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When using pigging to clean pipes of different types, it is necessary to select the appropriate pig based on factors such as the specific characteristics of the dirt attached to the pipe wall, the degree of attachment, and the solubility of that dirt in chemical agents. Moreover, sometimes it is necessary to consider compatibility with the chemicals used, which is why different cleaning methods using pigging are employed for various pipelines. (1) Domestic research and applications: The Zhongyuan Oilfield has developed a cleaning pig capable of automatic de-blocking. The liquid inside this pig is ejected through nozzles at the front end of the pig via a filter, creating a high-pressure liquid jet that disperses the dirt accumulated in front of the pig and clears the path for its progress, thereby achieving automatic de-blocking and effectively preventing the pig from getting stuck. This type of pig has been successfully applied in oil pipelines and water supply pipes. The problem with this type of pig is that the strength of the spring cannot be controlled; either too high or too low a strength fails to effectively address the issue of blockages. CNPC Pipeline Technology Company has developed a magnetic pig. A magnetic pig is one in which magnets are installed inside the framework of a conventional pig; these magnets can attract magnetic materials within the pipeline, thereby enabling the detection of faults in the pipeline using magnetic flux leakage testing. Magnetic pigging devices can remove deposits and debris from within pipes, as well as draw out magnetic materials such as iron filings from the pipes, thereby creating the necessary conditions for pipeline inspection and ensuring the safe operation of the pipes. (II) Application of pigging in the cleaning of oil pipelines: After being in use for a period of time, oil pipelines accumulate oil residues and wax on their pipe walls. When cleaning oil pipelines with pigs, a multi-layer cleaning method is employed. The cleaning of the entire pig is divided into several stages; organic solvents or degreasers are used for cleaning between two pigs, or water is employed to dissolve them. Cleaning and drying take place continuously in the pipeline. When air is used as the force to propel the pig forward, an antistatic agent should be added to the solvent, and clean water should be injected as an interlayer between the pig at the beginning and end of the solvent to prevent damage caused by static electricity. (III) Application of pigging in desulfurization of boiler pipes. Boiler pipes accumulate scale and form coke over time during use. When using pigs to remove scale from pipelines, factors such as the hardness of the pipeline material and the hardness of the attached scale must be taken into account, in order to select pigs with the appropriate material, hardness, and shape that can effectively remove the scale without causing damage to the pipeline. In summary, pigging for pipeline cleaning offers wide adaptability, is suitable for cleaning very long pipelines, can employ multi-layer cleaning methods, and features simple equipment, a low need for personnel, and high economic efficiency. Whether it’s cracks, pits, or dirt, modern pipeline monitoring systems provide extremely valuable assistance in assessing the operational condition of pipeline systems through pigging. Researching self-deblocking, wear-resistant, pipe-diameter adaptable, and multi-functional pigging devices is the current goal of researchers. As oil and gas exploration moves into deeper waters. In ultra-deep water areas, higher requirements are placed on pigging devices. This also places higher demands on the design methods and materials of pigging devices. To address the issue of wear, the sealing and worn parts of the pig should be made from materials that are resistant to wear and pressure, or the manufacturing process for the inner wall of the pipeline should be improved to make it smooth enough ； For clogging removal and issues related to different pipe diameters, it is possible to design pigging devices that can automatically change their diameter according to energy requirements. ■ This article is reprinted from Jilin Zhaoxi Petroleum Technology Co., Ltd. http://www.jilinzhao*.com/