Valve procurement only a clear specification, type, pressure to meet the procurement requirements of the practice in the current market economy environment is imperfect. Because the valve manufacturer in order to compete for the product, each in the valve under the concept of a unified design, different innovations, formed their own corporate standards and product personality. Therefore, when the valve procurement more detailed technical requirements, and manufacturers to obtain consensus, as the annex to the valve procurement contract is necessary. First, the general requirements 1, the valve specifications and categories should be consistent with the requirements of the pipeline design documents. 2, the valve model should be marked on the basis of GB number requirements. If the enterprise standard, should indicate the relevant description of the model. 3, the working pressure of the valve, the required working pressure of the pipeline, without affecting the price of the premise, the valve can withstand the pressure should be greater than the actual working pressure of the pipeline; the valve closed on either side should be able to withstand 1.1 times the valve Pressure without leakage; valve open condition, the valve body should be able to withstand the pressure twice the valve requirements. 4, valve manufacturing standards should be based on the national standard number, if the enterprise standards, procurement contracts should be accompanied by corporate documents. Second, the valve quality 1, the valve body material, ductile iron should be based, and indicate the grades and cast iron actual physical and chemical testing data. 2, stem material, and strive to stainless steel stem (2CR13), large-diameter valve should also be stainless steel embedded valve stem. 3, nut material, the use of cast aluminum brass or cast aluminum bronze, and the hardness and strength are greater than the stem. 4, stem bushing material, the hardness and strength should not be greater than the stem, and in the water soaking conditions with the stem, the valve body does not form electrochemical corrosion. 5, the sealing surface of the material â‘ different types of valves, sealing methods and material requirements vary; â‘¡ ordinary wedge gate valve, copper ring material, fixing methods, grinding methods should be described; â‘¢ soft seal gate valve, valve lining rubber material Of the physical and chemical and health testing data; â‘£ butterfly valve should be marked on the sealing material on the valve body and sealing material on the disc; their physical and chemical testing data, especially the rubber hygiene requirements, anti-aging properties, wear resistance; NBR and EPDM rubber, non-doped with recycled rubber. 6, the valve shaft packing â‘ due to the valve in the pipe network, usually not frequent opening and closing, requiring filler in a few years inactivity, packing is not aging, long-term sealing effect; â‘¡ valve shaft packing should withstand frequent opening and closing , The sealing effect of good; â‘¢ In view of the above requirements, the valve shaft filler for life or do not change for more than ten years; â‘£ packing to be replaced, the valve design should be considered under water pressure conditions to replace the measures. Third, the gear box 1, the material inside and outside the cabinet and the anticorrosive requirements of the same principles. 2, the box should be sealed, the box assembly can withstand 3 meters water column status soak. 3, the opening and closing limit on the box device, the adjustment nut should be in the box or located outside the box, but need special tools to work. 4, Transmission structure design is reasonable, when opening and closing can only drive the valve shaft to rotate, not to make it move up and down, transmission parts bite moderately, do not produce separation and slipping with load hoist. 5, variable speed transmission box and the valve shaft seal can not be connected into a whole without leakage, otherwise there should be reliable anti-stringing measures. 6, no debris inside the box, the gear occlusion should have grease protection. Fourth, the valve operating mechanism 1, the valve opening and closing direction of operation, should be closed clockwise. 2, due to the valve in the pipe network, often manual opening and closing, opening and closing speed should not be too much, that is, large-diameter valves should be within 200-600 turn. 3, in order to facilitate a person's opening and closing operations, the plumbing pressure conditions, the maximum opening and closing torque should be 240N-m. 4, the valve opening and closing operation side should be square tenon, and size standardization, and facing the ground, so that people can directly operate from the ground. Valves with wheels are not suitable for underground pipe networks. 5, the degree of opening and closing of the valve display â‘ valve opening and closing of the scale line, should be cast in the gearbox cover or switch the direction of the display after the shell, all toward the ground, the scale brush on the phosphor to show eye-catching ; â‘¡ indicating the material of the needle plate can be used in the case of better management of stainless steel plate, or painted steel, do not use aluminum production; â‘¢ indicating needle needle eye-catching, fixed firmly, once the opening and closing adjustment is accurate, should be Rivet lock. 6, If the valve is buried deeply, when the operating mechanism and display panel are more than 1.5m away from the ground, it shall be provided with extension rod facilities which are fixed and firm so that people can observe and operate from the ground. In other words, pipe network valve opening and closing operation, should not go down to work. Fifth, the valve performance testing 1, the valve specifications of a batch manufacturing, authoritative agencies should be commissioned for the following performance testing: â‘ valve opening and closing moment under the pressure conditions; â‘¡ Under the pressure conditions, to ensure that the valve is closed Tight continuous opening and closing times; â‘¢ valve in the pipeline water flow resistance coefficient of detection. 2, the valve should be carried out in the factory the following tests: â‘ valve in the open condition, the valve body pressure should withstand twice the pressure test; â‘¡ the valve is closed, both sides were 1.1 times the valve pressure Value, no leakage; but the metal seal butterfly valve, the leakage value is not greater than the relevant requirements. Six, the valve inside and outside corrosion 1, the valve body (including variable speed transmission box) inside and outside, the first shot blasting sand rust, and strive electrostatic powder non-toxic epoxy resin, the thickness of 0.3mm or more. Extra-large valve electrostatic spraying non-toxic epoxy resin difficulties, should also be brushing, spraying similar non-toxic epoxy paint. 2, all parts of the valve body and the valve plate requires a full anti-corrosion, on the one hand soaked in water will not rust, electrochemical corrosion between the two metals does not produce; two smooth surface to reduce the water resistance. 3, the body of the anti-corrosion epoxy resin or paint the health requirements, there should be the corresponding authority of the test report. Chemical and physical properties should also meet the relevant requirements. Seven, the valve packaging and transportation 1, the valve should be set on both sides of light blocking plate solid seal. 2, medium and small-diameter valves should be tied with straw, and transport by container is appropriate. 3, large-diameter valves are also simple wooden frame solid packaging, in order to avoid collision damage during transport. Eight, the valve factory instructions The valve is also a device, the factory manual should be marked with the following relevant data: Valve Specifications Model; Working pressure; Manufacturing standards; Body material; Stem material; Sealing material; Stem packing material; Stem sleeve Material; inside and outside the anti-corrosion materials; Start the direction of operation; Revolutions; Opening and closing torque under conditions of work pressure; Factory name; Date of manufacture; Factory serial number; Weight; Connecting flange aperture, hole number, Indicate the overall length, width and height control dimensions; valve flow resistance coefficient; the number of effective opening and closing; the valve factory inspection of the relevant data and installation, maintenance precautions and so on.
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