Valve procurement is only a clear specification, type, work pressure to meet the procurement requirements on the practice of a market economy in the current environment is not perfect. Because the valve manufacturers for products, competition, each valve were unified design concept, innovation differently, forming their own company standards and product personality. Therefore, the valve procurement made a more detailed technical requirements, coordinating with manufacturers to reach a consensus, as the valve procurement annex to the contract is very necessary.
1. General Requirements
1.1 valve size and type of pipe should be consistent with the requirements of design documents.
1.2 Valve model should be specified based on the GB number required. If the enterprise standards, should be specified models for instructions.
1.3 valve job pressure ≥ pipeline working pressure, without affecting the price under the premise of the valve can withstand the public pressure should be greater than the actual working pressure pipelines; valve closed position, or any side should be able to withstand 1.1 times the value of the valve working pressure without leakage; the valve open position, the valve should be able to withstand twice the working pressure valve requirements.
1.4 valve manufacturing standards, should indicate the basis of the national standard number, if the enterprise standards, procurement contracts shall be attached to business documents.
2. Valve-standard quality
2.1 The valve body material should be ductile iron-based, and indicate the actual grade and the cast iron the physical and chemical test data.
2.2 stem material, and strive to stainless steel stem (2CR13), large diameter valves also should be embedded in the package of stainless steel stem.
2.3 nut material, brass or cast aluminum with cast aluminum bronze, and the hardness and strength are greater than the stem.
2.4 Stem bushing material, its hardness and strength shall be not more than stem, and in the water-soaked conditions and the valve stem, valve did not form a electrochemical corrosion.
2.5 sealing surface of the material: ① different valve type, sealing methods and materials require different; ② Ordinary wedge gate valve, copper rings of material, fixed method, grinding method should show; ③ soft sealing gate valve, valve plate Lining Material Physical Chemistry and health testing data; ④ valve should be marked on the sealing surface of valve body materials and sealing surface material butterflies board; their physical and chemical test data, especially in rubber health requirements, anti-aging properties, wear resistance performance; usually nitrile rubber and EPDM rubber, recycled plastic mixed with strictly prohibited.
2.6 valve shaft packing: ① As the pipe network in the valves, usually do not open and close frequently, requiring the filling in a few years of inactivity, filler is not aging, long-term effects remain sealed; ② fill valve shaft should also bear the frequent Kai closed, the sealing effect of the good; ③ light of the above requirements, fill valve shaft for life does not seek to change or 10 years without replacing them; ④ For packing replacement, the valve should be designed to have a situation of pressure change measures.
3. Speed gearbox
3.1 box and the internal and external anti-corrosion material requirements and body principles.
3.2 The cabinet should be sealed measures assembled box can withstand 3 meters on water-immersion.
3.3 The cabinet on hoist limit devices, adjustment of nuts should be located in cabinets or boxes outside, but special tools need to be operating.
3.4 Drive structural design is reasonable, open and close valves can only be driven axis, not from top to bottom so that it ran a modest bite transmission parts, does not produce when the separation skid with a load hoisting.
3.5 Variable Speed Drive Cabinet Office with the valve shaft seal is not linked into the overall leak-free, or string should be a reliable anti-leakage measures.
3.6 cabinets without debris, the gear meshing parts of grease should be protected.
4. Valve operating mechanism
4.1 Valve operation of the hoist direction should always be clockwise closing.
4.2 As the pipe network of valves, often manual hoist, hoist a few should not be too much to switch, that is, large-diameter valves should also be within the 200-600 turn.
4.3 In order to facilitate a person's open and close operation, pressure conditions in the plumber, the biggest might be desirable for hoisting torque 240N-m.
4.4 The valve should open and close operation of client side tenon, and the size of standardization, and facing the ground so that people can be directly manipulated from the ground. With a wheel valve does not apply to underground pipe network.
4.5 degree of the valve open and close the display plate: ① the valve open and close degree of scale-line should be cast in the gearbox cover or change the direction of the shell plate after the show, the all facing the ground, scale wire brush on the phosphor to show eye-catching; ② direct dial & hand in the management of the materials available under better circumstances stainless steel plate, otherwise the painting of the steel plate, not to use aluminum leather production; ③ direct dial & hand eye-catching, fixed solid, once open and close and accurate adjustment After the rivet should be locked.
4.6 If the valve buried deep, operating mechanism and display the distance ≥ 1.5m from the ground plate, the pole should have added facilities, and secure a fixed so that people from the ground observation and operation. In other words, pipe network in the valves open and close operation, should not work underground operations.
5. Valve performance testing
5.1 valve of a standard high-volume manufacturing, the authoritative body should be entrusted to make the following performance test: ① valve pressure conditions in the work of hoisting torque; ② pressure conditions in the industry can ensure the valve closes tightly continuous Kai closing times; ③ water valve in the pipeline resistance coefficient of flow conditions testing.
5.2 The valve should be carried out before leaving the factory the following test: ① the valve in the open position, the valve should withstand twice the value of the valve working pressure of the internal pressure test; ② valve closure situation, both sides were to withstand 1.1 times the the value of working pressure valve, no leakage; but metal sealed butterfly valve, leakage value is not greater than the relevant requirements.
6. Valve's internal and external corrosion
6.1 Body (including the variable speed transmission box) inside and outside, we should first shot blasting sand blasting, and strive to electrostatic spraying epoxy resin powder non-toxic, thickness of 0.3mm or more. Large non-toxic epoxy electrostatic spray valves have difficulties, they should do brushing, spraying a similar non-toxic epoxy paint.
6.2 Valve and valve plate all parts of the house for a full anti-corrosion, on the one hand immersed in water will not rust, in between the two metals does not produce the electrochemical corrosion; two areas over the water resistance of a smooth surface to decrease.
6.3 The valve body paint anti-corrosion epoxy resin or health requirements, there should be the appropriate authority of the organs of test report. Chemical physical properties should also meet the relevant requirements.
7. Valve Packing, Transport
7.1 The valve should be located on both sides of light blocking plate solid seal.
7.2, the small-caliber valve should be bundled straw, and transported in suitable containers.
7.3 The large-diameter valves are also simple framework for solid wood packaging, so as to avoid damage during transport in touch.
8. Valve factory specifications
Valves are devices in the factory manual should indicate the following data: the valve specifications; model; work pressure; manufacturing standards; valve body material; stem material; sealing material; valve shaft packing material; stem sleeve material; inside and outside the anti-corrosion material; Action start direction; rpm; public pressure situations headstock moment; factory factory name; factory date; serial number; weight; connecting flange diameter, pore number, the center pitch; with graphic images indicate overall length, width and height of the control size; valve flow resistance coefficient; effectively open and close times; valve factory testing data and installation, maintenance for attention.
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