Power plant valves are mainly used to control a variety of equipment and their pipeline fluid medium operation, gas valve for the special valve leaks often occur in the packing, flange seals and valve body, the valve can cause leakage for a long time stem and flange Erosion of the sealing surface, the valve can eventually scrapped, coupled with the loss of fluid medium, the power plant to increase consumption, rising costs, economic decline. If the medium fluid is toxic, flammable, explosive, corrosive and so on, leakage, such as poisoning, fire, explosion and other casualties and accelerating the corrosion rate of plant equipment, shorten the service life, pollute the surrounding environment and destroy electricity in serious cases Production, damage people's health. The existence of the leak poses a serious threat to safe production, resulting in an increase in unplanned downtime of power plants. The following describes some of the causes of valve leakage and plugging methods and the valve repair and maintenance methods for reference. Valve leakage form and factors: 1 valve filler leakage and the reasons for the stop valve in operation during use, the valve stem with the filler there is a relative movement, which includes rotation and axial movement. As the number of switches increases, the number of relative motions also increases, as well as temperature, pressure and the characteristics of the fluid medium and other effects, the valve packing is the most prone to leakage sites. It is due to the gradual reduction of contact pressure of packing, filler aging itself, loss of elasticity and other causes. At this time, the pressure medium will leak outwardly along the contact gap between the packing and the stem, and will blow away a part of the filler and flush the stem out of the groove for a long time, so as to enlarge the leakage. 2 Flange Leakage Flange valve seal is mainly relying on the bolt preload, through the gasket to achieve a sufficient seal than the pressure to prevent the leakage of sealed pressure fluid medium. There are many reasons for its leakage, gasket insufficient pressure, the surface roughness does not meet the requirements, gasket deformation and mechanical vibration, etc. will cause the seal gasket and the flange surface of the joint lax strict leak . In addition bolt deformation or elongation, gasket aging, resilience decline, such as cracks can also cause the flange surface sealing lax and strict. Flange leaks can not be ignored as human factors, such as partial installation of gaskets, partial pressure than partial tight tight, over the gasket design limits, and the uneven force in the process of flange fastening or two methods Lan center line offset, resulting in fake tight phenomenon are prone to leakage. Three eccentric multi-level seal butterfly valve 3 Leakage and leakage of the body The main reason for the leakage of the body is due to casting or forging defects in the valve manufacturing process, such as trachoma, porosity, cracks, etc., and the erosion of the fluid medium and gas Erosion is also a common cause of valve leakage. The principle and advantages of pressure with plugging: A principle of pressure with plugging The principle of pressure plugging is based on the liquid medium under dynamic conditions, the sealing mechanism of solid sealing material as the basic basis. Method is to install special equipment leak site, the use of sealing parts and special equipment formed between the chamber, the use of special high-pressure plastic injection tools will be injected into the chamber sealant, and filled the entire chamber space, the sealant squeeze The force is balanced with the pressure of the leakage medium, and a new sealing structure is established to block the passage of the leakage pores and block the leakage of the medium. 2 pressure seal advantages (1) does not require downtime or isolation of the system. (2) No pressure relief to the system. (3) Save a lot of energy and manpower. (4) greatly reduce the power loss caused by equipment isolation or downtime. (5) Reduce the social and economic losses.
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