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Valve material and valve standards-(3)-sealing material

Section 2: Sealing surface material
The sealing surface is the most critical working surface of the valve. The quality of the sealing surface is related to the service life of the valve. Generally, the sealing surface material considers factors such as corrosion resistance, scratch resistance, erosion resistance, and oxidation resistance. Generally, sealing surface materials are divided into two categories:
1. Soft materials

soft sealing marine valve, rubber sealing, valve seat parts

soft sealing marine valve, rubber sealing, valve seat parts

1. Rubber (including nitrile rubber, ethylene propylene rubber, fluorine rubber, etc.)
2. Plastics (polytetrafluoroethylene, nylon, etc.)
2. Hard sealing material
1. Copper alloy (for low pressure valve)
2. Chrome stainless steel (used for ordinary high and medium pressure valves)
3. Stellite alloy (used for high temperature and high pressure valves and strong corrosion valves)
4. Nickel-based alloy (used for corrosive media)

Section 3: Valve Stem Material
During the opening and closing of the valve, the valve stem bears tensile, compressive and torsional forces, and is in direct contact with the medium. At the same time, there is relative frictional movement with the packing. Therefore, the valve stem material must ensure sufficient strength at the specified temperature And impact toughness, a certain degree of corrosion resistance and abrasion resistance, and good manufacturability. Commonly used valve stem materials are as follows:
1. Carbon steel: For water with low temperature and medium temperature not exceeding 300°C, when steam

18 buttefly-valve-stem-shaft-parts-1

18 buttefly-valve-stem-shaft-parts-1

medium, A5 ordinary carbon steel is generally selected (now Q275, A3 is Q235)
2. Alloy steel: For medium pressure and high pressure, when the medium temperature does not exceed 450°C, 40Cr (chromium steel) is generally used when the medium temperature does not exceed 450°C. Water, the medium temperature does not exceed 540°C For steam and other media, 38CrMoAlA nitriding steel can be selected; for high-pressure steam media with a medium temperature not exceeding 570°C, 25Cr2MoVA chromium molybdenum vanadium steel is generally selected.
3. Stainless and acid-resistant steel: used for medium and high pressure, non-corrosive and weakly corrosive media with a medium temperature not exceeding 450°C. 1Cr13, 2Cr13, 3Cr13 chromium stainless steel can be selected; when used in corrosive media, it can be used Use Cr17Ni2, 1Cr18Ni9Ti, Cr18Ni12Mo2Ti, Cr18Ni12Mo3Ti and other stainless acid-resistant steels and PH15-7Mo precipitation hardening steels.
4. Heat-resistant steel: 4Cr10Si2Mo martensitic heat-resistant steel and 4Cr14Ni14W2Mo austenitic heat-resistant steel can be used for high-temperature valves whose medium temperature does not exceed 600°C.

Section 4: Valve Stem Nut Material
The stem nut directly bears the axial force of the stem during the opening and closing of the valve, so it must have a certain strength. At the same time, it and the valve stem are threaded transmission, which requires a small coefficient of friction, no rust and avoid seizure. The main materials are as follows:
1. Copper alloy: Copper alloy has a small friction coefficient and does not rust. It is one of the commonly used materials. For low pressure valves with Pg<1.6Mpa, ZHMn58-2-2 cast brass can be used.
2. Steel: When the working conditions do not allow the use of copper alloys, high-quality carbon steels such as 35, 40, 2Cr13, 1Cr18Ni9, Cr17Ni2 and other stainless and acid-resistant steels can be selected. The working conditions do not allow the following:
For electric valves, stem nuts with gua-shaped clutches require heat treatment to obtain high hardness or surface hardness.
When the working medium or the surrounding environment is not suitable for copper alloys, such as ammonia medium that is corrosive to copper.
When selecting steel stem nuts, pay special attention to thread seizure.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Related news/knowledge:
Valve material and valve standards-(4)-fastener material;
What is the material of the butterfly valve stem?
What is the material of Bolts and nuts of Valve Stem?
What is the material of the main parts of the butterfly valve?-(2)

What is the material of Bolts and nuts of Valve Stem?

Bolts and nuts material of valve stem:

bolts and nuts for butterfly valve

bolts and nuts for butterfly valve

The stem nut directly bears the axial force of the stem during the opening and closing of the valve, so it must have a certain strength. At the same time, it and the valve stem are threaded transmission, which requires a small friction coefficient, no rust and avoid seizure.

1. Copper alloy Copper alloy has a small friction coefficient and does not rust. It is one of the commonly used materials. For low pressure valves with Pg<1.6Mpa, ZHMn58-2-2 cast brass can be used. ZQAL9-4 Wuxi bronze can be used for Pg16-6.4Mpa medium pressure valve. For high-pressure valves, ZHAL66-6-3-2 cast brass can be used.

2. Steel When the working conditions do not allow the use of copper alloys, high-quality carbon steels such as 35 and 40 can be selected, and stainless acid-resistant steels such as 2Cr13, 1Cr18Ni9, and Cr17Ni2 can be used. Working conditions are not allowed to refer to the following situations.

1. For electric valves, stem nuts with melon clutches need heat treatment to obtain high hardness or surface hardness.

2. When the working medium or the surrounding environment is not suitable for copper alloy, such as ammonia medium that corrodes copper. When selecting steel stem nuts, pay special attention to thread seizure.

Tianjin Tanghai Valve Manufacturing Co., Ltd. is one of the largest valve bolts and nuts manufacturers in China, main products are butterfly valves, check valves, gate valve and globe valves. Key words:  butterfly valve, lug type butterfly valve, wafer type butterfly valve, U-type butterfly valve, double flange butterfly valve, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…)

What is the material of the butterfly valve stem?

Stem material classification:
During the opening and closing of the butterfly valve, the valve stem bears the forces of tension, pressure and

buttefly valve stem shaft parts (6)

buttefly valve stem shaft parts (6)

torsion, and is in direct contact with the medium. At the same time, there is relative frictional movement with the packing. Therefore, the valve stem material must ensure that there is enough at the specified temperature Strength and impact toughness, a certain degree of corrosion resistance and scratch resistance, and good manufacturability. The commonly used stem materials are as follows.

1. When carbon steel is used in water and steam medium with low pressure and medium temperature not exceeding 300℃, A5 ordinary carbon steel is generally used. When used in water and steam medium with medium pressure and medium temperature not exceeding 450℃, 35 high-quality carbon steel is generally used.

2. When alloy steel is used for medium pressure and high pressure, and the medium temperature does not exceed 450 ℃ water, steam, petroleum and other media, 40Cr (chromium steel) is generally used. 38CrMoALA nitriding steel can be used when it is used in water, steam and other media with high pressure and medium temperature not exceeding 540℃. 25Cr2MoVA chromium molybdenum vanadium steel is generally used when used in high pressure steam medium with medium temperature not exceeding 570℃.

3. Stainless acid-resistant steel S is used for non-corrosive and weakly corrosive media with medium and high pressure and medium temperature not exceeding 450℃. 1Cr13, 2Cr13, 3Cr13 chromium stainless steel can be selected. When used in corrosive media, stainless acid-resistant steel such as Cr17Ni2, 1Cr18Ni9Ti, Cr18Ni12Mo2Ti, Cr18Ni12Mo3Ti, and PH15-7Mo precipitation hardening steel can be selected.

4. When heat-resistant steel is used for high-temperature valves whose medium temperature does not exceed 600℃, 4Cr10Si2Mo martensitic heat-resistant steel and 4Cr14Ni14W2Mo austenitic heat-resistant steel can be selected.

Tianjin Tanghai Valve Manufacturing Co., Ltd. is one of the largest valve stem/shaft manufacturers in China, main products are butterfly valves, check valves, gate valve and globe valves. Key words:  butterfly valve, lug type butterfly valve, wafer type butterfly valve, U-type butterfly valve, double flange butterfly valve, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…)

What is the material of the main parts of the butterfly valve?-(1)

Selection of butterfly valve parts materials:
There are many materials for manufacturing butterfly valves, including ferrous and non-ferrous metals and their

16 U-type-flange-butterfly-vlave-body

16 U-type-flange-butterfly-vlave-body

alloys of different brands, and various non-metallic materials. The materials for manufacturing valve parts should be selected based on the following factors:

1. Pressure, temperature and characteristics of working medium.

2. The force of the part and its function in the valve structure.

3. It has better manufacturability.

4. If the above conditions are met, there must be a lower cost.

The material of the valve body, bonnet and disc (disc) The body, bonnet and gate (disc) are one of the main parts of the valve, which directly bear the pressure of the medium, and the material used must meet the “pressure and temperature rating of the valve” Provisions.

Commonly used material types for butterfly valves:

1. Gray cast iron: Gray cast iron is suitable for water, steam, air, gas, oil and other media with a nominal pressure of PN≤1.0MPa and a temperature of -10℃~200℃. The commonly used grades of gray cast iron are: HT200, HT250, HT300, HT350.

2. Malleable cast iron: Suitable for water, steam, air and oil media with a nominal pressure

17 center-line-butterfly-valve-plate-disc-parts-4

17 center-line-butterfly-valve-plate-disc-parts-4

of PN≤2.5MPa and a temperature of -30~300℃. Commonly used grades are: KTH300-06, KTH330-08, KTH350-10.

3. Ductile iron: suitable for water, steam, air and oil with PN≤4.0MPa and temperature of -30~350℃. Commonly used grades are: QT400-15, QT450-10, QT500-7. In view of the current level of domestic technology, the plants are uneven, and users are often not easy to inspect. According to experience, it is recommended that PN≤2.5MPa, and the valve should be made of steel for safety.

4. Acid-resistant high-silicon ductile iron: suitable for corrosive media with nominal pressure PN≤0.25MPa and temperature below 120℃.

5. Carbon steel: suitable for water, steam, air, hydrogen, ammonia, nitrogen and petroleum products with a nominal pressure of PN≤32.0MPa and a temperature of -30~425℃. Commonly used grades are WC1, WCB, ZG25 and high-quality steel 20, 25, 30 and low-alloy structural steel 16Mn. Six, copper alloy: suitable for water, sea water, oxygen, air, oil and other media with PN ≤ 2.5MPa, and steam media with a temperature of -40 to 250 ℃, commonly used brands are ZGnSn10Zn2 (tin bronze), H62, Hpb59-1 (Brass), QAZ19-2, QA19-4 (aluminum bronze).

18 buttefly-valve-stem-shaft-parts-1

18 buttefly-valve-stem-shaft-parts-1

7. High temperature steel: suitable for steam and petroleum products with nominal pressure PN≤17.0MPA and temperature≤570℃. Commonly used grades are ZGCr5Mo, 1Cr5M0. ZG20CrMoV, ZG15Gr1Mo1V, 12CrMoV, WC6, WC9, etc. The specific selection must be in accordance with the valve pressure and temperature specifications. 8. Low temperature steel, suitable for nominal pressure PN≤6.4Mpa, temperature≥—196℃ ethylene, propylene, liquid natural gas, liquid nitrogen and other media, commonly used grades) ZG1Cr18Ni9, 0Cr18Ni9, 1Cr18Ni9Ti, ZG0Cr18Ni9.

9. Stainless acid-resistant steel, suitable for nitric acid, acetic acid and other media with nominal pressure PN≤6.4Mpa and temperature≤200℃. Commonly used grades are ZG0Cr18Ni9Ti, ZG0Cr18Ni10<nitric acid>, ZG0Cr18Ni12Mo2Ti, ZG1Cr18Ni12Mo2Ti<acid and urea>.

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