Analysis of Sealing Methods for Gate Valves

As a core cut-off valve, the sealing performance of gate valves directly determines the operational safety, service life, and maintenance costs of pipeline networks. The mainstream sluice valve in the current market are mainly divided into three categories based on differences in sealing structure and sealing materials: ductile iron EPDM seat gate valves, ductile iron brass seat gate valves, and WCB/SS metal seat gate valves.

This article combines the structural characteristics of the product to explain in detail the sealing principles, core advantages, and adaptation conditions of various types of gate valves, providing professional references for engineering selection and project procurement.

1.Ductile iron EPDM seat gate valve: elastic seal, focusing on zero leakage in civil and municipal scenarios

The ductile iron EPDM seat gate valve, with ductile iron as the main body of the valve body, is the most widely used product in the fields of municipal water supply and building drainage. The sealing method of soft seal gate valve is rubber elastic soft sealing, and the GGG40 gate is covered with a high-quality rubber sealing layer on the outside. The DI gate valve relies on the pressure of the medium to tightly adhere to the sealing surface of the valve body, forming a surface sealing structure.

During the working process, rubber material has good elasticity and deformation ability, which can automatically compensate for the sealing gap. Even if there are a small amount of small impurities and scale in the pipeline, it can maintain the integrity of the seal and achieve zero leakage throughout the entire diameter. At the same time, the slide gate valve has a small opening and closing torque, easy operation, and low flow resistance.

This water gate valve is suitable for normal temperature and pressure clean water media, and its main application scenarios are urban tap water pipelines, residential area water supply and drainage, park water supply, ordinary fire protection pipelines, rural drinking water projects and other civil and light municipal projects. Not suitable for high temperature, high pressure, corrosive media, and industrial pipelines containing a large amount of solid particles.

2. Ductile iron brass seat gate valve: metal hard seal, balancing durability and universal working conditions

Brass seat gate valves also use ductile iron valve bodies, which belong to the category of traditional metal hard sealed gate valves. The sealing method of this hard seal gate valve is copper alloy wear-resistant sealing, and the sealing surfaces of the valve body, valve seat, and gate are embedded with wear-resistant copper alloy material, relying on precise fitting of the metal surface to achieve cut-off sealing.

Copper alloy has high hardness, wear resistance, aging resistance, and friction resistance, which is far superior to rubber material. It is not easy to cause wear, aging, and deformation of the sealing surface when repeatedly opening and closing for a long time. This CI gate valve is more resistant to high temperature and water pressure impact, and has a long service life. Compared to soft sealed products, it can withstand higher pressure levels and has outstanding resistance to external damage.

With its stable metal hard sealing characteristics, this product is widely applicable in various scenarios, including urban main water supply pipelines, municipal old pipe network renovation, small and medium-sized water conservancy transmission channels, factory circulating water systems, general HVAC pipelines, etc. Suitable for room temperature clean water and micro impurity fluids, it is a cost-effective choice between civilian and general industrial use, and is also a commonly used mainstream model in engineering bidding.

3. WCB/SS metal seat gate valves: all metal hard seal, deeply rooted in harsh industrial conditions

WCB/SS metal seat gate valves are pure metal hard sealing structures. The WCB gate valve bodies are formed by forging/casting processes of carbon steel and stainless steel, respectively. The sealing method is direct sealing of the body metal, and the valve seat and gate plate are processed from the same material as the valve body without additional embedded seals. They rely on high-precision mechanical processing to achieve tight sealing of the metal surface.

Carbon steel material has high mechanical strength, extremely strong pressure bearing capacity, high pressure resistance, and impact resistance; Stainless steel additionally possesses excellent acid and alkali resistance, corrosion resistance, and rust prevention capabilities. The overall structure is resistant to high temperature, high pressure, and erosion, and can adapt to complex media such as high-temperature steam, oil products, chemical fluids, corrosive liquids, etc. The sealing surface is resistant to high temperature and wear, and is not easy to fail under harsh working conditions.

This type of flanged gate valve is positioned for industrial applications, mainly used in harsh working environments such as petrochemicals, power plants, thermal steam pipelines, corrosive medium pipelines in sewage treatment plants, mining fluid transportation, and high-pressure industrial pipelines. The carbon steel version is mostly used for high-pressure water, steam, and oil pipelines, while the stainless steel version is mainly used for transporting acid, alkali, salt spray, and strongly corrosive media.

Summary

When selecting engineering models, it is necessary to make a comprehensive judgment based on the type of medium, temperature, pressure, and usage environment, and match the corresponding sealing structure of the gate valve product, in order to ensure sealing performance while reducing later operation and maintenance costs and improving the operational stability of the entire pipeline network system.

KR VALVE (TIANJIN) Co., LTD

Email: info@tjkrvalve.com

Telephone: 0086 18920615838