How to choose a high quality electric ball valve


Electric ball valve procurement only clear specifications, categories, work pressure to meet the procurement requirements of the practice, in the current market economy is not perfect. Because the electric ball valve manufacturers in order to product competition, each in the electric ball valve under the unified design of the concept, different innovations, the formation of their own corporate standards and product personality. Therefore, it is necessary to put forward the technical requirements in more detail when purchasing electric ball valves, coordinate with manufacturers to obtain consensus, as an annex to the electric ball valve procurement contract.


  1. General requirements


  1.1 Electric ball valve specifications and categories, should be in line with the requirements of the pipeline design documents.


  1.2 The model number of electric ball valve should indicate the national standard number requirement based on. If it is a corporate standard, the relevant description of the model number should be indicated.


  1.3 Electric ball valve working pressure, required ≥ the working pressure of the pipeline, without affecting the price, electric ball valve can withstand the working pressure should be greater than the actual working pressure of the pipeline; electric ball valve closed condition of either side should be able to withstand 1.1 times the electric ball valve working pressure value without leakage; electric ball valve open condition, the valve body should be able to withstand two times the electric ball valve working pressure requirements.


  1.4 Electric ball valve manufacturing standards, should state the national standard number based on, if it is a corporate standard, the procurement contract should be attached to the corporate documents.

  2. Variable speed transmission box


  2.1 Box material and internal and external anti-corrosion requirements are consistent with the valve body principle.


  2.2 The box body should have sealing measures, the box body can withstand the immersion of 3 meters water column condition after assembly.


  2.3 The box body on the opening and closing limit device, its adjustment nut should be in the box or located outside the box, but special tools are required to work.


  2.4 Drive structure design is reasonable, open and close can only drive the valve shaft rotation, not to make it up and down, drive parts bite moderate, not to produce with load open and close when the separation of slippage.


  2.5 Variable speed transmission box body and valve shaft seal can not be connected into a leak-free whole, otherwise there should be a reliable anti-string leakage measures.


  2.6 No debris in the box, gear bite parts should be protected by grease.


  3. Electric ball valve standard quality


  3.1 Valve body material, should be mainly ductile iron, and specify the brand name and the actual physical and chemical test data of cast iron.


  3.2 stem material, strive to stainless steel stem (2CR13), large diameter electric ball valves should also be stainless steel embedded stem.


  3.3 Nut material, using cast aluminum brass or cast aluminum bronze, and hardness and strength are greater than the stem.


  3.4 stem bushing material, its hardness and strength should be no greater than the stem, and in the case of water immersion and the stem, the valve body does not form electrochemical corrosion.


  3.5 sealing surface material: ① electric ball valve categories vary, sealing methods and material requirements vary; ② ordinary wedge gate valve, copper ring material, fixed way, grinding method should be described; ③ soft seal gate valve, valve plate rubber lining material physicochemical and health testing data; ④ butterfly valve should indicate the sealing surface material on the valve body and the sealing surface material on the butterfly plate; their physicochemical testing data, especially the rubber health Requirements, chemical performance, wear resistance; usually using nitrile rubber and EPDM rubber, etc., is strictly prohibited to adulterate with recycled rubber.


  3.6 spool packing: ① due to the electric ball valve in the pipe network, usually open and close infrequently, the packing is not required in a few years, the packing is not aging, long-term sealing effect; ② spool packing should also withstand frequent opening and closing, the good sealing effect; ③ in view of the above requirements, the spool packing strive not to change or more than ten years not to replace; ④ packing if you need to replace, electric ball valve design should consider the water pressure can be The replacement measures under the condition of water pressure.


  4. Electric ball valve performance testing


  4.1 electric ball valve a specification batch manufacturing, should be entrusted to authoritative institutions to carry out the following performance testing: ① electric ball valve in the working pressure of the opening and closing torque; ② in the working pressure, can ensure that the electric ball valve closed tight continuous opening and closing times; ③ electric ball valve in the pipeline under the condition of the detection of the flow resistance coefficient.


  4.2 electric ball valve in the factory should be the following tests: ① electric ball valve in the open condition, the valve body should be subjected to electric ball valve pressure value two times the internal pressure test; ② electric ball valve in the closed condition, both sides are subjected to 1.1 times the electric ball valve pressure value, no leakage; but metal sealed butterfly valve, leakage value is not greater than the relevant requirements.


  5. Electric ball valve operating mechanism


  5.1 The opening and closing direction of the electric ball valve should be closed clockwise.


  5.2 As the electric ball valve in the pipeline network, often manually open and close, open and close the number of revolutions should not be too much, is a large diameter electric ball valve should also be within 200-600 revolutions.


  5.3 In order to facilitate the opening and closing operation of a person, in the pipeline pressure condition, the opening and closing torque should be 240N-m.


  5.4 The opening and closing operation end of the electric ball valve should be square and standardized in size, and face the ground so that people can operate directly from the ground. The electric ball valve with wheel is not suitable for underground pipeline network.


  5.5 electric ball valve opening and closing degree of the display plate: ① electric ball valve opening and closing degree of the scale, should be cast in the gearbox cover or switch the direction of the display plate on the shell, all facing the ground, the scale line brush fluorescent powder, to show eye-catching; ② indication of the plate needle material in the case of better management available stainless steel plate, otherwise painted steel plate, do not use aluminum skin production; ③ indication of the plate needle eye-catching, fixed securely, once the opening and closing adjustment is accurate. Once the opening and closing adjustment is accurate, should be locked with rivets.


  5.6 If the electric ball valve is buried deeper, the operating mechanism and display disk from the ground distance of ≥ 1.5m, should be equipped with extension pole facilities, and fixed stable and firm, so that people from the ground to observe and operate. It is also said that the electric ball valve opening and closing operation in the pipe network, should not be down the well operation.


  6. Electric ball valve packaging and transportation


  6.1 Electric ball valve should be set up on both sides of the light blocking plate fixed seal.


  6.2 Medium and small diameter electric ball valves should be bundled with straw ropes and transported in containers is appropriate.


  6.3 Large diameter electric ball valves also have a simple wooden frame solid packaging to avoid damage during transportation.


  7. Electric ball valve internal and external anti-corrosion


  7.1 Valve body (including variable speed transmission box body) inside and outside, first of all, should be shot blasting and sand removal, and strive to electrostatic spraying powder epoxy resin, thickness of 0.3mm or more. When there is difficulty in electrostatic spraying epoxy resin for extra-large electric ball valves, it should also be brushed and sprayed with similar epoxy paint.


  7.2 Valve body internal and various parts of the valve plate require comprehensive anti-corrosion, on the one hand, immersed in water will not rust, between the two metals do not produce electrochemical corrosion; two aspects of the surface is smooth so that the water resistance is reduced.


  7.3 valve body anti-corrosion epoxy resin or paint health requirements, there should be a corresponding test report. Chemical physical properties should also meet the relevant requirements.


  8. Factory instructions for electric ball valves


  Electric ball valve is equipment, the factory manual should indicate the following relevant data: electric ball valve specifications; model; working pressure; manufacturing standards; valve body material; stem material; sealing material; valve shaft packing material; stem sleeve material; internal and external anti-corrosion material; operation start direction; number of revolutions; working pressure opening and closing torque; manufacturer's name; factory date; factory number; weight; connecting flange aperture, the number of holes, center hole distance; to The number of holes, the center hole distance; the overall length, width and height of the control dimensions; electric ball valve flow resistance coefficient; effective opening and closing times; electric ball valve factory test data and installation, maintenance considerations, etc.