阅读说明：本技术 阀等压力设备的耐压检查方法及其耐压检查装置以及压力设备 (Method for testing pressure resistance of pressure equipment such as valve, pressure resistance testing device therefor, and pressure equipment ) 是由 吉良直树 花冈达幸 三井忠茂 于 2018-12-21 设计创作，主要内容包括：本发明提供能够在阀等压力设备的装配途中进行耐压检查、通过将检查用气体迅速排出来在短时间实施耐压检查的压力设备的耐压检查方法及其耐压检查装置以及阀等压力设备。为了实现该目的,向由阀等压力设备构成的工件(2)供给示踪气体来检测泄漏的有无。通过进行耐压预备检查,在早期检测工件(2)的缺陷、加工不良,前述耐压预备检查为,呈将工件(2)的构成零件的一部分装配的状态,之后立即将工件(2)的检查对象部位(22)以减少检查空间(S)的容积的状态覆盖,进行向工件(2)内装入示踪气体来检测检查空间(S)的示踪气体的泄漏的有无。(The invention provides a pressure equipment pressure resistance inspection method, a pressure resistance inspection device and a pressure equipment such as a valve, wherein the pressure equipment pressure resistance inspection can be carried out in the assembly process of the pressure equipment such as the valve, and the pressure equipment pressure resistance inspection can be carried out in a short time by quickly discharging inspection gas. To achieve this object, a trace gas is supplied to a workpiece (2) composed of a pressure device such as a valve to detect the presence or absence of a leak. Defects and machining defects of a workpiece (2) are detected early by performing a pressure-resistant preliminary inspection in which a part of the components of the workpiece (2) is assembled, immediately thereafter, an inspection target portion (22) of the workpiece (2) is covered with a reduced volume of an inspection space (S), and a trace gas is filled into the workpiece (2) to detect the presence or absence of leakage of the trace gas from the inspection space (S).)

1. A method of testing a pressure resistance of a pressure equipment such as a valve by supplying a trace gas to a work constituted by the pressure equipment such as the valve to detect the presence or absence of a leak,

by performing a pressure-resistant preliminary inspection, defects and processing defects of the workpiece are detected at an early stage,

the pressure-resistant preliminary inspection is a process in which a part of the components of the workpiece is assembled, and immediately thereafter, the inspection target site of the workpiece is covered with the volume of the inspection space reduced, and a trace gas is introduced into the workpiece to detect the presence or absence of leakage of the trace gas in the inspection space.

2. The method of inspecting a pressure resistance of a pressure equipment such as a valve according to claim 1,

the workpiece is formed using a cast part.

3. The method of inspecting a pressure resistance of a pressure equipment such as a valve according to claim 1 or 2,

the inspection target portion of the workpiece includes a seal portion sealed by an O-ring.

4. The method of inspecting a pressure resistance of a pressure equipment such as a valve according to claim 1 or 2,

the inspection target portion of the workpiece includes a valve stem shaft seal portion of the valve.

5. The method of inspecting a pressure resistance of a pressure equipment such as a valve according to any one of claims 1 to 4,

performing a pressure resistance preliminary inspection of the workpiece and then a pressure resistance final inspection,

the pressure proof main test is to assemble all the components for applying pressure to the workpiece, provide a large test space for covering the entire workpiece, load a trace gas into the workpiece, and detect the presence or absence of leakage of the trace gas in the large test space.

6. A pressure resistance inspection device for a pressure equipment such as a valve,

the inspection apparatus includes an inspection space having an opening portion in a part thereof, the opening portion being capable of attaching and detaching a workpiece including a pressure device such as a valve, and a gas sensor for sensing leakage of a trace gas supplied into the workpiece is provided in the inspection space.

7. The apparatus for checking pressure resistance of a pressure equipment such as a valve according to claim 6,

the gas sensor is provided inside a semi-open type chamber having an open bottom, and an inspection space surrounding an inspection target portion of the workpiece is provided in the chamber.

8. The apparatus for checking pressure resistance of a pressure equipment such as a valve according to claim 6 or 7,

an exhaust fan is provided in the inspection space and a space where the trace gas is evacuated from the gas sensor.

9. The apparatus for checking pressure resistance of a pressure equipment such as a valve according to any one of claims 6 to 8,

the tracer gas supplied into the workpiece is hydrogen gas.

10. The apparatus for checking pressure resistance of a pressure equipment such as a valve according to any one of claims 6 to 9,

a purge flow path is provided for purging the trace gas in the workpiece by air pressure after the inspection is completed and discharging the trace gas to the outside of the inspection space.

11. The apparatus for checking pressure resistance of a pressure equipment such as a valve according to any one of claims 7 to 10,

the advancing and retreating direction of the cavity and the advancing and retreating direction of the clamping jig holding the workpiece are made to be the same.

12. A press device, characterized in that,

the pressure-resistant test apparatus according to any one of claims 6 to 11, wherein the test object is a pressure device such as a valve.

Technical Field

The present invention relates to a pressure resistance test method for a pressure device that applies pressure from the inside of a valve or the like, a pressure resistance test apparatus therefor, and a pressure device.

Background

Conventionally, pressure equipment such as valves is required to have high pressure resistance, and therefore, pressure equipment before shipment is subjected to a pressure resistance test (shell test) for checking the strength of a pressure resistant part and the presence or absence of a seed leak. In this case, the pressure resistance test is usually performed after the completion of the assembly of the pressure equipment, and the pressure resistance of the valve used as a product is confirmed.

As such a pressure resistance test method, for example, a submerged method, a sniffing method, a vacuum chamber method, and the like are known. The immersion method is a method in which a test piece whose interior is pressurized with gas is immersed in water, and leakage is detected from bubbles from the interior of the test piece, and the sniffing method is a method in which a trace gas is injected into the test piece, a probe is brought close to gas flowing out to the outside of the test piece, and leakage is detected by the probe. The vacuum chamber method is a method in which a test body is housed in a vacuum container, a tracer gas is injected into the test body, and a gas flowing out of the test body into the vacuum container is detected.

For example, when the test body is a ball valve and the ball valve is subjected to pressure resistance inspection by the immersion method, the presence or absence of leakage from the cast parts constituting the valve and leakage from each sealed portion is checked by applying air pressure of about 1.2MPa to the inside of the entire ball valve in a state in which the ball valve is immersed.

In this case, in the ball valve, a self-sealing member, i.e., an O-ring is used for the shaft sealing portion of the stem, and the O-ring moves in the fitting groove and elastically deforms when air pressure is applied, thereby exhibiting close contact sealing performance. When the O-ring is elastically deformed by high air pressure as described above, defects in a machined portion such as a valve stem or defects in a cast part constituting the valve, for example, molding defects due to misalignment of the center of the shaft tube portion of the valve body at the time of casting, or the like may not be found by the pressure resistance inspection.

In order to solve this problem, the applicant, for example, applied low air pressure of about 0.2MPa to the inside of the valve before applying high air pressure of 1.2MPa, and confirmed the presence or absence of leakage from the valve stem, i.e., shaft leakage, due to machining defects or molding defects without elastic deformation caused by movement of the O-ring.

In this case, the local inspection near the shaft leakage portion is performed in the same inspection space as the entire inspection of the inspection valve, that is, a space surrounding the entire valve. In this inspection flow, as in other pressure resistance tests such as the sniffing method and the vacuum chamber method, a local inspection for checking a shaft leakage is performed in the same inspection space as the entire inspection before the entire inspection for checking a leakage from a cast part and each seal portion.

As a pressure resistance inspection device for a valve, for example, an inspection device of patent document 1 is disclosed. In this inspection apparatus, in a state where a fluid controller such as an integrally mounted valve is disposed in an inspection chamber, an inspection fluid is supplied into the fluid controller and the interior thereof is pressurized. The fluid controller is configured to detect a leakage of the inspection fluid into the inspection chamber by a leakage detector connected to the inspection chamber in a communicating state, thereby making it possible to check the pressure resistance of the fluid controller.

Patent document 1 japanese patent No. 3325357.

As described above, in the pressure resistance test by the immersion method, the sniffing method, the vacuum chamber method, or the like, the pressure resistance test is performed on the valve after the assembly. Therefore, even in the case where the shaft leakage is not inspected locally before the overall inspection for checking the machining defect or the molding defect, the same treatment as that in the case of the overall inspection is required. Specifically, the valve body, the valve stem, the seal parts, and the like are detached from the valve body to disassemble the entire valve, and repair and replacement of a portion where a failure occurs are performed, and it is necessary to reassemble the valve body into a highly accurate sealed state. Therefore, excessive land costs are decomposed and seeding time.

In the case of performing a local inspection, since the inspection is performed in a wide inspection space surrounding the entire valve as in the case of a global inspection, when a pressure resistance inspection is performed using a gas such as hydrogen, the wide inspection space is left with the gas after the valve is removed. Therefore, it takes time to exhaust the residual gas, and it is difficult to perform rapid pressure resistance inspection of the next inspection valve, and it is difficult to perform continuous pressure resistance inspection in a short time.

Further, in the local inspection near the shaft leakage portion, the valve stem is rotated in advance to bring the valve into a half-open state, and in the cavity of the valve, for example, in the case of a float valve, it is necessary to fill the space surrounded by the ball valve body, the ball seat, the valve body, and the cover with an inspection gas such as hydrogen. Therefore, the flow of the pressure resistance test increases, and thus, the work is required. Further, when the integrity check is performed after the local check, the valve stem needs to be rotated again to open or close the valve.

Disclosure of Invention

The present invention has been made to solve the conventional problems, and an object of the present invention is to provide a pressure resistance inspection method for a pressure equipment, a pressure resistance inspection apparatus for a pressure equipment, and a pressure equipment such as a valve, which can perform a pressure resistance inspection during the assembly of the pressure equipment such as a valve and can perform a pressure resistance inspection in a short time by quickly discharging an inspection gas.

In order to achieve the above object, the invention according to claim 1 is a pressure resistance inspection method for detecting the presence or absence of leakage by supplying a trace gas to a workpiece constituted by a pressure device such as a valve, wherein a defect or a machining failure of the workpiece is detected at an early stage by performing a pressure resistance preliminary inspection in which a part of component parts of the workpiece is assembled, and immediately thereafter, an inspection target portion of the workpiece is covered with the trace gas in a state where the volume of an inspection space is reduced, and the presence or absence of leakage of the trace gas in the inspection space is detected by filling the trace gas into the workpiece.

The invention according to claim 2 is a pressure resistance inspection method for a pressure equipment such as a valve, wherein the workpiece is formed of a cast part.

The invention according to claim 3 is a pressure resistance inspection method for a pressure device such as a valve, wherein an inspection target portion of a workpiece includes a seal portion by an O-ring.

The invention according to claim 4 is a pressure resistance inspection method for a pressure apparatus such as a valve, wherein an inspection target portion of a workpiece includes a stem shaft seal portion of the valve.

The invention according to claim 5 is a pressure resistance inspection method for a pressure equipment such as a valve, wherein after a pressure resistance preliminary inspection of a workpiece, a pressure resistance final inspection is performed in which all components for applying pressure are assembled to the workpiece and a large inspection space for covering the entire workpiece is provided, and a trace gas is filled into the workpiece to detect the presence or absence of leakage of the trace gas in the large inspection space.

The invention according to claim 6 is a pressure resistance inspection apparatus for a pressure equipment such as a valve, which includes an inspection space having an opening portion in a part thereof, the opening portion being capable of attaching and detaching a workpiece including a pressure equipment such as a valve, wherein a gas sensor for sensing leakage of a trace gas supplied into the workpiece is provided in the inspection space, and the gas sensor discharges a residual gas in the inspection space in a state of being evacuated sideways from an inspection target portion of the workpiece, thereby rapidly and accurately inspecting a subsequent workpiece.

The invention according to claim 7 is a pressure resistance inspection apparatus for a pressure device such as a valve, wherein the gas sensor is provided inside a semi-open type chamber having an open bottom, and an inspection space surrounding an inspection target portion of a workpiece is provided in the chamber.

The invention according to claim 8 is a pressure resistance inspection apparatus for pressure equipment such as a valve, wherein an exhaust fan is provided in an inspection space and a space side where a trace gas is evacuated from a gas sensor.

The invention according to claim 9 is a pressure resistance inspection apparatus for pressure equipment such as a valve, wherein the tracer gas supplied into the work is hydrogen gas.

The invention according to claim 10 is a pressure resistance inspection apparatus for a pressure device such as a valve, wherein after inspection is completed, a trace gas in a workpiece is purged by air pressure, and a purge flow path for discharging the trace gas to the outside of an inspection space is provided.

The invention according to claim 11 is a pressure resistance inspection apparatus for a pressure equipment such as a valve, wherein the advancing and retreating directions of the chamber and the gripping jig for holding a workpiece are the same.

The invention according to claim 12 is a pressure device in which the object to be inspected of the pressure resistance inspection apparatus is a pressure device such as a valve.

Effects of the invention

According to the invention of claim 1, since the defects and machining defects of the workpiece are detected early by the pressure resistance inspection during the assembly of the component parts of the workpiece, the workpiece is easily decomposed when the component parts become defective, and decomposition and seeding can be carried out in a short time to repair and replace the defective parts. In the pressure-resistant preliminary inspection, the trace gas is filled into the workpiece in a state where the volume of the inspection space is reduced, and the presence or absence of leakage of the trace gas is detected. In this way, by minimizing the diffusion range of the trace gas, the residual gas after the test can be quickly discharged, and the pressure resistance test can be continuously performed in a short time. Since the trace gas can be filled into the workpiece during assembly, the pressure resistance test can be performed without modifying the workpiece.

According to the invention of claim 2, defects such as misalignment during casting can be found early, and the coating of the inspection-finished part can be performed immediately after the pressure resistance inspection.

According to the invention of claim 3, by performing the pressure resistance test while suppressing the elastic deformation due to the movement of the O-ring, it is possible to confirm the presence or absence of local leakage such as shaft leakage due to a processing defect or a molding defect.

According to the invention of claim 4, the pressure resistance test of the stem shaft seal portion of the valve can be immediately performed in a state where the stem is inserted, regardless of the rotational position of the stem.

According to the invention of claim 5, after the pressure resistance preliminary inspection, which is a local inspection for a processing defect or a molding defect, a pressure resistance final inspection, which is a global inspection for confirming leakage from each seal portion, and specifying of a defect position such as leakage can be easily performed. In addition, these local inspections and the global inspections can be performed quickly in the same inspection space with the use of a minimum trace gas.

According to the invention of claim 6, continuous pressure resistance inspection can be performed while the workpiece is attached to and detached from the inspection space through the opening portion. The gas sensor provided in the inspection space is evacuated in a state of being evacuated from the inspection target portion of the workpiece, thereby preventing the trace gas from remaining near the inspection target portion of the inspected workpiece, and the residual gas is quickly evacuated from the inspection space, so that the next workpiece can be quickly and quickly removed.

According to the invention of claim 7, by moving the semi-open chamber to cover the workpiece and providing the inspection space surrounding the inspection target portion of the workpiece, it is possible to accurately sense the leakage of the gas from the inspection target portion of the workpiece in the small-volume inspection space during the pressure resistance inspection. After the inspection, the gas accumulated around the workpiece can be easily and quickly discharged by moving the chamber.

According to the invention of claim 8, the gas released by the reverse clamping of the inspected workpiece is discharged to the outside through the exhaust fan, and the pressure resistance inspection can be performed quickly and accurately on the next workpiece.

According to the invention of claim 9, since the hydrogen gas is a gas having a diffusibility, when the hydrogen gas leaks from the inside of the workpiece, the pressure resistance test can be performed with high accuracy by reliably detecting the hydrogen gas with the gas sensor. This enables highly sensitive detection of even a low concentration gas.

According to the invention of claim 10, the trace gas introduced into the workpiece through the purge flow path can be quickly discharged, and the workpiece can be replaced with a next workpiece for inspection immediately after the inspection, thereby reducing the time and enabling the follow-up-resistant inspection.

According to the invention of claim 11, the advancing and retreating direction of the cavity and the advancing and retreating direction of the holding jig are made to be the same direction, whereby the entire device can be made compact.

According to the invention of claim 12, by using the pressure equipment such as a valve as the object to be inspected of the pressure resistance inspection apparatus, it is possible to accurately check the presence or absence of shaft leakage due to a machining defect or a molding defect together with the presence or absence of leakage from parts such as cast parts constituting the valve and leakage from each seal portion, and it is possible to provide high-precision pressure equipment such as a valve excellent in pressure resistance.

Drawings

FIG. 1 is a schematic cross-sectional view showing a pressure resistance test apparatus.

Fig. 2 is an enlarged cross-sectional view showing a pressure resistance test state of the pressure equipment.

Fig. 3 is a block diagram showing an inspection line of the pressure-resistant preliminary inspection.

Fig. 4 is a flowchart showing the steps of the inspection by the withstand voltage inspection method.

Fig. 5 is a flowchart showing the steps of the withstand voltage preliminary test.

Fig. 6 is a longitudinal sectional view showing the assembled workpiece.

Detailed Description

Hereinafter, a pressure resistance test method of a pressure device such as a valve, a pressure resistance test apparatus (hereinafter, referred to as an apparatus main body 1), and a pressure device according to the present invention will be described in detail based on embodiments.

Fig. 1 is a schematic cross-sectional view of a pressure resistance inspection apparatus, fig. 2 is a pressure resistance inspection state of a pressure device by the pressure resistance inspection apparatus, and fig. 3 is a flowchart of an inspection process by the pressure resistance inspection method according to the present embodiment.

The apparatus main body 1 shown in fig. 1 is capable of performing a pressure resistance test of a workpiece 2 as an object to be tested by supplying a trace gas to the workpiece 2, more specifically, a pressure resistance preliminary test before a pressure resistance main test described later, and includes a housing 10, a chamber 11, a gas sensor 12, a support jig 13, and a clamp jig 14.

The frame 10 is formed in a frame shape in which the workpiece 2 can be mounted inside, and an inspection space R for performing a pressure resistance inspection of the workpiece 2 is provided inside. An opening portion 20 is provided in a part of the housing 10, and the workpiece 2 can be attached and detached from the right side or the near side of the housing 10 in fig. 1 through the opening portion 20. In the figure, two exhaust fans 21 indicated by a chain line are attached to the back side of the housing 10 via a plate member or the like not shown in the figure, and the exhaust in the inspection space R can be performed by the rotation of the exhaust fans 21. Inside the housing 10, a cavity 11, a support jig 13, and a clamping jig 14 are mounted.

The cavity 11 has a substantially rectangular cover portion 23 having a size capable of accommodating the inspection target portion 22 of the workpiece 2 therein, and a suspension portion 24 integrally provided on the upper surface side of the cover portion 23, and is provided so as to be capable of advancing, seeding, retreating, and ascending, seeding, descending and moving within the inspection space R via the suspension portion 24. The chamber 11 is a semi-open type with an open bottom, and the inspection target portion 22 of the workpiece 2 can be guided into the chamber 11 from the bottom side. A predetermined volume of the inspection space S is provided in the chamber 11, and the pressure resistance inspection can be performed in the inspection space S in a state of surrounding the inspection target portion 22. The gas sensor 12 and the exhaust fan 26 are mounted on the chamber 11.

The inspection space S of the chamber 11 is referred to as a space in which the trace gas supplied to the workpiece 2 can diffuse, and is provided in a state isolated from the outside. The "state of being isolated from the outside" in the present embodiment does not mean that the inside of the chamber 11 is in a sealed state, but means a state of preventing the influence of external wind or the like from reaching the workpiece 2 and allowing the flow of gas to the extent that hydrogen leaking from the workpiece 2 in the chamber 11 reaches the gas sensor 12 within the inspection time.

The gas sensors 12 are provided at predetermined plural locations within the chamber 11, respectively, and in this example, at two locations on the inner surface of the chamber 11 and at one location on the inner upper surface of the chamber 11, respectively, and the gas sensors 12 can sense, within the chamber 11, leakage of the trace gas supplied into the workpiece 2 from the inspection target location 22. The number of the gas sensors 12 can be set arbitrarily, and increasing the number can improve the detection capability and shorten the detection time and automate it.

The gas sensor 12 is provided so as to be capable of escaping sideways from the inspection target portion 22 of the workpiece 2 in accordance with the movement of the chamber 11. After the pressure resistance inspection, the residual gas in the inspection space R is discharged in the retracted state of the gas sensor 12, and the next work 2 can be inspected quickly and accurately.

The gas sensor 12 of the present embodiment is constituted by a hydrogen sensor, and can detect a hydrogen gas, which is a trace gas supplied into the workpiece 2, as will be described later. By using the hydrogen sensor 12, leakage of hydrogen in a mixed gas of hydrogen and nitrogen, which is a diffusible gas, is reliably detected. The gas sensor 12 is fixed to the chamber 11, but may be movably attached for position adjustment. Helium gas can be used as the trace gas, and in this case, a gas heat conduction type sensor may be used as the gas sensor.

The gas sensor 12 is configured by a block that outputs a voltage corresponding to the concentration of leaked hydrogen by applying a predetermined voltage. Before the test, the output voltage is changed by the volume for resistance adjustment, and it is necessary to finely adjust the sensitivity in accordance with the warm-up state of the gas sensor 12 and the change in the hydrogen concentration in the atmosphere.

As the gas sensor 12, a commercially available semiconductor type sensor capable of outputting an analog signal (0 to 5V), for example, a hot-wire type semiconductor type hydrogen sensor, is used. The hydrogen sensor 12 is a sensor utilizing a sensor made of tin dioxide (SnO)₂) And the like, due to adsorption of hydrogen gas on the surface of the metal oxide semiconductor. In this case, the output voltage is logarithmic with respect to the gas concentration, and a high-sensitivity output can be performed even at a low concentration.

When a plurality of gas sensors 12 are used, it is preferable to have an adjustment function of matching the reference voltage with a predetermined value via a CPU described later. This makes it possible to equalize the sensitivity of each gas sensor 12 and detect the leaked hydrogen gas with high accuracy.

The exhaust fan 26 is provided on the space side of the chamber 11 where the trace gas escapes from the gas sensor 12. The exhaust fan 26 can exhaust the hydrogen gas remaining in the inspection space S in the chamber 11 to the outside. A narrow portion 27 for narrowing the flow path is provided between the exhaust fan 26 and the inspection space S. When the exhaust fan 26 exhausts the gas, the exhaust speed is increased through the narrow portion 27, whereby the residual gas in the chamber 11 is efficiently purged.

The support jigs 13 are provided in the frame 10 at a predetermined interval at which the vicinities of both sides of the workpiece 2 can be placed, and can support the workpiece 2 from below. The mounting surface 28 on the upper surface side of the supporting jig 13 is provided in an appropriate shape such as a tapered shape capable of holding a polygonal valve (workpiece 2) side portion such as a hexagon or an octagon, or an arc shape capable of holding a cylindrical valve side portion.

The clamping jig 14 includes a fixed clamping jig 30 and a movable clamping jig 31.

The fixed clamp 30 is disposed at a position that is a primary side of the workpiece 2 via a fixing holder 32, and a primary-side flow path 33 for supplying a trace gas into the workpiece 2 is formed near the center of the fixed clamp 30. A seal member 34 formed of an annular gasket is attached to a primary-side facing surface of the workpiece 2 to which the clamping jig 30 is fixed, and leakage from a pressure-contact portion with which the workpiece 2 is pressure-contacted when the workpiece 2 is fixed is prevented by the gasket 34.

In fig. 2, a movable clamp 31 is disposed on the secondary side of the workpiece 2, and is attached to be able to advance and retreat in the fastening direction so as to hold the workpiece 2 by the movable clamp 31 and the fixed clamp 30.

The advancing and retreating directions of the cavity 11 and the movable clamp 31 as a clamp of the workpiece 2 are arranged in the same direction. A secondary-side flow path 35 as a purge flow path is provided inside the movable clamping member 31, and after the pressure resistance test of the workpiece 2, the trace gas inside the workpiece 2 is purged by air pressure through the purge flow path 35 and discharged to the outside of the test space S and the test space R.

A seal member 34 formed of an annular gasket is attached to a secondary-side facing surface of the workpiece 2 of the movable clamp 31 in the same manner as the fixed clamp 30. The gasket 34 prevents leakage from a pressure contact portion that is in pressure contact with the movable clamp 31 when the workpiece 2 is fixed.

The workpiece 2 as the object to be inspected by the apparatus main body 1 is a pressure device such as a valve, and in the present embodiment, the object to be inspected is a ball valve, and a state in which a part of components of the ball valve is assembled is used.

The workpiece 2 is formed as a valve body 40 as a casting component, a valve rod 42 for rotational operation is inserted into a shaft cylindrical portion 41 formed in the valve body 40, a gland 43 is attached thereto, and the valve rod 42 is rotatably provided in a positioned state. O-rings 45 are fitted to two portions of the outer periphery of the stem 42, and sealing portions 46 are provided by these O-rings 45, and in the present embodiment, the work 2 is a ball valve, and therefore the sealing portions 46 are stem shaft sealing portions of the valve.

As the trace gas to be supplied for the valve seat inspection and the pressure resistance inspection with respect to the workpiece 2, for example, a hydrogen gas including hydrogen, in which a mixed gas containing 5% of hydrogen as a gas having diffusivity and 95% of nitrogen as an inert gas is used. When external leakage occurs during the pressure resistance test, the mixed gas has a property of leaking from the vicinity of the threaded joint between the cylindrical shaft portion 41 of the valve body 40 and the gland 43.

A mixed gas of 5% hydrogen and 95% nitrogen as a tracer gas is a high-pressure gas which is incombustible, and therefore can be safely used. The tracer gas may be a gas other than a gas containing hydrogen, and for example, various gases such as helium gas and methane gas can be used. When helium is used as the tracer gas, the diffusivity is high as in the case of the mixed gas containing hydrogen.

Next, fig. 3 shows an example of an inspection line 50 provided with the apparatus body 1 when the workpiece 2 is a ball valve. In the inspection line 50, a flow path from the hydrogen gas supply side to the primary side of the apparatus body 1 is defined as a first flow path 51, and a flow path after the secondary side of the apparatus body 1 is defined as a second flow path 52.

The inspection line 50 includes a hydrogen gas supply source 53, a regulator 54, a purge air supply source 55, electromagnetic valves 56, 57, 58, and 59, a pressure gauge 60, and a pressure sensor 61, in addition to the apparatus main body 1.

The hydrogen gas supply source 53 is provided so as to be able to supply hydrogen gas from the first flow path 51 of the inspection line 50 to the workpiece 2, and the hydrogen gas adjusted to about 0.2MPa is supplied to the electromagnetic valve 56 via the regulator 54. The solenoid valve 56 is provided to supply hydrogen gas into the workpiece 2 during the pressure resistance test by its opening and closing operation. The purge air supply source 55 is provided so as to be able to supply purge air having a pressure of about 0.6MPa from the first flow path 51 to the workpiece 2, and supplies purge air into the workpiece 2 after the pressure resistance test is completed by opening and closing the electromagnetic valve 57. A vacuum flow path 62 is provided between the solenoid valves 56 and 57 and the fixed clamp fitting 30, and the vacuum flow path 62 is provided so that the hydrogen gas or purge air in the first flow path 51 can be discharged to the outside by opening and closing the solenoid valve 58. The first flow path 51 is evacuated by exhausting the internal pressure and sucking the pressure from the outside.

An exhaust passage 63 is provided in the second passage 52, and the exhaust passage 63 is provided so as to be openable and closable by a solenoid valve 59. A pressure gauge 60 and a pressure sensor 61 are provided in the exhaust passage 63, and the pressure of the hydrogen gas in the workpiece 2 can be measured through these.

Although not shown in the figure, a control unit constituted by a CPU (central processing unit) is connected to the inspection line 60, and the control unit is electrically connected to the gas sensor 12, the solenoid valves 56 to 59, the hydrogen gas supply source 53, the purge air supply source 55, and the like. The control unit stores a table (installation data) set based on the nominal pressure, nominal diameter, valve type, and the like of the workpiece 2, and controls the operation of each unit based on the table.

Further, when the controller is provided with a digital display unit and hydrogen leakage occurs from the workpiece 2, the hydrogen leakage is output to the digital display unit as a voltage corresponding to the hydrogen gas concentration via a signal processing unit provided in the controller, the digital display unit has L CD (liquid crystal display), and the output voltage of each gas sensor 12 is indicated and displayed at L CD.

Next, an embodiment of a method for testing the pressure resistance of a pressure device such as a valve according to the present invention will be described based on a test line 50 in fig. 3. The pressure resistance test method according to the present embodiment is, for example, each air pressure test according to the valve box pressure resistance test specified in JIS B2003 (general rule for valve inspection).

In the flowchart shown in fig. 4, as steps of the pressure resistance inspection method of the present embodiment, a pressure resistance preliminary inspection for performing a partial inspection of the component parts of the workpiece 2, and a pressure resistance final inspection for performing a total inspection of the entire workpiece 2 and each sealed portion are performed continuously.

When the pressure resistance preliminary inspection is performed, first, a part of the components of the workpiece 2, that is, the valve body 40, the valve stem 42, the O-ring 45, and the gland 43 are integrally assembled to be in a semi-finished state. In this way, the primary side of the workpiece 2 in a semi-finished state including at least the sealing portion between the components is brought into contact with the pad 34 of the fixed clamping jig 30, and the workpiece 2 is placed on the supporting jig 13, and in this state, the movable clamping jig 31 is moved in the holding direction from the secondary side of the workpiece 2, and the workpiece 2 is clamped at a predetermined position. At this time, the gaskets 34, 34 are sealed at the primary and secondary side end portions of the workpiece 2, respectively, and the primary side flow path 33 of the fixed clamping jig 30 and the purge flow path 35 of the movable clamping jig 31 can be communicated with each other at the primary and secondary side opening sides of the workpiece 2 in a leak-proof state.

Fig. 5 is a flowchart showing a step of pressure-resistant preliminary inspection after holding the workpiece 2.

In fig. 5, after the work 2 is held, all the gas sensors 12 in fig. 1 are zeroed, and the acceptance/rejection determination criteria of these gas sensors 12 are stored in the CPU. This state is a standby state before the start of the inspection, and the withstand voltage preliminary inspection is started in response to the input of the inspection start signal.

Then, immediately thereafter, the cavity 11 advances or descends, and the inspection target portion 22 of the workpiece 2, i.e., the sealing portion sealed by the O-ring, i.e., the shaft cylindrical portion 41 of the valve body 40 including the stem shaft sealing portion 46 of the valve 2, is covered with the cavity 11. As a result, as shown in fig. 2, the inspection target portion 22 of the workpiece 2 is surrounded in a state where the volume of the inspection space S is reduced.

In this state, hydrogen gas as a trace gas is supplied into the workpiece 2, and the workpiece 2 is pressurized by being filled with hydrogen gas, and the presence or absence of leakage of hydrogen gas in the inspection space S in the chamber 11 is detected. This makes it possible to detect defects and machining defects of the workpiece 2 at an early stage.

In this case, the withstand voltage preliminary test is controlled by the CPU as follows in fig. 5.

When the pressure value (the pressure value in the workpiece 2) measured by the pressure sensor 61 of the inspection line 50 in fig. 3 is smaller than the predetermined pressure, the process ends (failure (NG)), and a failure signal is output to return to the initial state. On the other hand, when the measured pressure value is equal to or higher than the predetermined pressure, the process proceeds to the next pressure drop detection step. At this time, the supply of hydrogen gas is stopped.

In the pressure drop detection step, after the stop of the pressurization by the hydrogen gas, it is confirmed that the measured value (the pressure value in the workpiece 2) by the pressure sensor 61 is greater than 97% of the initial value, and in this state, the pressure in the inspection space S is measured by the gas sensor 12 in the next pressure-resistant leakage detection step. This measurement is continued until the measurement value of the pressure sensor 61 is 97% or less of the initial value and 97% or less, and the pressure is considered to have dropped to a pressure value unsuitable for inspection in the workpiece 2, and the measurement is terminated (defective), and a defective signal is output to return to the initial state. In this case, the workpiece 2 is not qualified for the pressure-resistant preliminary inspection.

In the pressure-resistant leakage detection step, if the value measured by the gas sensor 12 is smaller than the threshold value at which it is determined that leakage has occurred, the process proceeds to the next detection time measurement step. When the measured value of the gas sensor 12 becomes equal to or more than the leak threshold value, it is considered that the pressure-resistant leak from the workpiece 2 is detected, and the process is terminated (defective), and a defective signal is output, and the process returns to the initial state. In this case, the workpiece 2 is not qualified for the pressure-resistant preliminary inspection.

In the detection time measuring step, whether or not a preset detection time has elapsed is measured, and if the preset detection time has not been reached, the pressure is fed back to the pressure drop detecting step.

The steps from the pressure drop detection step to the detection time measurement step are repeatedly circulated until the detection time of the detection time measurement step reaches a predetermined time. When a failure does not occur in the pressure drop detection step and the pressure-resistant leakage detection step until the predetermined time, the leakage of hydrogen gas at the predetermined pressure is maintained at the reference value or less, and the workpiece 2 is qualified for the pressure-resistant preliminary inspection.

After a predetermined time has elapsed, the chamber 11 is raised or retreated relative to the inspection target site 22 of the workpiece 2, purge air is supplied into the workpiece 2, and vacuum is drawn from the vacuum flow path 62, whereby the inside of the workpiece 2 in a sealed state is flushed. Thereafter, the workpiece 2 is removed from the apparatus main body 1 by reverse clamping in which the movable clamping jig 31 is moved in a direction away from the workpiece 2. In this case, the tracer gas in the inspection space S is discharged to the inspection space R by the exhaust fan 26, and the tracer gas in the inspection space R is discharged to the outside by the exhaust fan 21, thereby preventing the tracer gas from remaining in the inspection space S and the inspection space R.

Next, when the subsequent preliminary withstand voltage inspection of the workpiece 2 is performed, the same procedure as the aforementioned inspection method may be used.

After the pressure resistance preliminary inspection, as shown in fig. 6, all the components for applying pressure, such as the valve body 70, the ball seat 71, and the cap 72, are assembled and integrated with the partially assembled workpiece 2, and the handle 75 is fixed to the upper portion of the valve stem 42 via the washer 73 and the nut 74, thereby providing the workpiece (valve) 80 in a state of being used as a product. The workpiece 80 is held by a clamp for a large inspection space in a large inspection apparatus not shown in the drawing, and a main pressure-resistant inspection is performed in a state where the entire large inspection space workpiece 80 is covered.

In this case, after the valve stem 42 is rotated via the handle 75 to bring the valve 80 into a half-open state, a trace gas made of hydrogen is also introduced into the workpiece 80 including the valve cavity Ca, and the presence or absence of leakage of the trace gas is detected by the gas sensor, whereby the pass or fail of the pressure proof main test of each workpiece is determined. The workpieces that are qualified in both the pressure-resistant preliminary inspection and the pressure-resistant final inspection are qualified products of the pressure-resistant inspection. When the pressure-resistant test is determined to be defective, the cause of the failure may be a confirmation of the sealed portion other than the portion that is defective in the pressure-resistant preliminary test, and the cause may be specified relatively quickly. After the pressure resistance inspection, the inside of the workpiece was purged to discharge residual gas, and thereafter, the workpiece was removed by releasing the clamp.

Next, the operation of the above-described embodiment of the pressure equipment pressure resistance inspection method and the pressure resistance inspection apparatus according to the present invention will be described.

As the pressure resistance test, a pressure resistance preliminary test is performed in which a valve in which a part of the component parts is mounted is targeted in a state in which the valve stem 42 to which the O-ring 45 is mounted is inserted into the valve body 40, and therefore, when the pressure resistance preliminary test fails, the valve stem 42 can be easily removed from the valve body 40 to repair or repair a portion where a failure has occurred. In this way, the pressure resistance preliminary inspection is performed using the state of the semi-finished product before the valve finish as the workpiece 2, whereby the decomposition and seeding time associated with the undesirable conditions can be shortened.

The workpiece 2 subjected to the pressure resistance preliminary inspection is a cast part, and the inspection target portion 22 is a sealing portion of the O-ring 45, and in the present embodiment, a portion of the valve including the stem shaft sealing portion 46, and leakage is measured in the inspection space S in the cavity 11 covering the inspection target portion 22 by the gas sensor 12. This minimizes the volume of the inspection space S, reduces the hydrogen gas stagnation area, and allows the exhaust fan 26 on the hydrogen gas escape space side to quickly exhaust the residual gas. The discharged gas is discharged to the outside of the inspection space R by two exhaust fans 21 attached to the housing 10. At this time, since the amount of residual gas from the inspection space S is small, the gas is quickly discharged from the inspection space to the outside of the apparatus main body 1, and the inspection space S and the inspection space R can be cleaned in a short time.

Since the valve body 70 and the ball seat 71 are not assembled to the workpiece 2 at the time of the pressure resistance preliminary inspection, the rotation operation of the stem 42 is not required, and the hydrogen gas is filled into the stem shaft sealing portion 46 regardless of the rotation state of the stem 42, so that the pressure resistance inspection can be performed without extra labor.

Since the valve element 2, which is a semi-finished product after the pressure resistance preliminary inspection, can be subjected to rust-preventive coating, rust prevention of the valve, which is likely to rust due to cast iron parts, can be achieved at an early stage without mounting the valve element 2 in a valve-finished product.

While the embodiments of the present invention have been described in detail, the present invention is not limited to the embodiments described above, and various changes and modifications can be made without departing from the spirit of the invention described in the patent claims of the present invention. For example, the present invention is applicable to valves other than ball valves such as globe valves and gate valves, and to various pressure devices such as pneumatic actuators including piping devices other than valves. In the case of performing the pressure resistance test, the amount of leakage may be measured instead of the presence or absence of leakage. After the pressure resistance test, the valve seat test may be performed continuously.

Description of the reference numerals

1 device body

2 ball valve (workpiece)

11-cavity 12 gas sensor

14 clamping fixture

20 open part

22 examination target part

26 exhaust fan

30 fixed clamping fixture

31 movable clamping fixture

35 purge flow path

45O-shaped ring

46 valve rod shaft sealing part

R examination space

S checking the space.