Choosing the Right Gate Valve: Types, Advantages and Considerations

 
Choosing the right type of gate valve is a critical issue in engineering design. Gate valves can be classified into several types based on their internal structure, each with unique applications and characteristics. From wedge single disc gate valves to double disc gate valves and parallel disc gate valves, each structure affects sealing performance, suitability for different media, and operational characteristics. This article delves into the internal structures and features of various gate valve types to assist in making informed choices for different operating conditions.
 

Key Advantages of Gate Valves

 
Low fluid resistance: Designed as through-conduit valves, gate valves minimize fluid resistance by maintaining a straight flow path, making them more suitable than other valve types.
Superior sealing performance: Gate valves outperform globe valves in terms of sealing performance, requiring less force to open and close.
Wide application range: Gate valves handle not only steam and oil-based media but also fluids containing solid particles and high-viscosity fluids, serving as both isolation valves and vent valves in low vacuum systems.
Bidirectional flow capability: Gate valves facilitate bidirectional flow, unaffected by the direction of media flow, making them suitable for pipelines where flow direction may change, with easy installation.
 

Key Disadvantages of Gate Valves

 
Large size and long operation time: Gate valves have larger design dimensions and longer operation times. Opening requires lifting the gate to the top of the valve body, while closing involves dropping the gate fully onto the seat, resulting in a longer stroke and operation time.
Vulnerability of sealing surfaces: Friction between the gate and seat sealing surfaces during valve operation can lead to surface wear, affecting sealing performance and service life, with more complex maintenance procedures.
 

Types of Gate Valves Based on Internal Structure

 
Gate valves are categorized into several types based on their internal structure, each designed to meet specific operational needs and environmental conditions.
 

1. Wedge Single Disc Gate Valve

 

• Simple structure.
• Less effective sealing performance at high temperatures compared to resilient-seated or double-disc gate valves.
• Suitable for high-temperature media prone to clogging.

 

2. Resilient-Seated Gate Valve

 

• A special form of wedge single-disc gate valve.
• Offers good sealing performance at high temperatures with minimal risk of sticking due to thermal expansion.
• Mainly used for steam, high-temperature oils, and oil-gas media, especially where frequent operation is required.
• Not suitable for clogging-prone media.

 

3. Double Disc Gate Valve

 

• Better sealing performance than wedge gate valves.
• Maintains good sealing even with imperfect alignment between seat and disc sealing surfaces.
• Easy maintenance, typically requiring only bottom metal seat replacement without welding or grinding of sealing surfaces.
• Suitable for steam, high-temperature oils, and oil-gas media, especially where frequent operation is required.
• Not suitable for clogging-prone media.

 

4. Parallel Disc Gate Valve

 

• Inferior sealing performance compared to other gate valve forms.
• Mainly suitable for low-temperature and low-pressure media.
• Processing and maintenance of disc and seat sealing surfaces are relatively straightforward.

 
In conclusion, gate valves offer advantages such as low fluid resistance, superior sealing performance, a wide range of applications, and bidirectional flow capability. However, they are characterized by large size, long operation times, and vulnerable sealing surfaces. When selecting the appropriate gate valve type, specific operational requirements must be considered, including media type, temperature, and operational frequency.