1. Under the normal working pressure of the valve leakage device, the leakage of the valve flap and the seat sealing surface exceeds the allowable degree, and the leakage of the safety valve may cause the medium to be lost. In addition, the continuous leakage of the medium will also damage the hard sealing material. The sealing surface of the common safety valve is made of metal material to metal material, and it is very difficult to make it smooth and smooth. The working medium is a steam safety valve. Under the specified pressure value, the outlet end is invisible to the naked eye, and there is no leak, and the sealing performance is considered to be qualified. There are three main reasons for the leakage of the valve:
In one case, the dirt impurities fall on the sealing surface, and the sealing surface is padded, causing a gap between the valve core and the valve seat, and the valve leaks. The way to eliminate this kind of failure is to remove the dirt and impurities that fall to the sealing surface. When the boiler is ready to be shut down, the safety door running test is first carried out. It is found that the leaking and shutting down the furnace is carried out after dismantling and repairing. During the test, the safety door leak was found. It is estimated that this situation is caused by the fact that it can be cooled after running for 20 minutes and then steered once again to flush the sealing surface.
Another situation is damage to the sealing surface. The main reasons for the damage of the sealing surface are as follows: First, the sealing surface material is poor. For example, the main safety door of the No. 3 to No. 9 furnace has been overhauled for many years. The sealing surface of the main safety valve spool and the valve seat has been studied very low, so that the hardness of the sealing surface is also greatly reduced, resulting in a decrease in sealing performance. A good way to eliminate this phenomenon is to The original sealing surface is turned and then re-welded according to the drawings to improve the surface hardness of the sealing surface. Pay attention to the processing quality during the processing, such as cracks on the sealing surface, trachoma and other defects must be turned and reworked. The newly machined valve seat must meet the drawing requirements. At present, it is better to use the YST103 universal steel electrode to weld the valve core sealing surface. Second, the quality of the inspection is poor, and the valve seat is not up to the quality standard. The method to eliminate this failure is to repair the sealing surface by grinding or grinding.
Another cause of leakage of the safety valve is improper assembly or improper size of the part. During the assembly process, the valve seat of the valve core is not completely aligned or the coupling surface has a light transmission phenomenon, and the sealing surface of the valve seat is too wide to be good for sealing. The elimination method is to check the size and uniformity of the fit around the valve core, and ensure that the valve core* hole and the sealing surface have the same squareness. It is not allowed to lift the valve core to check the gap of each part; the drawings require that the sealing surface width be appropriately reduced to achieve effective sealing.
2. Leakage of the valve body joint surface refers to the leakage phenomenon at the joint surface between the upper and lower valve bodies. The main reasons for this leakage are as follows: First, the joint bolt tightening force is not enough or tightly biased, resulting in a bad joint surface seal. .
The elimination method is to adjust the tightening force of the bolts. When tightening the bolts, it must be carried out in a diagonal manner. The Zui is to measure the gaps at the tight side, tighten the bolts tightly, and make the gaps of the joint surfaces consistent. Second, the valve body combined with the toothed gasket does not meet the standard. For example, the toothed seal has a slight groove in the radial direction, and the parallelism is poor, and the tooth shape is too sharp or over-slope to cause the seal to fail. Leakage of the valve body joint surface. The quality of the spare parts is checked during maintenance, and this phenomenon can be avoided by using a standard toothed gasket. Third, the flatness of the valve body joint surface is too poor or the hard impurities are padded to cause the seal to fail. The flatness of the valve body joint surface is too poor to cause leakage of the valve body joint surface. The elimination method is to disassemble the valve and re-grind the joint surface until it meets the quality standard. Impurities are padded and the seal is ineffective. When the valve is assembled, the joint surface is carefully cleaned to prevent impurities from falling in.
In one case, the dirt impurities fall on the sealing surface, and the sealing surface is padded, causing a gap between the valve core and the valve seat, and the valve leaks. The way to eliminate this kind of failure is to remove the dirt and impurities that fall to the sealing surface. When the boiler is ready to be shut down, the safety door running test is first carried out. It is found that the leaking and shutting down the furnace is carried out after dismantling and repairing. During the test, the safety door leak was found. It is estimated that this situation is caused by the fact that it can be cooled after running for 20 minutes and then steered once again to flush the sealing surface.
Another situation is damage to the sealing surface. The main reasons for the damage of the sealing surface are as follows: First, the sealing surface material is poor. For example, the main safety door of the No. 3 to No. 9 furnace has been overhauled for many years. The sealing surface of the main safety valve spool and the valve seat has been studied very low, so that the hardness of the sealing surface is also greatly reduced, resulting in a decrease in sealing performance. A good way to eliminate this phenomenon is to The original sealing surface is turned and then re-welded according to the drawings to improve the surface hardness of the sealing surface. Pay attention to the processing quality during the processing, such as cracks on the sealing surface, trachoma and other defects must be turned and reworked. The newly machined valve seat must meet the drawing requirements. At present, it is better to use the YST103 universal steel electrode to weld the valve core sealing surface. Second, the quality of the inspection is poor, and the valve seat is not up to the quality standard. The method to eliminate this failure is to repair the sealing surface by grinding or grinding.
Another cause of leakage of the safety valve is improper assembly or improper size of the part. During the assembly process, the valve seat of the valve core is not completely aligned or the coupling surface has a light transmission phenomenon, and the sealing surface of the valve seat is too wide to be good for sealing. The elimination method is to check the size and uniformity of the fit around the valve core, and ensure that the valve core* hole and the sealing surface have the same squareness. It is not allowed to lift the valve core to check the gap of each part; the drawings require that the sealing surface width be appropriately reduced to achieve effective sealing.
2. Leakage of the valve body joint surface refers to the leakage phenomenon at the joint surface between the upper and lower valve bodies. The main reasons for this leakage are as follows: First, the joint bolt tightening force is not enough or tightly biased, resulting in a bad joint surface seal. .
The elimination method is to adjust the tightening force of the bolts. When tightening the bolts, it must be carried out in a diagonal manner. The Zui is to measure the gaps at the tight side, tighten the bolts tightly, and make the gaps of the joint surfaces consistent. Second, the valve body combined with the toothed gasket does not meet the standard. For example, the toothed seal has a slight groove in the radial direction, and the parallelism is poor, and the tooth shape is too sharp or over-slope to cause the seal to fail. Leakage of the valve body joint surface. The quality of the spare parts is checked during maintenance, and this phenomenon can be avoided by using a standard toothed gasket. Third, the flatness of the valve body joint surface is too poor or the hard impurities are padded to cause the seal to fail. The flatness of the valve body joint surface is too poor to cause leakage of the valve body joint surface. The elimination method is to disassemble the valve and re-grind the joint surface until it meets the quality standard. Impurities are padded and the seal is ineffective. When the valve is assembled, the joint surface is carefully cleaned to prevent impurities from falling in.
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