valve seal Archives

Valve seal (ring) material usage range comparison table

October 27, 2020

The selection of valve sealing material is determined according to the operating conditions of the valve, such as: pipeline medium, temperature range (high and low temperature), pressure and internal structure of the valve. For

soft sealing marine valve, rubber sealing, valve seat parts

different occasions, the selected seals are also different. Valve seals can generally be divided into two categories: soft seals and hard seals. Users should have a detailed understanding of their codes, operating temperature, pressure, medium and other parameters.

Comparison table of valve sealing material usage range:
Valve sealing material and valve sealing material use range:
Rubber (X) Nominal pressure PN ≤ 1 MPa, operating temperature t ≤ 150℃, applicable valves: globe valves, diaphragm valves, butterfly valves, check valves, etc.
Nylon (N) Nominal pressure PN ≤ 32 MPa, operating temperature t ≤ 90°C, applicable valves: globe valves, ball valves, etc.
PTFE (F) Nominal pressure PN ≤ 6.4 MPa, operating temperature t ≤ 180°C, applicable valves: globe valves, ball valves, gate valves, diaphragm valves, butterfly valves, check valves, etc.
Bus alloy (B) Nominal pressure PN ≤ 2.5 MPa, operating temperature t ≤ 150°C, applicable valves: stop valves for ammonia, etc.
Ceramic (G) Nominal pressure PN ≤ 1.6 MPa, operating temperature t ≤ 150°C, applicable valves: ball valves, plug valves, etc.
Enamel (C) Nominal pressure PN ≤ 1.0 MPa, operating temperature t ≤ 80°C, applicable valves: globe valve, diaphragm valve, check valve, discharge valve, etc.
Copper alloy (T) Nominal pressure PN ≤ 1.6 MPa, operating temperature t ≤ 200℃, applicable valves: gate valve, globe valve, check valve, plug valve, etc.
Stainless steel (H) Nominal pressure PN ≤ 32 MPa, operating temperature t ≤ 450°C, applicable valves: globe valves, ball valves (medium and high pressure valves), etc.
Nitrided steel (D) Nominal pressure PN ≤ 10 MPa, operating temperature t ≤ 540℃, applicable valves: power station gate valves, only for general use
Cemented carbide (Y) Nominal pressure (PN) and operating temperature (t) are determined according to the material of the valve body. Applicable valves: high pressure, ultra high pressure valves, high temperature and low temperature valves

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 are the main factors affecting valve sealing?

September 11, 2020

Valve leakage is very common in daily life and industrial production, and the impact is very large. It will cause waste or bring danger to life. For example, the leakage of tap water valve will lead to serious consequences, such as the

ductile iron, DI, butterfly valve, manufacturer, center line, TH valve

chemical industry. Toxic, harmful, flammable, explosive and corrosive media leakage, etc., serious threats to personal safety, property safety and environmental pollution accidents. A valve that relies on external force to rotate and drive to open and close is designed with a sealing device. It is used to install a certain number of packing seals in the packing culvert to achieve a sealing effect, but how about the sealing? Leakage at the packing of the valve is one of the most prone to leakage failure in the valve, but the reasons are largely the following reasons.

1. The structure of the sealing pair

The structure of the sealing pair will change when the temperature or sealing force changes. Moreover, this change will affect and change the mutual force between the sealing pairs, thereby reducing the performance of the valve sealing. Therefore, when choosing a seal, be sure to choose a seal with elastic deformation. At the same time, pay attention to the width of the sealing surface. The reason is that the contact surfaces of the sealing pair cannot be completely matched. When the width of the sealing surface increases, the force required for sealing must be increased.

2. The specific pressure of the sealing surface

The specific pressure of the sealing surface affects the sealing performance of the valve and the service life of the valve. Therefore, the specific pressure of the sealing surface is also a very important factor. Under the same conditions, too much specific pressure will cause damage to the valve, but too little wine will cause valve leakage. Therefore, we need to fully consider the appropriateness of the specific pressure when designing.

3. The physical properties of the medium

The physical properties of the medium also affect the sealing performance of the valve. These physical properties include temperature, viscosity and surface hydrophilicity. The temperature change not only affects the slackness of the sealing pair and changes in the size of the parts, but also has an inseparable relationship with the viscosity of the gas. The gas viscosity increases or decreases as the temperature increases or decreases. Therefore, in order to reduce the influence of temperature on the sealing performance of the valve, when we design the sealing pair, we must design it into a valve with thermal compensation such as an elastic valve seat. Viscosity is related to the permeability of the fluid. When under the same conditions, the greater the viscosity, the smaller the permeability of the fluid. The hydrophilicity of the surface means that when there is a thin film on the metal surface, the thin film should be removed. Because this thin oil film will destroy the hydrophilicity of the surface and block the fluid channel.

4. The quality of the sealing pair

The quality of the sealing pair mainly refers to the selection, matching, and manufacturing accuracy of materials. For example, the valve disc and the sealing surface of the valve seat are very consistent, which can improve the sealing performance. The characteristic of many hoop waviness is its good labyrinth sealing performance.

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

The main classification and use conditions of valve sealing materials

September 10, 2020

The valve seal is the most important part of the entire valve. Its main purpose is to prevent leakage. The valve sealing

soft sealing marine valve, rubber sealing, valve seat parts

seat is also called a sealing ring. It is an organization that directly contacts the medium in the pipeline and prevents the medium from flowing. When the valve is in use, there are a variety of different media in the pipeline, such as liquid, gas, oil, corrosive media, etc., and different valve seals are used in different places and can adapt to various medium.
Then, valve seal materials can be divided into two major categories, namely, metallic materials and non-metallic materials. Non-metallic seals are generally used for pipelines at room temperature and pressure, while metal seals are widely used and can be used for high temperature and high pressure!
The following briefly introduces the use conditions of various sealing materials and the commonly used valve types.

1. Synthetic rubber
Synthetic rubber is better than natural rubber in oil resistance, temperature resistance and corrosion resistance. Generally, the use temperature of synthetic rubber t≤150℃, natural rubber t≤60℃, and rubber is used for the sealing of stop valves, gate valves, diaphragm valves, butterfly valves, check valves, pinch valves and other valves with a nominal pressure of PN≤1MPa. Commonly used types of synthetic rubber: NBR, EPDM, VITON.
2. Nylon
Nylon has the characteristics of low friction coefficient and good corrosion resistance. Nylon is mostly used for ball valves and globe valves with temperature t≤90℃ and nominal pressure PN≤32MPa.
3. Polytetrafluoroethylene Polytetrafluoroethylene is mostly used for globe valves, gate valves, and ball valves with a temperature t≤232℃ and a nominal pressure of PN≤6.4MPa. Short name: PTFE
4. Cast iron
Cast iron is used for gate valves, stop valves, cock valves, etc. for temperature t≤100℃, nominal pressure PN≤1.6MPa, gas and oil. main types: GI, DI
5. Babbitt alloy
Babbitt alloy is used for ammonia stop valves with temperature t-70~150℃ and nominal pressure PN≤2.5MPa.
6. Copper alloy
Commonly used copper alloy materials include 6-6-3 tin bronze and 58-2-2 manganese brass. Copper alloy has good wear resistance, suitable for water and steam with temperature t≤200℃ and nominal pressure PN≤1.6MPa. It is often used in gate valves, globe valves, check valves, plug valves, etc.
7. Chromium stainless steel
Commonly used grades of chromium stainless steel are 2Cr13 and 3Cr13 after quenching and tempering treatment, which has good corrosion resistance. It is commonly used on valves of water, steam, petroleum and other media with temperature t≤450℃ and nominal pressure PN≤32MPa.
8. Chromium nickel titanium stainless steel
The commonly used grade of chromium nickel titanium stainless steel is 1Cr18Ni9ti, which has good corrosion resistance, erosion resistance and heat resistance. It is suitable for steam, nitric acid and other media with temperature t≤600℃ and nominal pressure PN≤6.4MPa, used in stop valves, ball valves, etc.
9. Nitrided steel
The commonly used grade of nitriding steel is 38CrMoAlA, which has good corrosion resistance and scratch resistance after carburizing treatment. Commonly used for power station gate valves with temperature t≤540℃ and nominal pressure PN≤10MPa.
10. Boronizing
Boronizing is directly processed from the valve body or valve clack body material to form the sealing surface, and then boronizing surface treatment, the sealing surface has good wear resistance. Used in power station blowdown valves. To
When the valve is in use, the matters that should be paid attention to are:
1. The sealing performance of the valve should be tested to ensure its performance.

2. Check whether the sealing surface of the valve is worn, and repair or replace it according to the situation.

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Valve seal (ring) material usage range comparison table

What are the main factors affecting valve sealing?

The main classification and use conditions of valve sealing materials

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