Purging method

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Piping purging cannot be generalized; it depends on the purpose of purging and certain specific requirements: 1. Piping purging is necessary in the later stages of building new chemical plants: it is carried out using air, with the aim of removing debris, dust, and other impurities from the pipes. This task is usually performed by the construction company, and nitrogen is not used during this process. Checks are done at the vent points to determine whether any impurities remain； 2. Purging of chemical plants before commissioning: Steam, air, or nitrogen can be used for this purpose of purging. Generally, steam is used first; firstly, the high temperature of steam helps to clean the pipes more thoroughly, and secondly, thermal expansion makes it possible to inspect the installation or maintenance work. Then, air is used for purging, primarily to remove any water remaining in the pipes; it may also serve as a means of conducting a leak test. However, whether to use air for purging depends on the process requirements of the device. In some devices or systems, the introduction of air is prohibited, in which case nitrogen is used for purging instead. Finally, there is nitrogen purging, a step that is essential in most chemical processing units. Of course, in such cases a air compressor system is not necessary; in other words, the medium to be used for purging depends on the requirements of the process. 3. Plant shutdown purging: Basically, all petrochemical plants need to be shut down for maintenance after completing one operating cycle. At this time, shutdown purging is extremely important and critical, as it affects the subsequent maintenance work and must not be taken lightly. In most cases, washing with water is carried out first (especially in the oil refining industry), and the organic phase remaining in the pipes is collected in a recovery tank for treatment during the next operation. At this point, it is determined whether the standards are met by checking the organic content in the water. After washing, steam is generally used for purging; air is usually not used for this purpose (except in utility systems), as most chemical processing plants have issues related to explosion limits. After purging with steam, residual moisture can be removed appropriately using air. 4. Pipeline purging during emergency repairs: This situation usually arises when there are damages, leaks, or malfunctions in the piping; in such cases, the faulty section must be removed from the system. It is absolutely not advisable to rely too much on valves for this purpose – a blind flange must be used after cutting off the flow with valves. Then purge with steam (if it is a wind, steam, water, or nitrogen system, steam is not necessary; air can be used directly). The purging must be thorough and complete. Due to time constraints, this is all I can write. Those who are more knowledgeable are invited to add more details; thank you! ! ! !