Multi-branch rapid detection method for helium test

Abstract

The invention relates to a multi-branch rapid detection method for a helium test, which comprises the following steps: a plurality of detection personnel respectively carry a suction gun to scan a welding seam, control an automatic multi-path switching valve to sequentially rotate, synchronously read a voltage value of a channel corresponding to the suction gun, and then convert the voltage value into a leak rate value; recording and outputting the currently read leak rate value and the channel number corresponding to the leak rate value; according to the obtained leak rate values of the branch suction guns and the corresponding channel number information, leak rate curves of different colors are drawn, and the leak rate values of the multiple branch guns are displayed in real time; when the leakage rate value of any path exceeds the preset target leakage rate, the system gives out a buzzing alarm and displays the number of the channel generating the leakage rate, so that leakage point detection and leakage rate recording of field staff are facilitated, and the situation that after a helium detector detects a leakage signal, multiple groups of branch suction guns need to reverse to determine the position of the leakage point can be avoided. Therefore, the detection efficiency of the multi-branch suction gun in the helium detection process is improved, the workload of field detection is reduced, and the cost is reduced.

Description

Technical Field

[0001] This invention relates to the technical field of weld leak detection, specifically a multi-branch rapid detection method for helium testing, and more particularly to a rapid detection method for welds in a confined space using helium as a tracer gas and an aspiration method. Background Technology

[0002] In current leak detection processes for LNG ships and storage tanks, the multi-path suction gun method for helium gas detection and surface scanning of weld seams is a crucial method for leak detection in membrane-type containment systems of LNG ships and storage tanks. The multi-path suction gun method involves injecting a certain concentration of helium gas into the main shielded space, creating a slight positive pressure state within the confined space. A specially designed gas detection suction gun connected to a helium detector then scans the weld seam surface. An alarm is triggered when the leakage rate of helium molecules detected by the detector along the scanning path exceeds the standard, indicating the presence of a leak of a certain size within the scanning path.

[0003] In practical applications, on-site inspection personnel manually scan the weld seam using a suction gun, significantly increasing the workload. Subsequently, to improve efficiency, the single-channel suction gun, which could only scan one weld seam, was modified into a three-channel or branchless suction gun for on-site use. Multiple inspectors can each carry one suction gun for scanning. When the helium detector alarms, the inspector simultaneously reverses the suction gun in the opposite direction until the leak detector alarms again, thus locating the leak in that detection channel. However, due to the typically wide detection range and long suction gun length, the alarm feedback time of the leak detector is long, making it time-consuming to locate the leak again and reducing inspection efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide an improved multi-branch rapid detection method for helium testing. Through the improvement of the method, the location of leaks can be detected in a timely and accurate manner, the detection efficiency of multi-branch suction guns in the helium testing process can be improved, and the workload of on-site testing can be reduced.

[0005] To achieve the above objectives, the technical solution of the present invention is: a multi-branch rapid detection method for helium gas testing, characterized in that the detection method steps are as follows: a) Preparation: Connect each of the multi-branch suction guns to the inlet of the automatic multi-way switching valve through a pipeline, and connect the common outlet of the automatic multi-way switching valve to a helium leak detector through a pipeline; b) Connect the coaxial cable interface of the helium leak detector to the multi-branch data acquisition card through a coaxial cable, and connect the valve controller to the automatic multi-way switching valve; connect the multi-branch data acquisition card to a PC; c) Multiple testing personnel divide... Do not carry a single suction gun to scan the weld. Control the automatic multi-channel switching valve to rotate sequentially, and simultaneously read the voltage value of the corresponding channel of the suction gun. Then convert it into a leak rate value, record and output the currently read leak rate value and its corresponding channel number; d. Plot the leak rate values ​​of the branch suction guns and the corresponding channel number information obtained in step c into leak rate curves of different colors, and display the leak rate values ​​of multiple guns in real time; e. When the leak rate value of any channel exceeds the preset target leak rate, the system will sound an alarm and display the channel number that caused the leak, which will facilitate the on-site personnel to detect leaks and record leak rates.

[0006] Preferably, in step c, to avoid missed detections, the automatic multi-way switching valve switching time and the total time of one cycle should be set to be less than the time required for the operator to scan a leak point with a handheld suction gun.

[0007] Furthermore, if the operator's scanning speed is v (mm / s), and assuming the smallest leak size scanned is D mm, The time required to scan the leak point: ; Data acquisition time for each channel: ; The total period of a cyclic system: ; For any channel, the maximum blind time is: ; When the time taken to scan a leak point is greater than the blind zone time, the leak point signal will definitely fall within the acquisition time of a certain channel, thus avoiding missed detection.

[0008] Furthermore, in step c, before the inspectors scan the weld, the switching time of the automatic multi-channel switching valve is set, and an alarm value for the leak rate is set. In step c, during the actual inspection process, the time to scan a leak point is twice the time of the blind zone. Under these circumstances, there is a high degree of overlap between the scanning paths, and no area will be missed during the scanning.

[0009] Furthermore, in step e, when scanning the weld, the automatic multiplexer valve automatically cycles according to the set switching time; when the leak rate value of any channel exceeds the preset target leak rate, the automatic multiplexer valve stops cycling, then locks on the currently existing leak rate signal channel, and performs continuous measurement; when the leak rate value falls back below the target leak rate value, the automatic multiplexer valve resumes automatic cycling.

[0010] Compared with the prior art, the technical solution of the present invention not only improves the overall technical solution, but also includes many improvements in details. Specifically, it has the following beneficial effects: 1. The improved solution described in this invention involves multiple inspectors each carrying a suction gun to scan the weld seam. An automatic multi-channel switching valve is controlled to rotate sequentially, synchronously reading the voltage value of the corresponding channel of each suction gun. This voltage value is then converted into a leak rate value. The currently read leak rate value and its corresponding channel number are recorded and output. The obtained leak rate values ​​of the branch suction guns and their corresponding channel numbers are plotted as leak rate curves of different colors, displaying the leak rate values ​​of multiple suction guns in real time. When the leak rate value of any channel exceeds the preset target leak rate, the system issues a buzzer alarm and displays the channel number that caused the leak. This facilitates leak detection and leak rate recording by on-site personnel, avoiding the need for multiple suction guns to backtrack to determine the leak location after the helium detector detects a leak signal. This improves the detection efficiency of multiple suction guns during helium testing, reduces the workload of on-site testing, and lowers costs. 2. In the technical solution of the present invention, in order to avoid missed detection, the switching time of the automatic multi-way switching valve and the total time of one cycle should be less than the time required for the operator to sweep a leak point with a handheld suction gun. This can avoid missed detection and improve efficiency. 3. In the structure of this invention, when scanning the weld, the automatic multi-channel switching valve automatically cycles according to the set switching time; when the leakage rate value of any channel exceeds the preset target leakage rate, the automatic multi-channel switching valve stops cycling, then locks on the currently existing leakage rate signal channel, and performs continuous measurement; when the leakage rate value falls back below the target leakage rate value, the automatic multi-channel switching valve resumes automatic cycling, which can accurately locate the leak and avoid losing the signal again due to the automatic switching valve switching after a leak occurs, thus achieving the purpose of precision and efficiency. 4. The invention is simple to use and easy to operate, while also providing good detection results, saving manpower, and facilitating promotion and utilization. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of the present invention.

[0012] Figure label: 1 Automatic multi-channel switching valve, 2 Valve controller, 3 Multi-channel data acquisition card, 4 PC, 5 Data acquisition software, 6 Cables and connectors, 7 Multi-channel suction gun, 8 Helium leak detector, 9 Helium cylinder group. Detailed Implementation

[0013] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] This invention provides a rapid multi-channel detection method for helium testing, which differs from existing technologies in that the detection method involves the following steps: a) Preparation: Connect each of the multi-channel suction guns 7 to the inlet of the automatic multi-channel switching valve 1 via a pipeline, and connect the common outlet of the automatic multi-channel switching valve to the helium leak detector 8 via a pipeline; b) Connect the coaxial cable interface of the helium leak detector to the multi-channel data acquisition card 3 via a coaxial cable, connect the valve controller 2 to the automatic multi-channel switching valve, and connect the multi-channel data acquisition card 3 to the PC 4; c) Have multiple inspectors, each carrying one suction gun, scan the weld seam and control the automatic multi-channel switching valve. The door rotates sequentially, synchronously reading the voltage value of the corresponding channel of each suction gun, then converting it into a leakage rate value. The currently read leakage rate value and its corresponding channel number are recorded and output; d) The leakage rate values ​​of the branch suction guns and the corresponding channel number information obtained in step c are plotted into leakage rate curves of different colors, and the leakage rate values ​​of multiple guns are displayed in real time; e) When the leakage rate value of any channel exceeds the preset target leakage rate, the system issues a buzzer alarm and displays the channel number that caused the leakage, facilitating leak detection and leakage rate recording by on-site personnel.

[0015] During implementation, when the leak rate value of any channel exceeds the preset target leak rate, the system will issue a buzzer alarm and display the channel number that caused the leak. This method can avoid the need for multiple branch suction guns to backtrack to determine the leak location after the helium detector detects a leak signal, thereby improving the detection efficiency of multiple branch suction guns in the helium detection process, reducing the workload of on-site detection, and reducing costs.

[0016] Example 1 In this embodiment, see Figure 1This paper describes a rapid multi-channel detection method for helium testing. The steps of the method are as follows: a) Preparation: Connect each of the multi-channel suction guns to the inlet of an automatic multi-channel switching valve through a pipeline, and connect the common outlet of the automatic multi-channel switching valve to a helium leak detector through a pipeline; b) Connect the coaxial cable interface of the helium leak detector to the multi-channel data acquisition card through a coaxial cable, and connect the valve controller to the automatic multi-channel switching valve; connect the multi-channel data acquisition card to a PC; c) Have multiple testing personnel, each carrying one suction gun, perform a scan. For weld seams, the automatic multi-channel switching valve rotates sequentially, synchronously reading the voltage value of the corresponding channel of each suction gun, then converting it into a leak rate value. The currently read leak rate value and its corresponding channel number are recorded and output; d) The leak rate values ​​of the branch suction guns and the corresponding channel number information obtained in step c are plotted into leak rate curves of different colors, and the leak rate values ​​of multiple branch guns are displayed in real time; e) When the leak rate value of any channel exceeds the preset target leak rate, the system issues a buzzer alarm and displays the channel number that caused the leak, facilitating leak detection and leak rate recording by on-site personnel.

[0017] Specifically, in step c, to avoid missed detections, the switching time of the automatic multi-way switching valve and the total time of one cycle should be less than the time required for the operator to scan a leak point with a handheld suction gun.

[0018] Furthermore, if the operator's scanning speed is v (mm / s), and assuming the smallest leak size scanned is D mm, The time required to scan the leak point: ; Data acquisition time for each channel: ; The total period of a cyclic system: ; For any channel, the maximum blind time is: ; When the time taken to scan a leak point is greater than the blind zone time, the leak point signal will definitely fall within the acquisition time of a certain channel, thus avoiding missed detection.

[0019] In step c, before the inspectors scan the weld, the switching time of the automatic multi-channel switching valve is set, and an alarm value for the leak rate is set. In step c, during the actual inspection process, the time to scan a leak point is twice the time for the blind zone. Under these circumstances, there is a high degree of overlap between the scanning paths, and no area will be missed during the scanning.

[0020] In step e, during weld inspection, the automatic multiplexer valve cycles automatically according to the set switching time. When any leak rate value is detected to exceed the preset target leak rate, the automatic multiplexer valve stops cycling, then locks onto the currently present leak rate signal channel and performs continuous measurement. When the leak rate value falls below the target leak rate value, the automatic multiplexer valve resumes automatic cycling. This ensures precise location and avoids signal loss due to the automatic switching valve re-switching after a leak occurs, achieving precise and efficient operation.

[0021] Example 2 In this embodiment, a multi-branch rapid detection method for helium gas testing is described, with the following steps: 1. Hardware connection and installation: Connect the tubing of the three suction guns to the three inlets of the automatic switching valve (e.g., Port 1, 2, 3). Connect the common outlet of the switching valve to the detection inlet of the 340 leak detector via tubing.

[0022] 2. Connect the leak detector signal output: Locate the analog output interface on the leak detector, confirm the output specifications of the signal, and set the output function to "leakage rate value" in the leak detector's settings menu. Taking the leak detector's BNC interface as an example, use a BNC cable to connect this output port to the analog input channel of the data acquisition card.

[0023] 3. Connect the automatic switching valve controller: Correctly connect the valve controller to the switching valve. Locate the level output port on the switching valve controller that indicates the current channel status; a high level indicates the currently represented channel. Then connect these status output lines to the digital input channels of the data acquisition card.

[0024] 4. Connect the data acquisition card to the PC and install the card's driver. Configure the acquisition card channels, determining the channel connected to the leak detector and the corresponding channel for controlling the switching valve status. Set the valve switching frequency and the leak rate alarm value.

[0025] 5. The control valve controller starts rotating. Simultaneously, the voltage value of the channel is continuously read and converted into the corresponding leak rate value and the current digital status of the channel according to the output specifications of the leak detector. This value is then decoded into the corresponding channel number. The read leak rate value and the current channel number are then combined and output.

[0026] 6. Draw three leakage rate curves of different colors, corresponding to the leakage rate display of the three suction guns, and display the current leakage rate of the three channels in real time. On the leakage rate display, when the leakage rate value of any channel exceeds the preset target leakage rate, the leakage rate value and leakage rate display curve of the corresponding channel are highlighted, a buzzer alarm is sounded, and the channel that caused the leakage rate is displayed, which facilitates the on-site staff to detect leaks and record leakage rates.

[0027] In this implementation, multi-branch cyclic detection is achieved through cyclic detection, avoiding the backtracking detection that occurs during on-site testing, which would reduce detection efficiency and increase workload. However, avoiding the risk of missed detections is a crucial aspect of this invention during parameter setting.

[0028] This invention carries the risk of sampling blind spots. Specifically, when the system switches to the first suction chamber, the second and third chambers are in an "unmonitored state." If a leak occurs in the scanning path of the second chamber at the exact moment the switching valve leaves the second chamber and switches to the third suction gun, the leak signal will be completely missed.

[0029] This problem manifests as a detection blind spot caused by the flawed application of this invention. The probability of missed detection is directly related to the duration of the leakage event and the valve switching cycle.

[0030] Furthermore, when the amount of leakage is very small, such as when a suction gun quickly sweeps across a small leak, the generated pulse signal may be shorter than the sampling time of a single channel. This brief signal will be averaged across the entire sampling window, causing the leak pulse signal to be averaged out, thus failing to exceed the set alarm threshold. Therefore, for any detectable leak, its duration needs to be much longer than the system's blind zone period.

[0031] The solution in this invention is to set the switching cycle and the total duration of one cycle to be much shorter than the time required for an operator to sweep a small leak point with a handheld suction gun.

[0032] The operator scans at a speed of v (mm / s). Assuming the smallest leak size scanned is D mm, the time required to scan the leak is: Parameter settings: Acquisition time for each channel: Therefore, if the acquisition time for each channel is 20ms and the number of channels is 3, then the total system cycle time is: That is, the total system cycle is 60ms, and the maximum dead zone time for any channel is: In this scenario, the time taken to scan for leaks is greater than or equal to the system's blind zone time. Therefore, as long as a leak is detected on the scanning path, the leak rate signal will definitely fall within the sampling window of a certain channel, thus avoiding missed detections. Furthermore, if the scanning speed is slower or the leak size is larger, the security will be even higher.

[0033] In the actual on-site testing process, 200% scanning is required. Under these circumstances, there is a high degree of overlap between the scanning paths, and no scanning area will be missed.

[0034] Furthermore, to optimize the accuracy of the hardware and system, the switching valve is selected as a solenoid valve with fast response speed and small size, thereby reducing the delay and signal mixing caused by the switching itself.

[0035] During weld inspection, the automatic multiplexer valve cycles automatically according to the set switching time. When any leak rate value is detected to exceed the preset target leak rate, the automatic multiplexer valve stops cycling, locks onto the currently present leak rate signal channel, and performs continuous measurement. When the leak rate value falls below the target leak rate value, the automatic multiplexer valve resumes automatic cycling. When the signal falls below the preset threshold, it automatically returns to the cycling state. This ensures accurate location and prevents signal loss due to the automatic switching valve re-switching after a leak occurs.

[0036] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A multi-branch rapid detection method for helium gas testing, characterized in that: The testing method is as follows: a) Preparation: Connect each of the multi-channel suction guns to the inlet of the automatic multi-channel switching valve through a pipeline, and connect the common outlet of the automatic multi-channel switching valve to the helium leak detector through a pipeline; b) Connect the coaxial cable interface of the helium leak detector to the multi-channel data acquisition card through a coaxial cable, and connect the valve controller to the automatic multi-channel switching valve; connect the multi-channel data acquisition card to the PC; c) Multiple inspectors each carry one suction gun to scan the weld, control the automatic multi-channel switching valve to rotate sequentially, and synchronously read the voltage value of the corresponding channel of the suction gun, then convert it into a leak rate value, record and output the currently read leak rate value and its corresponding channel number; d. Plot the leakage rate values ​​of the branch suction guns and the corresponding channel number information obtained in step c into leakage rate curves of different colors, and display the leakage rate values ​​of multiple branch guns in real time; e. When the leakage rate value of any channel exceeds the preset target leakage rate, the system will sound an alarm and display the channel number that caused the leakage, so as to facilitate the on-site staff to detect leaks and record leakage rates.

2. The multi-branch rapid detection method for helium gas testing according to claim 1, characterized in that: In step c, to avoid missed detections, the switching time of the automatic multi-way switching valve and the total time of one cycle should be less than the time required for the operator to scan a leak point with a handheld suction gun.

3. The multi-branch rapid detection method for helium gas testing according to claim 2, characterized in that: If the operator's scanning speed is v (mm / s), and assuming the smallest leak size scanned is D mm, The time required to scan the leak point: ; Data acquisition time for each channel: ; The total period of a cyclic system: ; For any channel, the maximum blind time is: ; When the time taken to scan a leak point is greater than the blind zone time, the leak point signal will definitely fall within the acquisition time of a certain channel, thus avoiding missed detection.

4. The multi-branch rapid detection method for helium gas testing according to claim 1, characterized in that: In step c, before the inspectors scan the weld, the switching time of the automatic multi-channel switching valve is set, and the alarm value for the leakage rate is set.

5. The multi-branch rapid detection method for helium gas testing according to claim 1, characterized in that: In step e, when scanning the weld, the automatic multiplexer valve automatically cycles according to the set switching time; when the leak rate value of any channel exceeds the preset target leak rate, the automatic multiplexer valve stops cycling, then locks on the currently existing leak rate signal channel, and performs continuous measurement; when the leak rate value falls back below the target leak rate value, the automatic multiplexer valve resumes automatic cycling.

6. The multi-branch rapid detection method for helium gas testing according to claim 3, characterized in that: In step c, during the actual detection process, the time to scan a leak point is twice the time to scan a blind spot. Under these circumstances, there is a high degree of overlap between the scanning paths, and no area will be missed during the scanning process.

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