Identification and Models of Valves
The identification of valves is of great significance to the correct use of valves, repair of valves and replacement of valves in the absence of valve drawings, nameplates or in case of incomplete valve parts. The valve identification, models, and material identification are described as follows:
According to the nameplates and marks on the valves and the painted colors on the valves, the types, structural forms, materials, nominal sizes, nominal pressures (or working pressures), adaptive media, temperatures and closing directions of the valves can be directly identified.
1. The nameplate is fixed on the valve body or handwheel. The nameplate data is relatively complete, reflecting the basic characteristics of the valve. According to the manufacturer on the nameplate, ask the Factory for the drawings and data of the valve vulnerability, and refer to the repair contents according to the date of manufacture. According to the service conditions provided on the nameplate, determine the materials and forms for replacing gaskets and packing, and determine the materials for replacing other valves.
2. Signs are used to marking the nominal pressure, working pressure, nominal diameter and medium flow direction of the valve body by casting and printing. There is also a sign on the valve-opening indicator, which has an open scale line or an arrow indicating opening and closing, etc. Opening indicators are installed at the upper ends of throttle valves and hidden stem gate valves, and arrows are marked on the handwheels to indicate the closing direction. On the end surface of the valve stem, a straight groove is engraved. The opening is consistent with the valve channel, and it is closed when the groove and the channel form an angle of 90 degrees.
3. The valve is coated with all kinds of paints, not only for rust prevention and beauty but for the convenience of identifying the material of the valve. It indicates the painting of the valve body material and the painting of sealing surface material. In order to see the structure, material and basic characteristics of the valve from its appearance, 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, which paint different colors on the outer edges of the valve body, the handwheel and the flange as required.
According to JB 106-59 No.1 Machine Department standard, it means that the paint of the valve body should be brushed on the unprocessed outer surface. The relationship between its color and the valve material is as follows:
Material of valve body: gray cast iron, malleable cast iron, painted in black
Material of valve body: nodular cast iron, painted in silver
Material of valve body: carbon steel, painted in gray
Material of valve body: acid-resistant steel or stainless steel, painted in light blue
Material of valve body: alloy steel, painted in blue
However, acid-resistant steel or stainless steel bodies may not be painted. Non-ferrous metal valves are not necessary to be painted.
Paint representing the sealing surface material is brushed on the cover of handwheel, handle or automatic valves and the relationship between its color and sealing surface material is as follows:
Sealing surface material: bronze or brass, painted in red
Sealing surface material: babbitt alloy, painted in yellow
Sealing material: aluminum, painted in white
Sealing surface material: acid-resistant steel or stainless steel, painted in light blue
Sealing surface material: nitriding steel, painted in light purple
Sealing material: cemented carbide, painted in gray with the red periphery
Sealing surface material: plastic, painted in gray with the blue periphery
Sealing surface material: leather or rubber, painted in brown
Sealing surface material: hard rubber, painted in green
Sealing surface material: if the seal is made directly on the valve body, and the paint color is the same as that of the valve body.
For valves with lining, the external surface of the connecting flange should be painted with supplementary identification paint, with the following colors:
Lining Material: enamel, painted in red
Lining Materials: rubber and hard rubber, painted in green
Lining Material: plastic, painted in blue
Lining Material: Al-Sb alloy, painted in yellow
Lining Material: aluminum, painted in white
Examples of Meanings on Valves
1. Meaning of DN on Valves
DN refers to the nominal size of the valve, usually followed by a number, such as a nominal size of 250mm, which should be marked as DN250. This number is directly related to the dimensions such as the aperture or outer diameter (mm) of the connector at the end. 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 with it is connected with a standard steel pipe flange, the actual channel diameter of the valve is not equal to the nominal size DN.
2. Meaning of WCB on valves
WCB written on the valve indicates the material of the valve body, while other parts of the valve may be other materials. WCB refers to the WCB level in ASTM A216, which is the first letter of carbon steel casting (W- weldable), indicating that the material has good weldability; C refers to the first letter of cast steel; B refers that the mechanical properties of steel are B level. Together, they are: weldable steel castings with mechanical properties of B Level. It is ordinary carbon steel, equivalent to 25 or 35 carbon steel.
3. Meaning of PN on valves
PN refers to the nominal pressure of the valve, followed by an integer number. In China, when it comes to nominal pressure, 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, that is, 100Kgf/cm2.
Key Points of Valve Identification
1. Except for other states, American standard valves shall comply with API600, API6D or MSS SP-25. The valve of the national standard has a permanent mark according to G/T 12220 standard, and the mark should include the furnace number of casting and melting or the casting mark of the manufacturer.
2. The label should be firmly fixed on the obvious part of the valve, and its contents must be neat and correct, conforming to GB/T 13306. Its materials should be made of 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 on the nameplate. However, the mark indicating the flow direction of the valve must be marked on the valve body, which is the same for any standard valve.
4. The paint used for color code and marking shall not contain any harmful metals or metal salts, such as zinc, lead, sulfur, copper, tin, chloride and other substances that can cause corrosion in a hot state. The paint shall be resistant to corrosion in the saltwater, tropical environment or similar situations.
5. For small-sized objects that are difficult to mark, stainless steel wire bolts and stainless steel signs should be used to mark them.
6. The signs engraved on the nameplate are generally model, material, pressure, standard, applicable temperature, the medium used and production date, which are all indispensable, so as to facilitate procurement during maintenance and replacement.
Marking Method of Identification
1. If the valve body is formed by casting or die casting, 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 die forging, the mark can be stamped on the valve body besides die forging or die casting at the same time. When the shape of the valve body is machined by forging, rolled and welded by steel pipe or steel plate, the mark can be formed by other methods that do not affect the performance of the valve body besides stamping.
Marking Style of Logo
The nominal dimension adopts numerical marks. Pressure code or working pressure code adopt flow direction signs and numerical marks.
Marking Position of Identity
1. The content of the sign is generally marked on the easy-to-watch part of the valve body. The mark should be marked at the central control position of the vertical center line on the valve body as much as possible.
2. When the marking content 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. Signs should be obvious, clear and neat.
Marking Size
1. The size of casting marks, the arrangement of fonts and arrows, the size of fonts and arrows shall be arranged, and a convex section shall be made.
2. Stamping mark size and arrow size are specified by the design drawing.
3. The font number of each product logo can also be specified by the design drawing according to the size of the specific product.
Understanding of Signs
The sign is usually fixed on the valve body, the flange or the handwheel, and the data of the sign is relatively complete, reflecting the basic characteristics of the valve. Different kinds of valves have different signs contents.
Painting of Valves
1. valves made of cast iron, carbon steel and alloy steel should be painted on their outer surfaces before leaving the factory, and the inner and outer surfaces of valves can be replaced by plastic spraying technology.
2. The paint layer should be durable and beautiful, and the sign should be clear. Use non-toxic and pollution-free paint that can meet the service temperature.
3. Paint layer of handwheel parts shall be as stipulated in the contract or enterprise standard.
4. The pressure-bearing shell of the copper alloy valve is not painted.
5. The pressure shell surfaces of acid-resistant steel valves, stainless steel valves are not painted. If required by the contract, paint them according to the requirements.
6. Painting of valve driving device: the painting color of the manual gear transmission mechanism and the valve driving device (pneumatic, electric and hydraulic) are generally in accordance with the provisions of the enterprise standard.
According to the nameplates and marks on the valves and the painted colors on the valves, the types, structural forms, materials, nominal sizes, nominal pressures (or working pressures), adaptive media, temperatures and closing directions of the valves can be directly identified.
1. The nameplate is fixed on the valve body or handwheel. The nameplate data is relatively complete, reflecting the basic characteristics of the valve. According to the manufacturer on the nameplate, ask the Factory for the drawings and data of the valve vulnerability, and refer to the repair contents according to the date of manufacture. According to the service conditions provided on the nameplate, determine the materials and forms for replacing gaskets and packing, and determine the materials for replacing other valves.
2. Signs are used to marking the nominal pressure, working pressure, nominal diameter and medium flow direction of the valve body by casting and printing. There is also a sign on the valve-opening indicator, which has an open scale line or an arrow indicating opening and closing, etc. Opening indicators are installed at the upper ends of throttle valves and hidden stem gate valves, and arrows are marked on the handwheels to indicate the closing direction. On the end surface of the valve stem, a straight groove is engraved. The opening is consistent with the valve channel, and it is closed when the groove and the channel form an angle of 90 degrees.
3. The valve is coated with all kinds of paints, not only for rust prevention and beauty but for the convenience of identifying the material of the valve. It indicates the painting of the valve body material and the painting of sealing surface material. In order to see the structure, material and basic characteristics of the valve from its appearance, 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, which paint different colors on the outer edges of the valve body, the handwheel and the flange as required.
According to JB 106-59 No.1 Machine Department standard, it means that the paint of the valve body should be brushed on the unprocessed outer surface. The relationship between its color and the valve material is as follows:
Material of valve body: gray cast iron, malleable cast iron, painted in black
Material of valve body: nodular cast iron, painted in silver
Material of valve body: carbon steel, painted in gray
Material of valve body: acid-resistant steel or stainless steel, painted in light blue
Material of valve body: alloy steel, painted in blue
However, acid-resistant steel or stainless steel bodies may not be painted. Non-ferrous metal valves are not necessary to be painted.
Paint representing the sealing surface material is brushed on the cover of handwheel, handle or automatic valves and the relationship between its color and sealing surface material is as follows:
Sealing surface material: bronze or brass, painted in red
Sealing surface material: babbitt alloy, painted in yellow
Sealing material: aluminum, painted in white
Sealing surface material: acid-resistant steel or stainless steel, painted in light blue
Sealing surface material: nitriding steel, painted in light purple
Sealing material: cemented carbide, painted in gray with the red periphery
Sealing surface material: plastic, painted in gray with the blue periphery
Sealing surface material: leather or rubber, painted in brown
Sealing surface material: hard rubber, painted in green
Sealing surface material: if the seal is made directly on the valve body, and the paint color is the same as that of the valve body.
For valves with lining, the external surface of the connecting flange should be painted with supplementary identification paint, with the following colors:
Lining Material: enamel, painted in red
Lining Materials: rubber and hard rubber, painted in green
Lining Material: plastic, painted in blue
Lining Material: Al-Sb alloy, painted in yellow
Lining Material: aluminum, painted in white
Examples of Meanings on Valves
1. Meaning of DN on Valves
DN refers to the nominal size of the valve, usually followed by a number, such as a nominal size of 250mm, which should be marked as DN250. This number is directly related to the dimensions such as the aperture or outer diameter (mm) of the connector at the end. 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 with it is connected with a standard steel pipe flange, the actual channel diameter of the valve is not equal to the nominal size DN.
2. Meaning of WCB on valves
WCB written on the valve indicates the material of the valve body, while other parts of the valve may be other materials. WCB refers to the WCB level in ASTM A216, which is the first letter of carbon steel casting (W- weldable), indicating that the material has good weldability; C refers to the first letter of cast steel; B refers that the mechanical properties of steel are B level. Together, they are: weldable steel castings with mechanical properties of B Level. It is ordinary carbon steel, equivalent to 25 or 35 carbon steel.
3. Meaning of PN on valves
PN refers to the nominal pressure of the valve, followed by an integer number. In China, when it comes to nominal pressure, 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, that is, 100Kgf/cm2.
Key Points of Valve Identification
1. Except for other states, American standard valves shall comply with API600, API6D or MSS SP-25. The valve of the national standard has a permanent mark according to G/T 12220 standard, and the mark should include the furnace number of casting and melting or the casting mark of the manufacturer.
2. The label should be firmly fixed on the obvious part of the valve, and its contents must be neat and correct, conforming to GB/T 13306. Its materials should be made of 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 on the nameplate. However, the mark indicating the flow direction of the valve must be marked on the valve body, which is the same for any standard valve.
4. The paint used for color code and marking shall not contain any harmful metals or metal salts, such as zinc, lead, sulfur, copper, tin, chloride and other substances that can cause corrosion in a hot state. The paint shall be resistant to corrosion in the saltwater, tropical environment or similar situations.
5. For small-sized objects that are difficult to mark, stainless steel wire bolts and stainless steel signs should be used to mark them.
6. The signs engraved on the nameplate are generally model, material, pressure, standard, applicable temperature, the medium used and production date, which are all indispensable, so as to facilitate procurement during maintenance and replacement.
Marking Method of Identification
1. If the valve body is formed by casting or die casting, 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 die forging, the mark can be stamped on the valve body besides die forging or die casting at the same time. When the shape of the valve body is machined by forging, rolled and welded by steel pipe or steel plate, the mark can be formed by other methods that do not affect the performance of the valve body besides stamping.
Marking Style of Logo
The nominal dimension adopts numerical marks. Pressure code or working pressure code adopt flow direction signs and numerical marks.
Marking Position of Identity
1. The content of the sign is generally marked on the easy-to-watch part of the valve body. The mark should be marked at the central control position of the vertical center line on the valve body as much as possible.
2. When the marking content 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. Signs should be obvious, clear and neat.
Marking Size
1. The size of casting marks, the arrangement of fonts and arrows, the size of fonts and arrows shall be arranged, and a convex section shall be made.
2. Stamping mark size and arrow size are specified by the design drawing.
3. The font number of each product logo can also be specified by the design drawing according to the size of the specific product.
Understanding of Signs
The sign is usually fixed on the valve body, the flange or the handwheel, and the data of the sign is relatively complete, reflecting the basic characteristics of the valve. Different kinds of valves have different signs contents.
Painting of Valves
1. valves made of cast iron, carbon steel and alloy steel should be painted on their outer surfaces before leaving the factory, and the inner and outer surfaces of valves can be replaced by plastic spraying technology.
2. The paint layer should be durable and beautiful, and the sign should be clear. Use non-toxic and pollution-free paint that can meet the service temperature.
3. Paint layer of handwheel parts shall be as stipulated in the contract or enterprise standard.
4. The pressure-bearing shell of the copper alloy valve is not painted.
5. The pressure shell surfaces of acid-resistant steel valves, stainless steel valves are not painted. If required by the contract, paint them according to the requirements.
6. Painting of valve driving device: the painting color of the manual gear transmission mechanism and the valve driving device (pneumatic, electric and hydraulic) are generally in accordance with the provisions of the enterprise standard.
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