Monitoring the airtightness of ductile iron pipes is an essential process in the production and use of ductile iron pipes. It is an important process to ensure product quality and production safety. Gas leakage detection includes toxic gas leakage detection, combustible gas leakage detection, and airtightness detection. The first two can mostly be detected through chemical sensors, usually during the use of components or systems. If there are suitable sensors, the method is relatively simple. The airtightness testing introduced in this article is generally conducted during the manufacturing process of components or systems, usually requiring quantitative testing and requiring rapid and large-scale testing at the production site.
1、 The ductile iron pipeline is protected by a 180 degree plain concrete wall. Air tightness testing requires covering the cast iron pipe with soil. If there is leakage, the soil needs to be cleaned and the plain concrete needs to be broken, which inevitably affects the project progress. In common project implementation methods, we generally adopt the following methods for checking the air tightness of ductile iron pipes: commonly used methods for air tightness testing include bubble method, coating method, chemical gas tracer leak detection method, pressure change method, flow rate method, ultrasonic method, etc.
2、 The traditional leak detection methods for ductile iron pipes often use bubble method and coating method. The bubble method is to immerse the workpiece in water, fill it with compressed air, and then collect the leaked bubbles within a certain period of time to measure the leakage amount. The application method is to apply a liquid that is prone to producing bubbles, such as soapy water, on the surface of a workpiece that is filled with a certain pressure inside, and observe the occurrence of bubbles to detect the size of the leakage. These two methods are easy to operate and can directly observe the location and situation of the leak. However, due to the lack of prior knowledge of the location and number of leaks in the workpiece, it is difficult to collect all the bubbles, which affects the accuracy of the measurement;
3、 For large, bulky, and complex outer surface parts in ductile iron pipes, bubbles adhere to the bottom and folds of the parts and are difficult to observe; After testing, it is necessary to clean and dry the workpiece, which cannot achieve automatic and quantitative leak detection. Therefore, these two methods seem inadequate in meeting the production requirements of high precision and efficiency.
With the rapid development of computer, electronic, and sensing technologies, the development of leak detection technology for ductile iron pipes will usher in new opportunities for growth. The future airtightness detection technology will further develop towards high precision, high efficiency, and intelligence.