Requirements for the installation of natural gas vent pipes

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In accordance with the \"Code for Design of Urban Gas Systems\" (GB 50028-2020) and relevant industry standards, the requirements for installing gas vent pipes are as follows: 1. Installation location – In gas production and purification systems, gas vent pipes must be installed on the raw coal gas pipes of vertical furnaces or on the gas collection pipes of coke ovens; an ignition device should be installed at the outlet of these vent pipes； Gas purification equipment, waste heat boilers, and pipelines shall be equipped with vent pipes and purge pipe connections, positioned in such a way as to allow the media inside the equipment to be completely purged. Gas distribution system: On sub-high pressure and medium pressure gas main lines, vent pipes should be installed on both sides of the sectional valves ； Low-pressure gas storage tanks and high-pressure gas storage tanks should be equipped with vent pipes respectively ； A safety valve must be installed between the two isolation valves on the liquefied natural gas pipeline, and the released gas should be discharged in a centralized manner ； Liquefied natural gas storage tanks should be equipped with vent pipes for their safety valves. Courtyard gas pipeline network: Vent pipes should be installed on the gas pipelines in the gas-using workshops of industrial enterprises, boiler rooms, and large and medium-sized gas-consuming equipment. The outlets of these vent pipes should be at least 1 meter above the roof ridge (or at ground level in a safe location), and measures should be taken to prevent rain, snow from entering the pipelines, as well as to prevent the emitted gases from entering the buildings ； A vent pipe should be installed between the main gas valve of the gas-powered equipment and the burner valve. 2. Selection of pipe diameter: The diameter of the exhaust pipe is determined by the capacity of the system or equipment; for specific details, refer to the relevant standards in the \"Power Pipeline Design Manual.\" Different types and lengths of pipes correspond to different nominal diameters (DN/mm). 3. Height requirement for the pipe outlet: When the diameter of the vent pipe is greater than 150 mm, its outlet must be at least 4 m above the roof of the factory building, as well as above gas pipelines, equipment, and walkways ； When the diameter of the vent pipe is 150 mm or less, the outlet of the vent pipe shall be at least 2.5 m above the roof of the plant, gas pipelines, equipment, and walkways ； The height of the outlet of the safety vent pipe on a voltage regulation cabinet from the ground level should be no less than 4 meters. For voltage regulation cabinets installed on building walls, the outlet of their safety vent pipes should be 1.0 meter above the roof edge of that building. The outlets of safety vent pipes in underground voltage regulation stations and underground cabinets should also be installed in accordance with the requirements applicable to those on above-ground voltage regulation cabinets. 4. Other requirements: The vent pipes should be protected against rain and lightning strikes; when the building is located outside a lightning protection zone, the leads of the vent pipes must be grounded, with the grounding resistance to be less than 10Ω ； The installation of exhaust pipes should facilitate operation and maintenance, and must not affect the surrounding environment or public safety. The above requirements are intended to ensure that natural gas vent pipes can discharge gas safely and effectively in emergency situations, preventing safety accidents caused by gas accumulation, while also taking into account the needs for equipment inspection and maintenance.