipe insertion hole 2 in contact with the outer peripheral surface of the pipe P as a test object.

  The annular packing 7 is made of an elastic member such as rubber and is configured as a hollow or solid annular body having a U-shaped cross section, and an inner peripheral portion corresponding to the bottom of the U shape is connected to the pipe P The both side wall portions corresponding to the U-shaped side are brought into contact with the side wall 6a of the annular groove 6 of the flange 3 and are mounted in the annular groove 6 toward the outer peripheral surface side. Each of the flanges 3 and 3 is provided with a pressurized gas introduction hole 12 that opens to the outer periphery of the annular groove 6, and pressurized gas is introduced into the annular groove 6 from the pressurized gas introduction hole 12. The annular packing 7 is pressed against the outer periphery of the pipe P by the pressure of the pressurized gas, and the annular space E of the vacuum vessel 8 surrounded by the cylindrical member 4, the flanges 3, 3 and the pipe P is formed. It is designed to be hermetically sealed. The tubular member 4 is provided with a vacuum exhaust port 13 that communicates with the annular space E and exhausts the gas in the annular space E.

  Further, the helium leak test unit 1 includes annular shafts 15, 15 provided on the outer circumferences of both ends, a shaft-like member 14 inserted through the pipe P, and the annular grooves 15, 15 of the shaft-like member 14. Annular packings (second annular packings) 16, 16 disposed in the cylindrical member 14, pressurized gas introduction holes 17 provided in the shaft-like member 14 for introducing pressurized gas into the annular grooves 15, 15, A test gas introduction hole 18 for introducing helium gas into an annular gap e2 between the outer peripheral surface of the shaft-shaped member 14 and the inner peripheral surface of the pipe P between the annular packings 16, 16 provided in the shaft-shaped member 14. A pressurizing unit 19 is provided.

  Projection shaft portions 14a, 14a having a small diameter are provided on the outer end surface of the shaft-shaped member 14, and a plurality of (in the example shown in the figure) are provided outside the projection shaft portions 14a, 14a at predetermined intervals in the circumferential direction. 3) casters 20 are provided. As shown in FIG. 2, each caster 20 is supported on the projecting shaft portion 14a on the outer peripheral portion of the projecting shaft portion 14a via a shaft 20a directed in the diameter direction, and rotates around the shaft 20a. And a ball (rolling part) 20c rotatably held at the tip of the ball holder 20b, and the tip of the ball 20c protruding from the ball holder 20b is the pipe. A minute annular gap e <b> 2 is formed between the inner peripheral surface of the pipe P and the outer peripheral surface of the shaft-shaped member 14 by being in contact with the inner peripheral surface of P.

  The annular packing 16 is formed of an elastic member such as rubber like the annular packing 7 and is configured as a hollow or solid annular body having a U-shaped cross section, and corresponds to the bottom of the U-shape. The outer peripheral portion is directed to the inner peripheral surface side of the pipe P inserted through the pipe insertion hole 2, and both side walls corresponding to the U-shaped side are end surfaces on both sides of the annular grooves 15, 15 of the shaft member 14. It is mounted in the annular groove 15 so as to be in contact with 15a, 15a. The pressurized gas introduction hole 17 has a pressurized gas introduction hole portion 17a provided along the axial direction of the shaft-like member 14, and one end side (left end side in FIG. 1) of the annular groove 15 at one end side. As shown in FIG. 3, one or more (in the illustrated example) communication holes 17b in the radial direction and the other end side (right end side in FIG. 1) of the pressurized gas introduction hole portion 17a are opened as shown in FIG. It is composed of one or a plurality of (in the illustrated example) communication holes 17b in the radial direction that are opened in the annular groove 15 on the end side.

When the pressurized gas is introduced into the annular grooves 15 and 15 from the pressurized gas introduction hole 17, the annular packings 16 and 16 are pressed against the inner peripheral surface of the pipe P by the pressure of the pressurized gas. The both ends of the annular gap e2 between the outer peripheral surface of the shaft-shaped member 14 and the inner peripheral surface of the pipe P are hermetically sealed.
Further, the test gas introduction hole 18 is formed between the test gas introduction hole portion 18 a provided in the shaft member 14 along the axial direction from the other end side and the pair of annular packings 16, 16. The test gas introduction hole portion 18a is connected to one end side of the test gas introduction hole portion 18a (illustrated example) or a plurality of communication holes 18b.

  Next, the configuration of the helium leak test apparatus 22 according to the first embodiment of the present invention will be described with reference to FIGS. The helium leak test apparatus 22 includes a pressurization gas supply unit 24 connected to the pressurization gas introduction holes 12 and 17 of the helium leak test unit 1 via a pipe 23, and a test gas introduction hole of the helium leak test unit 1. 18, a helium gas supply unit 26 connected via a pipe 25, a rough exhaust pump unit 28 connected via a pipe 27 to the vacuum exhaust port 13 of the vacuum vessel 8 in the helium leak test unit 1, and a helium leak test. The helium leak test unit 1 is provided with a portion 29 and a standard leak unit 31 connected to the annular space E of the vacuum vessel 8 of the helium leak test unit 1 via a pipe 30.

  The pressurized gas supply unit 24 is connected to a gas cylinder 32 for storing a high-pressure gas such as nitrogen gas, and an outlet of the gas cylinder 32. From the gas cylinder 32 side, a pressure reducing valve (pressure adjusting valve) 33a, an on-off valve 33b, And a pressurized gas delivery pipe 33 provided with an on-off valve 33d. The proximal end of the pipe 23 is connected between the pressure gauge 33c and the on-off valve 33d in the pressurized gas delivery pipe 33, and the pipe 23 Is connected to the pressurized gas introduction hole 12 provided in the vacuum vessel 8 of the helium leak test unit 1 through one branch pipe (pipe) 23a, and through the other branch pipe (pipe) 23b. The helium leak test unit 1 is connected to the other end of the pressurization gas introduction hole 17 provided in the pressurization unit 19 (the outer end of the pressurization gas introduction hole 17a).

The pressurized gas is not supplied from the same pressurized gas supply unit 24 to the pressurized gas introducing hole 12 of the vacuum vessel 8 and the pressurized gas introducing hole 17 of the pressurized unit 19 as described above. The pressure may be adjusted individually by a separately provided pressurized gas supply unit.
The helium gas supply unit 26 is connected to a helium bomb 34 for storing helium gas, and an outlet of the helium bomb 34. And a helium delivery pipe 35 provided with an opening / closing valve 35d, the proximal end of the pipe 25 being connected between the pressure gauge 35c and the opening / closing valve 35d in the helium delivery pipe 35, and the distal end of the pipe 25 being the helium leak The other end of the test gas introduction hole 18 of the test unit 1 (the outer end of the test gas introduction hole 18a) is connected.

The roughing exhaust pump unit 28 is connected to a suction pipe 37 having a switching valve 37a at the inlet of a conventionally known roughing exhaust pump 36, and is branched from the suction pipe 37 on the downstream side of the switching valve 37a. The pipes 38 and 39 are respectively provided with an automatic switching valve 38 a and a leak valve 39 a, and the suction pipe 37 is connected to the vacuum exhaust port 13 of the vacuum vessel 8 through a pipe 27. The automatic switching valve 38a is connected to a vacuum indicator 40 that detects the vacuum pressure in the annular space E of the vacuum vessel 8, and is automatically controlled to open and close according to the vacuum pressure detected by the vacuum indicator 40. It has become so.
The helium leak test unit 29 is formed by connecting a known helium leak detector 41 downstream of the automatic switching valve 38a in the branch pipe 38 of the roughing exhaust pump unit 26 via a suction pipe 42 having an on-off valve 42a. . The branch pipe 38 can be provided in communication with the annular space E of the vacuum vessel 8 instead of being branched from the suction pipe 37.

  The standard leak unit 31 has a suction pipe 44 having a pair of on-off valves 44a and 44a connected to the inlet of the vacuum pump 43, and a branch pipe 45 branched from the suction pipe 44 between the on-off valves 44a and 44a. A helium vessel 46 connected via an on-off valve 45 a is provided, and the suction pipe 44 is communicated with the annular space E of the vacuum vessel 8 by a pipe 30. The helium container 46 is a conventionally well-known container in which a glass container filled with helium gas is housed in a case with a capillary tube at the tip, and the tip of the capillary tube is broken during use to make the glass container. Helium gas is allowed to flow out from the container at a reference minute flow rate.

Next, the configuration of the helium leak test apparatus 47 according to the second embodiment of the present invention will be described with reference to FIG. This helium leak test apparatus 47 is a sorption pump unit between the branch pipe 38 of the rough exhaust pump unit 28 and the suction pipe 42 of the helium leak detector 41 in the helium leak test apparatus 22 according to the first embodiment. 48 is provided. Since other configurations are the same as those of the helium leak test apparatus 22, the same reference numerals are given to the same components, and description of those configurations will be omitted.
In the sorption pump unit 48, a pair of conventionally known sorption pumps 49, 49 are arranged in parallel with the branch pipe 38 and the suction pipe 42 by pipes 50, 50 having on-off valves 50a, 50b above and downstream thereof. The sorption pumps 49 and 49 can be switched and operated individually or simultaneously by switching the opening and closing of the on-off valves 50a and 50b.

  Next, the configuration of the helium leak test apparatus 51 according to the third embodiment of the present invention will be described with reference to FIGS. 1 and 5 to 7. This helium leak test apparatus 51 has a pair of horizontal and parallel guide rails (guide members) 52a and 52a along both edges of the upper surface, and is installed on the floor and extended to the left and right in FIG. A long base (guide member) 52, and before and after being connected to each other by a connecting rod (connecting member) 53 arranged in the longitudinal direction of the base 52 (left and right in FIG. 7) and connected to each other by a connecting rod (connecting member) 53 (FIG. 7). A pair of carts 54a and 54b. Each of the carriages 54a and 54b is configured by providing wheels 55c at the four corners of the lower ends of the pedestals 55a and 55b formed in a rectangular frame shape by assembling frame members vertically and horizontally, and the wheels 55c on the guide rails 52a and 52a. , 55c are guided and moved on the base 52 in the longitudinal direction by moving means as appropriate.

  The vacuum vessel 8 of the helium leak test unit 1 is placed on the upper surface of the gantry (one gantry) 55a of the front (one) trolley 54a via a support member as appropriate. It is fixed horizontally (in the axial direction of the pipe P). Further, in the pressurizing unit 19 of the helium leak test unit 1, as shown in FIGS. 1 and 4, a supporting tube 56 fitted with a protruding shaft portion 14a on the other end side is a bolt 56a. The support pipe 56 is connected to the upper surface of the base (the other base) 55b of the rear (the other) carriage 54b. Thereby, the pressurizing unit 19 is inserted into the pipe insertion holes 2 and 2 of the flanges 3 and 3 of the vacuum vessel 8, and the vacuum vessel 8 and the pressurizing unit 19 are positioned close to each other in the axial direction between them. It is set so as not to move relatively in the axial direction in a state where it is adjusted to.

  Further, in the case of the rough evacuation pump unit 28, the helium leak test unit 29, the standard leak unit 31, and the helium leak test apparatus 47 of the helium leak test apparatus 22, the sorption pump unit 48 is further provided on the front mount 55a. A control panel (not shown) for operating these devices is housed and mounted in a housing 57a or the like. Further, the pressurized gas supply unit 24, the helium gas supply unit 26, and a control panel (not shown) for operating them are collected and mounted on a frame 57b or the like on the mount 55b of the rear carriage 54b. ing. A branch pipe 23b connecting the pressurization unit 19 and the pressurization gas supply unit 24 and a pipe 25 connecting the pressurization unit 19 and the helium gas supply unit 26 are located behind the support pipe 56. The frame 55b extends horizontally from the frame 55b to the front frame 55a.

  In front of the helium leak test apparatus 51 (on the left in FIG. 7), a welding machine (not shown) is installed that abuts the pipe in the axial direction and welds the periphery of the abutting portion. The pipe P having a circumferential welded joint (welded portion) w welded by the above-mentioned is in a state in which its axis is aligned with the axis of the pipe insertion hole 2 of the vacuum vessel 8, and the V-shaped groove is formed at the tip. It is supported by a supporting means 58 a such as a roller having a roller, and is transferred to the helium leak test apparatus 51 side by the conveying means 58. The helium leak test apparatus 51 is provided with a support plate 59 that spans the one base 55a and the other base 55b, and is inserted into the helium leak test unit 1 on the support plate 59. Guide support means 60 such as a roller for supporting the free end side of the pipe P is provided, and the pipe P is guided so as to go straight in the axial direction thereof.

Next, the helium leak test method according to the embodiment of the present invention will be described together with the operation of the helium leak test unit 1, the helium leak test apparatus 22, 47, and 51 according to the above embodiment.
First, a pipe P as a test object welded by a welding machine is transferred rearward (rightward in FIG. 7) toward the carriage 54a by the conveying means 58, and the tip of the pipe P is predetermined in the longitudinal direction of the base 52. When positioned, the carriages 54a and 54b of the helium leak test apparatus 51 are moved forward along the guide rails 52a and 52a by the moving means, and the vacuum container of the helium leak test unit 1 on the front carriage 54a is moved. The pipe P is inserted into the 8 pipe insertion holes 2 and 2 and the pressure unit 19. At that time, the conveying means 58 is retracted to the left in FIG. 7 in conjunction with the carriages 54a and 54b. When the position of the circumferential weld joint w of the pipe P reaches the axial center of the annular space E of the vacuum vessel 8, the movement of the carriages 54a and 54b is stopped.
The pipe P inserted through the pipe insertion holes 2 and 2 and the pressure unit 19 is guided by the casters 11 at both ends of the vacuum vessel 8 and the inner periphery is casters 20 at both ends of the pressure unit 19. Therefore, the axial center of the pipe P is kept accurately aligned with the axial centers of the vacuum vessel 8 and the pressurizing unit 19.
As a result, when the vacuum vessel 8 and the pressure unit 19 move relative to the pipe P in the axial direction, the first and second annular packings 7 and 16 that are in a restored state by releasing the seal are connected to the pipe. It is possible to prevent the outer peripheral surface and inner peripheral surface of P from being abnormally contacted and damaged.

  When the carriages 54a and 54b are stopped, the pressurized gas supply unit 24 is operated to open the on-off valve 33b, and pressurized gas whose pressure is adjusted to a predetermined value by the pressure reducing valve 33a from the gas cylinder 32 is supplied to the piping. 23 and its branch pipes 23a and 23b through the pressurized gas introduction hole 12 of the flange 3 of the vacuum vessel 8 into the annular grooves 6 and 6 and from the pressurized gas introduction hole 17 of the pressure unit 19 to the inside. It enters the inside of the annular grooves 15 and 15. The annular packings 7 and 16 are pressed against the outer peripheral surface and the inner peripheral surface of the pipe P by the pressure of the pressurized gas introduced into the annular grooves 6 and 15, respectively. The annular space E is hermetically closed, and the annular gap e2 between the inner peripheral surface of the pipe P and the outer peripheral surface of the shaft-like member 14 between the annular packings 16 and 16 is hermetically closed.

  Subsequently, the helium gas supply unit 26 is operated to open the opening / closing valve 35b, and the helium gas whose pressure is adjusted to a predetermined value by the pressure reducing valve 35a from the helium cylinder 34 passes through the pipe 25 and the helium in the pressurizing unit 19. The gas is introduced from the gas introduction hole 18 into the annular gap e2. At this time, since the pressure of the pressurized gas supplied into the annular grooves 15 and 15 is set slightly higher than the pressure of the helium gas supplied to the annular gap e2, the helium gas is discharged from the annular gap e2. There is no leakage to the outside of the annular packing 16. Simultaneously with the introduction of helium gas into the annular gap e2, the roughing exhaust pump unit 28 is operated to open the on-off valve 37a. The roughing exhaust pump 36 causes the vacuum vessel 8 to pass through the suction pipe 37 and the pipe 27. The gas in the annular space E is sucked to start the helium leak test. When the vacuum degree of the annular space E reaches a set value by the suction of the roughing exhaust pump 36, the automatic switching valve 38a is opened by the vacuum indicator 40 and the on-off valve 37a is closed to stop the roughing exhaust pump. Is done. At the same time, the leak detector 41 causes the leak detector 41 to evacuate the gas in the annular space E by an internal vacuum pump through the suction pipe 42 in which the on-off valve 42a is opened in advance, and whether or not helium gas exists in the suction gas. By detecting this, the quality of the airtightness of the circumferential weld joint w of the pipe P is determined.

  In the above description, when the sorption pump unit 48 is provided on the upstream side of the helium leak test section (see FIG. 6), the gas sucked from the annular space E to the helium leak detector 41 is the sorption pump on the way. 49 and 49 can increase the suction / exhaust speed to adsorb and remove impure gases such as air, so that even when the annular packings 7 and 7 of the vacuum vessel 8 are damaged and a large amount of air enters the annular space E. In addition, it is possible to avoid failure of the detection unit of the leak detector 41 and to perform a leak test using the helium detector 41 more accurately. The sorption pumps 49, 49 are operated one by one alternately by switching the on-off valves 50a, 50a before and after them, or simultaneously when necessary. When operating alternately, it can be operated such that one is in operation and the other is regenerated.

If helium gas is not detected in the suction gas by the helium leak detector 41 and the determination result is good, the on-off valve 33b of the pressurized gas supply unit 24 and the on-off valve 35b of the helium gas supply unit 26 are closed. The supply of pressurized gas and helium gas to the helium leak test unit 1 is stopped, and the helium leak test is terminated.
When the helium leak test is ended, the helium gas supply unit 26 is opened and closed while the pressurized gas is supplied to the pressurized gas introduction holes 12 and 17 of the helium leak test unit 1 by the pressurized gas supply unit 24. After opening the valve 35d to release the pressure of the helium gas in the pipe 25, the pressurized gas introduction hole 18 of the pressurizing unit 19 and the annular gap e2, the on-off valve 33d of the pressurized gas supply unit 24 is opened, The pressure of the pressurized gas in the pipe 23 and the branch pipes 23a and 23b is released, and the pressure on the pipe P of the annular packings 7 and 16 is released. As a result, the annular packings 7 and 16 are elastically restored to be separated from the pipe P and accommodated in the annular grooves 6 and 15. And prepare for the next helium leak test.

As described above, when the opening / closing valve 35d of the helium gas supply unit 26 is opened, helium gas is discharged from the pipe 25. This helium gas is discharged by installing the helium leak test unit 1 on the helium leak test. Since the test is performed at the position of the other base 55b on which the helium supply unit 26 is mounted at a position sufficiently away from one base 55a to be tested rearward (rightward in FIG. 7), the next leak test is performed. The discharged helium gas has no adverse effect.
When there are a plurality of circumferential welded joints w in the pipe P, if the position of the next circumferential welded joint w is within the moving stroke range of each of the carriages 54a and 54b, the carriages 54a and 54b are shown in FIG. If it is moved forward to the left and is not within the range of the moving stroke, the leak test can be continued by moving the pipe P toward the rear carriage 54b. Thus, by moving each mount 55a, 55b along the guide rails 52a, 52a, the helium leak test unit 1 can be accurately moved to the welded portion w of the pipe P, and a plurality of welded portions w are formed. Even a certain pipe P can perform a leak test efficiently.
In addition, during the leak test work, since the equipment constituting the helium leak test apparatus is mounted on the pedestals 55a and 55b, it is not necessary to install the equipment on the floor, and the work area around the test apparatus is widened. It can be secured and work can be performed safely and smoothly.

  The standard leak unit 31 is used to open the on-off valves 45a and 44a before the start of the test of the pipe P as the first object to be tested, and at the end of the test. After the standard leak amount is measured by sucking with a vacuum pump 43 equipped with a leak detector, the on-off valve 45a is closed, the on-off valve 44a is opened, and the piping 30 is evacuated with the gas in the annular space E of the vacuum vessel 8 by the vacuum pump 43. The sensitivity of the vacuum suction system of the vacuum vessel 8 as equipment for performing the leak test is confirmed from the ratio of the measured values when sucked, and the sensitivity calibration of the helium leak test unit 41 is performed. Thereby, the leak test in the weld part of the pipe P by the helium leak test part 41 can be accurately performed. After confirming the sensitivity, the on-off valve 44a is closed.

  As described above, in the helium leak test method according to the embodiment, the annular grooves 6 and 6 are provided in the inner peripheral portions of the pipe insertion holes 2 and 2 of the flanges 3 and 3 fixed to both ends of the cylindrical member 4. The vacuum vessel 8 in which the first annular packings 7 and 7 having a U-shaped cross section are arranged in the annular grooves 6 and 6 and the annular grooves 15 and 15 provided at both ends of the shaft-like member 14 have a U-shaped cross section. And a pressurizing unit 19 in which second annular packings 16 and 16 are arranged, and the welded part w is a pipe P having a welded part w as a test object in each pipe insertion hole 2 and 2 of the vacuum vessel 8. After inserting the flanges 3 and 3 until they are located between the flanges 3 and 3 and inserting the pressurizing unit 19 into the pipe P, the pressurized gas introduced into the flanges 3 and 3 and the shaft member 14 is introduced. A pressurized gas is introduced into the annular grooves 6 and 15 from the holes 17. By pressing the first and second annular packings 7 and 16, between the outer periphery of the pipe P and the inner periphery of the flanges 3 and 3, and the inner periphery of the pipe P and the outer periphery of the shaft-like member 14 After that, from the test gas introduction hole 18 provided in the shaft-shaped member 14, the inner peripheral surface of the pipe P sealed by the second annular packing 16, 16 and the shaft-shaped member 14 are sealed. An helium gas is introduced into the annular gap e2 between the outer peripheral surface and an annular space between the inner side of the cylindrical member 4 and the outer periphery of the pipe P sealed by the first annular packings 7,7. E is evacuated by a helium leak detector 41.

  Therefore, according to the helium leak test method according to the embodiment, an airtight annular gap e2 and an annular space E are formed in the inner and outer peripheral portions of the welded portion w of the pipe P, which is a test object, by the pressurizing unit 19 and the vacuum vessel 8. When the helium gas supplied to the annular gap e2 inside the pipe P leaks from the welded part w to the annular space E outside the pipe P, the By evacuating the annular space E, the leakage can be reliably detected by the helium detector 41, and the leak test of the welded portion w of the pipe P by the pressure sniffer method can be easily and reliably performed.

  Further, in the helium leak test unit 1 according to the embodiment, the flanges 3 and 3 provided with the pipe insertion holes 2 are hermetically fixed to both ends, and the welded parts are inserted into the pipe insertion holes 2 of the flanges 3 and 3. a cylindrical member 4 that forms an annular space E with the pipe P having w, and annular grooves 6 and 6 provided in the inner peripheral portions of the flanges 3 and 3; The first annular packing 7, 7 made of a hollow or solid elastic member having a U-shaped cross section toward the outer peripheral surface side of P, and the annular grooves 6, 6 provided in the flanges 3, 3. Of the annular space E provided in the tubular member 4 and the pressurized gas introduction holes 12 and 17 for introducing the pressurized gas for pressing the first annular packings 7 and 7 against the outer peripheral surface of the pipe P. A vacuum vessel 8 provided with a vacuum exhaust port 13 for exhausting gas is provided. Annular grooves 15 and 15 are provided on the outer periphery of both ends, and the shaft-like member 14 inserted into the pipe P is disposed in the annular grooves 15 and 15 of the shaft-like member 14. A second annular packing 16, 16 made of a hollow or solid elastic member having a U-shaped cross section toward the inner peripheral surface side, and an annular groove of the shaft-shaped member 14 provided on the shaft-shaped member 14. 15 and 15, the second annular packings 16 and 16 are provided in the pressurized gas introduction hole 17 for introducing the pressurized gas that presses the inner circumferential surface of the pipe P, and the shaft-like member 14 is provided in each second. A pressurizing unit 19 provided with a test gas introduction hole 18 for introducing helium gas into an annular gap between the outer peripheral surface of the shaft-like member 14 and the inner peripheral surface of the pipe P between the annular packings 16 and 16 is provided. It has been configured.

  Therefore, according to the helium leak test unit according to the embodiment, the annular packings 7 and 7 are pressed against the outer peripheral surface of the pipe P by supplying pressurized gas to the inside of the flanges 3 and 3 at the end of the tubular member 4. The airtight space can be surely formed in the annular space E surrounding the welded portion w of the pipe P by the vacuum vessel 8 to which the pipe P is attached, and is pressed against the inner peripheral surface of the pipe by supplying pressurized gas to the outer ends of both ends. An airtight space can be reliably formed in the annular gap e2 for introducing helium gas into the inner peripheral portion of the pipe P by the pressurizing unit 19 to which the annular packings 16 and 16 are attached. As a result, if the helium gas supplied to the annular gap e2 inside the pipe P leaks outside through the welded portion w of the pipe P from the annular gap e2, even if the leaked helium gas is minute, the vacuum The helium leak test method can be reliably implemented by evacuating the gas in the annular space E and inspecting with a helium leak detector.

  The helium leak test apparatus 22, 47, 51 according to the embodiment is configured to add pressurized gas to the pressurized gas introduction holes 12, 17 of the vacuum vessel 8 and the pressurized unit 19 in the helium leak test unit 1. A pressure gas supply unit 24 is connected via a pipe 23 and branch pipes 23 a and 23 b, and a helium gas supply unit 26 that supplies helium gas to the test gas introduction hole 18 of the pressurizing unit 19 is provided via a pipe 25. The rough exhaust pump 36 and the helium leak detector 41 are connected to the vacuum exhaust port 13 of the vacuum vessel 8 via a pipe 27.

Therefore, according to the helium leak test apparatus 22, 47, 51 according to the embodiment, the pipe P having the welded portion w is inserted between the vacuum vessel 8 and the pressurizing unit 19, and then from the pressurized gas supply unit 26. By supplying pressurized gas to the pressurized gas introduction holes 12 and 17 of the vacuum vessel 8 and the pressure unit 19, an airtight annular space E formed outside the pipe P inside the vacuum vessel 8, and the pipe P After forming a gas-tight annular gap e2 formed outside the pressurizing unit 19 inside the gas, helium gas is supplied from the helium gas supply unit 26 to the test gas introduction hole 18 of the pressurizing unit 19 and roughing is performed. A minute helium gas leaking from the welded portion of the pipe P by evacuating the annular space E of the vacuum vessel 8 from the vacuum exhaust port 13 by the exhaust pump 36. Whether quicker and to reliably detected with helium leak detector 41, easily leak test can be performed efficiently.
In addition, helium gas supplied from the test gas introduction hole 18 to the annular gap e2 outside the pressurizing unit 19 is very small because the volume of the annular gap e2 (volume of vacuum exhaust) is very small, and helium is sufficient. Gas consumption can be reduced as much as possible. Also, when performing a helium leak test by the pressurized sniffer method, masking is performed with vinyl or the like around the welded portion w of the pipe P as in the past. Therefore, workability is extremely good.

  The helium leak test unit 1 according to the embodiment can be preferably applied when the pipe having the welded portion has a circular cross section, but is not limited to a pipe having a circular cross section, an elliptical cross section, a rectangular cross section, It can also be applied to pipes having other polygonal cross sections. In the case of a polygonal cross section, it is preferable to round each corner. In that case, the cross-sectional shape of the pipe insertion hole 2 of the vacuum vessel 8 and the shaft-like member 14 of the pressure unit 19 and the ring outer diameter of the annular packings 7 and 16 are similar to the cross-sectional shape of the pipe P. The

It is a longitudinal cross-sectional view which shows the helium leak test unit which concerns on one embodiment of this invention. FIG. 2 is a perspective view of FIG. 1. FIG. 2 is a cross-sectional view of FIG. FIG. 2 is a cross-sectional view of FIG. 1 is a system diagram showing a helium leak test apparatus according to a first embodiment of the present invention. It is a systematic diagram which shows the helium leak test apparatus which concerns on the 2nd Embodiment of this invention. It is a perspective view which shows the helium leak test apparatus based on the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Helium leak test unit 2 Pipe insertion hole 3 Flange 4 Cylindrical member 6,15 Annular groove 7,16 Annular packing 8 Vacuum vessel 11,20 Caster 12,17 Pressurized gas introduction hole 13 Vacuum exhaust port 14 Shaft-shaped member 18 Test Gas introduction hole 19 Pressurization unit 22, 47, 51 Helium leak test device 24 Pressurized gas supply unit 26 Helium gas supply unit 28 Rough exhaust pump unit 29 Helium leak test section 31 Standard leak unit 32 Gas cylinder 34 Helium cylinder 36 Rough exhaust Exhaust pump 41 helium leak detector 48 sorption pump unit 49 sorption pump 52a guide rail (guide member)
54a, 54b Bogie 55a, 55b Mount E Annular space e1, e2 Annular gap P Pipe w Pipe weld

Claims (10)

Equipped with a vacuum vessel and a pressure unit,
The vacuum vessel includes a first annular packing comprising a cylindrical member having flanges provided with pipe insertion holes fixed to both ends, and an elastic member disposed in an annular groove provided in an inner peripheral portion of each flange. And having
The pressurizing unit has a shaft-shaped member and a second annular packing made of an elastic member disposed in an annular groove provided on the outer periphery of both end portions of the shaft-shaped member. A helium leak test method using
Each pipe insertion hole of the vacuum vessel, inserting a pipe having a welded portion which is the test object, until the weld is positioned between each other of each flange,
The first annular packing and the second annular packing are pressed by introducing pressurized gas into the annular grooves from the pressurized gas introduction holes provided in the flanges and the shaft-shaped member. a step of sealing between the outer periphery of the inner periphery and the shaft-shaped member between the inner periphery of the outer peripheral of the pipe flange and the pipe,
Helium gas is introduced into the annular gap between the inner peripheral surface of the pipe sealed by the second annular packing and the outer peripheral surface of the shaft-shaped member from the test gas introduction hole provided in the shaft-shaped member, And a step of evacuating an annular space between the inside of the cylindrical member sealed by the first annular packing and the outer periphery of the pipe. The pressurized gas introduction hole provided in the shaft-shaped member includes a pressurized gas introduction hole provided along the axial direction of the shaft-shaped member, and the shaft-shaped member communicating with the pressurized gas introduction hole. And a communication hole provided in the radial direction of
The test gas introduction hole provided in the shaft-shaped member includes a test gas introduction hole provided along the axial direction of the shaft-shaped member, and a radial direction of the shaft-shaped member communicating with the test gas introduction hole. And a communication hole provided in the
The helium leak test method according to claim 1, wherein the first annular packing and the second annular packing are formed in a U-shaped cross section. A helium leak test unit comprising a vacuum vessel and a pressurizing unit,
The vacuum vessel has a cylindrical member that forms an annular space between a flange having a pipe insertion hole and airtightly fixed at both ends and a pipe having a welded portion that is inserted into the pipe insertion hole of each flange ;
A first annular packing made of an elastic member disposed in an annular groove provided in the inner peripheral portion of each flange ;
Wherein provided in each flange, said the inside first annular packing pressurized gas introduction hole for introducing a pressurized gas that presses the outer peripheral surface of the pipe in each annular groove,
A vacuum exhaust port provided in the cylindrical member and exhausting the gas in the annular space ;
The pressure unit is provided with an annular groove on the outer periphery of both ends , and a shaft-shaped member inserted into the pipe ;
A second annular packing made of an elastic member disposed in the annular groove of the shaft-shaped member ;
A pressurized gas introduction hole that is provided in the shaft-shaped member and introduces a pressurized gas that presses the second annular packing against the inner peripheral surface of the pipe inside the annular groove of the shaft-shaped member ;
Wherein provided on the shaft member, and a test gas inlet for introducing a helium gas into the annular gap between the outer peripheral surface and the inner peripheral surface of the pipe shaft-like member between each other the second annular packing,
The pressurized gas introduction hole provided in the shaft-shaped member includes a pressurized gas introduction hole provided along the axial direction of the shaft-shaped member, and the shaft-shaped member communicating with the pressurized gas introduction hole. And a communication hole provided in the radial direction of
The test gas introduction hole provided in the shaft-shaped member includes a test gas introduction hole provided along the axial direction of the shaft-shaped member, and a radial direction of the shaft-shaped member communicating with the test gas introduction hole. And a communication hole provided in the
The helium leak test unit, wherein the first annular packing and the second annular packing are formed in a U-shaped cross section . At the end of the vacuum vessel in the axial direction, the vacuum vessel is placed in a state where the tip of the rolling portion is in contact with the outer peripheral surface of the pipe and the axis of the pipe insertion hole of the flange is aligned with the axis of the pipe. The helium leak test unit according to claim 3, wherein a plurality of casters for guiding in the axial direction of the pipe are provided at intervals in the circumferential direction of the pipe insertion hole.   At the axial end of the shaft-shaped member, the shaft-shaped member is placed in a state where the tip of the rolling portion is in contact with the inner peripheral surface of the pipe and the axis of the shaft-shaped member is aligned with the axis of the pipe. The helium leak test unit according to claim 3, wherein a plurality of casters for guiding in the axial direction of the pipe are provided at intervals in the circumferential direction of the shaft-like member. A pressurized gas supply unit that supplies pressurized gas to each pressurized gas introduction hole of the vacuum vessel and the pressurized unit in the helium leak test unit according to any one of claims 3 to 5 via a pipe. And a helium gas supply unit for supplying helium gas to the test gas introduction hole of the pressurization unit is connected via a pipe ,
The pipe for supplying pressurized gas and the pipe for supplying helium gas are arranged inside a support pipe connected to the shaft-shaped member,
A helium leak test apparatus characterized in that a roughing exhaust pump and a helium leak detector are connected to a vacuum exhaust port of the vacuum vessel via a pipe.   The helium leak test apparatus according to claim 6, wherein a sorption pump is provided in a pipe connecting the vacuum exhaust port and the helium leak detector. The helium leak test apparatus according to claim 6 or 7 , wherein a standard leak unit is connected to the annular space of the vacuum vessel via a pipe. Are arranged at a predetermined distance in the axial direction of the pressure unit, and a one frame and the other frame which is connected by a connecting member, a helium leak test unit, helium leak detectors, crude引排air pump of one frame The pressurized gas supply unit and the helium gas supply unit are mounted on the other gantry, and the support tube is fixed to the other gantry. The helium leak test apparatus according to the item .   The helium leak test apparatus according to claim 9, wherein the one base and the other base are supported by a guide member and are movable in the axial direction with respect to the pipe.

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