JPH1019717A - Apparatus and method for inspecting pressure of tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve safety and working efficiency by setting a connecting part which is opened at three sides, connected to an air feed pipe at two of the three sides and can be shut by a shielding member at the remaining one side, at a low workable position on the ground in the middle of the air feed pipe. SOLUTION: One end of an air feed pipe 7 communicates with an upper part of an underground tank, and the other end comprises a horizontal pipe 7a, a vertical pipe 7b and an air feed opening 7c. A connection main body 11 is set in the middle of the vertical pipe 7b at a height accessible by an operator. The connection body 11 has a space 31 thereinside. The vertical pipe 7b is screwed in inner peripheries of connection ports 35, 36 formed at an upper and a lower parts of the main body 11. On the occasion of a pressure inspection, a pressure detection joint 38 consisting of a joint body 40 and a pressure-detecting pipe 41 is inserted into the space 31 of the connection body 11. The space 31 is shut by an O ring 42 of the joint body 40, so that the underground tank and the air feed pipe 7 are brought into a sealed state. Nitrogen gas is supplied to the underground tank via the pressure detection joint 38 and air feed pipe 7. When a pressure in the underground tank reaches an inspection pressure, the supply of the gas is stopped. A change of a liquid level is monitored by a manometer and a pressure change is detected by a pressure transmitter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tank pressure inspection apparatus and a tank pressure inspection method, and more particularly to a tank pressure inspection apparatus and a tank pressure inspection method for inspecting the presence or absence of leakage due to pressure fluctuations in a tank.

[0002]

2. Description of the Related Art In a gas station, for example, an underground tank for storing an oil solution is buried. Facilities that store flammable fuel in such underground tanks are required to regularly inspect the underground tanks and underground pipes for leaks by the Dangerous Goods Notice from the Fire and Disaster Management Agency.

[0003] As this kind of inspection method, a water pressurization test for applying a water pressure to an underground tank to inspect for leaks,
Filling the underground tank with nitrogen gas and pressurizing the tank to check for leaks.Gas pressurization test to pressurize the tank to low pressure to check for leaks. There is a micro-decompression test or the like in which the pressure is reduced to below atmospheric pressure to check for leakage.

In general, a micro-pressurization test is widely used, and a description will be given below of a case in which the presence or absence of leakage in an underground tank and an underground pipe is inspected by the micro-pressurization test. still,
Each of the test methods (1) to (4) is specified by a notice from the Fire and Disaster Management Agency, etc., and the pressure inspection (leakage inspection) of the underground tank is performed according to the method.

[0005] When performing a micro-pressurization test, the pressure test may be performed after the underground tank is empty, or the pressure test may be performed while the oil liquid is stored in the underground tank. It is. In the inspection method of the micro-pressurization test, nitrogen gas is sealed in an underground tank, and whether or not pressure fluctuation in the underground tank occurs is monitored for a predetermined time.

[0006] The underground tank is pressurized to approximately 200 mmAq, and the presence or absence of leakage is determined by the presence or absence of a pressure change within a certain period of time.

[0007]

In order to perform a pressure test on an underground tank using a conventional apparatus, a pipe for measuring pressure is connected to a measuring port provided immediately above the underground tank in advance, and Vent at the upper end of the ventilation pipe (keeping the upper space in the underground tank at atmospheric pressure) connected to the underground tank (4 m above the ground)
The above height) must be sealed with a cap or the like.

[0008] Since the ventilation port of the ventilation pipe is located at a high position, the operator must use a ladder to climb to the level where the ventilation port is provided. Therefore, when performing such high-altitude work, it is necessary to pay attention to safety, so that not only the nerve is used but also a worker who supports the ladder is required. Since the pressure of the underground tank is regularly inspected, each inspection requires a lot of labor.

In addition, since the inspection is performed with the manhole of the weighing section open, the safety around the manhole must be checked during the inspection. Therefore, a plurality of workers respectively share the department in charge until the pressure inspection is completed. Watch out for changes in tank pressure.

Accordingly, an object of the present invention is to provide a tank pressure inspection device and a tank pressure inspection method which solve the above-mentioned problems.

[0011]

In order to solve the above problems, the present invention has the following features. Claim 1
According to the invention, the tank pressure is determined by detecting pressure fluctuations in an underground tank having a vent pipe having one end connected to an underground tank and the other end extending to a high place and open to the atmosphere by a pressure detection device to determine the presence or absence of leakage. In the inspection device, in the middle of the ventilation pipe, and at a low position where work on the ground is possible, three sides are open, two of which are connected to the ventilation pipe, and the other is for shutting off the underground tank in an airtight manner. A connection portion which can be closed by a member is provided.

Therefore, according to the first aspect of the present invention, since the connecting member for blocking the communication of the ventilation pipe is provided at a low position of the ventilation pipe communicating with the underground tank, the work of sealing the ventilation pipe can be performed on the ground. Since a ladder is not required, the safety is improved, the work can be performed by one person, and the work efficiency is also improved. Therefore, the work of the periodic inspection is facilitated, and the leak inspection of the tank can be performed safely and in a short time.

According to a second aspect of the present invention, a pressure detecting device detects a pressure fluctuation in an underground tank having a vent pipe having one end connected to the underground tank and the other end extending to a high place and open to the atmosphere. In the tank pressure inspection device for determining the presence or absence of leakage, in the middle of the ventilation pipe, and at a low position where work can be performed on the ground, three sides are opened, two of which are connected to the ventilation pipe, and the other is the pressure detection. A connection portion in which a joint for connecting a device can be inserted is provided.

Therefore, according to the second aspect of the present invention, since the connecting portion into which the joint can be inserted is provided in the middle of the vent pipe, the pressure test pipe can be connected to the vent pipe, and the pressure test pipe is separated. Since it is not necessary to connect to the location, the preparation work before performing the pressure test can be easily performed. The invention according to claim 3 is characterized in that one end is connected to an underground tank and the other end is extended to a high place, and three sides are opened at a low position where the work can be performed on the ground in the middle of a vent pipe which is open to the atmosphere. A method for inspecting tank pressure of an underground tank having a connection portion which is connected to the ventilation pipe and the other of which can be closed by a blocking member for airtightly blocking the underground tank, wherein the underground tank is airtight. When connecting to the atmosphere by the connection, and pressurizing or depressurizing the underground tank, and detecting pressure fluctuations in the underground tank by a pressure detection device,
Judging the presence or absence of leakage based on the detection result.

Therefore, according to the third aspect, the work of sealing the ventilation pipe for closing the underground tank by closing the other one of the connection portions connected to the ventilation pipe by the blocking member can be performed on the ground. Leak inspection of underground tanks can be performed efficiently.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a first embodiment of a tank pressure inspection device according to the present invention. At a gas station, a weighing machine 1 for refueling is installed on the ground, and an underground tank 2 for storing the oil liquid supplied to the weighing machine 1 is buried underground. The underground tank 2 has an end portion of a suction pipe 3 connected to a pump (not shown) in the weighing machine 1 inserted therein. When the pump is activated, the oil liquid in the underground tank 2 is pumped up and the fuel tank of the vehicle is opened. (Not shown).

The underground tank 2 has a measuring port 4 into which a measuring rod (not shown) for measuring the storage amount (remaining amount) of the oil liquid is inserted, and a load of a tank truck (not shown). Injection pipe 6 connected to the hose connection 5 to which the unloading hose is connected
And a ventilation pipe 7 for keeping the upper space in the underground tank 2 at atmospheric pressure.
And The suction pipe 3 and the measuring port 4 are connected to the manhole 8,
9 is stored. When the inspection work is performed, the lids 8a and 9a of the manholes 8 and 9 are removed, and the suction tube 3 is inspected or the liquid level is checked using a measuring rod.

The ventilation pipe 7 has one end communicating with the upper part of the underground tank 2 and the other end extending horizontally, and a horizontal pipe 7a extending above the ground along a wall 10 provided at the end of the gas station. It comprises a vertical tube 7b extending and a vent 7c provided at the upper end of the vertical tube 7b. Since the vent 7c is provided at a height of 4 m or more above the ground, when closing the vent 7c as in the related art, the worker must use a ladder to climb up to the level of the vent 7c. Was.

The ventilation pipe 7 has a connection body 11 provided in the middle of the vertical pipe 7b (for example, at a height of 1 m above the ground).
The connection main body 11 serves to shut off the ventilation pipe 7 and detect the pressure of the underground tank 2 via the ventilation pipe 7 as described later. Further, since the connection main body 11 is provided at a height that can be reached without the operator using a ladder or the like, the connection operation can be performed easily and safely by one person.

Next, the configuration of the tank pressure inspection device 12 will be described. The tank pressure inspection device 12 includes a nitrogen gas container 13 filled with nitrogen gas, a fine pressure device 16 to which nitrogen gas is supplied via a pressure reducing valve 14 and a connection hose 15 of the nitrogen gas container 13, A detecting joint 18 to which nitrogen gas having a pressure adjusted by the device 16 is supplied via an intake hose 17, and a thermometer 19 provided on the detecting joint 18.
, A connection tube 20 for communicating the detection joint 18 with the connection main body 11, a ventilation tube 7, and connection tubes 20, 21.
Pressure transmitter 22 for converting the pressure detected through the pressure sensor into an electric signal, and a manometer 24 for detecting a pressure difference between the pressure detected through the ventilation pipe 7 and the connection tube 23 and the atmospheric pressure.
And

The temperature data detected by the thermometer 19 and the pressure signal output from the pressure transmitter 22 are transmitted to a DB converter 25 and an A / D converter 26 installed in a non-hazardous area.
Is transmitted to the notebook personal computer 27 via. In the notebook computer 27, the pressure change is stored in a memory and a printer 28.
And the presence or absence of leakage is determined from the magnitude of the pressure change.

The manometer 24 can visually check a liquid level change corresponding to the pressure difference between the pressure of the underground tank 2 and the atmospheric pressure detected by the ventilation pipe 7 at both ends of the transparent U-shaped pipe. is there. Therefore, the operator can monitor the pressure fluctuation of the underground tank 2 from the liquid level change of the manometer 24.

Here, the structure of the connection main body 11 provided in the middle of the vertical pipe 7b of the ventilation pipe 7 will be described. 2 to 4 show the connection body 11 in a closed state. The connection main body 11 has a space 31 therein as a joint storage portion, and the space 31 is usually closed by a lid 32. Lid 3
2 is detachably attached by a bolt 33. Then, it is separated from the connection main body 11 when performing a pressure test as described later. The space between the lid 32 and the lid mounting portion 11a of the connection body 11 is sealed by a packing 34.

The upper and lower parts of the connection body 11
Connection ports 35 and 36 to which the ventilation pipe 7 is connected are provided. The connection ports 35 and 36 are formed with an internal thread on the inner periphery to which the vertical pipe 7b of the ventilation pipe 7 is screwed. Further, a stopper groove 37 is provided on the inner wall of the space 31 of the connection main body 11.

Normally, since the inside of the connection main body 11 is empty, the vertical pipe 7 of the ventilation pipe 7 connected to the connection ports 35 and 36 is used.
b is communicated through the space 31 of the connection main body 11.
Therefore, the upper space of the underground tank 2 is maintained at the atmospheric pressure by the air introduced from the ventilation pipe 7.

Next, a procedure for performing a pressure test will be described. FIGS. 5 and 6 show the state of attachment of the pressure detecting joint when performing a pressure test. When the pressure test of the underground tank 2 is performed, first, the lid 32 of the connection main body 11 is removed, and the connection main body 1 is removed.
The pressure detecting joint 38 is inserted into the space 31. The pressure detecting joint 38 has a cylindrical joint body 40 inserted into a fitting portion 39 formed below the space 31 of the connection body 11.
And a pressure detecting tube 41 connected to the outer periphery of the joint body 40 from the side.

A vertical passage 41a is formed inside the pressure detecting tube 41 so as to communicate with the lower connection port 35, and extends horizontally in a direction perpendicular to the passage 41a. An extending passage 41b is formed.
Further, one end of the pressure detection tube 41 communicates with the passage 41b. The other end of the pressure detection tube 41 is connected to the connection tubes 23 and 24.

When the joint body 40 of the pressure detecting joint 38 is inserted into the space 31 of the connection body 11 and displaced downward,
The lower end portion of the joint body 40 fits into the fitting portion 39. Since the O-ring 42 is mounted on the outer periphery of the joint main body 40, the space between the joint body 40 and the inner wall of the fitting portion 39 is sealed. Thereby, the inside of the space 31 of the connection main body 11 is shut off by the joint main body 40, and the inside of the underground tank 2 and the ventilation pipe 7 are closed.

Thereafter, the stopper member 4 formed in a plate shape
3 is inserted into the stopper groove 37 of the connection body 11,
The upper end of the joint body 40 abuts against the stopper member 43 to restrict upward displacement, thereby preventing the joint body 40 from being detached from the space 31 of the connection body 11. Therefore, when the pressure in the underground tank 2 rises due to nitrogen gas filling as described later,
Although the joint body 40 is pressed upward by the pressure increase in the ventilation pipe 7, it comes into contact with the stopper member 43, thereby preventing the pressure detecting joint 38 from dropping off from the connection body 11 due to the nitrogen gas pressure.

As described above, since the connection main body 11 is provided at a position lower than the vent 7c and at a height of 1 m above the ground, the operator can use the pressure detection joint 38 without using a ladder or the like. It can be attached to the connection body 11.
Therefore, the operator can perform the preparation work for the pressure test by himself, and can perform the mounting work of the pressure detection joint 38 in a short time.

The nitrogen gas sealed in the nitrogen gas container 13 is reduced to a predetermined pressure or less by a pressure reducing valve 14 and then supplied to a fine pressurizing device 16 via a connection hose 15. The nitrogen gas adjusted to a predetermined pressure by the fine pressurizing device 16 is supplied to the detection joint 18 via the intake hose 17 and further supplied to the pressure detection joint 38 via the connection tube 20.

The passages 41a, 41a,
The nitrogen gas that has passed through 41b is supplied to the underground tank 2 through the ventilation pipe 7. Eventually, the upper space of the underground tank 2 is filled with nitrogen gas, and the pressure in the underground tank 2 rises above atmospheric pressure. As described above, the nitrogen gas can be supplied to the underground tank 2 via the pressure detecting joint 38 and the ventilation pipe 7, so that the gas supply port of the metering port 4 can be supplied with the lid 9a of the manhole 9 opened as in the related art. It is not necessary to connect the tube of the above, and it is not necessary to take care that a third person does not approach the manhole 9.

When the pressure in the underground tank 2 reaches the inspection pressure, the supply of nitrogen gas is stopped, and after waiting for a predetermined time (static time), the liquid level of the manometer 24 is maintained until a predetermined time elapses. The change is monitored, and the pressure change in the underground tank 2 is detected by the pressure transmitter 22.

FIGS. 7 and 8 show a second embodiment of the present invention. Here, a pipe joint 51 is provided in the middle of the vertical pipe 7 b of the ventilation pipe 7. This pipe joint 51 has connection ports 51a to 51c in three directions, and connection ports 51a in the vertical direction.
A connection port 51c is provided in a direction inclined upward by 45 ° with respect to 51b. On the inner periphery of each of the connection ports 51a to 51c, a female screw for screwing each pipe is provided.

A connection port 51 provided above the pipe joint 51
A cover 52 is screwed to a. A vertical pipe 7b communicating with the underground tank 2 is screwed into a connection port 51b provided below the pipe joint 51, and an inclined pipe communicating with the ventilation port 7c is connected to the connection port 51c inclined upward. 7d is screwed.

Normally, the connection port 51a of the pipe joint 51 is
2, the vertical pipe 7 b and the inclined pipe 7 d communicate with each other via the pipe joint 51. Therefore, the upper space of the underground tank 2 is maintained at the atmospheric pressure by the air introduced from the ventilation pipe 7.

Next, a procedure for performing a pressure test will be described. FIG. 9 is a longitudinal sectional view showing a state when a pressure test is performed. When testing the pressure of the underground tank 2, first,
The lid 52 is removed from the connection port 51a of the pipe joint 51, and the pipe joint 5
The obturator plug 53 made of a rubber bag is inserted into the inside of the device 1.
The plug 53 is inserted into the vertical pipe 7b from the connection port 51a of the pipe joint 51 while being crushed.

A gas supply tube 54 is connected to the plug 53. An end of the gas supply tube 54 is connected to a nitrogen gas cylinder (not shown) or the like. And
When the valve 55 disposed on the gas supply tube 54 is opened, nitrogen gas is supplied to the plug 53 and the plug 53 is closed.
Is pressurized. Since the stopper plug 53 is made of a rubber bag, as the nitrogen gas is supplied, the internal pressure increases and expands outward to closely adhere to the inner surface of the vertical pipe 7b. Thereby, the vertical tube 7b is expanded by the expanded plug 53.
Is closed, and the ventilation pipe 7 is shut off.

In this case, since the nitrogen gas cannot be supplied from the pipe joint 51 into the underground tank 2, the connection tube 20 is connected to the measuring port 4, and the underground tank 2 is connected to the measuring port 4.
Supply nitrogen gas inside. Thereby, when the pressure in the underground tank 2 reaches the inspection pressure, the supply of the nitrogen gas is stopped, and after waiting for a predetermined time (static time),
The change in the liquid level of the manometer 24 is monitored until a certain time elapses, and the change in the pressure in the underground tank 2 is detected by the pressure transmitter 22.

If the pressure change detected by the pressure transmitter 22 is equal to or greater than a specified value, it is determined that there is a leak in the underground tank 2 or the vent pipe 7, and the pressure transmitter 2
If the pressure change detected in Step 2 is equal to or less than the specified value, it is determined that there is no leakage. 10 and 11 show a third embodiment of the present invention.

Here, a pipe joint 61 is provided in the middle of the vertical pipe 7b of the ventilation pipe 7. This pipe joint 61 is
It has connection ports 61a to 61c in three directions, and the connection port 61c is provided in a direction inclined 45 ° upward with respect to the connection ports 61a and 61b in the vertical direction. Each connection port 61a-61c
Is provided with an internal thread for screwing each tube. A seat 62 for closing is provided inside the pipe joint 61 facing the connection port 61c.

A connection port 61 provided above the pipe joint 61
The vertical pipe 7b communicating with the vent 7c is screwed into a. A connection port 61 provided below the pipe joint 61
A vertical pipe 7b communicated with the underground tank 2 is screwed into b, and a lid 63 is screwed into a connection port 61c inclined upward.

Normally, the connection port 61c of the pipe joint 61 is
3, the lower vertical pipe 7 b and the upper vertical pipe 7 b communicate with each other via the pipe joint 61. Therefore, the upper space of the underground tank 2 is
It is maintained at atmospheric pressure by the air introduced from.

Next, a procedure for performing a pressure test will be described. FIG. 12 is a longitudinal sectional view showing a state when a pressure test is performed. When performing the pressure test of the underground tank 2, first, the lid 63 is removed from the connection port 61 c of the pipe joint 61, and a plug 64 made of a rubber bag is inserted into the pipe joint 61. The plug 64 is inserted into the pipe joint 61 while being crushed.
Is inserted into the vertical pipe 7b extending downward from the connection port 61c.

A gas supply tube 65 is connected to the plug 64, and an end of the gas supply tube 65 is connected to a nitrogen gas cylinder (not shown) or the like. And
When the valve 66 disposed in the gas supply tube 65 is opened, nitrogen gas is supplied to the plug 64 and the plug 64 is closed.
Is pressurized. Since the stopper plug 64 is made of a rubber bag, as the nitrogen gas is supplied, the internal pressure increases and expands outward to closely adhere to the inner surface of the vertical pipe 7b. Thereby, the vertical tube 7b is expanded by the expanded plug 64.
Is closed, and the ventilation pipe 7 is shut off.

In this case, the nitrogen gas cannot be supplied from the pipe joint 61 into the underground tank 2 as in the second embodiment described above. A nitrogen gas is supplied into the tank 2. Thereby, when the pressure in the underground tank 2 reaches the inspection pressure, the supply of the nitrogen gas is stopped, and after waiting for a predetermined time (stationary time), the liquid level of the manometer 24 is kept until a predetermined time elapses. The change is monitored, and the pressure change in the underground tank 2 is detected by the pressure transmitter 22.

When the pressure change detected by the pressure transmitter 22 is equal to or greater than a specified value, it is determined that there is a leak in the underground tank 2 or the ventilation pipe 7, and the pressure transmitter 2
If the pressure change detected in Step 2 is equal to or less than the specified value, it is determined that there is no leakage. FIG. 12 shows a modification of the third embodiment.

When the pressure test of the underground tank 2 is performed, first, the lid 63 is removed from the connection port 61c of the pipe joint 61, and a tapered valve body 67 is inserted into the seat portion 62. Then, the lid 63 is screwed into the connection port 61c with the coil spring 68 in contact with the valve body 67. As the lid 63 is screwed into the connection port 61c, the coil spring 68 is compressed, and the pressing force of the coil spring 68 increases. As a result, the valve body 67 comes into close contact with the seat portion 62 by the pressing force of the coil spring 68 and shuts off the flow path. Note that the spring force of the coil spring 68 is
The spring constant is determined so that a force greater than the pressure acting on the valve body 67 is applied to the valve body 67.

After the valve 67 shuts off the ventilation pipe 7 as described above, the connection tube 20 is connected to the measuring port 4 as described above, and nitrogen gas is supplied from the measuring port 4 into the underground tank 2. Thereby, when the pressure in the underground tank 2 reaches the inspection pressure, the supply of the nitrogen gas is stopped, and after waiting for a predetermined time (stationary time), the liquid level of the manometer 24 is kept until a predetermined time elapses. The change is monitored, and the pressure change in the underground tank 2 is detected by the pressure transmitter 22.

If the pressure change detected by the pressure transmitter 22 is equal to or greater than the specified value, it is determined that there is a leak in the underground tank 2 or the ventilation pipe 7, and the pressure transmitter 2
If the pressure change detected in Step 2 is equal to or less than the specified value, it is determined that there is no leakage. In the above embodiment, the underground tank 2 of the gas station was described as an example, but the invention is not limited to this.
For example, the present invention can be applied to a case where an underground tank installed in a factory or the like or an underground tank for a boiler such as a building is inspected.

[0051]

As described above, according to the first aspect of the present invention, since the connecting member for blocking the communication of the ventilation pipe is provided at a low position of the ventilation pipe connected to the tank, the work of sealing the ventilation pipe can be performed on the ground. As a result, the ladder is not required, so that the safety is improved, the work can be performed by one person, and the work efficiency is also improved. Therefore, the work of the periodic inspection is facilitated, and the leak inspection of the tank can be performed safely and in a short time.

According to the second aspect of the present invention, since the connection portion into which the joint can be inserted is provided in the middle of the ventilation pipe, the pressure inspection pipeline can be connected to the ventilation pipe. Since there is no need to connect to a different location, preparation work before performing the pressure test can be easily performed, and the pressure can be tested at the end of the tank storage site where the ventilation pipe is provided. further,
Since it is not necessary to use nerves to confirm the safety around the manhole provided with the measuring port as in the related art, work efficiency can be improved. Therefore, the work of the periodic inspection is facilitated, and the leak inspection of the tank can be performed safely and in a short time.

According to the third aspect of the present invention, it is possible to perform a sealing operation of the ventilation pipe for sealing the underground tank by blocking the other one of the connecting portions connected to the ventilation pipe by the blocking member on the ground, Leak inspection of underground tanks can be performed efficiently.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment of a tank pressure inspection device according to the present invention.

FIG. 2 is a front view showing a closed state of the connection main body.

FIG. 3 is a longitudinal sectional view of the connection main body taken along line AA in FIG. 2;

FIG. 4 is a cross-sectional view of the connection main body taken along line BB in FIG. 2;

FIG. 5 is a longitudinal sectional view showing a mounting state of a pressure detecting joint when performing a pressure test.

FIG. 6 is a cross-sectional view of the connection main body taken along line CC in FIG.

FIG. 7 is a view showing a ventilation pipe according to a second embodiment.

FIG. 8 is a longitudinal sectional view showing the inside of the pipe joint of the second embodiment.

FIG. 9 is a longitudinal sectional view for explaining a pressure test of the second embodiment.

FIG. 10 is a view showing a ventilation pipe according to a third embodiment.

FIG. 11 is a longitudinal sectional view showing the inside of the pipe joint of the third embodiment.

FIG. 12 is a longitudinal sectional view for explaining a pressure test of a third embodiment.

FIG. 13 is a longitudinal sectional view for explaining a pressure test of a modification of the third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Measuring machine 2 Underground tank 4 Measuring port 6 Injection pipe 7 Ventilation pipe 11 Connection body 12 Tank pressure inspection device 13 Nitrogen gas container 16 Fine pressurization device 18 Detection joint 22 Pressure transmitter 24 Manometer 31 Space 32 Lid 35, 36 Connection port 37 Groove for stopper 38 Pressure detecting joint 40 Joint body 41 Pressure detecting pipe 51, 61 Fitting 52, 63 Lid 53, 64 Closing plug 54, 65 Gas supply tube 55, 66 Valve 62 Seat 67 Valve body 68 Coil spring

Claims (3)

[Claims] 1. A tank for detecting the presence or absence of leakage by detecting pressure fluctuations in an underground tank having a vent pipe open at one end and connected to an underground tank and having the other end open to the atmosphere by a pressure detecting device. In the pressure testing device, in the middle of the ventilation pipe, and at a low position where work on the ground is possible,
A tank pressure test, wherein three sides are opened, two of which are connected to the vent pipe, and the other one is provided with a connection part which can be closed by a blocking member for airtightly blocking the underground tank. apparatus. 2. A tank for detecting the presence or absence of a leak by detecting a pressure fluctuation in an underground tank having a vent pipe open at one end to the underground tank and open at the other end to an altitude by a pressure detecting device. In the pressure testing device, in the middle of the ventilation pipe, and at a low position where work on the ground is possible,
A tank pressure inspection device, characterized in that three sides are open, two of which are connected to the vent pipe, and the other one is provided with a connection portion into which a joint for connecting the pressure detection device can be inserted. 3. A vent pipe, one end of which is connected to an underground tank and the other end of which is extended to a high place, is open at a low position on the middle of a vent pipe which is open to the atmosphere and can be worked on the ground. A method for inspecting tank pressure of an underground tank having a connection portion which is connected and the other one of which is capable of being closed by a blocking member for hermetically closing the underground tank, wherein the underground tank is hermetically sealed. Shutting off from the atmosphere by a connection portion, pressurizing or depressurizing the underground tank, detecting pressure fluctuations in the underground tank with a pressure detecting device, and determining whether there is a leak based on the detection result. A tank pressure inspection method comprising the steps of: