How to conveniently monitor liquefied gas in LNG storage tanks and use magnetic particle testing in detection

（1） How to conveniently monitor the increasing budget of liquefied gases in low-temperature storage tanks, safety issues, and emergency calls to natural growth gas suppliers have made the environment of the natural growth gas industry more complex than ever before. With the expansion of factories and warehouses, improving safety, simplifying management, and balancing budgets have become particularly prominent. In order to change the supply chain, natural growth gas suppliers need to conduct real-time analysis of low-temperature storage tanks to understand the demand for refilling and the real-time distribution of liquefied gas. In times of economic hardship, improving operational efficiency and maintaining healthy checks on functionality are crucial. The unavailability of low-temperature liquids and emergency transportation of bulk gases are theoretically and literally expensive. The unavailability of low-temperature liquids can affect the revenue of natural growth gas companies. The emergency transportation of pressurized low-temperature storage tanks requires separate costs, which increases the expenses of natural growth gas companies and reduces budgets. The world has made technological progress to fill the monitoring gap, and technology has also developed. New technologies can monitor infrastructure and tank levels. The technology used by industrial gas cylinder suppliers and gas distributors in the past is now outdated. New technologies and tools can successfully overcome the shortcomings of manual measurement techniques to fill the monitoring gap. The monitoring system for liquefied gas availability and transportation in the cloud utilizes telemetry technology and sensing equipment to provide a solution for tank level monitoring. The liquefied gas monitoring instrument simplifies the tracking, processing, and real-time monitoring of liquefied gas consumption. It enables natural growth gas companies to inspect the condition of low-temperature storage tanks, as their availability and delivery are crucial and time sensitive. Changing the manual mode to automatic mode for recording tank data through a manual reading protocol is an inefficient data collection method. Throughout the day, the available low-temperature pressurized liquefied gas in the tank needs to be monitored. To complete this task, sufficient manpower is needed, and further training and review are required. This process is both time-consuming and expensive. The wireless tank monitoring system solves these problems through automatic monitoring, reducing human intervention and saving potential costs and valuable time. Not only can it accurately follow the liquid level of the storage tank, but it can also automatically update the intermediate system for document work. Maintaining a high level of safety from every corner, traditional leak detection technology has disappointed natural growth gas suppliers and created an unsafe environment for employees and customers. The low-temperature liquefied gas detection system provides an excellent solution for monitoring instantaneous leaks of low-temperature liquefied gases. The temperature drop caused by the leakage of low-temperature fluid gas is detected by the sensing device and an alarm is issued. （2） The application of magnetic particle testing in LNG tank inspection is stipulated in the "Rules for Periodic Inspection of Pressure Vessels". The inspection of pressure vessels in use mainly includes macroscopic inspection, thickness measurement, and surface non-destructive testing. The surface non-destructive testing mainly includes magnetic particle testing and penetrant testing. For ferromagnetic materials, JB4730.1~. 6-2005 "Non destructive Testing of Pressure Equipment" series standards stipulate that magnetic particle testing should be preferred. This is because magnetic particle testing has the advantages of good sensitivity, efficiency, low cost, and intuitive defect display compared to penetrant testing. At the same time, in actual inspections, a large number of defects are almost always discovered by magnetic particle testing. It can be seen that the magnetic particle testing method is a non-destructive testing method used for regular inspections of natural growth gas storage tanks. 1. The principle and characteristics of magnetic particle testing Magnetic particle testing, also known as magnetic particle inspection or magnetic particle testing, is one of the five conventional methods of non-destructive testing. Magnetic particle testing is the process of using ferromagnetic materials that are magnetized. Due to the presence of discontinuities, local distortions occur in the magnetic field lines on and near the surface of the workpiece, resulting in a leakage magnetic field (i.e., the magnetic field formed when the magnetic induction lines leave and enter the surface) that adsorbs the magnetic particles applied to the surface of the workpiece, forming visible magnetic traces under appropriate lighting, thereby displaying the location, shape, size, and severity of the discontinuities. It can detect defects such as cracks, hairlines, white spots, folds, and inclusions in ferromagnetic materials, and has high detection sensitivity. (1) Advantages of magnetic particle method: 1) It can visually display the shape, position, and size of defects, and roughly determine their properties; 2) Has high sensitivity and can detect cracks with a length of 0.1mm and a width of micrometers; 3) Almost unrestricted by the size and shape of the specimen; 4) The detection speed is suitable, the process is simple, and the cost is low. (2) Limitations 1) Can only be used for ferromagnetic materials; 2) Only surface and near surface defects can be detected, and the detectable range is generally 1mm~2mm; 3) The direction of the magnetization field should intersect with the main plane of the defect, with an angle of 45 °~90 °. Sometimes, multiple magnetizations from different directions are also required; 4) Unable to determine the depth of the defect and its own height; 5) Wide and shallow defects are also difficult to detect; 6) Not all ferromagnetic materials can be used. When the magnetic field strength H ≤ 2500A/m, the relative magnetic permeability of ferritic steel should be μ r ＜ 300, and the ferrite content of stainless steel should be greater than 70%; 7) Demagnetization and cleaning are often required after testing; 8) The surface of the test piece shall not have any grease or other substances that can adhere to magnetic powder. 2. Comparison of surface non-destructive testing methods: Magnetic particle testing, penetrant testing, and eddy current testing all belong to surface non-destructive testing methods, but their principles and scope of application differ greatly, and they have their own advantages and limitations. As container inspectors, one should be proficient in these three testing methods and be able to choose a reasonable method for testing based on the material, condition, and testing requirements of the workpiece. For example, magnetic particle testing has high detection sensitivity for surface and near surface defects of ferromagnetic material workpieces, and can detect small defects with micrometer widths. Therefore, in container inspection, magnetic particle testing should be given priority for the detection of surface and near surface defects of ferromagnetic material workpieces. If magnetic particle testing cannot be used due to the structure and shape of the workpiece, penetration testing or eddy current testing can be used.