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 Cabinet on the hoist limit devices, adjustment of nuts or cabinets should be located in 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.