JPH11316203A - Inspection method for high-pressure vessel for lp gas, etc. - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an inspection method in which the visual inspection of a high- pressure vessel for an LP gas or the like is automated simply and with good accuracy, by a method wherein the inside of the high-pressure vessel is heated, and a change in a temperature on the surface of the high-pressure vessel is detected by using a thermocamera. SOLUTION: Thermocameras 5a, 5b, 5c, 5d, 5e which detect a change with the passage of time in the distribution of a temperature on the surface of a gas cylinder (a high-pressure vessel) 1 whose inside in heated by dry steam are arranged and installed around the gas cylinder 1 which is suspended and held by a suspending and holding means 4. Then, on the basis of detection information from the thermocameras 5a to 5e, a detecting means detects whether a reduced plate thickness, a blow hole, a pin hole or the like exists or not. The detecting means is constituted of a computer, a microcomputer or the like. By a comparison means, the change, with the passage of time in the distribution of the temperature on the surface of the gas cylinder 1, detected by the thermocameras 5a to 5e is compared with a normal pattern. In addition, a judgment means judges that an abnormality is generated at a time when a sudden temperature rise deviated from the normal pattern is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection method for automatically inspecting the appearance of a high-pressure container in a factory for producing LP gas or the like, a re-inspection factory, and the like.

[0002]

2. Description of the Related Art Today, the durability and metal fatigue of a high-pressure container (cylinder) of LP gas or the like formed using a desired metal plate are scientifically inspected by a hydraulic test method or the like, and a safe container is developed. Is provided. However, even in the new high-pressure vessel manufactured in this way, blowholes and pinholes are generated when abnormalities occur in processing, construction management, etc., and inconvenient welding is performed at a plurality of welded joints. Inspection by the naked eye is also performed in manufacturing factories. In addition, on the user side, based on the Safety Law, when the expiration date of the high-pressure container approaches the expiration date, scientific inspections are carried out in accordance with safety standards at predetermined re-inspection factories, but even in this re-inspection process, plate thickness due to local corrosion It is difficult to detect the decrease and the pinhole, and visual inspection is performed with the naked eye.

[0003]

The above-described inspection work by the naked eye is very time-consuming, so that the work efficiency is poor, and the operator often overlooks the work because he depends heavily on the empirical rules of the worker, thereby stabilizing the inspection accuracy. There was room for improvement in making this happen. On the other hand, in both the container manufacturing plant and the re-inspection plant, after the water is filled in the high-pressure container for the above-mentioned water pressure test and the measurement of the internal volume, and the water is drained, the inside of the container is dried with steam for drying. A drying step has been performed (for example, see Japanese Patent Publication No. 60-24918).
The present invention has been made in view of such conventional circumstances, and an object thereof is to automate the appearance inspection of a high-pressure container such as LP gas easily and accurately.

[0004]

In order to achieve the above object, an inspection method according to the present invention heats the inside of a high-pressure vessel and detects a change in temperature on the surface of the high-pressure vessel by using a thermo camera from the outside. And reduced thickness due to localized corrosion,
The gist of the present invention is to detect the presence or absence of a blowhole, a pinhole and the like. That is, the distribution of temperature rise on the surface of the high-pressure vessel is monitored by a thermo camera, and the time-dependent change in the temperature distribution is compared with a normal pattern in the case where there is no decrease in plate thickness or no blowholes or pinholes. The time when the temperature suddenly rises is detected as abnormal occurrence.

[0005] The heating of the high-pressure vessel is carried out in a factory or a re-inspection factory of the high-pressure vessel, after a water filling test and a drainage process for measuring the internal volume are performed, and then the inside of the container is dried. In the internal drying process using steam, the internal drying process of the container and the container heating process in the inspection method according to the present invention can be performed at the same time, which is preferable in that the inspection operation is performed simply and efficiently.

[0006] As an example of an apparatus for carrying out the method for inspecting a high-pressure vessel according to the present invention, the high-pressure vessel is placed in a drying step stage in which the internal pressure of the high-pressure vessel is steamed after a hydraulic test or measurement of the internal volume of the high-pressure vessel. A suspending means for suspending and rotating around the container axis is provided, and a thermo camera for detecting a temporal change of a temperature distribution on the surface of the high-pressure vessel heated by the steam is suspended by the suspending means. An example is a device provided with a required number of devices around the high-pressure vessel and provided with detection means for detecting the presence or absence of a reduced plate thickness, a blow hole, a pin hole, or the like based on detection information from the thermo camera. The detecting means is, for example,
Comparison means for comparing the temporal change of the temperature distribution on the surface of the high-pressure container detected by the thermo camera with the above-mentioned normal pattern, and judgment means for judging when a sudden temperature rise outside the normal pattern is found as abnormal occurrence, It can be constituted by a personal computer or a microcomputer provided with a notifying unit for notifying the occurrence of an abnormality and other storage units.

[0007] It is preferable to install the thermo-camera at a plurality of required locations outside the high-pressure vessel where a plurality of welded joints and the vessel bottom can be measured in order to easily and accurately automate the vessel inspection.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an outline of an example of an apparatus for performing a method for inspecting a high-pressure container according to the present invention. The high-pressure vessel 1 in FIG. 1 is a large cylinder filled with LP gas or the like. The present apparatus is disposed in a drying process stage A for drying the inside of the cylinder 1 after performing a hydraulic test in a manufacturing factory or a re-inspection factory that manufactures the cylinder 1. In addition, the method and apparatus for performing a water pressure test and internal drying after the test are as follows.
For example, it is disclosed in Japanese Utility Model Publication No. 55-37872, Japanese Utility Model Publication No. 2-2669, Japanese Utility Model Publication No. 6-21005, Japanese Patent Publication No. 60-24918, Japanese Patent Application No. 9-206579, and the like. Although not described here in detail because it is well-known, a supply pipe 2 for drying steam and a discharge pipe 3 for drying steam are disposed in the drying stage A, and a tip injection port 2 a of the supply pipe 2 is located above the inside of the cylinder 1. On the other hand, the tip outlet 3a of the discharge pipe 3 is disposed below the inside of the cylinder 1, and the drying steam injected from the supply pipe 2 is sucked by the discharge pipe 3 to dry the inside of the cylinder 1. I have.

The cylinder 1 includes a body 11 formed of a desired metal plate such as high-strength steel, and upper and lower lids 12 and 13.
It has a known structure in which the valve mounting opening (neck ring) 14, the skirt portion 15, and the like are integrated with each other by welding. The body portion 11 is a cylindrical body obtained by bending a single plate into a cylindrical shape, and welding its ends to each other via a welding joint portion 20. The body portion 11 is formed in a substantially bowl shape at the upper end or lower end opening. The upper and lower lids 12 and 13 are welded and integrated via a weld joint 21 or 22. The upper lid 12 has a container axis 1 ′.
The valve mounting opening 14 is welded integrally with the opening formed substantially concentrically through the welding joint 23. The skirt portion 15 is welded integrally to the lower surface of the lower lid portion 13 via welding joint portions 24 and 25.

As described above, the cylinder 1 is provided with a plurality of welded joints 20, 21, 22, 23, 24, and 25. In each of the welded joints 20 to 25, there is an abnormality in processing, construction management, and the like. When an inconvenient welding is performed due to occurrence of blow, a blow hole or a pin hole may be generated. Although the occurrence rate of blowholes and pinholes is extremely rare, conventionally, inspections have been conducted with the naked eye at manufacturing plants and reinspection plants.

On the bottom surface (bottom surface of the lower lid portion 13) 13 'of the cylinder 1, pinholes occur due to sea breeze when installed on a coastal portion or the like. When a potential difference occurs due to the inclination of soil and the adhesion of soil to the bottom, corrosion may occur and the plate thickness may decrease (reduced plate thickness). Conventionally, inspections of this kind of pinholes and reductions in plate thickness have been conducted with the naked eye at a reinspection factory.

The inspection method and the inspection apparatus according to this embodiment detect the above-mentioned reduced plate thickness, the presence of blow holes, pin holes, and the like. In addition to the provision of the suspending means 4 for rotating about 1 ', the thermo cameras 5a, 5b, 5c, 5d, 5e for detecting the temporal change of the temperature distribution on the surface of the cylinder 1 heated inside by the drying steam as described above.
Is disposed around the cylinder 1 suspended by the suspending means 4, and the presence or absence of the reduced plate thickness, blowhole, pinhole, etc. is detected based on the detection information from the thermo cameras 5a to 5e. It is provided with detection means.

The suspension means 4 may be a prior art proposed by the applicant of the present invention, for example, as disclosed in Japanese Examined Patent Publication No. 60-24918, a suspending tool provided with a hook screwed into the valve mounting opening 14, As disclosed in Japanese Patent Application Laid-Open No. 9-206579, the supply pipe 2 and the discharge pipe 3 are disposed inside the hanging tool and the nozzle.

The thermo cameras 5a to 5e have an observation wavelength of 8
In the present example, the thermo camera 5a is used for measuring the corrosion state of the entire bottom surface 13 'of the cylinder 1 and the state of the weld joint portion 25 which is located at the back of the skirt portion 15. , Camera 5b to body 1
The camera 5c is used for measuring the condition of the welded joint 20 in the body 11 and the camera 5d is used for measuring the condition of the welded joint 21 between the body 1 and the upper cover 12. Each of the thermo cameras 5a to 5e is provided with a field of view capable of measuring the condition of the joint 22 and the camera 5e for measuring the condition of the weld joint 23 between the upper lid 12 and the valve mounting port 14. And at a position where the measurement is possible.

The detecting means comprises a detecting device composed of a personal computer or a microcomputer, for example, an industrial thermography device, and detects a temporal change in the temperature distribution on the surface of the cylinder 1 detected by each of the thermo cameras 5a to 5e. Comparing means for comparing with a normal pattern; determining means for judging when a sudden temperature rise outside the normal pattern is observed as an abnormal occurrence; notifying means for informing the occurrence of the abnormality; and temperature distribution of the heated cylinder 1 surface. It is provided with an analyzing means for detecting a change with time by each of the thermo cameras 5a to 5e and analyzing the thermal image data, and other storage means, etc., and detects and reports the occurrence of the abnormality. The normal pattern refers to a temporal change in the temperature rise distribution on the surface of the cylinder 1 when the inside of the cylinder 1 having no reduced plate thickness, blowholes, pinholes, etc. is heated by the drying steam. This is the pattern detected in 5e. Incidentally, the detecting means can be built in each of the thermo cameras 5a to 5e.

Hereinafter, an inspection operation by the inspection apparatus of the present invention configured as described above will be described based on a more detailed embodiment. FIG. 2 shows that the temperature change of the temperature rise distribution on the surface of the cylinder 1 whose inside is heated by the drying steam is detected by each of the thermo cameras 5a to 5e, and the thermal image data is analyzed by the detecting means. The above normal pattern is represented by an isotherm diagram, wherein a curve a1 is a thermo camera 5a and a curve a2 is
Represents a detection result of the camera 5d, a curve a3 represents a detection result of the camera 5c, a curve a4 represents a detection result of the camera 5e, and a curve a5 represents a detection result of the camera 5b. The normal pattern is stored in the storage unit of the detection device.

The cylinder 1 supplied to the drying process stage A after performing the hydraulic test is mounted with the suspending means 4 in the valve mounting port 14 after being supplied to the stage A or after the completion of the hydraulic test. After the supply pipe 2 and the discharge pipe 3 are inserted and the reference core of the drying process stage A is aligned with the container axis 1 ′, drying steam is injected from the end of the supply pipe 2 to dry the inside of the cylinder 1. I do.
Almost simultaneously with the drying steam injection, the suspending means 4 is driven to rotate to rotate the cylinder 1 about the reference core, and starts detection by each of the thermo cameras 5a to 5e. In the same manner as in the normal pattern, an isotherm shown in FIG. 3 was obtained, and the normal pattern was compared with a detection result (measurement result) by a detection device. In this case, as is clear from the comparison of the isotherm diagrams shown in FIGS. 2 and 3, in the detection result a1 obtained by the camera 5a, a time-dependent change (rapid temperature rise) of the temperature distribution that does not match the normal pattern is observed. This was detected as abnormal occurrence and reported. As shown in FIG. 1, the abnormality was confirmed to be a reduced thickness 30 caused by coastal corrosion or the like on the bottom surface 13 'of the cylinder 1.

After the inspection and the internal drying have been completed, the cylinder 1 is removed by the transporting means such as a conveyor after the hanging means 4 is removed. The cylinder 1 which is judged as having passed the visual inspection and sent to the next step, and which has been judged to be abnormal (occurrence of reduced plate thickness, blowholes, pinholes, etc.) is provided in the conveying means and is detected by the detecting device based on the judgment result. The line is automatically lined out automatically by the opening and closing of a gate operated by the command of the above, or manually by an operator based on the notification of the detection device based on the determination result provided at an appropriate place, and rechecked by the operator is performed. . Here, if it is determined that it can be used, it is returned to the line again and sent to the next process, and if it is determined that it cannot be used, it is collected.

In this embodiment, each of the thermo cameras 5a to 5e
Is installed in a substantially horizontal or downwardly inclined shape or an upwardly inclined shape as shown in the figure, and by setting the upwardly inclined angle to an acute angle, dust and dirt are prevented from adhering to the lens portion of the thermo camera 5a. This prevents a decrease in detection accuracy due to dust and dirt being captured in the bottom image of the cylinder 1. If a mechanism for preventing dust and dirt from adhering to the lens is separately provided, the upward inclination angle of the thermo camera 5a can be set to an obtuse angle or arranged almost upright so that the bottom of the cylinder 1 can be imaged. Such a configuration is also possible. Further, it is needless to say that a change such as providing a notifying means for notifying the presence or absence of abnormality by the detecting means, for example, a buzzer or the like is within the scope of the present invention.

[0020]

As described above, according to the present invention, the inside of the high-pressure vessel is heated, and the time-dependent change of the temperature rise distribution on the surface of the high-pressure vessel is detected by using a thermo camera to reduce the thickness, blowhole, Since the inspection method for detecting the presence or absence of a pinhole or the like is used, it is possible to automatically determine the pass / fail of the appearance inspection of a large number of manufactured or recovered high-pressure containers in the middle of the transport path. Therefore, compared with the conventional work in which the operator visually inspects and determines good / bad, the work efficiency of the inspection process is greatly improved, and the number of workers in the inspection process is reduced and the number of unmanned persons is promoted. It is possible to stabilize the inspection accuracy as compared with a conventional inspection method which can rely on the empirical rules of the operator.

Further, if the heat treatment inside the high-pressure container is performed in a steam processing step of drying the inside of the container subjected to the water pressure test and the measurement of the internal volume in a manufacturing plant or a re-inspection plant of the container, The internal drying step of the high-pressure container and the container heating step in the inspection method according to the present invention can be performed at the same time, and the inspection operation can be performed simply and efficiently.

If the thermo-camera is installed at a plurality of required locations where the plurality of welded joints and the bottom of the vessel in the high-pressure vessel can be measured, the vessel inspection can be easily and accurately automated.

[Brief description of the drawings]

FIG. 1 is a front view schematically showing an example of an embodiment of an inspection method according to the present invention, which is partially shown in section.

FIG. 2 shows a normal pattern obtained by detecting a temporal change of a temperature distribution on a heated cylinder surface with each thermo camera and analyzing thermal image data by a detecting means in one embodiment of the inspection method according to the present invention. Isotherm diagram of.

FIG. 3 shows a measurement result obtained by detecting a temporal change in the temperature distribution on the surface of a heated cylinder with each thermo camera and analyzing the thermal image data by the detection means in one embodiment of the inspection method according to the present invention. Isotherm diagram of.

[Explanation of symbols]

 A: Drying process stage 1: Cylinder (high-pressure vessel) 1 ': Container axis 2: Steam supply pipe 3: Steam discharge pipe 4: Suspension means 5a to 5e: Thermo camera 11: Body 12: Upper lid 13 : Lower lid part 14: Valve mounting port (neck ring) 15: Skirt part 20, 21, 22, 23, 24, 25: Weld joint part

Claims (2)

[Claims] In a step of drying the inside of a high-pressure container, the inside of the container is heated, a temperature change on the surface of the high-pressure container is detected using a thermo camera, and the reduced plate thickness due to local corrosion, blow holes, pins A method for inspecting a high-pressure container for LP gas or the like, characterized by detecting the presence or absence of a hole or the like. 2. The method according to claim 1, wherein the internal drying step is performed after a water pressure test or a measurement of the internal volume of the high pressure vessel.