The bell-type safety valve used in the complete set of production line equipment in our country are all supplied with complete sets of equipment. The users reflect large amount of leakage, inconvenient maintenance and replacement, and are expensive. The development of complete sets of equipment supporting safety valve, both for users save money, to solve worries, but also for our factory to create a new safety valve products to find a new path. 1, the structural analysis of the user to provide the original structure of the three different safety valves, in accordance with GB 12243? 89 "spring direct load relief valve" for setting pressure, sealing and mechanical properties of the project test, the results of three kinds of safety valve setting pressure Deviations are in line with the requirements, flexible action, no jamming, good mechanical properties, but the sealing is poor, the number of bubbles per minute were 480,455 and 265, respectively, the amount of leakage exceeded the provisions of the national standard 10 times. To find out the cause of the leak, we analyzed its structure. This type of safety valve consists of valve body, valve seat, valve flap, guide sleeve, bell jar, valve stem, spring and bonnet and other major components, Bell form bell, bell and recoil plate, Import and export of the same diameter, an export than the import amplification 1, and amplification of 2 or more, the parts processing precision, valve cavity cleanliness. But the flap (Figure 1a) is thinner, with a minimum of 2.5 mm and a low hardness (HRC <30), which can easily deform and wear due to hot take-off and cause leakage. Figure 1 disc structure 2, improvement and trial For the heat deformation of the leakage problem, after repeated comparative tests, improved the original safety valve sealing structure, the valve flap and guide block into one, the cone seal to a flat seal, an increase of Disc thickness, and in the valve seat and disc sealing surface welding cobalt-based hard alloy, in order to improve the sealing surface of the temperature performance and surface hardness to solve the problem of leakage of heat deformation, improved valve structure shown in Figure 1b. According to the installation size of the complete set of equipment and performance parameters, the first trial of two varieties, three specifications a total of seven flat seal safety valve, the applicable medium is biphenyl plus diphenyl ether, the working temperature is less than or equal to 330 ℃, opening pressure, respectively 0.45 MPa, 0.55 MPa and 1.2 MPa. Installed in a production line for 123 days of continuous trial, remove the maintenance shutdown when the opening pressure and tightness test, the results shown in Table 1. The data in the table shows that the batch of safety valves tested, the opening pressure and the sealing performance meet the requirements of national quality standards. Table 1 test results 3, to promote the application of improved trial after the success of the plant on the safety valve equipment and gradually transformed. By the end of 1992, all the original safety valves on the production line of the plant were completely replaced with safety valves manufactured by our factory. After 2 years of operation, all safety valves operated stably, opened sensitively, sealed well and found no abnormalities. Saving for the plant to buy foreign exchange safety valve costs (equivalent to more than 180 million yuan), but also for my factory safety valve product quality plays a reference and promote the role.
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