Valve identification, model, connection method——HERO VALVE

Beginners of valves always mistakenly believe that the faucet is a valve. In fact, the faucet actually belongs to the bathroom series. Valves are divided into gate valves, butterfly valves, globe valves, low pressure valves, high pressure valves, safety valves, pressure relief valves, filters, anti-corrosion valves, check valves, pressure relief valves, ceramic valves, over flow valves, high temperature valves, low temperature valves, etc. .

1. Classification

By power

Automatic valve: a valve that relies on the power of the medium to act. Such as check valves, pressure relief valves, steam traps, safety valves, etc.

Drive valve: a valve that relies on external forces such as manpower, electricity, hydraulic power, and pneumatic power to operate. Such as globe valve, throttle valve, gate valve, disc valve, ball valve, plug valve, etc.

According to structural characteristics

By usage

Breaking valve: cut off or connect the pipeline medium. Such as stop valve, gate valve, ball valve, plug valve, etc.;

Regulating valve: Regulate the pressure or flow of the medium. Such as pressure reducing valve, regulating valve;

Check valve: to prevent backflow of medium. Such as check valve.

Distributing valve: change the flow direction of the medium and play a distribution role. Such as three-way cock, three-way stop valve, etc.

Safety valve: When the pressure exceeds the limit value, the excess medium is discharged to ensure the safety of the equipment. Such as safety valve, accident valve;

Gas barrier drain valve: to retain gas and exclude condensed water, such as a trap.

Breaking valve: cut off or connect the pipeline medium. Such as stop valve, gate valve, ball valve, plug valve, etc.;

Regulating valve: Regulate the pressure or flow of the medium. Such as pressure reducing valve, regulating valve;

Check valve: to prevent backflow of medium. Such as check valve.

Distributing valve: change the flow direction of the medium and play a distribution role. Such as three-way cock, three-way stop valve, etc.

Safety valve: When the pressure exceeds the limit value, the excess medium is discharged to ensure the safety of the equipment. Such as safety valve, accident valve;

Gas barrier drain valve: to retain gas and exclude condensed water, such as a trap.

According to the operation method

Manual valve: a valve operated by human power with the help of handwheel, handle, lever, sprocket, gear, worm gear, etc.

Electric valve: a valve that is controlled by electricity.

Pneumatic valve: a valve operated by means of compressed air.

Hydraulic valve: A valve operated by transmitting external force with the help of liquids such as water and oil.

By pressure

Vacuum: a valve with an absolute pressure of less than 1 kg/cm2.

Low pressure: Valves with a nominal pressure of less than 16 kg/cm2.

Medium pressure: a valve with a nominal pressure of 25-64 kg/cm2.

High pressure: a valve with a nominal pressure of 100-800 kg/cm2.

Super high: a valve with a nominal pressure of 1000 kg/cm2 or more.

According to the medium temperature

Ordinary valve: -40 to 450 ℃ (medium temperature)} valve.

High temperature valve: 450 to 600 ℃ (medium temperature) valve.

Heat-resistant valve: a valve above 600℃ (medium temperature).

Low temperature valve: -40 to -70 ℃ (medium temperature) valve.

Cryogenic valve: a valve from -70 to -196°C (medium temperature).

Ultra-low temperature valve: a valve below 196℃ (medium temperature).

According to nominal diameter

Small caliber: a valve with a nominal diameter of less than 40 mm.

Medium caliber: a valve with a nominal diameter of 50 to 300 mm.

Large diameter: a valve with a nominal diameter of 350 to 1200 mm.

Extra large diameter: a valve with a nominal diameter greater than 1400 mm.

The above classification is not absolute, it can be classified from other angles, as long as you master these basic classifications, it is still very beneficial to understand the wide variety of valves.

Second, the model

As can be seen from the above classification, there are many types of valves; so many categories, there must be a unified model compilation method, so that the purchaser can know the structure, characteristics and materials of a certain valve through the nameplate.

According to the "Valve Model Preparation Method", the valve model is divided into seven units:

Note: The fifth and sixth units are connected by a horizontal bar.

The first unit is the type code, expressed in pinyin:

For low temperature valves used below minus 40°C, thermal insulation valves with heating jacket material and valves with bellows (instead of stuffing boxes), Chinese Pinyin letters D, B and W are added before the type code.

The second unit is the transmission mode code, which is expressed in Arabic numerals:

Pneumatic or hydraulic valves are usually divided into two types: normally open and normally closed. The normally open type is indicated by 6K and 7K, and the normally closed type is indicated by 6B and 7B.

The third unit is the connection form code, which is represented by Arabic numerals:

The fourth unit is the structure model code, which is represented by Arabic numerals:

For lever-type safety valves, the G code is added before the type code, and the digital code is not specified in the new standard. Old standards: 1 single lever micro-lift, 2 single lever full-lift, 3 double lever micro-lift, 4 double lever full-lift, 6 pulse.

The fifth unit is the code name of the sealing surface of the valve seat or the lining material, which is represented by the pinyin letters in Chinese

When the sealing surface is directly machined on the valve body, it is represented by W.

Unit 6: Represents the nominal pressure value. The so-called nominal pressure refers to the nominal pressure of the valve. In fact, the pressure bearing capacity is larger. For safety, control within the nominal pressure. According to the JB74-59 standard, the nominal pressure values are expressed as follows: 1, 1.5, 4, 6, 10, 16, 25, 40, 64, 100, 200, 250, 320, 400, 500, 640, 800, 1000. 1000 or more. Not specified.

Finally, in the seventh unit, the pinyin letters are used to represent the valve body material:

But the gray cast iron valve body with nominal pressure kg/cm2 and carbon steel valve body with kg/cm2 can be omitted.

3. Logo

01

Valve identification function:

The identification of the valve is of great significance for the correct use of the valve, welding and repairing the valve, repairing the valve and replacing the valve in the absence of valve drawings, missing nameplates and incomplete valve parts. Now the valve identification, material identification and valve identification are described as follows:

Use the "basic knowledge of the valve" to learn the knowledge, according to the nameplate and logo on the valve and the paint color on the valve. You can directly identify the valve type, structure, material, nominal diameter, nominal pressure (or working pressure ), adapt to the medium, temperature and closing direction, etc.

1. The nameplate is fixed on the valve body or handwheel. The data on the nameplate is relatively complete, reflecting the basic characteristics of the valve. According to the manufacturer on the nameplate, obtain the vulnerable drawings and materials of the valve from the Iwai Factory, and refer to the repair content according to the date of delivery. According to the conditions of use provided on the nameplate, determine the replacement gasket and packing materials and forms, as well as determine the replacement of other valve materials

2. The logo is marked on the valve body by casting, printing and other methods to indicate the nominal pressure, working pressure, nominal diameter and medium flow direction.

There is also a sign on the valve-the opening indicator, which has an opening scale or an arrow indicating opening and closing. An opening indicator is installed on the upper end of the throttle valve and the dark rod gate valve, and the hand wheel is marked with an arrow to indicate the closing direction. A straight groove opening engraved on the end surface of the valve stem is consistent with the valve channel to indicate opening, and the groove is closed when the groove and the channel are at 90°.

3. The valve is coated with various paints, not only for rust prevention and good looks. But to facilitate the identification of the valve material. The paint of the valve body material. Paint for the sealing surface material.

In order to see its structure, material and basic characteristics from the appearance of the valve, it is required to cast, print or install a nameplate on the valve body, indicating the valve model, nominal diameter, medium flow direction and factory name, and on the valve body, handwheel and Paint different colors of paint on the outer edge of the flange as required.

According to the standard of one machine department of JB106-59, the paint representing the valve body material should be brushed on the outer surface of the valve body without processing. The relationship between the color and the valve body material is as follows:

But the acid-resistant steel or stainless steel valve body can also be unpainted. Non-ferrous metal valve body, no need to paint.

The paint representing the sealing surface material is brushed on the cover of the hand wheel, handle or automatic valve. The relationship between the color and the sealing surface material is as follows:

The valve with lining should be painted on the outer surface of the connecting flange to supplement the identification paint, the color is as follows:

02

Examples of meanings on valves:

The meaning of DN on the valve

DN: refers to the nominal diameter of the valve, generally followed by a number. If the nominal diameter is 250mm, it should be marked as DN250. Normally, the channel diameter of the valve is the same as the nominal size, but when the valve body adopts a pipe welding structure or the pipe connected to it is connected with a standard steel pipe flange, the actual channel diameter of the valve is not equal to the nominal The value of dimension DN.

The meaning of WCB on the valve

WCB: indicates the valve body material, other parts of the valve may be other materials. WCB refers to the WCB grade in ASTM A216, which is a carbon steel casting (W-weldable: the first letter of welding, indicating that the material has good welding performance; C-cast steel: the first letter of cast steel; B—The mechanical properties of steel are grade B) Together, they are: weldable cast steel parts with mechanical properties of grade B. It is ordinary carbon steel, equivalent to 25 or 35 carbon steel.

The meaning of PN on the valve

PN: The nominal pressure of the valve, followed by the integer number. In my country, when the nominal pressure is involved, for the sake of clarity, the unit of measurement is usually given, expressed as "MPa". For example, PN100 indicates that the nominal pressure is 10Mpa, which is 100Kgf/cm2;

Sometimes the nominal pressure is also marked in the position below:

Key points of valve identification

1. Unless otherwise stated, American standard valves are in accordance with API600. API6D or MSS SP-25, the national standard valve has a permanent mark according to G/T 12220 standard, and the mark should include the furnace number of the casting or the casting mark of the manufacturer.

2. The nameplate should be firmly fixed on the obvious part of the valve, its content must be neat and correct, and should comply with the provisions of GB/T 13306, and its material should be manufactured and manufactured using stainless steel, copper alloy and aluminum alloy.

3. Only when it is not feasible to apply the required mark on the valve body, the mark can be applied to the nameplate, however, the label indicating the flow direction of the valve must be marked on the valve body, this is no matter what the standard valve is same.

4. The paint used for color coding and marking must not contain any harmful metals or metal salts, such as zinc, lead, sulfur, copper, tin, chloride, etc., which can cause corrosion in hot state, and the paint should be resistant to salt water , Corrosion in tropical environments or similar conditions.

5. For small-sized objects that are difficult to mark, use the method of stainless steel wire bolts and stainless steel labels to mark them.

6. The signs engraved on the nameplate are generally model, material, pressure, standard, applicable temperature, used medium, and production date, all of which are indispensable. In order to facilitate the procurement when replacement.

Marking method

1. The valve body is formed by casting or die-casting, and its logo is cast or die-cast on the valve body at the same time.

2. When the shape of the valve body is formed by the die forging method, in addition to the die forging or die casting formed with the valve body at the same time, it can also be marked on the valve body by the method of stamping. When the shape of the valve body is processed by forging, and the steel pipe or steel plate is rolled and welded, the mark can be formed by imprinting, and other methods that do not affect the performance of the valve body can also be used.

Marking specifications of the logo

The nominal size value is marked, the pressure code or the working pressure code, the flow direction mark, and the pressure code marked with the nominal size is above the pressure code.

Mark position

1. The content of the mark is generally marked on the easy-to-see part of the valve body. The mark should be marked on the central control position of the vertical center line of the valve body as much as possible.

2. When the content of the mark is not enough on one face of the valve body, it can be marked on the other face of the central control position of the valve body.

3. The logo should be obvious, clear and neatly arranged.

Logo mark size

1. The size of the cast logo mark, the arrangement of the font and arrows, and the size of the font and arrows should be arranged to form a protruding section.

2. Embossed logo size, arrow size is specified by design drawing.

3. The font number of each product logo can also be specified by the design drawings according to the specific product shape and size.

Sign recognition

The sign is usually fixed on the valve body, flange or hand wheel. The data of the sign is relatively complete, reflecting the basic characteristics of the valve. The contents given on the nameplate are different for various valves.

Valve painting

1. For the valves of cast iron, carbon steel and alloy steel, the outer surface needs to be painted and leave the factory. The inner and outer surfaces of the valve can be replaced by a satisfactory spraying process.

2. The paint layer should be durable, beautiful, and ensure that the sign is clearly and clearly. Use non-toxic, non-polluting paint that meets the operating temperature.

3. The paint layer of the hand wheel parts is in accordance with the contract or enterprise standards.

4. The surface of the pressure housing of the copper alloy valve is not painted.

5. The surface of the pressure-resistant housing of acid-resistant steel and stainless steel is not painted. If the contract stipulates that the paint needs to be painted, paint according to the contract requirements.

6. Painting of valve driving device: manual gear transmission mechanism, the color of its surface painting, and the color of valve driving device (pneumatic, electric, hydraulic) are generally in accordance with the standards of the enterprise, when required by the user's order contract , According to the color specified by the user.

4. Connection form

Flange connection, clamp connection, butt welding connection, threaded connection, ferrule connection, clamp connection, internal self-tightening connection How is the entire valve connected to the pipeline or equipment, this problem can not be ignored, because the valve runs Most of the phenomena such as slamming, dripping, dripping and leaking occur here. Flange connection

This is the most used connection form in valves. According to the shape of the joint surface, it can be divided into the following types:

1. Smooth type: used for valves with low pressure. Processing is more convenient

2. Concave and convex type: high working pressure, medium hard washer can be used

3. Tenon-groove type: a gasket with large plastic deformation can be used, which is widely used in corrosive media and has a good sealing effect.

4. Trapezoidal groove type: Oval metal ring is used as a gasket, which is used for valves with working pressure ≥64 kg/cm2, or high temperature valves.

5. Lens type: The gasket is in the shape of a lens and made of metal. Used for high pressure valves with working pressure ≥100 kg/cm2, or high temperature valves.

6. O-ring type: This is a relatively new form of flange connection. It was developed with the appearance of various rubber O-rings. It is more reliable than ordinary flat gaskets in sealing effect. Wafer connection The connection form that directly connects the valve and the two pipes with bolts. Butt welding connection Threaded connection This is a simple connection method, often used for small valves. There are two cases:

1. Direct sealing: internal and external threads directly seal. In order to ensure that the connection is not leaking, it is often filled with lead oil, hemp and PTFE raw tape; PTFE raw tape is widely used every day; this material has good corrosion resistance and excellent sealing effect It is good, easy to use and store, and can be completely removed when disassembling, because it is a non-sticky film, which is much superior to lead oil and hemp.

2. Indirect sealing: The force of the screw thread is transmitted to the gasket between the two planes, so that the gasket plays a sealing role. The connection of the ferrule has only been developed in China in recent years. Its connection and sealing principle is that when the nut is tightened, the ferrule is pressurized, causing its blade to bite into the outer wall of the pipe, and the outer cone surface of the ferrule is in contact with the joint body under pressure The tapered surfaces are close to each other, so leakage can be reliably prevented.

The advantages of this form of connection are:

1) Small size, light weight, simple structure, easy disassembly and assembly;

2) Strong connection force, wide use range, can withstand high pressure (1000 kg/cm2), high temperature (650℃) and shock vibration;

3) A variety of materials can be selected, suitable for anti-corrosion;

4) The processing accuracy is not high;

5) It is easy to install at high altitude.

At present, the ferrule connection form has been adopted in some small-caliber valve products in my country.

Clamp connection

This is a quick connection method. It requires only two bolts and is suitable for low-pressure valves that are frequently removed.

Internal self-tightening

The above various connection forms all use external force to counteract the pressure of the medium to achieve sealing. The following introduces the use of medium pressure for self-tightening connection. Its sealing ring is installed at the inner cone at a certain angle to the side facing the medium. The pressure of the medium is transmitted to the inner cone and to the sealing ring. On the cone surface at a certain angle, two component forces are generated, one with The center line of the valve body is parallel to the outside, and the other is pressed against the inner wall of the valve body. The latter component is the self-tightening force. The greater the medium pressure, the greater the self-tightening force. So this connection form is suitable for high-pressure valves. Compared with flange connection, it saves a lot of materials and manpower, but also requires a certain pre-tensioning force, so that it can be used reliably when the pressure in the valve is not high.

Valves made using the principle of self-tightening are generally high-pressure valves. There are many forms of valve connection, for example, some small valves that do not need to be removed are welded to the pipe; some non-metallic valves are socket-type connections, and so on. Valve users should be treated according to specific circumstances.

other

There are many other valve connection forms, such as some small valves that do not have to be removed, welded to the pipe; some non-metallic valves, which use socket connection, etc. Valve users should be treated according to specific circumstances.

——CHINA·HERO VALVE