Purchasing anti-corrosion valve technical factor analysis to take you to understand the characteristics and advantages of directly buried valve

Purchasing anti-corrosion valve technical factor analysis to take you to understand the characteristics and advantages of directly buried valve

Analysis of technical factors for purchasing anti-corrosion valves
Valve procurement only clear specifications, categories, working pressure to meet the procurement requirements of the practice, in the current market economic environment is not perfect. Because the valve manufacturers in order to product competition, under the concept of unified valve design, different innovation, formed their own enterprise standards and product personality. Therefore, it is very necessary to put forward the technical requirements in detail when purchasing valves, and coordinate with manufacturers to obtain consensus as an annex to the valve procurement contract.
General requirements
1.1 Valve specifications and categories shall meet the requirements of pipeline design documents.
1.2 The model of the valve shall be indicated according to the national standard number requirements. If the enterprise standard, should indicate the relevant description of the model.
1.3 The working pressure of the valve requires the working pressure of the pipeline. On the premise of not affecting the price, the working pressure that the valve can bear should be greater than the actual working pressure of the pipeline; Valve closed condition any side should be able to withstand 1.1 times the valve working pressure value without leakage; Valve open condition, the valve body should be able to withstand twice the valve pressure requirements.
1.4 The manufacturing standard of the valve should be stated according to the national standard number. If the enterprise standard is used, the enterprise document should be attached to the purchase contract.
The valve standard quality
2.1 The body material shall be ductile iron, and the brand number and actual physical and chemical test data of cast iron shall be indicated.
2.2 Stem material, strive to stainless steel stem (2CR13), large diameter valve should also be stainless steel embedded stem.
2.3 The nut material is cast aluminum brass or cast aluminum bronze, and the hardness and strength are greater than that of the valve stem.
2.4 The hardness and strength of the stem bushing material shall be no greater than that of the stem, and it shall not form electrochemical corrosion with the stem and valve body under the condition of water immersion.
2.5 Material of sealing surface: ¢Ù valve types are different, sealing methods and material requirements are different; (2) ordinary wedge gate valve, copper ring material, fixing method, grinding method should be explained; (3) Soft seal gate valve, the physical chemistry and health testing data of the rubber lining material of valve plate; ¢Ü The butterfly valve should be marked with the sealing surface material on the valve body and the sealing surface material on the butterfly plate; Their physical and chemical testing data, especially rubber hygiene requirements, aging resistance, wear resistance; Usually used butyl rubber and three ethylene propylene rubber, etc., strictly prohibited mixing with recycled rubber.
2.6 Valve shaft packing: ¢Ù Because the valve in the pipe network is usually opened and closed infrequently, the packing is required to be inactive for several years, the packing is not aging, and the sealing effect is maintained for a long time; ¢Ú The valve shaft packing should also be under frequent opening and closing, the good sealing effect; (3) In view of the above requirements, the valve shaft packing strive not to replace or not to replace for more than ten years; ¢Ü If the packing needs to be replaced, the valve design should consider the replacement measures under the condition of water pressure.
Variable speed drive box
3.1 The body material and internal and external anticorrosion requirements are consistent with the valve body principle.
3.2 The box shall have sealing measures, and the box shall be able to withstand the immersion of 3 meters water column after assembly.
3.3 The opening and closing limit device on the box body, its adjusting nut should be in the box body or outside the box, but it needs a ** tool to work.
3.4 The design of transmission structure is reasonable. When opening and closing, the valve shaft can only be driven to rotate, without making it move up and down. The bite of transmission parts is moderate, and the separation slip when opening and closing with load is not produced.
3.5 Variable speed transmission box and valve shaft seal shall not be connected into a leak-free whole, otherwise reliable series leakage prevention measures should be taken.
3.6 There is no sundries in the box, and the bite part of the gear should be protected by grease.
Valve operating mechanism
4.1 When the valve is operated, the opening and closing direction should be clockwise.
4.2 Because the valve in the pipe network is often manually opened and closed, the opening and closing rotation should not be too much, even the large diameter valve should also be within 200-600.
4.3 In order to facilitate the opening and closing operation of one person, the maximum opening and closing moment should be 240N-m under the condition of plumber pressure.
4.4 The valve opening and closing operation end should be square and tenon, with standardized size, and face the ground, so that people can directly operate from the ground. Valve with wheel is not suitable for underground pipe network.
4.5 Display plate of valve opening and closing degree: ¢Ù the scale line of valve opening and closing degree should be cast on the gearbox cover or the shell of the display plate after the change of direction, all facing the ground, and the scale line should be brushed with phosphor to show eye-catching; (2) The material of the indicator plate needle can be used in the case of better management of stainless steel plate, otherwise it is painted steel plate, do not use aluminum leather production; ¢Û Indicating disc needle eye-catching, fixed firmly, once the opening and closing adjustment is accurate, should be locked with rivets.
4.6 If the valve is buried deep and the operating mechanism and display panel are 1.5m away from the ground, an extended rod facility should be provided and fixed firmly for people to observe and operate from the ground. That is to say, the pipe network in the valve opening and closing operation, not under the well operation.
Valve performance testing
5.1 When a specification of the valve is manufactured in batches, the following performance should be tested by the commissioning organization: ¢Ù the opening and closing moment of the valve under working pressure; ¢Ú under the condition of industrial pressure, it can ensure the continuous opening and closing times of the valve closed tightly; (3) Valve in the pipeline under the condition of water flow resistance coefficient detection.
5.2 The valve shall be tested as follows before leaving the factory: ¢Ù The valve shall bear the internal pressure test twice the working pressure value of the valve when the valve is opened; ¢Ú Under the closed condition of the valve, both sides bear 1.1 times the valve working pressure value, no leakage; But metal seal butterfly valve, leakage value is not greater than the relevant requirements.
Internal and external corrosion protection of valve
6.1 Inside and outside the valve body (including variable speed transmission box), the first thing should be shot blasting, sand and rust removal, strive to electrostatic spray powder non-toxic epoxy resin, thickness of more than 0.3mm. When it is difficult to electrostatic spray non-toxic epoxy resin on oversized valves, similar non-toxic epoxy paint should also be brushed and sprayed.
6.2 The inside of the valve body and all parts of the valve plate shall be anti-corrosion. On the one hand, it will not rust when immersed in water, and it will not produce electrochemical corrosion between the two metals; Two aspects of the smooth surface to reduce the water resistance.
6.3 For the sanitary requirements of the anti-corrosion epoxy resin or paint in the valve body, the inspection report of the corresponding authority shall be provided. The chemical and physical properties shall also meet the relevant requirements.
Valve packing and transportation
7.1 Both sides of the valve shall be sealed with lightweight blocking plates.
7.2 Medium and small caliber valves should be tied with straw rope and transported in containers.
7.3 Large diameter valves also have simple wooden frame solid packaging to avoid damage during transportation.
8. Valve factory instruction
Valves are equipment, the factory instructions should indicate the following relevant data: valve specifications; Model; Working pressure; Manufacturing standard; Body material; Valve stem material; Sealing material; Valve shaft packing material; Valve stem sleeve material; Internal and external anti-corrosion material; Operation start direction; Revolutions; Opening and closing moment under working pressure; Name of the manufacturer; Date of delivery; Factory serial number; Weight; Aperture, hole number, center hole distance connecting flange; The control dimensions of overall length, width and height are indicated graphically; Valve flow resistance coefficient; Effective opening and closing times; Relevant data of valve factory inspection and matters needing attention in installation and maintenance.
Take you to understand the characteristics and advantages of the directly buried valve with the adjustment and development of urban construction, buried under the road of various cables and pipelines gradually increase, crowded, difficult to layout. The traditional installation of pipe network valves is in a valve well on the road. When impact crushing cover, make a noise, often can’t flush valve display above and the road, affect traffic running turbulence, and the influence of urban landscape, manhole covers stolen frequently occur, will also cause person casualties, vehicle damage, such as safety accidents, the directly buried installation can avoid these problems, also will save investment.
An overview of the
With the adjustment and development of urban construction, various cables and pipelines buried under roads are gradually increasing, which are crowded and difficult to arrange. The traditional installation of pipe network valves is in a valve well on the road. When impact crushing cover, make a noise, often can’t flush valve display above and the road, affect traffic running turbulence, and the influence of urban landscape, manhole covers stolen frequently occur, will also cause person casualties, vehicle damage, such as safety accidents, the directly buried installation can avoid these problems, also will save investment.
In the foreign industrial developed countries, the pipe network valve has already adopted the direct buried way, where meets the standard requirements of the gate valve, can be directly buried without the valve well.
classification
Directly buried valve can be directly buried in the ground, without building inspection Wells, reducing the area of road excavation. Small well chamber can keep the road surface beautiful, reduce the difficulty of construction, save the project cost. The directly buried soft seal gate valve is divided into two kinds of telescopic and fine-tuning fixed, which is telescopic and metal plastic type.
In the construction process, the telescopic type can be adjusted arbitrarily in a wide range according to the distance between the buried depth of the valve and the ground, and the fine-tuning fixed type can be micro-adjusted on site.
Directly buried valve in the flow resistance is small, the internal medium channel of the valve body is straight through, the medium flows in a straight line, the flow resistance is small. In addition, the opening and closing of the more dynamic, compared with the globe valve, whether open or closed, the direction of the gate movement is perpendicular to the direction of medium flow.
advantage
The old residential community has a poor living environment, a large population, and relatively perfect living facilities. At the same time, there are many and disorderly gas consumption points. The transformation of the gas pipeline network has a great impact on the gas consumption of residents’ travel and daily life. In order to ensure the safety of indoor gas supply and avoid the problem that the gas inlet valve is set in the room of residential users and can not be closed timely in case of emergency, the gas inlet valve of residential buildings should be set outside the building. There are two ways: ***, outdoor valve protection box should be set when the gas inlet is introduced on the ground; Second, the direct buried valve is set when the underground is introduced.
When the residential building does not have the conditions to set the outdoor valve protection box, the direct buried valve can be set on the buried inlet pipe in front of the building as the inlet valve. Buried valve should have good anti-corrosion performance, service life should not be lower than the service life of gas pipeline, and should have the function of maintenance free in the life cycle, and its supporting protection well application has anti-theft function. The direct buried valve can optimize the management of gas operation management unit to users and enhance the ability to deal with emergencies.