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technical requirements for procurement of valves

2015/11/5      view:
One, general requirements
Valve specifications and categories, should be in line with the requirements of design documents
Valve type should be indicated on the basis of the national standard code requirements. If the enterprise standard, should indicate the type of the relevant instructions
Valve working pressure, requires more than the work of the pipeline pressure, without affecting the price of the premise, the valve can withstand the pressure should be greater than the actual pressure of the pipe, the valve should be able to withstand any side of the valve pressure value, without leakage; valve opening, the valve should be able to withstand two times the valve pressure
Valve manufacturing standards, should be based on the national standard number, if the enterprise standards, procurement contracts should be attached to corporate documents
Two, valve material
Valve material, due to the gradual use of gray cast iron pipe, the valve body material should be ductile iron, and indicate the actual physical and chemical test data of the grades and casting
Stem material, and strive to stainless steel stem (2CR13), large diameter valve should also be stainless steel embedded in the valve stem
Nut material, brass or cast aluminum with cast aluminum bronze, and the hardness and strength are greater than the stem
Stem bushing material, its hardness and strength are not greater than the stem, and in the water immersion conditions and the valve stem, the body does not form an electrochemical corrosion
Three, sealing surface material
Valve type, sealing and material requirements
Ordinary wedge type gate valve, copper ring material, fixed way, grinding methods should be described
Physical and chemical and hygienic inspection data of soft sealing gate valve, valve plate lining rubber material
Valve shall be marked with the valve body sealing cover material and the butterfly plate sealing surface material; their physical and chemical test data, especially rubber, health requirements, aging resistance, wear resistance; usually used acrylonitrile butadiene rubber and ternary ethylene propylene rubber, non doped with recycled rubber
Four, valve shaft packing
Due to the pipe network in the valve, usually open and close is not frequent, the requirements of the packing in a few years, the packing is not aging, long-term maintenance sealing effect
Valve shaft packing should also be under the frequent opening and closing, sealing effect of the good
In view of the above requirements, the valve shaft packing is not for life, or more than 10 years without replacement
If the need to replace the packing, the valve design should consider the situation of water pressure to replace the measures
Five, transmission gearbox
Box material and internal and external anti-corrosion requirements and body principles
Box should be sealed measures, after the assembly can withstand the 3 m water column of the water immersion
Hoist limit devices on the box, the adjustment nut should be in the box body
Transmission structure design is reasonable, open and close can only drive the valve shaft rotation, does not make it up and down to move, the transmission parts of the appropriate, does not produce a load and when the separation of the separation
The transmission box and the valve shaft seal can not be connected to the whole, otherwise there should be reliable leakage prevention measures
There is no debris in the box body, and the gear bite part should be lubricated.
Six, valve operating mechanism
Valve operation, the opening and closing direction, all should be clockwise closing
Due to pipe network in the valve, often manually opening and closing, opening and closing speed should not be too much, is large-diameter valves should also be in the 200-600 turn in
In order to facilitate opening and closing operation of a person, the plumber pressure conditions, the maximum torque should open and close to 240mm
The valve opening and closing operation should end mortise and tenon, and the size standard, and for the ground, so that people can be directly manipulated from the ground. The valve is not suitable for the underground pipe network
If the valve buried deeper, the operating mechanism and display disc from the ground distance is more than or equal to 15m, extension bars are arranged facilities, and stability in prison so that people from the ground observation and operation. In the case of the valve opening and closing operation of the network, not to the next well
Seven, the valve opening and closing of the display panel
Valve opening and closing level of the calibration line, should be cast in the transmission cover or the direction of the display panel of the display, all face to the ground, scale line brush on the fluorescent powder, to show striking
Indicates that the material of the plate needle can be used in the case of better management. Otherwise, it will not be used in the case of the paint.
Indicating that the disc is striking and fixed firmly, and once the opening and closing adjustment is accurate, it should be locked by the rivet
Eight, the valve a specification of the bulk manufacturing, should be entrusted to the authority of the organization for the following performance testing
Valve opening and closing torque under pressure
Under the condition of working pressure, the valve can be closed tightly closed.
Detection of flow resistance coefficient of valve in the pipe flow
Nine, the valve should be carried out before the following detection
Valve in the open state, the valve should be under the pressure of two times the valve pressure test
Valve in the closed state, the two sides were subjected to 1.1 times the valve pressure value, no leakage; but the metal sealing butterfly valve, leakage value is not greater than the relevant requirements
Ten, valve internal and external corrosion
The valve body (including the variable speed transmission box) inside and outside, at first, blasting sand blasting, seek non-toxic powder electrostatic spraying epoxy resin, thickness of 0.3mm. Large type electrostatic spraying non-toxic epoxy resin has a difficult time, should also be painted, similar to the non-toxic epoxy paint
Valve body and valve plate all parts require a comprehensive anti-corrosion, on the one hand immersed in water will not rust, in the two kinds of metal does not produce electrochemical corrosion; the surface of the two smooth so that the water resistance to reduce
The health requirements of the epoxy resin or paint in the body of the valve body shall be the examination report of the relevant authorities. Chemical physical properties should also be in accordance with the relevant requirements
Eleven, valve packaging transportation
Valve should be located on both sides of light blocking plate fixation
In, small caliber valve should be tied to rope, and transportation to the container as appropriate
Large diameter valves are also simple wooden frame retention package, to avoid collision damage during transport