There are eight necessary technical factors to consider when purchasing valve products

There are eight necessary technical factors to consider when purchasing valve products

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Valve procurement only clear specifications, species, working pressure to meet the procurement requirements of the practice, in the current market economic environment is not perfect. Because valve manufacturers in order to compete with each other, they are in the same design of the valve under the idea of different innovation, the formation of their own enterprise scale and product personality. Therefore, it is very necessary to put forward detailed technical requirements in the valve procurement, and coordinate with the manufacturer to obtain resonance, as an attachment to the valve procurement contract.

1, the general requirements of valve specifications and types, should meet the requirements of pipeline design documents. The valve model should indicate the national standard number requirements. If the enterprise size, should indicate the relevant description of the model. Valve working pressure, requirements ≥ pipeline working pressure, without affecting the price of the condition, the valve can withstand the working pressure should be greater than the actual pipeline pressure; Any side of the valve closed condition 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 the requirements of two times the valve pressure. Valve manufacturing scale, should indicate the basis of the national standard number, if the enterprise scale, the procurement contract should be attached to the enterprise documents.

2, valve material Valve body material, should be based on ductile iron, and indicate the brand and the actual physical and chemical test data of cast iron. Stem material, strive to stainless steel stem (2CR13), large diameter valves should also be stainless steel embedded stem.

The nut is made of cast aluminum brass or cast aluminum bronze, and the hardness and strength are greater than the stem. Stem bushing material, its hardness and strength should not be greater than the stem, and under the condition of water immersion and stem, valve body does not form electrochemical erosion. The material of the sealing surface

(1) Different types of valves, sealing methods and material requirements;

② Common wedge gate valve, copper ring material, fixing way, grinding way should be described;

③ Physical, chemical and health test data of soft seal gate valve and valve plate lining rubber material;

(4) The butterfly valve should indicate the sealing surface material on the valve body and the sealing surface material on the butterfly plate; Their physical and chemical test data, especially rubber health requirements, anti-aging function, wear resistance function; Usually use butadiene rubber and EPDM rubber, it is strictly prohibited to mix with recycled rubber. Valve shaft packing

(1) Because the valve in the pipe network is usually opened and closed infrequently, the packing is required to not flow in a few years, the packing is not aging, and the sealing effect is maintained for a long time;

(2) Valve shaft packing should also withstand frequent opening and closing, sealing effect is good;

(3) In view of the above requirements, the valve shaft packing should not be replaced for life or more than 10 years;

④ If the packing needs to be replaced, the valve design should consider the replacement measures under the condition of water pressure.

3. Variable speed transmission box

The box material and internal and external anticorrosion requirements are consistent with the valve body principle.

The box body should be sealed and can withstand soaking of 3 meters of water column after assembly.

The adjusting nut of the opening and closing limit device on the box should be in the box or outside the box, but the tool is needed to operate.

Transmission structure design is reasonable, opening and closing can only drive the valve shaft rotation, do not make it move up and down, moderate transmission parts bite, do not produce load when opening and closing separation slip.

Variable speed transmission box and valve shaft sealing place shall not be connected into a leak-free whole, otherwise there should be implemented anti-leakage measures. There is no debris in the box, and the gear occlusal part should be protected by grease.

4. The opening and closing direction of the valve control mechanism should be closed clockwise.

Because the valve in the pipe network is often manually opened and closed, the opening and closing revolutions should not be too much, even the large diameter valve should also be within 200-600 revolutions.

In order to facilitate one person’s opening and closing operation, under the condition of plumber pressure, the relatively large opening and closing torque should be 240N-m. Valve opening and closing control end shall be square tenon, and size scale, and face the ground, so that people can directly operate from the ground. Valve with wheel is not suitable for underground pipe network. Display panel for valve opening and closing degree

(1) The scale line of the opening and closing degree of the valve should be forged on the gearbox cover or the shell of the display plate after the conversion direction, all facing the ground, and the scale line should be brushed with fluorescent powder 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 painted steel plate, do not use aluminum skin production;

(3) Indicator disc needle eye-catching, fixed, once the opening and closing adjustment is correct, should be locked with rivet.

5, the valve function test valve a certain specification batch manufacturing, should entrust institutions to test the following functions:

① Opening and closing torque of valve under working pressure condition;

(2) Under the working pressure condition, can ensure the valve closed tightly continuous opening and closing times;

③ The detection of flow resistance coefficient of valve under the condition of pipeline water transmission. The valve should be tested as follows before leaving the factory:

(1) The valve in the open condition, the valve body should bear the internal pressure detection of the valve working pressure value twice;

(2) Under the closed condition of the valve, both sides respectively bear 1.1 times the valve working pressure value, no leakage; But the metal seal butterfly valve, leakage value is not greater than the relevant requirements.

6, the internal and external anticorrosive valve body of the valve (including variable speed transmission box), the first should be shot sand cleaning and rust removal, and strive to electrostatic spraying powder solvent-free epoxy resin, thickness of more than 0.3mm. When solvent-free epoxy resin is difficult to be sprayed by electrostatic spraying on oversized valves, similar solvent-free epoxy paint should also be brushed and sprayed. Valve body internal and valve plate each part of the requirements of anti-corrosion, on the one hand immersion in water will not rust, between the two metals do not produce electrochemical erosion; Two aspects of smooth surface to reduce water resistance. The sanitary requirements of the anticorrosive epoxy resin or paint in the valve body shall be examined by the corresponding organ. Chemical physical function should also meet the relevant requirements.

7, the packaging of the valve transport valve on both sides should be set up light plugging plate seal.

Medium and small diameter valves should be tied with straw ropes and transported in containers. Large diameter valve basically uses wooden frame structure positioning valve, easy to transport and protect the valve

In order to better cooperate with the use of valve, valve control mechanism selection is essential, which requires valve manufacturers to screen out better suppliers

Gusu Sidad Mechanical Automatic Control Co., Ltd. has a complete set of valve supporting solutions, professional design and production of valve driving devices (worm gear box, gear box), perennial exports to the Middle East, Russia, Spain, and European countries, but also the Saike valve, the core of the Su valve, Newey valve, Fosse fluid and other large valve enterprises suppliers.

The purchase of valve products need to consider eight necessary technical factors valve procurement only clear specifications, species, working pressure to meet the procurement requirements of the practice, in the current market economic environment is not perfect. Because valve manufacturers in order to compete with each other, they are in the same design of the valve under the idea of different innovation, the formation of their own enterprise scale and product personality. Therefore, it is very necessary to put forward detailed technical requirements in the valve procurement, and coordinate with the manufacturer to obtain resonance, as an attachment to the valve procurement contract.

1. General requirements

1.1 Valve specifications and types shall conform to the requirements of pipeline design documents. 1.2 The valve model shall indicate the national standard numbering requirements. If the enterprise size, should indicate the relevant description of the model. 1.3 The working pressure of the valve shall be ≥ the working pressure of the pipeline. Under the condition of not affecting the price, the working pressure that the valve can bear shall be greater than the actual working pressure of the pipeline; Any side of the valve closed condition 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 the requirements of two times the valve pressure. 1.4 The manufacturing scale of the valve should indicate the national standard number based on it. If it is the enterprise scale, the enterprise document should be attached to the purchase contract.

2, valve quality standard

2.1 The body material shall be mainly nodular cast 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 valves should also be stainless steel embedded stem. 2.3 The nut is made of cast aluminum brass or cast aluminum bronze, and the hardness and strength are greater than the valve stem. 2.4 The hardness and strength of the valve stem bushing material shall not be greater than the valve stem, and there shall be no electrochemical erosion with the valve stem and valve body under the condition of water immersion. 2.5 Sealing surface material (1) Different types of valves, sealing methods and material requirements; ② Common wedge gate valve, copper ring material, fixing way, grinding way should be described; ③ Physical, chemical and health test data of soft seal gate valve and valve plate lining rubber material; (4) The butterfly valve should indicate the sealing surface material on the valve body and the sealing surface material on the butterfly plate; Their physical and chemical test data, especially rubber health requirements, anti-aging function, wear resistance function; Usually use butadiene rubber and EPDM rubber, it is strictly prohibited to mix with recycled rubber. 2.6 Valve shaft packing (1) Because the valve in the pipe network is usually opened and closed infrequently, the packing is required to not flow in several years, the packing is not aging, and the sealing effect is maintained for a long time; (2) Valve shaft packing should also withstand frequent opening and closing, sealing effect is good; (3) In view of the above requirements, the valve shaft packing should not be replaced for life or more than 10 years; ④ If the packing needs to be replaced, the valve design should consider the replacement measures under the condition of water pressure.

3. Variable speed transmission box

3.1 The material and internal and external anticorrosion requirements of the box body are consistent with the principle of the valve body.

3.2 The box body should be sealed and can withstand soaking of 3m water column after assembly.

3.3 The adjusting nuts of the opening and closing limit device on the box should be in the box or outside the box, but only the first tool can be used.

3.4 Reasonable transmission structure design, opening and closing can only drive the valve shaft rotation, do not make it move up and down, moderate transmission parts bite, do not produce load when opening and closing separation slip.

3.5 The sealing place between the gearbox and the valve shaft shall not be connected into a leak-free whole, otherwise reliable measures should be taken to prevent serial leakage.

3.6 There is no sundry matter in the box, and the gear occlusal part should be protected by grease.

4, the valve control mechanism

4.1 The opening and closing direction of valve operation should be closed clockwise.

4.2 Because the valves in the pipe network are often opened and closed manually, the opening and closing revolutions should not be too much, even the large diameter valves should also be within 200-600 revolutions.

4.3 In order to facilitate one person’s opening and closing operation, under the condition of plumber pressure, the relatively large opening and closing torque should be 240N-m.

4.4 Valve opening and closing control end shall be square tenon, scale, and face the ground, so that people can directly operate from the ground. Valve with wheel is not suitable for underground pipe network.

(1) The scale line of the valve opening and closing degree should be forged on the gearbox cover or the shell of the display plate after the conversion direction, all facing the ground, and the scale line is brush with fluorescent powder 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 painted steel plate, do not use aluminum skin production; The indicator disk needle eye-catching, fixed firmly, once the opening and closing adjustment is correct, should be locked with rivet.

4.6 If the valve is buried deeply and the distance between the control mechanism and the display panel from the ground is greater than or equal to 1.5m, the extension rod should be set and fixed firmly, so that people can observe and operate from the ground. That is to say, the valve in the pipe network is not suitable for operation.

5, valve function detection

5.1 When the valve is manufactured in batches of a certain specification, the following functions should be tested by the perfect mechanism: ① the opening and closing torque of the valve under the working pressure condition; (2) Under the working pressure condition, can ensure the valve closed tightly continuous opening and closing times; ③ The detection of flow resistance coefficient of valve under the condition of pipeline water transmission.

5.2 The following tests should be carried out before the valve leaves the factory: (1) When the valve is open, the valve body should bear the internal pressure test of twice the working pressure value of the valve; (2) Under the closed condition of the valve, both sides respectively bear 1.1 times the valve working pressure value, no leakage; But the metal seal butterfly valve, leakage value is not greater than the relevant requirements.

6, the internal and external corrosion of the valve

6.1 The inside and outside of the valve body (including the variable speed transmission box), the first thing should be shot blasting, sand cleaning and rust removal, and strive to electrostatic spraying powder non-toxic epoxy resin, the thickness of more than 0.3mm. When the electrostatic spraying of non-toxic epoxy resin is difficult for oversized valves, similar non-toxic epoxy paint should also be brushed and sprayed.

6.2 Corrosion prevention is required inside the valve body and various parts of the valve plate. On the one hand, it will not rust when soaked in water, and there will be no electrochemical erosion between the two metals; Two aspects of smooth surface to reduce water resistance.

6.3 For the sanitary requirements of the anticorrosive epoxy resin or paint in the valve body, the corresponding inspection speech should be given by the corresponding ** organ. Chemical physical function should also meet the relevant requirements.

7. Valve packaging and transportation

7.1 Light plugging plates shall be installed on both sides of the valve.

7.2 Medium and small diameter valves should be tied with straw ropes and transported in containers.

7.3 Large diameter valves also have simple wooden frame solid packaging to avoid damage during transportation.

8. Factory copy of valve

Valves are equipment, and the following relevant data should be marked in the factory copy: valve specifications; Model number; Working pressure; Manufacturing scale; Valve body material; Stem material; Sealing material; Valve shaft packing material; Valve stem sleeve material; Internal and external anticorrosive material; Control the starting direction; Revolutions; Opening and closing moment under working pressure; The name of the manufacturer; Date of delivery; Factory number; Weight; Connecting flange aperture, hole number, center hole distance; The control dimensions of overall length, width and height are indicated in graphic form; Valve flow resistance coefficient; Effective opening and closing times; Valve factory testing data and installation, maintenance precautions, etc.


Post time: Jan-07-2023

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