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Key words: natural gas; long-distance pipeline; valve; maintenance and maintenance of natural gas long-distance pipeline valve is a device that controls the circulation, flow direction and cut-off of natural gas in the pipeline, and can adjust the pressure and flow in the pipeline. It plays a very important role in protecting the normal operation of natural gas long-distance pipelines. Therefore, it is very important to maintain and maintain the valve.
1 The importance of operation and maintenance In the various modes of transportation of energy, pipeline transportation is a very important way. Especially in China, due to the problem of uneven energy distribution, it is often necessary to travel a long distance during transportation. Therefore, higher requirements are placed on the pipeline. As one of the important components in the pipeline, the pipeline valve can meet the needs of different users. For the valve of the natural gas transmission pipeline, if there is a problem that causes the pipeline to block or the gas leaks, it is very easy to cause huge losses. It affects the normal use of energy by downstream customers and even causes safety accidents. In order to prevent problems in the valves of natural gas transmission pipelines, it is necessary to strengthen the maintenance and overhaul work of them, and prevent problems that may occur in advance.
2 The emergence of natural gas long-distance pipeline valves China is currently quite mature and perfect in the construction of natural gas pipelines. However, in the actual use process, there will still be some problems in the valve part, for example: due to transportation and installation of valves If there is an error, the lifting, unreasonable handling, and impurities inside the valve will cause certain damage to the valve body or the sealing ring; if the pipeline is overheated during the valve welding installation, the sealing dam in the valve will be affected. Severe burns have affected the sealing of the valve, which in turn led to the occurrence of internal leakage during valve commissioning. If the internal leakage problem is not dealt with in time, it may cause a wider range of leakage problems. In addition, when the valve is in a high temperature, humidity or pressure environment, coupled with the chemical reaction between the metals in the pipeline, it will also cause certain corrosion to the natural gas valve, resulting in the pipeline can not run safely and smoothly.
3 Maintenance and maintenance of natural gas long-distance pipeline valves 3.1 Maintenance before operation 3.1.1 Selection of raw materials for valves Since valves are not used at one time, they have high requirements on the quality and service life of materials. Secondly, Since the valves of natural gas long-distance pipelines are generally in the external environment, they are easily corroded by various materials, and therefore their materials are required to have strong corrosion resistance. In addition, the relevant national standards and the price of materials are also important factors in the selection of valve raw materials.
3.1.2 Maintenance during valve storage When the valve is stored in the warehouse, the appearance and the matching of the nameplate and related documents must be checked first, and the valve should be tested for strength and sealing, if in the valve handling. Damage and loss of the valve parts have occurred, and they must be timely provided, and the corresponding inspection records and warehousing procedures should be completed. Secondly, it is necessary to do a good job of cleaning the warehousing valve. Use rust inhibitor or rust-proof sticker to prevent the rust of the valve's processing surface, valve stem, sealing surface, etc., and close the inlet and outlet of the valve. If the valve is temporarily unable to enter the warehouse, it should be placed in a dry, ventilated temporary storage shed, and ensure that the stem is up or flat. Protect the sealing surface of the valve by applying grease, close the two ports of the valve, and use butter. , grease, etc. to close the stuffing box, and finally cover with a felt or tarpaulin.
3.1.3 Maintenance before valve installation The maintenance and maintenance work performed before the valve is installed mainly includes the following aspects: 1 to thoroughly check the integrity of the valve body and accessories before the valve is installed; After being placed in the full open position, check the limit position; check the gap between the valve body and the seal seat and the surface of the seal ring by hand; 3 ensure that the grease injection port works normally, the grease injection is smooth, and the report is stopped. The return valve is unobstructed; ensure that the seal groove is clean before grease injection; 4 correctly use the lifting ring to carry the valve to the official cavity to be installed.
3.2 Maintenance in daily operation 3.2.1 Maintenance of the rotating part of the valve Since it is necessary to move the valve several times in the daily operation of the valve, it is necessary to ensure the flexibility of the rotating part. Regular inspection of the valve's flexibility, regular cleaning and use a small amount of grease into the valve seat or valve body sealing system, thereby reducing the friction between the metal, reducing the valve switching torque, to avoid the problem of valve lock .
3.2.2 Maintenance when valve is greased When the valve is greased, the amount of grease is a very important issue. Too little grease may cause the valve to wear faster and more grease. Will cause unnecessary waste. Therefore, in the case of grease injection operation, comprehensive consideration should be made according to the type of valve, switching frequency, circulating medium, temperature inside the tube, type of grease injection and pressure of grease injection, so as to ensure the rationality of the amount of grease injection.
3.2.3 Maintenance of valve packing The lack of valve packing will cause leakage of the valve. Therefore, it is necessary to periodically check the packing of the stem bearing, replenish it when it is insufficient, and properly inject new grease for lubrication, thus extending the valve. The service life.
3.2.4 Other maintenance measures In addition to the above-mentioned maintenance measures, the valve should be drained regularly through the drain nozzle to avoid the problem of freezing the valve in cold weather; check the flange, grease port and stem Whether there is a leakage problem; do a maintenance log of the valve to ensure the normal operation of the long-distance gas pipeline valve.
4 Conclusion With the increasing application of natural gas in China, the construction of natural gas long-distance pipelines is also increasing. Only through scientific and effective maintenance and maintenance of natural gas long-distance pipeline valves can we ensure the safety of pipeline transportation. Transportation efficiency provides an important guarantee.
references:
[1] Wei Liyan, Ma Guiyang, Wei Shugang, et al. Common faults and maintenance of valves [J]. Petrochemical Technology, 2016, 23 (3): 203-203.
[2] Han Jianxin. Discussion on the importance of maintenance of long-distance pipeline trunk valve [J]. China High-tech Enterprise, 2016 (35): 199-200.
Abstract: The maintenance and maintenance of natural gas long-distance pipeline valves is of great significance for the safety and transportation efficiency of natural gas pipeline transportation. This paper analyzes the importance of maintenance and repair of pipeline valves and the existing problems, and proposes several specific valve maintenance and maintenance measures.