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The current situation of natural gas in China and the development trends of pipeline valves http://www.oilnews.com.cn/bk/images/070821/A012007011.jpg China Petroleum News Center ??I. The current status and prospects of China’s natural gas industry?? With China’s long-term rapid economic growth driving up energy demand, there is also an increasing demand among the public for better living standards and a healthier environment. Century-scale projects such as the West-to-East Gas Pipeline, the Sichuan-to-East Gas Pipeline, and the import of Russian natural gas demonstrate that natural gas, an important energy source characterized by its high quality, cleanliness, and environmental friendliness, is receiving unprecedented attention in our country. China Gas has established 46 joint venture companies with exclusive rights to operate natural gas pipelines in more than a dozen provinces along the West-to-East Gas Transmission and Sichuan-to-East Gas Transmission projects, investing in over 50 natural gas pipeline networks; this figure is set to continue rising as the Chinese gas market expands rapidly. The successful implementation of the West-to-East Gas Transmission Project has improved the level of gas pipeline development in China, laying the foundation for the establishment of a national gas pipeline network. Starting with the West-to-East Gas Transmission Project, the level of gas pipeline construction in China has gradually approached international advanced standards, evolving toward long-distance, large-diameter pipelines, high pressures, and highly automated network management, thereby laying a solid material foundation for the rapid development of China’s gas industry. The completion of the West-East Gas Pipeline Project has created a major energy artery running across China from east to west. It will play a significant role in promoting the development of the western regions, accelerating growth in the central and western areas, bringing benefits to the people of Xinjiang and various ethnic groups along its route. It will also contribute to the adjustment of the industrial structure and the optimization of the energy structure, as well as to ensuring energy security. The West-to-East Gas Transmission Project starts in Lunnan, Xinjiang, and passes through 10 provinces, autonomous regions, and municipalities directly under the Central Government. It has a total length of about 4,000 kilometers, with a designed annual gas transmission capacity of 12 billion cubic meters. The ongoing capacity expansion project has reached 17 billion cubic meters. Two large underground gas storage facilities, Liu Zhuangzi and Jintan, will be built in the middle and lower reaches. The pipeline project passes through the Gobi Desert, the Loess Plateau, and the Taihang Mountains, and crosses the Yellow River, Huai River, and Yangtze River. It is currently China’s pipeline project with the largest diameter, thickest wall, highest pressure rating, and greatest technical complexity. It has set multiple records for natural gas pipelines in China, as well as achieving high speeds in the history of pipeline construction worldwide. The completion and operation of the West-to-East Gas Transmission Project marked a new level in the overall development of gas pipeline construction in China, laying the foundation for the country’s gas transmission network. It is understood that China will take the construction of the West-to-East Gas Transmission project as an opportunity to take into account natural gas resources in the eastern, central, and western regions as well as those offshore and on land. By actively implementing a strategy of expanding overseas operations to acquire foreign natural gas resources, China will further refine its plans for the development of its natural gas pipeline network. It will accelerate the construction of main pipelines, gas storage facilities, pressure boosting stations, and related branch lines, in order to create a national natural gas backbone network consisting of five horizontal and two vertical routes. This will gradually give rise to a gas supply pattern characterized by gas transport from the west to the east, from the north to the south, local supply sources, and the import of gas via sea routes. In the end, there will be regional natural gas networks centered around routes such as Lünan to Shanghai and Changqing to Beijing, as well as other networks in regions including Sichuan and Chongqing, the Beijing-Tianjin-Hebei-Shandong-Shanxi area, the Yangtze River Delta, the northwest region, and the Hunan and Hubei provinces. This will lead to a diversified source of natural gas resources, a networked supply system, and a market-oriented approach in China. II. Characteristics of natural gas pipeline valves ?? With the development of the natural gas pipeline industry, the demand for such valves is increasing. Natural gas pipeline valves differ from ordinary valves. Specifically, these are the following points: 1. Materials – The natural gas transported through pipelines contains large amounts of hydrogen sulfide before desulfurization (an extremely toxic and corrosive gas that reacts with iron to form iron sulfide, which can flake off in sheets and cause damage to mechanical equipment). Even natural gas that has been treated through processes such as desulfurization still contains residual hydrogen sulfide. Therefore, corrosion-resistant and sulfur-resistant materials should be chosen for pipeline valves. ??2. Leakage rate ??Natural gas pipelines are mostly built on the outskirts of cities, and their operation and management are different from those of ordinary factories, as workers are frequently involved in operations, maintenance, and inspections. In general, urban natural gas pipelines are over hundreds of kilometers long, requiring regular patrols and inspections. Moreover, sometimes these pipelines have to pass through complex areas, and leaks of the gas contained within them can lead to serious fire accidents. Especially for pipelines located near cities, it is particularly important to prevent leaks from the valves. ??The leakage requirements for natural gas valves are very strict; typically, buried and more critical valves employ a fully welded valve body structure. To ensure the sealing performance of pipeline valves, the sealing pair is required to have excellent corrosion resistance, wear resistance, self-lubricating properties, and elasticity. In recent years, the development of polymer materials has provided a wide range of options for selecting sealing materials for pipeline valves, such as polytetrafluoroethylene, nylon, nitrile rubber (NBR), and special synthetic rubbers like VITON. ??3. Application scenarios ??Once the pipeline is put into operation, it must not be shut down for several years; the longer it operates, the better. This is different from ordinary chemical plants or refineries, which have scheduled maintenance periods. Natural gas transported through pipelines serves a large number of users across the city, including residents, businesses, factories, etc. In particular, those business users that rely on natural gas as a raw material cannot afford any interruptions. If the pipeline valves connected in series along the pipeline fail, the consequences can be disastrous. Therefore, the main sealing components of pipeline valves, such as valve seats, are required to have a long service life. The service life requirement for valves in main pipeline systems is generally over 30 years. ??4. Driving mechanism ??Due to the high pressure, large diameter, and fast switching times in pipeline transportation, pipeline valves require driving mechanisms with high torque. Such as electric or pneumatic devices, gas-liquid actuated or electro-hydraulic actuated devices. The drive device must also meet explosion-proof requirements, specified as EExdIIBT4, with a protection rating of IP68. Since management and control personnel are usually located on-site or in the central control room, it is required that the pipeline valves can be automatically shut off in the event of major accidents such as pipe ruptures. Pipeline valves are required to have low operating force, and to enable accurate operation even when affected by changes in temperature or external forces. In particular, emergency shut-off valves must be able to remain in the fully open position for an extended period of time, and quickly seal off the pipeline when necessary. At the same time, it is required that the opening and closing positions of the valve as well as the opening degree indicators be accurate and easy to understand, while ensuring an appropriate switching speed.