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Purchasing antiseptic valve to consider necessary factors
Purchasing antiseptic valve to consider the necessary technical factors
When purchasing valves only clear specification, type, working pressure will meet the requirements of the procurement practice, in the current market economy, the environment is not perfect. Because the valve manufacturers in order to the product competition, each valve are in uniform design concept, carries on the different innovation, formed their enterprise standard and product personality. So in the valve when purchasing a detailed out technology requirements, and manufacturers coordination consensus has been reached, the procurement contract as valve attachment is very necessary.
1. General requirements
1.1 the valve specifications and categories, shall conform to the requirements of the pipeline design documents.
1.2 the valve type shall be marked based on the gb Numbers requirements. If the enterprise standard, should indicate the type of relevant specification.
1.3 the valve working pressure, the requirement of pipe or work pressure, in does not affect the price of the premise, the valve can bear work pressure should be greater than the actual pipe work pressure; The valve closed condition of any side should be able to withstand 1.1 times the valve working pressure value without leakage, The valve opens conditions, the body should be able to withstand double valve working pressure requirements.
1.4 valve manufacturing standard, that should be based on the gb Numbers, if the enterprise standard, purchasing contract shall attach enterprise file.
2. Valve standard quality
2.1 body material, should with spheroidal graphite cast iron is given priority to, and indicate the brand and cast iron actual physical and chemical testing data.
2.2 stem material, and strive to stainless steel stem (2 cr13), large diameter valves should also is stainless steel panel bag stem.
2.3 nut material, using casting aluminium brass or cast aluminum bronze, and the hardness and strength are greater than the valve stem.
2.4 stem bushing material, its hardness and strength which shall be no greater than the valve stem, and in the water soak conditions and valve stem, valve body do not form electrochemical corrosion.
2.5 sealing surface material: (1) the valve type is differ, seal way and material requirements differ; (2) the common wedge gate valve, copper ring material, fixed mode, grinding mode shall explain; (3) soft-sealing gate valve, valve plate rubber lining material of physical chemistry and health inspection data; (4) the butterfly valve sealing surface should be marked on the body material and butterfly plate on the sealing surface material; Their physical and chemical inspection data, especially rubber health requirements, ageing resistance, wear resistance, Usually the butadiene acrylonitrile rubber, epdm, etc., it is strictly prohibited to mixed with reclaimed rubber.
2.6 valve shaft packing: (1) due to the network in the valve opening and closing, usually is not frequent for packing in a number of years don't activities, packing or aging, long-term keep seal effect; (2) the valve shaft packing should also be under frequent opening and closing, seal effect good sex; (3) in view of the above requirements, valve shaft packing to life don't change or more than ten years not to change; (4) packing if need to change, the valve design should consider to have hydraulic pressure change under the condition of the measures.
3. Variable speed drive box
3.1 the inside and outside material and anticorrosion requirements and body principles.
The 3.2 should seal measures, housing after assembly can withstand the 3 meters water column status of soak.
3.3 the opening and closing the limit device, the adjustment nut should be in the cabinet or in the box, but need special tools to work.
3.4 drive structural design is reasonable, the opening and closing can drive the valve spindle rotation, don't make it up and down there still, transmission parts bite measurable, do not produce loading when opening and closing separation skid.
3.5 variable speed drive housing and valve shaft seal not linked to no leakage of the whole, or should have reliable anti string leakage measures.
3.6 the cabinet without sundry, gear bite site should have grease protection.
4. The valve operating mechanism
4.1 the valve opening and closing operation of the direction, all should be clockwise closed.
4.2 due to the network in the valve, often is artificial opening and closing, open the revolution is unfavorable and overmuch, large diameter valves should also be in 200-600 in turn.
4.3 in order to facilitate a person's opening and closing operation, the plumber pressure condition, the biggest opening and closing moment appropriate for 240 n - m.
4.4 the valve opening and closing operation end should be party tenon, and size of standardization, and to the ground, so that people from the ground can direct operation. Belt wheel disc valve does not apply to the underground pipe network.
4.5 the valve opening and closing degree of display panel: (1) the valve opening and closing degree of scale line, should be cast in gearbox cover or the transformation direction after the display panel shell, are facing the ground, scale line brush on fluorescent powder, in order to show marked; (2) the indicator panel needle material in the management of the good use of stainless steel plate, or to brush paint of steel, do not use the aluminum skin production; (3) indicator panel needle striking, fixed firm, once the on-off control accurate, should with rivet lock.
4.6 if the valve buried deep, operating mechanism and display panel from the ground distance was 1.5 m, should have lengthening bar facilities, and fixed firm prison, so that people from the face of the earth observation and operation. That is to say, the pipeline valve opening and closing operation, not the well operation.
5. Valve performance testing
5.1 the valve a specification batch manufacturing, should entrust authority institution for the following properties test: (1) the valve working pressure condition of opening and closing moment; (2) in the working pressure condition, can guarantee the valve closed tight continuous opening and closing times; (3) the valve in the pipeline condition of flow resistance coefficient detection.
5.2 the valve in the factory should be done before the following test: (1) the valve in open conditions, the body should bear the valve working pressure value two times of the internal pressure detection; (2) the valve closed conditions, respectively 1.1 times on both sides under the valve working pressure value, no leakage, But the metal sealing butterfly valve, leakage is not greater than the value requirements.
6. The valve inside and outside corrosion
6.1 the body (including variable speed drive housing) inside and outside, first of all should be blast cleaning rust removal, and strive to electrostatic spraying powder non-toxic epoxy resin, thickness of 0.3 mm above. Large valve electrostatic spraying non-toxic epoxy resin is in difficulty, should also be brush, spraying similar non-toxic epoxy paint.
6.2 inside of the body and valve plate parts for comprehensive anticorrosive, on the one hand, soaking in the water will not rust, in between two metal do not produce electrochemical corrosion; Two aspects of smooth surface that reduce water resistance.
6.3 the body anti-corrosive epoxy resin or paint health requirements, should have corresponding authorities inspection report. Chemical physics performance also should comply with the relevant requirements.
7. The valve packing and shipping
7.1 on both sides of the valve
