Do you know about air purging and explosive purging of pressure pipelines?

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Air purging is a method in which air is used as the medium; after being pressurized by a compressor (usually to 0.6–0.8 MPa), it is used to blow out any remaining dirt and debris from pipelines carrying gaseous media. When using air for purging, there must be an adequate volume of air such that the flow velocity of the purging gas is greater than that of the gas used in normal operation; generally, this velocity should be at least 20 m/s. This ensures that there is sufficient momentum to dislodge any residual deposits in the pipes and equipment, thus facilitating smooth commissioning of the installation and ensuring safe operation. During air purging, the amount of air consumed is generally high, and a certain purging time is required. The segmented purging method can also be used when the air volume is low; this involves dividing the system pipes into many sections, each of which is further divided into several sub-sections, and then purging each section one by one, isolating that section from the system after it has been purged. In this way, the purging quality can be ensured even when the gas supply is limited. For large-diameter pipes (generally larger than 4 inches) or those in which debris is difficult to remove, the explosive cleaning method can also be used. Oil-free air should be used for purging the oil-free pipeline and instrument air pipeline. Due to factors such as source, supply timing, and cost, nitrogen is generally not used as a purging gas for ordinary pipelines and equipment; instead, it is commonly employed for air purging, drying the air in systems, replacing the contents of pipelines and equipment after steam purging, and providing nitrogen sealing protection. Blasting purging is used for pipelines of 4 inches or larger. Air serves as the medium; at the exhaust points, rupture discs are pressed or sealed in place by flanges. At the air inlet points, air is pressurized by a compressor. When the pressure reaches the burst pressure (usually 0.6–0.8 MPa), the rupture discs burst, allowing compressed air to be discharged at high speed from the exhaust points of the pipeline. This process also carries away any remaining dirt and debris within the pipeline. The blast purging method is one way of removing such residual contaminants from pipelines. When using the blasting purge method, there must be an adequate supply of gas, such that the flow velocity of the purge gas is greater than that of the gas used in normal operation; generally, this velocity should be at least 20 m/s. This ensures that sufficient momentum is available to dislodge any residual deposits in the pipes and equipment, thereby facilitating smooth commissioning of the installation and ensuring safe operation. During blasting purging, the air consumption is generally very high, and it takes some time to build up pressure. The rupture discs used for blasting purging must be purchased uniformly, and there should be a dedicated person responsible for their storage. The bursting pressure of these rupture discs is generally between 0.6 and 0.8 MPa; for low-pressure and vacuum pipelines, it is usually between 0.15 and 0.20 MPa. In cases where high standards are required for the quality of purging, the bursting pressure can be increased slightly, but it must not exceed the operating pressure of the pipeline. The size of the rupture disc must match the diameter of the purge pipeline. During blasting purging, a dedicated person must be in charge and provide supervision. When pressurizing, it is necessary to ensure that the blast disc is properly installed and in good condition, that the flange screws are tightened, and that there are no people near the exhaust end equipped with a blast disc, or that any such people are in a safe location. The segmented blasting purging method can also be used when the air volume is low; this involves dividing the system pipes into many sections, each of which is further divided into several sub-sections, after which blasting and purging are carried out section by section, with each section being isolated from the system once purging is complete. In this way, the purging quality can be ensured even when the gas supply is limited. Due to factors such as source, supply timing, and cost, nitrogen is generally not used as a purging gas for ordinary pipelines and equipment; instead, it is commonly employed for air purging, drying the air in systems, replacing the contents of pipelines and equipment after steam purging, and providing nitrogen sealing protection.