For a long time, most industries in the country have replaced the old ones with new ones and discarded or sold the replaced valves. In particular, multi-purpose with flange valve industry. The replacement of high pressure, high temperature, large valve to repair, but do not know how to repair. Most still remain in the manual repair phase. It can be said that China's valve repair industry, waste and available benefits are enormous. A power station (4x5omw ~ 4x2oomw) every year to repair tens of thousands of turbine valves and bypass valves. Power plant only 1 in 1992 from Germany into the el grinding machine, the rest are manual operation, not only inefficient, but also the accuracy of less than the requirements. Bypass high-pressure relief valve leakage, the power plant can not be repaired. Send to Shanghai maintenance effect is not satisfactory. In recent years, with the gradual start of independent economic accounting of various units and the reduction of costs, maintenance personnel from the management staff to the frontline are gradually realizing the importance of repairing valves because the funds saved in this area are extremely substantial. However, the repair valve here does not mean simple repairs, but also includes the use of the correct repair methods and excellent grinding repair equipment. Due to the lack of concept and equipment for valve repair and overhaul, at present, only nuclear power plants in China can basically do all overhaul of valves during each downtime. A bad repair is a kind of maintenance without maintenance, which is extremely unfavorable to the safe operation of a full set of equipment and the service life of the valve. The potential emergency shutdown accident is extremely dangerous and the resulting loss is huge . For example, a petrochemical plant in Tianjin has a full set of imported production facilities from Germany. Since its commissioning in 1981 to 1996, it has never been overhauled. In 1996, several key packing valve leaks were discovered at the time and German manufacturers no longer manufactured this Special valve, if re ordering. It is not only expensive, but also has a long lead-time and huge economic losses. Therefore, the preventive maintenance and repair measures of industrial high temperature and high pressure valves are the most economical and reliable way to solve the problem of valve leakage and extend the service life. If the valve in the case of maintenance without maintenance, once the leak, often already very serious damage, which not only increased the difficulty of repair, and often even have lost the possibility and value of maintenance. Therefore, for the organization and management of a sound valve repair work, not only the relevant personnel should have the appropriate awareness, but more importantly preventive measures and maintenance measures, that is, regular inspection of the valve (for example, the valve seal relative to the outside world, The valve is closed in the closed state, etc.). Preventive maintenance of the valve is the first valve found to leak, immediately repair the valve, because the circulation of medium even in the case of very small sealing surface damage, but also in a short time caused by the sealing surface Large area damage, resulting in expensive maintenance costs.