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.
1, General requirements
Valve specifications and categories should be consistent with the requirements of the pipeline design documents.
Valve model should be marked on the basis of the national standard number requirements. If the enterprise standard, should indicate the relevant description of the model.
Valve working pressure, working pressure ≥ pipe, without affecting the price under the premise of the valve can withstand the working pressure should be greater than the actual working pressure pipe; valve closed condition on either side should be able to withstand 1.1 times the value of valve work Without leakage; the valve is open, the valve body should be able to withstand the pressure twice the valve requirements.
Valve manufacturing standards should be based on the national standard number, if the enterprise standards, procurement contracts should be accompanied by corporate documents.
2, the valve material
Valve body material, ductile iron should be the main, and indicate the grades and cast iron actual physical and chemical testing data.
Stem material, and strive to stainless steel stem (2CR13), large-diameter valve should also be stainless steel embedded valve stem.
Nut material, the use of cast aluminum brass or cast aluminum bronze, and the hardness and strength are greater than the stem.
Valve 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. Sealing surface material
â‘ different types of valves, sealing methods and material requirements vary;
â‘¡ ordinary wedge gate valve, copper ring material, fixed way, grinding methods should be described;
â‘¢ soft seal gate valve, valve lining rubber material physical and chemical and health testing data;
â‘£ butterfly valve should be marked on the valve body sealing surface material and the sealing material on the disc; their physical and chemical testing data, especially the rubber hygiene requirements, anti-aging properties, wear resistance; usually nitrile rubber and EPDM Rubber, etc., is strictly prohibited mixed with recycled rubber.
Valve shaft packing
â‘ due to the valve in the pipe network, usually not frequently open and close, requiring filler inactivity within a few years, the filler is not aging, long-term sealing effect;
â‘¡ valve shaft packing should also withstand frequent opening and closing, the sealing effect of the good;
â‘¢ In view of the above requirements, the valve shaft filler for life or do not change for more than 10 years;
â‘£ If the packing needs to be replaced, the valve design should consider the measures that can be changed under the condition of water pressure.
3, gearbox
Cabinet material and internal and external corrosion requirements and the same principle of the valve body.
Enclosure should be sealed, the box assembly can withstand the 3 m water column status soak.
Opening and closing of the box limit device, the adjustment nut should be in the box or set in the box, but need special tools to work.
Transmission structure design is reasonable, when opening and closing can only drive the valve shaft to rotate, do not make it move up and down, transmission parts bite moderate, do not produce separation and sliding with load hoist.
Transmission gearbox and valve shaft seal can not be connected into a whole without leakage, otherwise there should be anti-stringing measures can be implemented. No debris inside the box, gear meshing parts should be grease protection.
4, the valve operating mechanism
Valve opening and closing direction of operation, should be closed clockwise.
As the network of valves, often manual opening and closing, opening and closing rotation should not be too much, that is, large-diameter valves should be within 200-600 turn.
In order to facilitate a person's opening and closing operations, in the plumbing conditions, the maximum opening and closing torque should be 240N-m.
Valve opening and closing operation end 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.
Valve opening and closing of the display panel
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 in the management of better available stainless steel plate, otherwise painted steel, do not use aluminum production;
â‘¢ indicates that the needle plate eye-catching, fixed prison *, once the opening and closing adjustment is accurate, should rivet lock.
5, the valve performance testing
When a valve is manufactured in a batch of specifications, the authoritative agency shall be entrusted to conduct the following performance tests:
â‘ valve opening and closing moment under the conditions of work pressure;
â‘¡ in the working pressure conditions, to ensure that the valve closed tight opening and closing times;
â‘¢ valve in the pipeline under the water flow resistance coefficient of detection.
The valve should be tested at the factory as follows:
â‘ valve in the open condition, the valve body pressure should withstand twice the pressure test;
â‘¡ closed the valve, both sides were 1.1 times the valve pressure, no leakage; but the metal seal butterfly valve, the leakage value is not greater than the relevant requirements.
6, the valve inside and outside corrosion
Valve body (including variable speed transmission box) inside and outside, the first shot blasting sand rust, and strive to electrostatic spray powder solvent-free epoxy resin, the thickness of 0.3mm or more. Extra large valve electrostatic spray solvent-free epoxy resin is also difficult, it should be brushing, spraying similar solvent-free epoxy paint.
All parts of the valve body as well as the valve plate requires full corrosion protection. On the one hand, it will not be eroded when immersed in water. Electrochemical corrosion will not occur between the two metals; on the other hand, the smoothness of the surface will reduce the over-water resistance.
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.
7, the valve packaging and transportation
Valve should be set on both sides of light blocking plate solid seal.
Medium and small-diameter valves should be tied with straw, and transported by container is appropriate.
Large-caliber valve basically wooden structure positioning valve, easy to transport and protect the valve
In order to better with the use of the valve, the valve operating mechanism selection is essential, which requires the valve manufacturers to filter out a better supplier
Suzhou Sidade Mechanical Control Co., Ltd. has a complete set of valve supporting solutions, professional design and production of valve drives (worm gear boxes, gear boxes), perennial exports to the Middle East, Russia, Spain, and many European countries, but also Secco Valves, nuclear Su valve, Neway valves, Flowserve and many other large valve companies supplier.
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