JPH11352000A - Tank inspection method and apparatus - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To eliminate the need for a large-scale scaffold, to accurately and quickly detect a defective portion such as a minute through-hole in a tank without using a gas detection liquid, and to enable automation. SOLUTION: After the test gas is charged into the outer surface of the tank,
Manipulator 2 from a position away from tank inner surface 16a
To operate the inspection device in which a plurality of gas sensors 1 attached to the tip of the arm of the manipulator 2 are arranged.
6a, by detecting the leakage of the gas to be detected in a predetermined area at a time, the through holes in the predetermined area are inspected, and the leakage of the gas to be detected is detected by each of the gas sensors 1. When notified, the leakage point of the test gas is marked with a marker 4 provided corresponding to each gas sensor 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for inspecting a tank for inspecting the presence or absence of a defect such as a through-hole which causes a fluid leak from a tank and searching for a defective portion.

[0002]

2. Description of the Related Art After a tank is manufactured, it is necessary to inspect for defects such as through holes which may cause fluid leakage, and to search for a defective portion. Conventionally, this tank inspection is performed in the following procedure.

That is, after the tank is manufactured, a scaffold for inspection is erected inside the tank, and a gas detection liquid that changes color by a test gas (for example, ammonia gas) is applied to the inner surface of the tank, and the outer surface of the tank (the outer surface of the tank and the heat insulating layer) The gap between the gas detection liquid and ammonia gas was charged into the tank, and the discoloration of the applied gas detection liquid was examined by visual observation to see if the ammonia gas passed through defects such as through holes and leaked to the tank inner surface. inspect.

[0004]

As described above, conventionally,
The tank inspection was performed by applying a gas detection liquid to the inside of the tank and then visually monitoring the discoloration of the gas detection liquid for the ammonia gas charged on the outside of the tank to leak to the inside of the tank. Such problems existed. Since all scaffolds need to be erected in the tank,
A large amount of work is required for disassembly, and a large amount of work time and cost is required. The tank inner surface may be damaged during scaffolding or dismantling, and repair may be required. As the inspection work, cleaning the inside surface of the tank, applying a gas detection liquid, charging ammonia gas, visual inspection after a lapse of a predetermined time,
Although the work of wiping and cleaning the gas detection liquid is performed, the work is performed on a scaffold, and measures to prevent a fall or the like are required. If the tank is large, it takes tens of hours or more for ammonia gas to spread throughout the tank, penetrate through holes, react with the gas detection liquid applied on the inner surface, and change color after the ammonia gas is charged. And waiting time occurs, resulting in poor efficiency. Since the detection accuracy of the through-hole depends on the thickness of the applied gas detection liquid, the detection accuracy varies. In other words, since the gas detection liquid changes color by contacting and reacting with the ammonia gas for a predetermined time or more, when the coating film thickness is small, the ammonia gas permeates the gas detection liquid film in a short time, and If the contact time cannot be long, and the coating film thickness is large, the discoloration of the gas detection liquid film due to the ammonia gas remains inside the film and does not appear on the gas detection liquid film surface. In either case, detection of the through-hole may not be possible. Appropriate gas detection liquid coating thickness is 50 ± 10μ
m, but it takes time and effort to control and apply the film thickness in this range.

A technical object of the present invention is to make it possible to accurately and quickly detect a defective portion such as a minute through-hole in a tank without using a gas detecting liquid, and to make automation possible. It is in.

[0006]

According to a first aspect of the present invention, there is provided a tank inspection method, wherein after a test gas is charged into an outer surface of a tank, the manipulator is operated from a position distant from the inner surface of the tank. An inspection device consisting of a plurality of gas sensors attached to the tip of the arm is placed close to the inner surface of the tank, and by detecting gas leakage in a predetermined area at once, the through hole in the predetermined area is inspected. When it is notified that the leak of the test gas has been detected by each gas sensor, marking is performed on the leak location of the test gas detected by each gas sensor. It is characterized in that the tank inner surface is scanned by sequentially performing these series of steps while moving the manipulator along the tank inner surface.

In the apparatus according to a third aspect of the present invention, a predetermined number of gas sensors for detecting a gas to be detected are arranged at the tip of the arm of the manipulator so that the respective measurement surfaces are held in the same direction. Along with attaching the holder made of
A marker is installed to mark the leak location of the test gas detected by each gas sensor, and a notification means is provided on the holder or a movable carriage that becomes the traveling section of the manipulator to notify that each gas sensor has detected the leak of the test gas. It is a thing.

According to a second aspect of the present invention, there is provided a tank inspection method, wherein after the test gas is charged into the outer surface of the tank, the traveling vehicle with the adsorption means is operated from a position away from the inner surface of the tank. An inspection device having a plurality of gas sensors mounted on the tank is located near the inner surface of the tank, and by detecting gas leakage of a predetermined area at a time, the through holes in the predetermined area are inspected. Is notified that the leakage of the test gas has been detected, marking is performed on the leak location of the test gas detected by each gas sensor. It is characterized in that the tank inner surface is scanned by sequentially performing these series of steps while moving the traveling carriage along the tank inner surface.

In the apparatus according to a fourth aspect of the present invention, a predetermined number of gas sensors for detecting a gas to be detected are arranged and mounted on a traveling carriage with suction means such that respective measurement surfaces are in the same direction. At the same time, a marker for marking the leak point of the test gas detected by each gas sensor is installed independently near each gas sensor, and each gas sensor is attached to the traveling vehicle or a control operating device that controls this traveling vehicle. And a notifying means for notifying that the leakage of the data has been detected.

In each of the methods of claim 1 and claim 2 and the apparatus of claim 3 and claim 4, the gas to be detected is:
For example, ammonia gas, carbon dioxide gas, helium gas, acetylene gas, laughing gas, or the like can be used. The gas sensors that can be used are roughly classified into an electrochemical sensor and a ceramic sensor. Further, when ammonia gas is used as the test gas, for example, a constant potential electrolytic sensor classified as an electrochemical sensor, a semiconductor sensor classified as a ceramic sensor, a hot wire semiconductor sensor, or the like can be used. When using another gas as the test gas, depending on the type of gas, the catalytic combustion type, the thermal conductivity type,
It is possible to use a sensor having a detection principle such as a galvanic cell type, a non-dispersive infrared type, and a mass spectrometer type. In addition, the gas sensor only needs to be able to install markers corresponding thereto, and the number and the number of rows are not limited. Further, the marker may be set to automatically mark the tank surface when the corresponding gas sensor detects the leakage of the gas to be detected, and the marker corresponding to the gas sensor that has detected the leakage of the gas to be detected may be an operator. May be selected by a selection switch to perform a marking operation.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. Hereinafter, the first of the present invention.
A tank inspection method according to the embodiment and an apparatus used in the method will be described with reference to FIGS. 1A and 1B are diagrams showing a configuration of a tank inspection apparatus according to the first embodiment, in which FIG. 1A is a plan view of a gas sensor unit, and FIG. 1B is a diagram schematically showing a relationship between the gas sensor unit, a manipulator, and a movable cart. 2 to 4 are explanatory views of a method for inspecting a tank using the apparatus of FIG. 1, and FIG. 5 is a through hole showing the detection performance when an ammonia gas sensor is employed in the apparatus of FIG. -A diagram showing the relationship between the inter-sensor distance and the detection limit minimum through hole, FIG. 6 is a circuit diagram for explaining the detection principle of a potentiostatic electrolytic sensor that is an ammonia gas sensor,
FIG. 7 is a circuit diagram for explaining the detection principle of a semiconductor sensor which is also an ammonia gas sensor.

The tank inspection apparatus according to the first embodiment has a plurality of gas sensors 1 for detecting a gas to be detected as shown in FIG.
... are arrayed (here, 40 rows per row are 2 rows: 2 × 40
Are arranged in a rectangular holder 3 attached to the tip of the arm of the manipulator 2 so that the measuring surfaces 1a having a diameter of 30 mm of the gas sensors 1 are in the same direction.
The 200 mm range can be inspected at a time. In the vicinity of each gas sensor 1 in the holder 3, a marker 4 composed of an ink jet marking nozzle for marking a leak location of the test gas detected by each gas sensor 1 is installed independently, A gas detection lamp 5 is provided on the back surface of the holder 3 which is easily attached to the gas, as first notification means for notifying that each gas sensor 1 has detected leakage of the test gas. Further, a control unit 6 connected to each gas sensor 1,..., A gas detection lamp 5, a marker 4,.

The control device 6 includes at least each gas sensor 1
Are detected by each of the gas sensors 1 on the basis of coordinates set in advance, and a display 7 having a function as a second notification means for identifying and indicating that the leakage of the test gas has been detected for each sensor. It has a controller 8 having an operation means for calculating the leaked portion of the test gas by operation, a recorder 9 for recording the operation result, a manipulator operating device 13, and a drive power source 11 composed of a battery. The controller 8 further adjusts the sensitivity of each of the gas sensors 1..., Sets a near-hold time timer of the inspection device to the inner surface 16 a of the tank 16 to be inspected,
It has functions such as marking control. The manipulator operating device 13 is provided with an operation button of the movable carriage 12 in addition to an operation button of the manipulator 2.

Four wheels 15 are mounted on both outer surfaces of the longitudinal end walls of the holder 3 via suspension devices 14, respectively. Normally, the wheels 15 are operated by the spring of the suspension device 14. Project from the tip end surface of the holder 3, that is, the measurement surface 1a of each gas sensor 1, so that the main body of the inspection device is lifted from the surface to be measured, so that the inspection device can be moved smoothly and a defect location is searched. When pushed by the manipulator 2 at the site, it retracts from the distal end surface of the holder 3 against the spring force of the suspension device 14,
The measurement surface 1a of each gas sensor 1 can be provided near the inner surface 16a of the tank 16 to be inspected. In addition, as the suspension device 14, a swing system in which the axle support link can swing as shown by an arrow 17 in FIG. 1 or a straight type in which the axle support link can advance and retreat with respect to the surface to be measured as shown by an arrow 18 It goes without saying that various methods such as a dynamic method can be adopted.

At the four corners in the holder 3, distance sensors 19 are arranged so that their distance measurement surfaces are in the same direction as the measurement surfaces 1a of the gas sensors 1, and are connected to the control device 6. I have. Further, on the back surface of the holder 3, a proximity detection lamp 21 is provided for notifying an operator that the measurement surface 1a of each gas sensor 1 has been disposed close to the tank inner surface 16a. The determination as to whether or not the measurement surface 1a of each gas sensor 1 is located close to the tank inner surface 16a is made by the distance sensor 1
When the distance from the tank inner surface 16a detected at step 9 is less than or equal to a predetermined distance (for example, 3 mm or less), the control device 6 determines that the vehicle is near and turns on the near detection lamp 21.

Next, a method of inspecting a tank using the apparatus of the first embodiment will be described. In the apparatus of the first embodiment, ammonia gas is used as a test gas,
Although a constant-potential electrolytic sensor shown in FIG. 6 capable of detecting ammonia gas is used as the gas sensor, a semiconductor sensor or a hot-wire semiconductor sensor (not shown) shown in FIG. 7 can be used as the gas sensor. .

As shown in FIG. 6, the potentiostatic electrolytic sensor has three electrodes, a working electrode (WE), a counter electrode (CE), and a comparison electrode (RE), as is well known. Each electrode is immersed in an electrolytic solution and held by an electrolytic cell, and each electrode is connected to a potentiostat circuit. Therefore, when gas is ventilated to the working electrode (WE) which is kept at a constant potential with respect to the comparison electrode (RE), the working electrode (WE)
And a counter electrode (CE) occur simultaneously, and an electrolytic current i flows in an external circuit. Since the electrolytic current i is proportional to the gas concentration according to Faraday's law, the gas concentration can be measured by measuring the electrolytic current i.

As shown in FIG. 7, the semiconductor sensor comprises an n-type semiconductor made of a metal oxide (SnO ₂ ), two electrodes, and a heater coil, as shown in FIG. Let me. When the activated semiconductor comes into contact with the reducing gas, the resistance value between the electrodes changes. Therefore, the gas concentration can be measured by extracting the resistance with a voltage.

As is well known, a hot wire type semiconductor sensor has a structure in which a metal oxide semiconductor is frozen on a platinum wire coil, and has the same basic principle as a semiconductor type sensor.

The inspection of the tank 16 is carried out mainly on the welding site where a leak may be present. First, a test gas, that is, an ammonia gas, is charged into the outer surface of the tank (a gap between the outer surface of the tank and the heat insulating layer). Next, the operator operates the manipulator 2 or the moving trolley 12 holding the inspection device from a position away from the tank inner surface 16a by using the operation button of the manipulator operating device 13 to move the tip of the holder 3 of the inspection device to the top wall of the tank inner surface 16a. And a welded portion of the side wall (shown by a solid line in FIGS. 2 and 3) and pressed until the proximity detection lamp 21 is turned on. When the proximity detection lamp 21 is turned on, the measurement surface 1 of each gas sensor 1.
are located near the tank inner surface 16a, and this state is maintained for a predetermined time (for example, one minute). For the measurement of the sensor proximity holding time, an operator manually operates a timer (not shown) or the controller 8 operates the proximity detection lamp 2.
This is performed by automatically operating a built-in timer in conjunction with the lighting of 1. Thus, a range of 60 × 1200 mm is inspected at a time.

If the gas detection lamp 5 does not turn on even after one minute, the pressing force of the sensor is reduced, and the measurement surface 1a of each gas sensor 1 is floated from the tank inner surface 16a by the spring force of the suspension device 14. The wheels 15 are operated and moved to the next inspection point, and the same operation as described above is performed. These series of operations are repeated while sequentially moving along the welding line of the tank inner surface 16a as shown by broken lines in FIGS. 3 and 4, thereby scanning the tank inner surface 16a.

The time (1 minute) during which the measurement surface 1a of each gas sensor 1 is held close to the tank inner surface 16a.
When the gas detection lamp 5 is turned on, the leakage point is confirmed by the indicator 7 of the control device 6, and the switch (not shown) of the marker 4 at the corresponding point is pressed to mark the leakage point and detect the leakage point. The recorded coordinate data of the leak location is recorded in the recorder 9.

This marking operation can be performed by the controller 8 by setting the automatic mode. That is, the controller 8 grasps the positions of the gas sensors 1 in the holder 3 and the corresponding markers 4. When the leak is detected, the gas sensor that detects the leak using the detection signal as a trigger is provided. The marker 4 corresponding to 1 is actuated to automatically eject ink to the leak location, and the recorder 9 automatically records the coordinate data of the detected leak location.

Calibration of each of the gas sensors 1... Is performed by allowing the gas to be detected to pass through the calibration reference material provided with a through hole having a standard size and detecting the gas by the gas sensor 1.

The gas detection performance of the ammonia gas sensor of the potentiostatic electrolytic type used in the first embodiment is as shown in the experimental result diagram of FIG. In FIG. 5, the vertical axis represents the minimum detection limit through-hole diameter, and the horizontal axis represents the distance between the through-hole and the measurement surface of the gas sensor. In this experiment, 1-5μ
A cell provided with a through-hole standard material having a through-hole of m was filled with ammonia gas, and the relationship between the distance between the measurement surface of the gas sensor and the through-hole of the standard material and the detection limit minimum through-hole diameter was examined. Things.

As is clear from FIG. 5, the smaller the distance between the measurement surface of the gas sensor and the through-hole of the standard material, the smaller the through-hole can be detected, and the apparatus of the first embodiment is used. According to the tank inspection method, it was confirmed that it was possible to detect even a through hole having a diameter of 1 μm. That is, as a result of the experiment, it was found that it is important to make the measurement surface of the gas sensor close to the inner surface of the tank in order to enable detection of a smaller through hole.

Next, the effect of the first embodiment will be described with reference to the fact that the stainless steel plate is welded and welded to a depth dimension of 20 m.
Width 20m, height 20m, capacity 8000m ³ , inner surface area 2
An example in which the present invention is applied to detection of a through hole in a tank having a length of 400 m ² and a welding line length of 4000 m will be described in comparison with a conventional gas detection liquid application method. In this case, the concentration 2
A 5% ammonia gas was charged, and the inside of the tank was inspected 24 hours after the charging so that the ammonia gas spread over the entire tank and was diluted to a concentration of about 1 to 2%. In addition, the time for approaching the inner surface of the tank for detecting the through-hole by the device of the first embodiment was set to 1 minute per unit.

Inspection required time T (inspection work only) In the case of the embodiment, T = (T1 10 T2) .L / (W.60) = 72 hours → 9 days (8 hours / day) T1: Holding time 1 minute T2 : Marking time for moving and positioning 10 minutes 0.3 minutes L: Total length of welding line 4000m W: Inspection sensor length 1.2m Other required time In the case of the embodiment, the passing time is 24 hours (1 day) after charging ammonia gas. 8 hours (1 day) That is, the total number of days required for the inspection work is 11 days in the case of the first embodiment.

In the case of the comparative example In other words, when the tank of the same size was inspected by the conventional gas detection liquid application method, the scaffold was erected 5 days, ammonia gas was charged, and the reaction wait time was 2 days Liquid application) Visual inspection 4 days Wiping and cleaning of detection liquid 2 days Scaffold dismantling 5 days Total 18 days

That is, according to the tank inspection method of the first embodiment, the number of days required for inspection can be remarkably reduced as compared with the comparative example, and the total number of days required for the operation can be reduced by as much as 7 days.

In the case of the embodiment, the number of workers and man-hours required for the inspection are as follows: ammonia gas charging 5 persons × 1 day Carriage loading / unloading 5 persons × 1 day Inspection 2 persons × 9 days 28 persons / day Comparative example (gas detection liquid application method) Scaffold erection 10 persons x 5 days Ammonia gas charging 5 persons x 1 day Visual inspection 10 persons x 4 days Detector liquid wiping and cleaning 10 persons x 2 days Scaffold dismantling 10 Person x 5 days Total work man-hours 165 people / day

That is, according to the tank inspection method of the first embodiment, the number of workers and man-hours required for inspection can be remarkably reduced as compared with the comparative example. 137 people / day could be reduced.

Embodiment 2 FIG. 8 is a view showing a configuration of an apparatus used in a tank inspection method according to a second embodiment of the present invention. FIG. 8 (a) shows a traveling vehicle with an adsorption means equipped with a gas sensor and a parent vehicle equipped with a control device. FIG. 9B is an explanatory view schematically showing the relationship, FIG. 9B is a cross-sectional view showing the traveling vehicle along the line AA in FIG. 8A, FIG. 9C is a right side view of the traveling vehicle, and FIG.
It is an explanatory view of a method of inspecting a tank using the apparatus of the present invention,
In the respective drawings, the same portions as those of the first embodiment are denoted by the same reference numerals.

The tank inspection apparatus according to the second embodiment has a plurality of gas sensors 1 for detecting a test gas as shown in FIG.
... are arranged in an array (again, two rows each having 40 rows): 2 × 40
And a traveling carriage 22 provided with a plurality of suction means 21 comprising vacuum suction pads on both sides such that the measurement surface 1a having a diameter of 30 mm of each gas sensor 1 is in the same direction as the lower surface of the vehicle body. It is mounted so that a range of 60 × 1200 mm can be inspected at a time. In the vicinity of each of the gas sensors 1 in the traveling carriage 22, a marker 4 composed of an ink jet marking nozzle for marking a leaked portion of the test gas detected by each of the gas sensors 1 is independently provided.
, And a gas detection lamp 5 is provided on the upper surface of the traveling vehicle, which is easily visible to the operator, as first notification means for notifying that each of the gas sensors 1 has detected leakage of the gas to be detected.

The four wheels 23 of the traveling carriage 22 are attached to the vehicle body via a suspension device (not shown). Normally, each wheel 23... , Protruding from the measurement surface 1a of the inspection apparatus, the main body of the inspection apparatus is lifted from the surface to be measured, so that the inspection apparatus can be moved smoothly. When the force is increased, it contracts from the lower surface of the vehicle body against the spring force of the suspension device, and the measurement surface 1a of each gas sensor 1 can be located closer to the inner surface 16a of the tank 16 to be inspected. ing.

The traveling carriage 22 is connected to the parent carriage 24 via a flexible hose 20a and a cable 20b. The flexible hose 20a connects the vacuum blower 25 mounted on the parent carriage 24 to the traveling carriage 22 side. Are connected to the control device 6A installed on the upper surface of the parent carriage 24, the gas sensors 1 on the traveling carriage 22 side, the gas detection lamps 5, the markers 4,. A truck drive motor (not shown) is connected to each.

The suction force is adjusted when the traveling carriage 22 travels on the wall or ceiling of the tank inner surface 16a, and the suction force is increased when the output surface is increased to bring the measurement surface 1a of the gas sensor 1 closer to the tank inner surface 16a. The force adjustment is performed by the control device 6A controlling the vacuum blower 25. In addition, the traveling carriage 22 can be driven by a turbine system using suction air from the vacuum blower 25. In addition, each adsorption means 2
The magnetic force may be used as 1 and the signal transmission may be performed wirelessly. In this case, it is necessary to mount an exciting coil, a battery, a motor for driving the trolley, etc. on the trolley 22, but it is not necessary to pull up a flexible hose or cable. The effect of offsetting the load weight with the method becomes large and effective.

The control device 6A includes a display 7 having a function as a second notification means for identifying and indicating at least each gas sensor 1... Having detected the leak of the gas to be detected by each sensor. A controller 8 having a calculating means for calculating a leak point of the test gas detected by each of the gas sensors 1... Based on the calculated coordinates, a recorder 9 for recording the calculation result, a traveling bogie controller 26, a battery And a driving power supply 11 comprising: The controller 8 further has functions such as sensitivity adjustment of the gas sensors 1,..., Setting of a timer for keeping the inspection apparatus close to the inner surface 16a of the tank 16 to be inspected, control of marking, and the like. Traveling cart controller 2
6 is provided with an operation button of the traveling vehicle 22.

At the four corners of the traveling carriage 22 in the vehicle body,
Each of the distance sensors 19 is arranged so that its distance measurement surface is in the same direction as the measurement surface 1a of each gas sensor 1, and is connected to the control device 6A. Traveling cart 22
Is provided on the upper surface of the sensor for notifying an operator that the measurement surface 1a of each gas sensor 1 is located closer to the tank inner surface 16a. The determination as to whether or not the measurement surface 1a of each gas sensor 1 is located close to the tank inner surface 16a is made by the tank inner surface 16a detected by each distance sensor 19.
The controller 6A determines that the vehicle is near when the distance between the vehicle and the vehicle is less than a predetermined distance (for example, 3 mm or less), and turns on the proximity detection lamp 21.

Next, a method for inspecting a tank using the apparatus of the second embodiment will be described. Also in the apparatus of the second embodiment, ammonia gas is used as a test gas,
A constant potential electrolytic sensor capable of detecting ammonia gas is used as a gas sensor.

The inspection of the tank 16 is carried out mainly on the welding site where a leak may be present. First, a test gas, that is, an ammonia gas, is charged into the outer surface of the tank (a gap between the outer surface of the tank and the heat insulating layer). Next, the operator operates the traveling vehicle 22 equipped with the inspection device from a position distant from the tank inner surface 16a with the operation button of the traveling vehicle operation device 26, and moves the traveling vehicle 22 to an inspection site on the wall or ceiling of the tank inner surface 16a. Let it run. When you come to the inspection site,
By increasing the output of the vacuum blower 25, the proximity detection lamp 2
The lower surface of the vehicle body is brought close to the welding site until 1 lights up. When the proximity detection lamp 21 is turned on, the measurement surface 1a of each gas sensor 1 is close to the tank inner surface 16a, and this state is maintained for a predetermined time (for example, one minute). The measurement of the sensor proximity holding time is performed by manually operating a timer (not shown) by the operator, or by the controller 8 automatically operating a built-in timer in conjunction with the lighting of the proximity detection lamp 21. Thereby, 60 × 1200mm
Inspect the area at once.

If the gas detection lamp 5 does not turn on even after one minute has passed, the traveling carriage 22 is moved to the wall or ceiling of the tank inner surface 16a.
Vacuum blower 2
5 is lowered to reduce the sensor pressing force, the spring force of the suspension device causes the measurement surface 1a of each gas sensor 1 to float above the tank inner surface 16a, and the wheels 23 are operated, so that the traveling vehicle reaches the next inspection point. Then, the same operation as described above is performed. These series of operations are performed on the tank inner surface 16.
By repeating the traveling carriage 22 while traveling along the welding line a, the inner surface 16a of the tank is scanned.

The time (1 minute) during which the measurement surface 1a of each gas sensor 1 is held close to the tank inner surface 16a.
When the gas detection lamp 5 is turned on, the leakage point is confirmed by the indicator 7 of the control device 6A, and a switch (not shown) of the marker 4 at the corresponding point is pressed to mark the leakage point and detect the leakage point. The recorded coordinate data of the leak location is recorded in the recorder 9.

Also in the second embodiment, the marking operation can be performed by the controller 8 by setting the automatic operation mode. That is, in the controller 8, each gas sensor 1
... in the holder 3 and the markers 4 corresponding to them are grasped. When a leak is detected, the detection signal is used as a trigger to activate the marker 4 corresponding to the gas sensor 1 which has detected the leak. Ink is automatically ejected to the leak location, and the coordinate data of the detected leak location is automatically recorded in the recorder 9.

[0045]

As described above, according to the tank inspection method of the present invention, after the test gas is charged into the outer surface of the tank,
By operating a manipulator or a traveling carriage with suction means from a position away from the inner surface of the tank, an inspection device having a plurality of gas sensors arranged near the inner surface of the tank, and detecting a leak of the gas to be detected in a predetermined area at one time. In this way, the through hole of a predetermined area portion is inspected, and when it is notified that the leak of the test gas is detected by each gas sensor, marking is performed on the leak location of the test gas detected by each gas sensor, and these are marked. A series of processes are performed sequentially while moving the manipulator or traveling carriage along the tank inner surface, so that the inner surface of the tank is scanned, so a large scaffold is not required, and the small through hole of the tank is used without using a gas detection liquid. A small number of people can accurately and quickly detect defective spots such as cleaning the inside of the tank, applying the detection liquid, visually inspecting, wiping the gas detection liquid, etc. Work is not required, there is no reaction latency between the detection liquid and the gas to be detected, automation is facilitated, it is possible to greatly compress the cost of the inspection.

Further, a wide variety of gas sensors used in the apparatus used in this method have been developed and are commercially available, and may be appropriately selected and used, so that there is no need to newly develop a sensor. However, the cost can be reduced accordingly.

[Brief description of the drawings]

FIG. 1 is a view showing an apparatus used in a tank inspection method according to a first embodiment of the present invention, wherein (a) is a plan view of a gas sensor unit, and (b) shows a relationship between the gas sensor unit, a manipulator, and a movable cart. FIG. 3 is a side view including a schematic partial sectional view.

FIG. 2 is an explanatory diagram of a tank inspection method according to the first embodiment.

FIG. 3 is an explanatory diagram of a tank inspection method according to the first embodiment.

FIG. 4 is an explanatory diagram of a tank inspection method according to the first embodiment.

FIG. 5 is a diagram showing the detection performance when an ammonia gas sensor is employed in the apparatus according to the first embodiment, as a relationship between the distance between the through-hole and the sensor and the minimum detection-limit through-hole;

FIG. 6 is a circuit diagram for explaining the detection principle of the potentiostatic sensor.

FIG. 7 is a circuit diagram for explaining the detection principle of the semiconductor sensor.

FIG. 8 is a view showing an apparatus used in a tank inspection method according to a second embodiment of the present invention, and (a) shows a relationship between a traveling vehicle with a suction device equipped with a gas sensor and a parent vehicle equipped with a control device. FIG. 2B is a cross-sectional view showing the traveling vehicle along the line AA in FIG. 3A, and FIG. 3C is a right side view of the traveling vehicle.

FIG. 9 is an explanatory diagram of a tank inspection method according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas sensor 1a Measurement surface of gas sensor 2 Manipulator 3 Holder 4 Marker 5 Gas detection lamp (informing means) 7 Display (informing means) 12 Moving trolley 13 Manipulator operating device 16 Tank 16a Tank inner surface 21 Suction means 22 Traveling trolley 24 Parent trolley 25 Vacuum blower 26 Traveling truck controller

Claims (4)

[Claims] 1. A step of charging a test gas to an outer surface of a tank, and operating a manipulator having a plurality of gas sensors arranged on an end of an arm at an end of the arm from a position away from the inner surface of the tank. A step of causing the inspection device to be close to the inner surface of the tank, detecting the leakage of the gas to be detected in a predetermined area at a time, and inspecting the through hole, and informing that the leakage of the gas to be detected has been detected by each gas sensor. And marking each of the leak points of the test gas detected by each gas sensor, and scanning the tank inner surface by sequentially performing each of the steps while moving the manipulator along the tank inner surface. A tank inspection method characterized by the following. 2. A step of charging a test gas to the outer surface of the tank, and operating a traveling vehicle with suction means mounted with an inspection device having a plurality of gas sensors arranged from a position away from the inner surface of the tank. A step of causing the inspection device to be close to the inner surface of the tank, detecting the leakage of the gas to be detected in a predetermined area at a time, and inspecting the through hole, and informing that the leakage of the gas to be detected has been detected by each gas sensor. Then, a step of marking each leak location of the test gas detected by each gas sensor, and scanning the inner surface of the tank by sequentially performing each of the steps while moving the traveling vehicle along the inner surface of the tank A tank inspection method characterized in that: 3. A holder comprising a predetermined number of gas sensors for detecting a gas to be detected arranged at the tip of the arm of the manipulator and holding the respective measurement surfaces in the same direction, and each gas sensor of the holder. A marker for marking a leak point of the test gas detected by each gas sensor is installed independently in the vicinity, and each of the gas sensors detects the leak of the test gas on the holder or a movable carriage serving as a traveling part of the manipulator. A tank inspecting device provided with a notifying means for notifying that the tank operation has been performed. 4. A predetermined number of gas sensors for detecting a test gas are arranged, mounted on a traveling vehicle with suction means such that respective measurement surfaces are in the same direction, and independently provided near each of the gas sensors. A marker for marking a leak point of the test gas detected by each gas sensor is installed, and the traveling vehicle or a control operating device controlling the traveling vehicle is notified that the gas sensor has detected the leakage of the test gas. A tank inspection device provided with a notification unit.