Procurement of valves should pay attention to what technical requirements: First, the valve specifications and categories should be consistent with the requirements of the pipeline design documents. 1, the type of valve should be marked on the basis of the national standard number requirements. If the enterprise standard, should indicate the relevant description of the model. 2, 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 working pressure should be greater than the actual working pressure of the pipeline; valve closed condition on either side should be able to withstand 1.1 times the valve work Pressure value, without leakage; valve open condition, the valve body should be able to withstand the pressure twice the valve requirements. 3, valve manufacturing standards should be based on the national standard number, if the enterprise standard, the procurement contract should be accompanied by corporate documents Second, choose the valve material: 1, the valve material, the gray cast iron pipe gradually not recommended, the valve body material should be mainly ductile iron, and indicate the actual physical and chemical testing of castings and castings. 2, stem material, and strive to stainless steel stem (2CR13), large-diameter valve should also be stainless steel embedded valve stem. 3, the 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 valve Rod, the valve body does not form electrochemical corrosion. 5, the sealing surface of the material ①different types of valves, sealing methods and material requirements vary; ② ordinary wedge gate valve, copper ring material, fixing methods, grinding methods should be described; ③ soft seal gate valve, valve lining rubber material Of the physical and chemical and health testing data; ④ 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, etc., is strictly prohibited mixed with recycled rubber. 6, the valve shaft packing ①due 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; ② valve shaft packing should withstand frequent opening and closing , The sealing effect of the good; In view of the above requirements, the valve shaft filler for life or do not change for more than ten years; Filler for replacement, the valve design should be considered under water pressure conditions to replace the measures. 3, gear box: 1, the material inside and outside the cabinet and anticorrosion requirements and 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. 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 valve shaft seal can not be connected into a whole without leakage. 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 operation, the plumbing pressure conditions, the maximum opening and closing torque should be 240m-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 ①valve 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 ; ② 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; ③ indicator needle needle eye-catching, fixed firmly, once the opening and closing adjustment is accurate, should be Rivet lock 6, If the valve is buried deep, the operating mechanism and the display panel from the ground distance ≥ 15m, should be equipped with additional rod facilities, and fixed firmly, so that people from the ground to observe and operate. In other words, pipe network valve opening and closing operation, should not go down to work. Fifth, the valve performance testing: 1, a batch of valves manufactured in a batch, authoritative agencies should be entrusted to the following performance testing: ①valve opening and closing moment under pressure conditions; ② Under the pressure conditions, to ensure that the valve Close the tight opening and closing times in a row; ③ valve in the pipeline water flow resistance coefficient of detection. 2, the valve should be carried out in the factory the following tests: ①valve in the open condition, the valve body should withstand pressure twice the internal pressure detection; ② valve in the closed condition, both sides to withstand 11 times the valve pressure Value, no leakage; but the metal seal butterfly valve, the leakage value is not greater than the relevant requirements VI, the valve inside and outside corrosion: 1, the valve body (including the transmission box body) inside and outside, the first shot blasting sand rust, and strive Electrostatic spray 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, valve packaging and transportation: 1, the valve should be set on both sides of the 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 retention packaging, in order to avoid collision damage during transport Eight, check the valve factory manual: 1, the valve is equipment, 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 material; Operation start direction; Factory name; factory date; factory number; weight; connecting flange aperture, the number of holes, the center of the hole pitch to indicate the overall length, width, height control size; effective opening and closing times; valve flow resistance coefficient ; Valve factory inspection of the relevant data and installation, maintenance precautions and so on.