Helium hood method long distance pipeline leak detection and positioning device and detection method

Abstract

The invention belongs to nondestructive testing technology, and specifically relates to a "helium hood method" long-distance pipeline leakage point investigation and positioning device and an investigation method. The device comprises a flow supply and control plate A arranged at the upstream of the detected pipeline and a helium hood and a helium application plate B connected to the detected pipeline; the helium hood and the helium application plate B are composed of a helium hood, a helium concentration detector, a pressure reducing valve, a helium supply switch, a helium pressure regulating tank, a helium cylinder, and a pressure gauge; the method purges the pipeline to remove residual working gas, installs the helium hood on the inspected pipe section after filling helium, and performs leakage inspection, takes the flange positions at both ends of the pipeline inlet and outlet as the detection interface, applies a long-distance helium hood on the process pipeline, and conducts pipeline leakage investigation and positioning in stages to determine the number and position of buried pipeline leakage points, which is safe and reliable, and can be implemented in high-risk places such as flammable and explosive places and high temperatures.

Description

Technical Field

[0001] The invention belongs to nondestructive testing technology, and specifically relates to a pipeline leakage detection and positioning device and a detection method. Background Art

[0002] Although there are many pipeline sealing verification methods in the field of non-destructive testing, there are fewer technical methods for locating pipeline leaks, especially for locating leak defects in outdoor long-distance pipelines. Therefore, it is necessary to develop a new method suitable for locating leaks in long-distance single-wall pipes.

[0003] The oil and gas transportation industry mainly pre-installs leak detection devices during the pipeline installation stage and needs to conduct leak detection work regularly through weak current. However, this method has low leak point sensitivity. In addition, since it needs to be powered on, it is not suitable for transportation pipelines of flammable and explosive media such as hydrogen and chlorine. The helium leak detection sniffing gun method is also used for external positioning of pipeline leaks, but the point-by-point inspection feature is not suitable for long-distance (more than 50 meters) outdoor pipeline leak detection. Therefore, developing an efficient, safe and reliable long-distance pipeline leak inspection and positioning technology is one of the main directions of method research. Summary of the invention

[0004] The purpose of the present invention is to provide a long-distance pipeline leak detection and positioning device and detection method using a helium hood method, so as to ensure that the positions of multiple leak points in the pipeline can be accurately located, thereby clarifying the direction and reducing the workload for subsequent internal pipe defect treatment work.

[0005] The technical solution of the present invention is as follows:

[0006] A long-distance pipeline leak detection and positioning device using a helium hood method comprises a flow supply and control block A disposed upstream of the pipeline to be detected and a helium hood and helium application block B connected to the pipeline to be detected;

[0007] The flow supply and control panel A comprises a compressed air source, an air pressure regulating tank, a flow regulating valve, an air switch, a bypass switch, a flow sensor, a dew point thermometer, a temperature sensor, and a reference leak hole reserved hole; wherein the compressed air source is connected to the air pressure regulating tank, the gas outlet of the air pressure regulating tank is connected to the pipeline through a hose joint, the flow regulating valve, the air switch, the flow sensor, the dew point thermometer, the temperature sensor, the reference leak hole reserved hole and the upstream connecting flange are sequentially installed on the outlet pipeline of the air pressure regulating tank, and the bypass pipeline and the bypass switch are connected in parallel at the air inlet end of the air switch and the outlet end of the flow sensor;

[0008] The helium hood and helium application plate B are composed of a helium hood, a helium concentration detector, a pressure reducing valve, a helium supply switch, a helium pressure regulating tank, and a helium cylinder; wherein the detected pipeline is connected to a helium pipeline, a helium hood is provided at the pipeline interface, the helium pipeline includes a helium cylinder and a helium pressure regulating tank providing a gas source, and a helium supply switch and a pressure reducing valve are sequentially installed on the helium pipeline along the direction of helium flow.

[0009] The helium hood is a retractable rubber airbag, and the connection between the helium hood and the pipeline is sealed with a rubber ring.

[0010] It includes a downstream measurement and data acquisition and analysis module C, which includes a downstream connecting flange arranged on the detected pipeline, a suction gun installed through the downstream connecting flange, a helium mass spectrometer, a digital / current converter, and an industrial computer; the helium mass spectrometer and the suction gun are used to detect the concentration change of helium in the inner tube; the industrial computer is used to analyze all data and finally obtain the precise position of the leakage point.

[0011] The industrial computer will calculate the distance between the leak point and the nozzle of the suction gun based on the time t between the flow change and the concentration change of the helium mass spectrometer leak detector, the measured air temperature T, the pipeline cross-sectional area S, the pipeline flow velocity V2, and the correction factor k.

[0012]

[0013] All connecting pipes use hard pressure hoses.

[0014] The helium mask method is a long-distance pipeline leak detection method, which uses the "helium mask method" long-distance pipeline leak detection and positioning device to perform the following steps:

[0015] Step 1: Install the Parts

[0016] Connect the upstream connection flange and downstream connection flange in the device to the pipeline to be tested; connect the digital / current converter, industrial computer and helium mass spectrometer leak detector to power supply respectively, and install the standard leak hole at the reserved hole position of the reference leak point;

[0017] Step 2: Pipeline Purging

[0018] Open the compressed air source, close the air switch, open the flow control valve and bypass switch, purge the pipeline, and remove residual working gas.

[0019] Step 3: System Accuracy Check

[0020] After the purge is completed, close the bypass switch and open the air switch, adjust the flow control valve to V1, and after the helium signal is monitored, adjust the flow control valve to V2, and record the time from when the flow changes to when the helium concentration curve on the helium mass spectrometer leak detector changes suddenly. The industrial computer calculates the distance between the reference leak point and the suction gun port based on the time t between the flow change and the concentration change of the helium mass spectrometer leak detector, the air temperature T, the pipeline cross-sectional area S, and the pipeline flow rate V2. Compare the calculated result with the actual distance to verify the positioning accuracy of the device. If the accuracy does not meet the requirements, remove the reference leak hole, otherwise check the equipment status and proceed to step 4;

[0021] Step 4: Fill the helium mask with helium

[0022] Install the helium hood on the pipe section to be inspected, seal the two ends with rubber rings, open the helium cylinder, turn on the helium supply switch, fill helium into the helium pressure regulator and helium hood, adjust the pressure reducing valve to stabilize the pressure in the helium pressure regulator and helium hood, and then close the helium cylinder;

[0023] Step 5: Initial inspection

[0024] After the helium hood is filled with helium, observe whether the signal curve of the leak detector has an upward trend. If the curve has an obvious upward trend, it means there is a leak. If not, end the process.

[0025] Step 6: Positioning

[0026] After confirming the existence of a leak, the flow in the pipe is stably supplied until the curve is stable. The flow sensor is adjusted to adjust the air flow in the inner pipe to V1. If a leak exists, the helium concentration curve of the helium mass spectrometer leak detector and the industrial computer will show obvious mutations. The number of mutations represents the number of leaks. The industrial computer will determine the distance between the leak and the suction port of the helium mass spectrometer leak detector based on the time t between the flow change and the concentration change of the helium mass spectrometer leak detector, the air temperature T, the pipe cross-sectional area S, the pipe flow velocity V2, and the correction coefficient k. The formula is as follows

[0027]

[0028] The positioning accuracy in step 3 is 0-2 meters.

[0029] Correction factor

[0030] Adjust the flow sensor to adjust the air flow in the inner tube to V1, which ranges from 0.3 to 0.8 m / s.

[0031] The observation time in step 5 is 0.5-1h.

[0032] The remarkable effects of the present invention are as follows: the long-distance pipeline leak detection and positioning device based on the "helium hood method" uses the flange positions at both ends of the pipeline inlet and outlet as the detection interface, applies a long-distance helium hood to the process pipeline, and conducts pipeline leak detection and positioning in stages to determine the number and position of buried pipeline leaks. When the helium environment outside the pipeline and the size of the leak remain unchanged, the change in the flow rate in the pipe will cause the helium mass spectrometer leak detector to change accordingly. The device of the present invention uses this principle to detect and calculate the leak distance, the mass spectrometer suction gun position and the number of leaks.

[0033] Based on the principle of correlation between leak rate and velocity, a detection device is provided that can segmentally check and locate leaks in long-distance single-layer pipelines, and can detect whether a pipe section is leaking and the number of leaks.

[0034] Based on the principle of correlation between the leakage rate and velocity of the leak hole, a positioning device is provided which can detect and locate the leakage point of a long-distance single-layer pipeline in sections, and can detect the distance between the specific leakage point and the position of the suction gun port;

[0035] The helium hood leak detection technology is used. The helium hood can be flexibly installed to monitor the pipeline in sections.

[0036] The length of the helium hood can be freely controlled. Compared with the common helium mass spectrometer sniffing method, the detection efficiency of the long pipe leak location is greatly improved. It is especially suitable for leak location work in outdoor long-distance transportation pipelines. When using it, only the termination work needs to be carried out at both ends of the pipeline to be inspected, which can protect the structure of the pipeline to be inspected from being damaged to the greatest extent.

[0037] The leak point locating device uses helium and compressed air as the working medium. It is safe and reliable and can be used for leak detection in high-risk places such as flammable, explosive, and high-temperature places. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic diagram of a long-distance pipeline leak detection and positioning device based on the "helium mask method";

[0039] In the figure: 1. Compressed air source; 2. Air pressure regulating tank; 3. Flow control valve; 4. Air switch; 5. Bypass switch; 6. Flow sensor; 7. Dew point thermometer; 8. Temperature sensor; 9. Reference leak point; 10. Upstream connecting flange; 11. Detected pipeline; 12. Helium hood; 13. Helium concentration detector; 14. Pressure reducing valve; 15. Helium supply switch; 16. Helium pressure regulating tank; 17. Helium cylinder; 18. Downstream connecting flange; 19. Suction gun; 20. Helium mass spectrometer; 21. Digital / current converter; 22. Industrial computer. DETAILED DESCRIPTION

[0040] The present invention will be further described below through the accompanying drawings and specific implementation methods.

[0041] like Figure 1 As shown, the long-distance pipeline leak detection and positioning device based on the "helium hood method" includes an upstream flow supply and control block A, a helium hood and helium application block B, and a downstream measurement and data acquisition and analysis block C.

[0042] Among them, the upstream flow supply and control block A is composed of a compressed air source 1, an air pressure regulating tank 2, a flow regulating valve 3, an air switch 4, a bypass switch 5, a flow sensor 6, a dew point thermometer 7, a temperature sensor 8, a reference leakage point 9, and an upstream connecting flange 10 (as shown in block A in the figure).

[0043] The compressed air source 1 is connected to the air pressure regulating tank 2, the gas outlet of the air pressure regulating tank 2 is connected to the pipeline through a hose joint, and the flow regulating valve 3, air switch 4, flow sensor 6, dew point thermometer 7, temperature sensor 8, reference leakage point 9 and upstream connection flange 10 are installed in sequence on the outlet pipeline of the air pressure regulating tank 2. In addition, a bypass pipeline and a bypass switch 5 are connected in parallel at the air inlet end of the air switch 4 and the outlet end of the flow sensor 6.

[0044] The pipes of upstream flow supply and control block A use hard pressure hoses.

[0045] The upstream flow supply and control module A is used to provide air of various flow rates. Among them, the air pressure regulating tank 2 introduces gas from the compressed air source 1 and provides a stable pressure source; the air switch 4 and the flow sensor 6 are used to control the internal pipe input flow; the bypass switch 5 is used in the pipeline purge mode to purge the residual medium in the pipe; the temperature sensor 8 and the dew point temperature sensor 7 are used to collect temperature and humidity.

[0046] The helium hood and helium application block B is composed of a helium hood 12 , a helium concentration detector 13 , a pressure reducing valve 14 , a helium supply switch 15 , a helium pressure regulating tank 16 , and a helium cylinder 17 .

[0047] The detected pipeline 11 is the pipeline leading out from the upstream flow supply and control plate A, which is connected to the helium pipeline through a tee, and a helium hood 12 is installed at the pipeline interface. The helium pipeline includes a helium bottle 17 and a helium pressure-stabilizing tank 16 for providing a gas source. A helium supply switch 15 and a pressure reducing valve 14 are installed in sequence on the helium pipeline along the direction of helium flow.

[0048] The helium hood and the helium application plate are used to provide a stable helium environment to the "outside of the tested pipe section". The helium hood 12 uses a pressure-bearing and retractable rubber airbag, and the connection with the pipeline is sealed with a rubber ring. The pressure reducing valve 14 is used to control the pressure in the helium hood.

[0049] A helium concentration detector 13 is installed on the helium hood 12 to detect the stability of the helium concentration in the helium hood.

[0050] The connecting pipes of the helium hood and the helium application block B are made of hard pressure hoses.

[0051] The helium pressure stabilizing tank 16 is equipped with a hose terminal joint to provide sufficient stable space for the introduced helium and ensure the stability of the pressure reducing valve inlet pressure.

[0052] The downstream measurement and data acquisition and analysis module C is composed of a downstream connecting flange 18 installed on the detected pipeline 11, a suction gun 19 installed through the downstream connecting flange 18, a helium mass spectrometer 20, a digital / current converter 21, and an industrial computer 22.

[0053] The downstream measurement and data acquisition and analysis module C is used to monitor the concentration of helium at the downstream outlet of the pipeline, and obtain the precise location of the leak point by collecting temperature and humidity data from the module A and analyzing the flow value. Among them, the helium mass spectrometer 20 and the suction gun 19 are used to detect the concentration change of helium in the inner tube, and the transmission cable is used to summarize the data of the flow supply and control module A.

[0054] The industrial computer 22 is used to analyze all the data and finally obtain the precise location of the leakage point.

[0055] Specifically, the industrial computer will determine the distance between the leak point and the muzzle of the suction gun 19 according to the time t between the flow change moment and the concentration change moment of the helium mass spectrometer leak detector, the measured air temperature T, the pipeline cross-sectional area S, the pipeline flow velocity V2, and the correction coefficient k. The formula is as follows.

[0056]

[0057] When using the above system to check for leaks, the specific steps are as follows:

[0058] Step 1: Install the Parts

[0059] The device is connected to the pipeline 11 to be inspected through the upstream connecting flange 10 and the downstream connecting flange 18; the industrial computer 22 and the helium mass spectrometer 20 are powered on respectively, and a suitable standard leak hole is selected and installed at the reference leak point 9;

[0060] Step 2: Pipeline Purging

[0061] Open the compressed air source 1, close the air switch 4, open the flow regulating valve 3 and the bypass switch 5, purge the pipeline, and remove the residual working gas.

[0062] Step 3: System Accuracy Check

[0063] After the purge is completed, close the bypass switch 5 and open the air switch 4, adjust the flow control valve 3 to adjust the flow to V1, and after the helium signal is monitored, adjust the flow control valve 3 to adjust the flow to V2, and record the time from the flow change to the sudden change of the helium concentration curve on the helium mass spectrometer 20. The industrial computer calculates the distance between the reference leak point 9 and the suction gun 19 according to the time t between the flow change moment and the concentration change moment of the helium mass spectrometer leak detector, the air temperature T, the pipeline cross-sectional area S, and the pipeline flow rate V2 parameters. Compare the calculated result with the actual distance to verify the positioning accuracy of the device. If the accuracy is within the acceptable range (determined according to user opinions, the general deviation is less than 2 meters), remove the reference leak hole, otherwise check the equipment status and proceed to step 4.

[0064] Step 4: Fill the helium mask with helium

[0065] Install the helium hood 12 on the inspected pipe section 11 (at this time the helium hood is in a fully deflated state), seal the two ends with rubber rings, open the helium cylinder 17, turn on the helium supply switch 15, fill the helium pressure regulating tank 16 and the helium hood 12 with helium, adjust the pressure reducing valve to stabilize the pressure in the helium pressure regulating tank 16 and the helium hood, and then close the helium cylinder 17.

[0066] Step 5: Initial inspection

[0067] After the helium hood 12 is filled with helium, observe for a period of time (0.5-1h) whether the signal curve of the helium mass spectrometer 20 has an upward trend. If the curve has an obvious upward trend, it means that there is a leak. If not, the process is terminated.

[0068] Step 6: Positioning

[0069] After confirming the existence of a leak, the flow in the pipe is stably supplied until the curve is stable, and the flow sensor 6 is adjusted to adjust the air flow in the inner pipe to V1. If there is a leak, the helium concentration curve on the helium mass spectrometer 20 and the industrial computer 22 will show obvious mutations. The number of mutations represents the number of leaks. The industrial computer will calculate the distance between the leak and the suction gun 19 according to the time t between the flow change moment and the concentration change moment of the helium mass spectrometer leak detector, the air temperature T, the pipe cross-sectional area S, the pipe flow velocity V2, the correction coefficient k and other parameters. The simple calculation formula is as follows.

[0070]

[0071] The values ​​of V1 and V2 are determined according to the pipe diameter. Generally, for pipes with a diameter of less than 20 cm, V1 is 0.5 m / s and V2 is 1 m / s.

Claims

1. Helium hood method long distance pipeline leak detection and positioning device, characterized by: It comprises a flow supply and control plate A arranged upstream of the detected pipeline (11) and a helium hood and helium application plate B connected to the detected pipeline (11); The flow supply and control module A comprises a compressed air source (1), an air pressure regulating tank (2), a flow regulating valve (3), an air switch (4), a bypass switch (5), a flow sensor (6), a dew point thermometer (7), a temperature sensor (8), and a reference leak point (9); wherein the compressed air source (1) is connected to the air pressure regulating tank (2), the gas outlet of the air pressure regulating tank (2) is connected to the pipeline via a hose joint, the flow regulating valve (3), the air switch (4), the flow sensor (6), the dew point thermometer (7), the temperature sensor (8), the reference leak point (9) and the upstream connecting flange (10) are sequentially installed on the outlet pipeline of the air pressure regulating tank (2), and the bypass pipeline and the bypass switch (5) are connected in parallel at the air inlet end of the air switch (4) and the outlet end of the flow sensor (6); The helium hood and helium application plate B are composed of a helium hood (12), a helium concentration detector (13), a pressure reducing valve (14), a helium supply switch (15), a helium pressure regulating tank (16), and a helium cylinder (17); wherein the detected pipeline (11) is connected to a helium pipeline, a helium hood (12) is provided at the pipeline interface, the helium pipeline includes a helium cylinder (17) and a helium pressure regulating tank (16) for providing a gas source, and a helium supply switch (15) and a pressure reducing valve (14) are installed in sequence on the helium pipeline along the direction of helium flow.

2. The long-distance pipeline leak detection and positioning device using the helium hood method as claimed in claim 1 is characterized by: The helium hood (12) is a retractable rubber airbag, and the connection between the helium hood and the pipeline is sealed with a rubber ring.

3. The long-distance pipeline leak detection and positioning device using the helium hood method as claimed in claim 1 is characterized by: The invention comprises a downstream measurement and data acquisition and analysis module C, which comprises a downstream connection flange (18) arranged on the detected pipeline (11), a suction gun (19) installed through the downstream connection flange (18), a helium mass spectrometer (20), a digital / current converter (21), and an industrial computer (22); the helium mass spectrometer (20) and the mass spectrometer suction gun (19) are used to detect the concentration change of helium in the inner tube; the industrial computer (22) is used to analyze all the data and finally obtain the precise position of the leakage point.

4. The long-distance pipeline leak detection and positioning device using the helium hood method as claimed in claim 3 is characterized by: The industrial computer will calculate the distance between the leak point and the muzzle of the suction gun (19) based on the time t between the flow change and the concentration change of the helium mass spectrometer leak detector, the measured air temperature T, the pipeline cross-sectional area S, the pipeline flow velocity V2, and the correction factor k.

5. The long-distance pipeline leak detection and positioning device using the helium hood method according to any one of claims 1 to 4, characterized in that: All connecting pipes use hard pressure hoses.

6. The helium mask method for long-distance pipeline leak detection is characterized by: The device for detecting and locating long-distance pipeline leaks by the helium hood method as claimed in claim 3 or 4 is used to perform the following steps: Step 1: Install the Parts The upstream connecting flange (10) and the downstream connecting flange (18) in the device are connected to the pipeline (11) to be tested; the digital / current converter (21), the industrial computer (22), and the helium mass spectrometer (20) are respectively powered, and the standard leak hole is installed at the reference leak point (9); Step 2: Pipeline Purging Open the compressed air source (1), close the air switch (4), open the flow control valve (3) and the bypass switch (5), purge the pipeline, and remove the residual working gas; Step 3: System Accuracy Check After the purging is completed, the bypass switch (5) is closed and the air switch (4) is opened. The flow regulating valve (3) is adjusted to adjust the flow rate to V1. After the helium signal is monitored, the flow regulating valve (3) is adjusted to adjust the flow rate to V2. The time when the flow rate changes to the time when the helium concentration curve on the helium mass spectrometer (20) changes suddenly is recorded. The industrial computer (22) calculates the distance between the reference leak point (9) and the suction gun (19) according to the time t between the flow rate change moment and the concentration change moment of the helium mass spectrometer leak detector, the air temperature T, the pipeline cross-sectional area S, and the pipeline flow rate V2. The calculated result is compared with the actual distance to verify the positioning accuracy of the device. If the accuracy does not meet the requirements, the reference leak hole is removed. Otherwise, the equipment condition is checked and step 4 is performed. Step 4: Fill the helium mask with helium Install the helium hood (12) on the pipeline (11) to be tested, seal the two ends with rubber rings, open the helium cylinder (17), turn on the helium supply switch (15), fill helium into the helium pressure regulating tank (16) and the helium hood (12), adjust the pressure reducing valve to stabilize the pressure in the helium pressure regulating tank (16) and the helium hood, and then close the helium cylinder (17); Step 5: Initial inspection After the helium hood (12) is filled with helium, observe whether the signal curve of the helium mass spectrometer (20) has an upward trend. If the curve has an obvious upward trend, it indicates that there is a leak. If not, the process is terminated; Step 6: Positioning After the presence of a leak is determined, the flow in the pipe is stably supplied until the curve is stable, and the flow sensor (6) is adjusted to adjust the air flow in the inner pipe to V1. If a leak exists, the helium concentration curve on the helium mass spectrometer (20) and the industrial computer (22) will show obvious mutations, and the number of mutations represents the number of leaks. The industrial computer will determine the distance between the leak and the helium mass spectrometer leak detector suction gun (19) based on the time t between the flow change moment and the helium mass spectrometer leak detector concentration change moment, the air temperature T, the pipe cross-sectional area S, the pipe flow velocity V2, and the correction coefficient k. The formula is as follows 7. The long-distance pipeline leak detection method using the helium hood method as claimed in claim 6 is characterized by: The positioning accuracy in step 3 is 0-2 meters.

8. The long-distance pipeline leak detection method using the helium hood method as claimed in claim 6, characterized in that: The flow sensor (6) is adjusted to adjust the air flow rate in the inner tube to V1, which ranges from 0.3 to 0.8 m / s.

9. The long-distance pipeline leak detection method using the helium hood method as claimed in claim 6, characterized in that: The observation time in step 5 is 0.5-1h.

Images