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Buy Valves Specification

Buy valves Specification

First, General requirements for

1, valve sizes and types shall comply with the requirements of design documents

2, valve part number should be indicated based on the national standard numbering requirements. If the enterprise standards, indicate the type of note

3, working pressure of the valve, required above the operating pressure of the pipeline, without affecting the price of the premise, the valve can withstand working pressure should be greater than the actual working pressure of valve closing conditions on either side should be able to withstand pressure value for 1.1 times the valve without leakage; condition of valve opening, valve shall withstand twice times the valve operating pressure requirements

4, the valve manufacturing standards, should indicate the basis of the standard number, if the enterprise standards, procurement contracts shall be attached to the enterprise files on

Second, the valve material

1, valve material, as grey cast iron pipe gradually deprecated, body material should be mainly ductile cast iron, and indicate the brand and casting actual physical and chemical data

2, the valve stem material, to stainless steel stem (2CR13), maintenance of large diameter valves should be embedded in the package of stainless steel valve stem

3, nut material, made of cast brass or cast aluminum bronze, and hardness and strength are greater than valve stem

4, the valve stem bushing material, hardness and strength shall be not more than the stem and water immersion condition and valve stem, valve does not form an electrochemical corrosion

Third, the sealing surface of the material

Category 1, valves, seals and materials with different demands

2, General wedge gate valve, brass ring material, fixed descriptions should be the way, the lapping

3, soft sealed floodgate valve, valve plate rubber lining material of physical-chemical and health inspection data

4, butterfly's valve should be marked on the valve body sealing surface material and seal the surface material on the disc; their physico-chemical data, especially rubber sanitary requirements, ageing resistance, good abrasion resistance; usually in small clear rubber and EPDM rubber, no mixing with recycled plastic

Four, valve shaft packing

1, because the valve in the pipe network is usually open and close frequently requires packing within a few years of inactivity, fill not aging, long-term sealing effect

2, when the axle of the valve filler should withstand frequent opening and closing, good sealing effect

3, in view of the above requirements, valve shaft packing to life does not change, or more than 10 years without replacement

4, filler replacement, valve design shall take into account measures can be changed under the condition of pressure

Five speed gearbox

1, box material and internal and external corrosion protection requirements consistent with the principles of the valve body

2, box sealing measures, after the box Assembly can withstand immersion 3 m water column conditions

3, box on the opening and closing limit device, the adjusting nut should be in the box body

4, transmission design and reasonable structure, open and close only when driven shaft rotation, does not make it bounce up, transmission parts occlude moderation, without a hoist with load-time separation skid

5, the transmission box is not connected with the valve shaft seal leak-free whole, otherwise reliable leak-proof measures

6, cabinets free of debris, grease gear occlusal parts protection

Six, valve operating mechanism

1, valve operation opening and closing directions, clockwise to close

2, because the valve in the pipe network, is often a manual opening and closing, opening and closing speed should not be too much, is a large diameter valves should also be within the 200-600

3 opening and closing operations, in order to facilitate a person, in relation to pipelines under pressure, maximum torque suitable for 240m-m

4, gate valve operation should end Tenon size standardization, and for the ground so that people can operate directly from the ground. Valves with Roulette does not apply to underground pipe network

5, if the valve is buried deeper, operators and show off the ground distance ≥ 15m, extension Rod facilities should be established, fixed and secure, so that people from the observation and operations on the ground. That is, the gate valve in the pipe network operation, should not be logging operations