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ã€Abstract】The valve is a relatively common device, which is mainly used to make the piping and the medium in the equipment flow or stop. The direction, pressure and flow of the air, water, oil and various corrosive media are carried out. Control, which provides the basis for the normal operation of the entire equipment. Because the valve has a wide application range, its function is very important. If the valve leaks, it will have very serious consequences. For equipment with special operating environment, it will not only cause energy waste, but also serious safety accidents. . Therefore, the cause of valve leakage should be analyzed, and effective preventive measures should be developed to ensure safe and stable operation of the valve.
[Keywords] valve leakage; valve body sealing surface valve structure is relatively simple, mainly composed of valve body, opening and closing member and valve cover, depending on the nature of use and the environment, the material of the valve and the design standard The requirements are different. In the daily use process, the valve is also operated in a relatively simple manner, and only needs to be rotated by the opening and closing member to complete the function. Due to the operating environment, the nature of the circulating medium and its own design defects, it may cause leakage of the valve at different parts, resulting in functional failure, waste of resources, and great impact on the operation of the entire equipment. . Therefore, the cause of the leakage should be analyzed, and then in the process of actual application, the corresponding preventive measures should be taken to ensure the quality of the valve and create favorable conditions for the normal operation of the valve supporting equipment.
1. Common leakage causes of valves 1.1 Valve design and manufacture There are quality defects. Valves are leaky due to quality defects caused by design and manufacture. The leakage is mainly manifested in two aspects, external leakage and internal leakage. Appearance leakage is easy in appearance. Observed, or can be found using a certain detection method. However, there is leakage inside, but it is not easy to detect. Under normal circumstances, the main reasons for internal leakage are loose casting, welding slag and sand holes, unreasonable design structure, and poor sealing of joint gaskets.
Most of the material of the valve is cast iron. In the process of production and processing, due to the lax control of the production process, there will be quality defects in the internal components of the valve, and the high pressure, corrosion and temperature change due to the different fluid properties controlled in the valve. In this case, the performance of the valve member is gradually lowered, and leakage occurs in the case where the internal valve flap is not in a good condition; and since the strength of the cast iron is low, various operating forces and corrosion and pressure are long-term. Under the action of the valve body, the valve body may be broken or the bracket may be broken, thereby causing leakage; and the internal components of the valve are connected by welding, so the quality control of the weld is particularly important, if in the welding operation. There are blisters or slag inclusions at the joints of the components, which will affect the firmness of the joints. If the surface of the valve is corroded or impacted, it will not be treated in time, and sand holes will be formed. In the case, it will expand into hole leakage; there are other phenomena such as unreasonable design structure and unsuitable gaskets. The reason is caused by valve leakage.
1.2 Daily operation and maintenance are not in place In the process of valve use, daily maintenance management is very important. If the insulation measures are not in place, under the influence of large temperature changes, the valve will be damaged and cause leakage. Improper operation can also cause damage to the valve, because in some devices, the frequency of use of the valve is not high, but should be done daily. Some units do not strictly control the daily management of the valve. They do not maintain and repair the valve. They do not perform lubrication treatment, which causes aging or rusting of components such as fillers, gaskets and valve stems. The switch can not be operated and is stuck. phenomenon. If the force is too strong during operation, the thread will be damaged, which will damage the components and cause leakage. The tolerance is not accurate, the bite is too tight; the stem nut is inclined; the thread is corroded by the medium (refers to the dark rod valve or the stem nut at the lower part of the valve); the open-air valve lacks protection, the stem thread is covered with dust sand, or is exposed to rain Frost and snow are rusted.
2, preventive measures for valve leakage 2.1 Strengthen the quality control of valve design and manufacturing In order to reduce valve leakage, quality control should be strengthened in the design and manufacturing process, which is also the main measure to prevent valve leakage fundamentally, so in the valve design process In the process, the technical parameters should be carefully analyzed, and then the design quality should be strengthened to ensure the rationality of the design structure. In the process of production and manufacturing, strengthen quality supervision and management, strictly follow the requirements of the normative standards, and at the same time strengthen the quality inspection of the manufacturing process, and find that unqualified products are not allowed to leave the factory. In particular, pay attention to the quality management of the welds of the components, improve the welding quality, and avoid the phenomenon of sand holes and slag inclusions in the weld. At the same time, the user of the valve should strictly control the quality of the valve when selecting the valve. The manufacturer must have the quality qualification. After the comparison, the manufacturer with strong strength and good reputation should cooperate.
2.2 Strengthen management and reasonable maintenance In production management, users should pay attention to system construction, establish and improve the management method of valve use, communicate with the technical department of the manufacturer in time, and require operators to operate and maintain strictly according to the regulations, and regularly check the performance of valve components. For example, whether the lubrication is good, whether the insulation is effective, etc. At the same time, pay attention to keep the valve surface clean, control external corrosion and prolong its service life.
Due to the large temperature difference between the working environment of most valves, it is necessary to protect the valve by taking good insulation measures. In addition to obtaining good energy-saving effects, it can also improve the safety and reliability of the valve and ensure safe production. Galvanized steel sheet shell insulation: It is mainly used for valves working in outdoor open air environment, and appropriate rain prevention should be taken. Wrapping: The method is to wrap the insulating material around the valve and bundle it with wire or rope. This kind of dispensing is simple and easy, the cost is low, but the appearance is not beautiful. Insulation energy-saving cover: The method is to use a mold in advance to make a split heat insulation shell, and then combine them into a valve to be fixed on the valve to form an external assembly of the valve. Apply thermal insulation coating: Apply some powder insulation coating on the valve insulation equipment, and take measures to prevent the device from falling off, thus maintaining the insulation effect.
3. Conclusion The valve has been widely used in industrial production in China and people's daily life. Because it is relatively simple to operate, it can be used in various equipment. However, due to the congenital quality defects of the valve or improper operation during use, valve leakage will occur. If the daily maintenance is not in place, the degree of leakage will be aggravated, which not only causes energy loss, but also causes different energy consumption. The occurrence of a security incident. Therefore, the design and production quality of the valve should be strictly controlled. In the daily use process, the correct operation and the maintenance management should be strengthened, and the leakage should be repaired or replaced in time to avoid causing greater losses.
references:
[1]Liu Zhaobin. Analysis of Causes of Leakage of Copper Valves by Scanning Electron Microscopy[J].Physical and Chemical Testing (Physical Section), 2010-02-08.
[2] Liu Tieying. Analysis of Causes and Countermeasures of Valve Leakage [J]. Modern Trade and Industry, 2013-04-15.
[3] Bai Xiaojie, Han Yu'an, Han Haisheng. Analysis of sealing characteristics and influencing factors of underground valve in oil and gas fields [J]. Western Exploration Engineering, 2010-09-15.
[Keywords] valve leakage; valve body sealing surface valve structure is relatively simple, mainly composed of valve body, opening and closing member and valve cover, depending on the nature of use and the environment, the material of the valve and the design standard The requirements are different. In the daily use process, the valve is also operated in a relatively simple manner, and only needs to be rotated by the opening and closing member to complete the function. Due to the operating environment, the nature of the circulating medium and its own design defects, it may cause leakage of the valve at different parts, resulting in functional failure, waste of resources, and great impact on the operation of the entire equipment. . Therefore, the cause of the leakage should be analyzed, and then in the process of actual application, the corresponding preventive measures should be taken to ensure the quality of the valve and create favorable conditions for the normal operation of the valve supporting equipment.
1. Common leakage causes of valves 1.1 Valve design and manufacture There are quality defects. Valves are leaky due to quality defects caused by design and manufacture. The leakage is mainly manifested in two aspects, external leakage and internal leakage. Appearance leakage is easy in appearance. Observed, or can be found using a certain detection method. However, there is leakage inside, but it is not easy to detect. Under normal circumstances, the main reasons for internal leakage are loose casting, welding slag and sand holes, unreasonable design structure, and poor sealing of joint gaskets.
Most of the material of the valve is cast iron. In the process of production and processing, due to the lax control of the production process, there will be quality defects in the internal components of the valve, and the high pressure, corrosion and temperature change due to the different fluid properties controlled in the valve. In this case, the performance of the valve member is gradually lowered, and leakage occurs in the case where the internal valve flap is not in a good condition; and since the strength of the cast iron is low, various operating forces and corrosion and pressure are long-term. Under the action of the valve body, the valve body may be broken or the bracket may be broken, thereby causing leakage; and the internal components of the valve are connected by welding, so the quality control of the weld is particularly important, if in the welding operation. There are blisters or slag inclusions at the joints of the components, which will affect the firmness of the joints. If the surface of the valve is corroded or impacted, it will not be treated in time, and sand holes will be formed. In the case, it will expand into hole leakage; there are other phenomena such as unreasonable design structure and unsuitable gaskets. The reason is caused by valve leakage.
1.2 Daily operation and maintenance are not in place In the process of valve use, daily maintenance management is very important. If the insulation measures are not in place, under the influence of large temperature changes, the valve will be damaged and cause leakage. Improper operation can also cause damage to the valve, because in some devices, the frequency of use of the valve is not high, but should be done daily. Some units do not strictly control the daily management of the valve. They do not maintain and repair the valve. They do not perform lubrication treatment, which causes aging or rusting of components such as fillers, gaskets and valve stems. The switch can not be operated and is stuck. phenomenon. If the force is too strong during operation, the thread will be damaged, which will damage the components and cause leakage. The tolerance is not accurate, the bite is too tight; the stem nut is inclined; the thread is corroded by the medium (refers to the dark rod valve or the stem nut at the lower part of the valve); the open-air valve lacks protection, the stem thread is covered with dust sand, or is exposed to rain Frost and snow are rusted.
2, preventive measures for valve leakage 2.1 Strengthen the quality control of valve design and manufacturing In order to reduce valve leakage, quality control should be strengthened in the design and manufacturing process, which is also the main measure to prevent valve leakage fundamentally, so in the valve design process In the process, the technical parameters should be carefully analyzed, and then the design quality should be strengthened to ensure the rationality of the design structure. In the process of production and manufacturing, strengthen quality supervision and management, strictly follow the requirements of the normative standards, and at the same time strengthen the quality inspection of the manufacturing process, and find that unqualified products are not allowed to leave the factory. In particular, pay attention to the quality management of the welds of the components, improve the welding quality, and avoid the phenomenon of sand holes and slag inclusions in the weld. At the same time, the user of the valve should strictly control the quality of the valve when selecting the valve. The manufacturer must have the quality qualification. After the comparison, the manufacturer with strong strength and good reputation should cooperate.
2.2 Strengthen management and reasonable maintenance In production management, users should pay attention to system construction, establish and improve the management method of valve use, communicate with the technical department of the manufacturer in time, and require operators to operate and maintain strictly according to the regulations, and regularly check the performance of valve components. For example, whether the lubrication is good, whether the insulation is effective, etc. At the same time, pay attention to keep the valve surface clean, control external corrosion and prolong its service life.
Due to the large temperature difference between the working environment of most valves, it is necessary to protect the valve by taking good insulation measures. In addition to obtaining good energy-saving effects, it can also improve the safety and reliability of the valve and ensure safe production. Galvanized steel sheet shell insulation: It is mainly used for valves working in outdoor open air environment, and appropriate rain prevention should be taken. Wrapping: The method is to wrap the insulating material around the valve and bundle it with wire or rope. This kind of dispensing is simple and easy, the cost is low, but the appearance is not beautiful. Insulation energy-saving cover: The method is to use a mold in advance to make a split heat insulation shell, and then combine them into a valve to be fixed on the valve to form an external assembly of the valve. Apply thermal insulation coating: Apply some powder insulation coating on the valve insulation equipment, and take measures to prevent the device from falling off, thus maintaining the insulation effect.
3. Conclusion The valve has been widely used in industrial production in China and people's daily life. Because it is relatively simple to operate, it can be used in various equipment. However, due to the congenital quality defects of the valve or improper operation during use, valve leakage will occur. If the daily maintenance is not in place, the degree of leakage will be aggravated, which not only causes energy loss, but also causes different energy consumption. The occurrence of a security incident. Therefore, the design and production quality of the valve should be strictly controlled. In the daily use process, the correct operation and the maintenance management should be strengthened, and the leakage should be repaired or replaced in time to avoid causing greater losses.
references:
[1]Liu Zhaobin. Analysis of Causes of Leakage of Copper Valves by Scanning Electron Microscopy[J].Physical and Chemical Testing (Physical Section), 2010-02-08.
[2] Liu Tieying. Analysis of Causes and Countermeasures of Valve Leakage [J]. Modern Trade and Industry, 2013-04-15.
[3] Bai Xiaojie, Han Yu'an, Han Haisheng. Analysis of sealing characteristics and influencing factors of underground valve in oil and gas fields [J]. Western Exploration Engineering, 2010-09-15.
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