Do these situations require the use of hard-sealed gate valves?

New Gate Valve - Advantages and Applications of Hard Seal Gate Valve

As one of the most common control devices in industrial pipelines, gate valves are widely used in petroleum, chemical industry, electric power, metallurgy and other fields. With the advancement of science and technology and the increase in industrial demand, the types and performance of gate valves have continued to improve. Among many types, hard-sealed gate valves have become one of the new gate valves that have attracted much attention on the market due to their excellent sealing performance and durability.

Hard-sealed gate valves mainly include valve body, valve cover, valve stem, valve disc, copper nut, O-ring, middle head gasket, and bolts. Hard-sealed gate valves are new products developed by Wesdom. They mainly have German standards, British standards, and American standards. The standard gate valve has a reasonable structure, compact design, and beautiful appearance. The current structure weight is relatively moderate, responding to the energy conservation and emission reduction policy;

Especially the design of the valve body and valve cover, the side streamline design, smooth transition, and reasonable technology. In terms of sealing, the design gap is reasonable. The design tolerance zone is considered based on the comprehensive factors of the assembly line casting process, casting tolerances, and tolerances caused by human operations. In practical production, it has been verified that when closing the valve, the torque is light, safe and reliable. 

The main differences between hard seal gate valves and soft seal gate valves:

The difference between hard-sealed gate valves and soft-sealed gate valves is mainly reflected in sealing materials, structural design and applicable occasions.

1. Differences in sealing materials

The sealing pair of a hard-sealed gate valve is usually composed of metal-to-metal, and the sealing surface is made of high-hardness, corrosion-resistant materials, such as stainless steel, alloy steel or tungsten carbide. These materials have high hardness and wear resistance, and can maintain stable sealing performance under high temperature, high pressure and strong corrosive environments. In contrast, the sealing pair of soft-sealing gate valves usually uses elastomer materials, such as rubber, plastic or polytetrafluoroethylene (PTFE). The advantage of soft sealing materials is that they are flexible and can provide excellent initial sealing performance. However, their high temperature resistance, corrosion resistance and wear resistance are relatively poor, and they are prone to aging or deformation under harsh working conditions, thus affecting the sealing effect.

2. Differences in structural design

The sealing pair of hard-sealed gate valves is usually manufactured through machining and grinding processes. The sealing surface is required to be flat and smooth, and undergoes strict matching and debugging to ensure that the sealing pair fits closely in high-temperature and high-pressure environments. Soft-sealing gate valves rely on the elasticity of the sealing material to achieve the sealing effect through deformation. Therefore, the structural design is relatively simple and the manufacturing cost is low.

3. Differences in applicable occasions

Due to different sealing materials and structural designs, hard-sealed gate valves and soft-sealed gate valves are suitable for different working conditions. Hard-sealed gate valves are usually used in medium situations with high temperature, high pressure, strong corrosion or solid particles, such as oil refineries, chemical plants and high-temperature steam pipelines. Soft seal gate valves are suitable for use in low temperature, normal pressure or non-corrosive media, such as water pipes, food processing and air conditioning systems.

Practical applications of hard seal gate valves:

The assembly diagram is as follows: The inner seal is made of material metal 1, and 2 is the sealing component that cooperates to form the sealing surface.

Main features:

Driven by the handwheel, the valve stem drives the copper nut to move downward, causing the two sealing surfaces of the valve disc and the valve body and valve seat to squeeze each other, thus acting as a seal. Under normal circumstances, there is no leakage from the inner seal. Due to processing The error causes the valve disc and the valve body to have different matching angles. The valve torque is too large or cannot be closed. The existing structure can solve the above problems, as shown in the figure below. The valve disc can be slightly deformed, has a slight deformation compensation function, and is easy to seal. Temperature changes are not easy to cause scratches, the wedge should not be high, and the versatility is good.

When the valve disc is under positive pressure, the valve stem will deform slightly. In order to prevent the elasticity from failing, limit devices are added at 3 places. It not only has a limiting function, but also can push the valve disc to both sides through the 4-3 device, which has a better sealing effect and can well solve the problem of side leakage.

 

 

Advantages and features of hard seal gate valve:

Hard-sealed gate valves exhibit many advantages in industrial applications due to their excellent performance and wide applicability.

1. Excellent high temperature resistance

The sealing pair of the hard seal gate valve is made of metal material and can maintain stable performance in high temperature environments. Under normal circumstances, the operating temperature of hard-sealed gate valves can reach over 300°C, and some specially designed hard-sealed gate valves can even operate normally in ultra-high temperature environments of 800°C. This makes hard-sealed gate valves play an irreplaceable role in high-temperature process pipelines, such as petroleum refining, chemical high-temperature reactions, and high-temperature steam pipelines in power plants.

2. Excellent wear resistance

The sealing pair of the hard-sealed gate valve has undergone special heat treatment and surface hardening treatment, and has extremely high hardness and wear resistance. In working conditions containing solid particles or abrasive media, the sealing surface of the hard-sealed gate valve can effectively resist the erosion and wear of the medium and extend the service life of the valve. In contrast, soft seal materials are prone to wear under such working conditions, leading to seal failure.

3. Excellent corrosion resistance

Hard-sealed gate valves often use corrosion-resistant alloy materials, such as stainless steel, nickel-based alloys, etc., and their sealing pairs have good resistance to strong acids, strong alkali and other corrosive media. Therefore, hard-sealed gate valves perform well in corrosive media pipelines in chemical, metallurgical and other industries.

4. Stable sealing under high pressure conditions

Due to the use of metal sealing pairs, hard-sealed gate valves can maintain a stable sealing effect under high-pressure conditions. The metal sealing pair is not easily deformed in a high-pressure environment and can ensure the safe operation of the valve in high-pressure pipelines. Soft sealing materials are prone to deformation or even extrusion under high pressure, leading to sealing failure.

5. Long service life 

The metal seal pair of hard-sealed gate valves has a long service life, usually ten years or more. Under harsh working conditions, the service life of hard-sealed gate valves is significantly better than that of soft-sealed gate valves, which can reduce the frequency of equipment maintenance and replacement, thereby reducing operating costs.

The applicable working conditions of hard seal gate valve:

Hard seal gate valves should generally be installed horizontally in pipelines. It has been widely used in chemical industry, liquefied gas, boiler steam system, mining, water supply and drainage, food, pharmaceutical, power generation, urban construction, municipal administration, and other fields

The excellent performance of hard-sealed gate valves makes them widely used in a variety of harsh working conditions.

1. Piping system for high temperature media

Due to its excellent high temperature resistance, hard seal gate valves are widely used in pipeline systems with high temperature media. For example, in the petroleum refining process, in the high-temperature pipelines and steam pipelines of crude oil heating furnaces, hard-sealed gate valves can maintain stable sealing performance under high temperatures and high pressures, ensuring the safety and efficiency of the production process.

2. Fluid control under high pressure conditions

In the oil, gas and power industries, fluid control under high-pressure conditions places strict requirements on the sealing performance of valves. Due to the characteristics of its metal seal pair, the hard-sealed gate valve can effectively prevent leakage in high-pressure environments and ensure the safety of the system.

3. Transportation pipelines for corrosive media

Many media in the chemical industry are highly corrosive, such as sulfuric acid, hydrochloric acid, etc. These media place high demands on the corrosion resistance of the valve. Due to the use of corrosion-resistant metal materials, hard-sealed gate valves can effectively resist corrosion from the medium and ensure long-term stable operation of the valve in corrosive environments.

4. Transport of media containing solid particles

In the production process of mining, metallurgy and other industries, the medium often contains solid particles, such as slurry, sediment, etc. These solid particles can cause severe wear to the valve sealing surface. The metal seal pair of the hard-sealed gate valve has excellent wear resistance and can maintain a good sealing effect for a long time under such working conditions.

5. Frequent operating conditions

In some working conditions that require frequent opening and closing operations, hard-sealed gate valves can withstand frequent operations and are not prone to leakage or damage due to the wear resistance and stability of their sealing surfaces. For example, in the automatic control system of petrochemical equipment, hard-sealed gate valves are often used as important control components.

As the representative of new type gate valves, hard-sealed gate valves are widely used in key working conditions in petroleum, chemical industry, electric power, metallurgy and other industries due to their excellent high temperature resistance, wear resistance, corrosion resistance and high pressure resistance. Compared with soft-sealed gate valves, hard-sealed gate valves show better stability and reliability in harsh environments. Therefore, with the continuous advancement of industrial technology, hard seal gate valves will have broader application prospects in the future and become an indispensable and important equipment in modern industrial production.