valve stem Archives

The difference and application of stainless steel 430, 304, 316

September 14, 2020

Stainless steel 430, 304,316 are the material of valve body, valve stem/shaft, or valve disc/plate.

lug type butterfly valve body

430 ferritic stainless steel containing more than 12% chromium can prevent oxidation caused by natural factors. It is called stainless steel. It belongs to 430 ferritic stainless steel. It has low thermal expansion rate, excellent formability and oxidation resistance. The code name in JIS is 430, so it is also called 430 stainless steel.

Application of 430 ferritic stainless steel: 430 stainless steel (16Cr) is often used to make household appliances, heat-resistant appliances, burners, home appliances, class 2 tableware, kitchen sinks, exterior decoration materials, bolts, nuts, CD rods, screens .

The difference between 430 stainless steel and 304, 316 austenitic stainless steel: 430 stainless steel and 304, 316 austenitic stainless steel are identified by spectral analysis and chemical element analysis. Both 304 and 316 are austenitic stainless steels. 316 is made of 304 stainless steel with molybdenum added. Therefore, 316 stainless steel has much better seawater and rust resistance than 304.
The difference between 304, 316 and 430 lies in the rust resistance. In addition to chromium, 304 and 316 also contain elements such as nickel and molybdenum, and are non-magnetic. Therefore, the rust resistance of 304/316 austenitic stainless steel is better than 430 stainless steel is much better and the price is much higher. To

Can the 430 stainless steel magnet hold it? 304 and 316 are not magnetic and cannot be attracted by magnets. Generally, it does not generate heat in a high-voltage electromagnetic environment, so it is used more. Martensitic and 430 ferritic stainless steel, precipitation hardening stainless steel are magnetic, and magnets can attract them.

Will 430 stainless steel rust? 430 stainless steel cannot resist the oxidation caused by chemicals in the air. Because there are more and more acidic chemicals in the air, 430 stainless steel will still be oxidized (rusted) due to unnatural factors after being used for a period of time.

Which is better, 430 stainless steel or 304? 304 austenitic stainless steel has excellent corrosion resistance and no magnetism. Relatively speaking, austenitic stainless steel 304 is better than 430 ferritic stainless steel.

How expensive is 430 stainless steel compared to 304? Generally speaking, austenitic stainless steel 304 is twice as expensive as 430 stainless steel.

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife 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

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

August 28, 2020

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

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

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 valve, gate valve, check valve, globe valve, knife 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

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

August 17, 2020

Bolts and nuts material of valve stem:

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 main parts of the butterfly valve?-(1)

August 17, 2020

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

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

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

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>.

Posts

The difference and application of stainless steel 430, 304, 316

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

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

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

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