Tag Archive for: stainless steel

Posts

How to extend the service life of stainless steel metal seated butterfly valve

In general, we are most worried about the problem of stainless steel metal seated butterfly valves is rust. This is the common concern of the majority of users for metal products. In fact, stainless steel material itself is not easy to rust, but stainless steel materials are also divided into five categories, such as ferritic stainless steel, martensitic stainless steel, austenitic stainless steel, austenitic-ferritic stainless steel and precipitated carbide stainless steel. The

D673H-16C-stainless steel pneumatic triple eccentric butterfly valve

D673H-16C-stainless steel pneumatic triple eccentric butterfly valve

austenitic stainless steel has good corrosion resistance after normal heat treatment and will not rust easily. If the stainless steel butterfly valve rusts in normal use, it is mostly due to the precipitation of carbides along the grain boundary in the material to form a chromium-depleted zone, which causes the stainless steel hard-seal butterfly valve to rust.
Let’s take a look at what specific maintenance methods we should maintain during use in order to effectively avoid corrosion of the stainless steel metal seated butterfly valve and prolong its service life:
1. The stainless steel metal seated butterfly valve should be cleaned frequently during use, and the transmission device should be maintained and lubricated. Frequently troubleshoot faults in order to find faults and clear them in time.
2. The packing should be evenly packed and the cover should be tightened to prevent the medium from leaking from the packing for a long time and rust.
3. Pay attention to the connection method and direction of the valve to prevent leakage and erosion caused by misalignment.
4. The stainless steel metal seated butterfly valve is only used for adjustment, not fully open or fully closed, because the structural characteristics of the butterfly valve are not suitable for truncation, which will cause accelerated wear of the sealing surface.
5. Valves that have not been put into use for a long time should also be checked regularly to clean up dirt in time. Both ends of the butterfly valve channel should be closed to prevent long-term air oxidation. The product should be placed in a ventilated and dry place, not stacked or stored in the open air.
6. Eliminate the dirt on the valve parts before installation, carefully check the pressure of the valve mark to see if the diameter meets the requirements for use, and eliminate the defects caused by the transportation process.
7. The product switch must use the equipped hand wheel or electric or pneumatic device. Do not use external tools to cause damage to the valve. The handwheel butterfly valve is turned clockwise to close, otherwise it is open.
For stainless steel metal seated butterfly valves to be used for a long time, it is important from product selection to post-maintenance. Choosing a trustworthy brand is the first step, and maintenance is the continuation of quality. Of course, good manufacturers will also have more guarantees after sales. If users do not understand maintenance or have any questions or questions, they can directly contact the manufacturer for professional assistance. Tanghai Valve solemnly promises to pay two for each failure within two years. Is your trustworthy butterfly valve manufacturer.

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:
The difference and application of stainless steel 430, 304, 316
Ways to Extend the Service Life of Valves
Features and application area of double eccentric butterfly valve
Valve actuator / actuation -(5)- advantages

Features of Stainless Steel Valves

Generally speaking, stainless steel valves are valves made of stainless steel. They are classified according to the stainless steel material grade of the valve body. They are mainly 301, 304, 316, 304L, 316L, etc. According to international standards, they can be divided into CF8, CF3, CF8M, CF3M, the quality of the material

D673H-16C-stainless steel pneumatic triple eccentric butterfly valve

D673H-16C-stainless steel pneumatic triple eccentric butterfly valve

CF8<CF3<CF8M<CF3M. Because stainless steel has strong corrosion resistance, is easy to form, has high compatibility, and can remain strong in a wide temperature range, many advantages make stainless steel valves widely used in heavy industry, light industry, daily necessities industry and architectural decoration industry. middle.
Stainless steel refers to steel that is resistant to corrosion by weak corrosive media such as air, steam, water and chemical corrosive media such as acids, alkalis, and salts. It is also called stainless acid-resistant steel. Stainless steel valves are also stainless acid-resistant steel valves. , And resistant to acid and alkali corrosion. Research tests have shown that the corrosion resistance of steel in weak media such as the atmosphere and water and oxidizing media such as nitric acid will increase with the increase of the chromium water content in the steel. When the chromium content reaches a certain percentage, the corrosion resistance of steel The sex changes, that is, from easy to rust to not easy to rust, from no corrosion resistance to corrosion resistance.
Common stainless steel valves mainly include stainless steel butterfly valves and stainless steel ball valves. The gate valve is rarely made of stainless steel, because the gate valve is usually used for low corrosive media such as water.
Stainless steel butterfly valve, also known as stainless steel flap valve, usually adopts three-eccentric metal hard sealing structure. The valve body, valve seat and butterfly plate sealing surface are all made of stainless steel with different hardness, which has strong corrosion resistance and long service life. It is widely used in metallurgical, electric power, petrochemical, water supply and drainage, municipal construction and other industrial pipelines with fluid pipeline medium temperature ≤ 425°C.
Stainless steel ball valves usually require horizontal installation in the pipeline. Stainless steel ball valves can be divided into stainless steel pneumatic ball valves, stainless steel electric ball valves, and stainless steel manual ball valves according to the driving mode. According to different stainless steel materials, it is divided into 304, 316, 321 stainless steel ball valves. The stainless steel ball valve switch is light and can also be made into a large diameter. It has reliable sealing, simple structure and convenient maintenance. The sealing surface and spherical surface are often in a closed state and are not easily eroded by the medium. It has applications in various industries.

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:
Prevention and treatment of valve corrosion
The main classification and use conditions of valve sealing materials
How to achieve internal and external anti-corrosion of pneumatic valves
The difference and application of stainless steel 430, 304, 316

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

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

lug type butterfly valve body

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 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:
Stainless steel vertical check valve;
Wafer type double disc swing check valve introduction;
Pneumatic ball valve model preparation method;
Pneumatic butterfly valve model name coding method

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>.

Stainless steel vertical check valve

Overview of Stainless steel vertical check valve:

H42W stainless steel flanged vertical check valve is a valve whose disc slides along the center line of the valve body. Pipeline vertical check valve is a new type of valve. It has the characteristics of simple structure, few parts, light weight, and good manufacturability. It is one of the development direc

lifting check valve (4)

lifting check valve (4)

tions of check valves. However, the fluid resistance coefficient is slightly larger than that of the swing check valve. Vertical check valves are widely used in various pipelines that need to prevent the medium from flowing back in the petroleum, chemical, pharmaceutical, and power industries. H42H can be equipped with spring or no spring according to vertical installation or horizontal installation.

Stainless steel vertical check valve H42W flange vertical check valve working principle:

H42W series vertical check valve can prevent the medium from flowing back and play the role of medium check. H42W stainless steel vertical check valve is open when the medium pressure at the inlet end is higher than the outlet end. Because under the pressure of the medium at the inlet end of the pipeline, the valve clack in the vertical check valve is pushed up to automatically open the valve. When the medium pressure at the inlet end is lower than the outlet end, the spring pushes the disc toward the valve seat to close the valve. Under the pressure, it will automatically close.

Related news /products:
Materials, installation and features of vertical check valve;
Use performance and working principle of vertical check valve;
What is vertical check valve;
The difference and application of stainless steel 430, 304, 316

Slow-closing design of stainless steel swing check valve

1. Structural improvement of swing check valve
A slow closing auxiliary valve is added on the flap of the original swing check valve. The auxiliary valve is installed on the lower side or both sides of the main valve

double-wing-check-valve-3

double-wing-check-valve-3

flap and is connected by threads. When the medium flow valve is opened, the medium pressure opens the auxiliary valve, and the medium flows into the main valve outlet through the small valve orifice, so that the main valve inlet end When the pressure is relieved, the valve flap of the main valve opens, and the pressure before and after the main valve tends to balance; when the medium reverses flow, the valve flap of the main valve closes quickly under the action of the reverse flow medium, and the upper part of the auxiliary valve body is a buffer cylinder, and the auxiliary valve cover is screwed into the valve.

There is a small hole on the cover of the upper part of the body. There is a certain gap between the valve flap of the auxiliary valve and the piston rod. The O-ring rubber seal is used between the piston and the buffer cylinder. The flat seal between the lower part of the piston and the valve flap; When the flap is closed with the main valve flap closed, the medium gradually flows into the upper chamber of the auxiliary valve buffer cylinder through the small hole due to the small hole of the auxiliary valve cover, and part of the medium flows back through the gap between the auxiliary valve flap and the piston rod Therefore, the auxiliary valve piston is closed slowly. In this structure, the closing of the main valve is equivalent to the fast closing stage, and the slow closing of the auxiliary valve is equivalent to the slow closing stage. According to the hydraulic and mechanical transition mechanism of the pump station unit, the structure design can effectively prevent the water hammer from boosting.

2. Improvement of lift check valve structure
The lifting check valve, also known as the bottom valve, can maintain the water column required for pumping when the pump is stopped; the feature of the valve structure improvement is that a slow closing auxiliary valve is added between the main valve flap and the valve body bracket as shown.

 lift-swing-check-valve-2

lift-swing-check-valve-2

A gasket ring is added between the valve body and the bottom net to increase the height of the valve flap. The buffer piston and the buffer cylinder are sealed with rubber. The valve flap shaft and the piston are rigidly connected, and the gap between the buffer cylinder and the valve flap shaft is small. When the medium flows downstream, the pressure medium pushes the valve flap into the main valve body cavity, and at the same time pushes the buffer piston upward; when the medium flows backward, the buffer cylinder is fully filled with the medium when it is opened, and the gap between the buffer cylinder and the valve disc shaft is relatively large. It is small, so as the medium in the buffer cylinder is gradually discharged through the gap, the main valve flap closes to play a buffering role, so that the water hammer boost in the pipe network can be controlled.

3. Test results before and after the improvement of the check valve slow closing structure
A calibrated pressure gauge is used, and the pressure signal is sent to the oscilloscope for recording by the differential pressure transmitter, and the water hammer pressure change value at each moment is read on the oscillogram with the calibrated ratio R.
The test valve has a diameter of 100mm, a system pressure of 0.5MPa, and a flow rate of 5L/s. When the pump stops suddenly, it shows the pressure-time curve of the inlet side of the check valve after the power is cut off
(1) The main valve flap opens and closes smoothly, the slow-closing auxiliary valve has a compact structure and reliable performance.
(2) The valve flap of the main valve closes first and then closes slowly, which can effectively prevent destructive water hammer and expand the use range of the check valve.
(3) The improved structure is simple and easy to produce and interchange.
(4) The slow-closing auxiliary valve can be repaired or replaced without hindering the use of the check valve.

The check valve is a valve that opens when the pipeline system is downstream and closes when it is upstream. It is mainly used to prevent backflow of the medium, prevent the pump and drive motor from reversing, and release the medium in the container. The rotary check valve with the shaft rotating and the lift check valve moving along the vertical center line of the valve body, but the valves of the above two structures both have the medium backflow speed rapidly reduced from the maximum to zero when the valve is closed, causing the pipeline The internal pressure on the side of the water inlet pipe rises rapidly, resulting in a water hammer phenomenon that has a destructive effect on the pipeline system, so the general check valve production caliber is 50 to 500 mm. In order to reduce the water hammer effect of the check valve and expand the range of use of the check valve, on the basis of the original product, a slow closing auxiliary valve was added to solve the problem of pipeline water hammer boosting.

Tianjin Tanghai Valve Manufacturing Co., Ltd. is one of the largest butterfly valve, check valve manufacturers in China. After 14+ years of continuous development and innovation, the company now has a group of high-tech engineers, technicians and skilled production workers, advanced production technology, sophisticated manufacturing equipment, complete testing methods, in strict accordance with international standards and quality management system, formed A comprehensive quality control network.

Related news/knowledges: Working principle diagram of lift check valve; Introduction of cast steel lift swing check valve

Portfolio Items