Gate Valve Body Structure and Flow Passage Design: Manufacturing Methods and Selection Guide

The structure of a gate valve body is determined by its connection methods to the pipeline and valve bonnet. Based on manufacturing techniques, gate valve bodies can be classified into several types: cast, forged, forge-welded, cast-welded, and tube-sheet welded. Forged valve bodies are increasingly used in large-diameter applications, while cast valve bodies are more common in small-diameter valves. The choice between forging and casting depends on user requirements and the manufacturer’s production capabilities.The main gate valves product names of China gate Valve Network include:

GB Bellows Wedge Gate Valve,High Temperature & pressure Power Station Gate Valve,Inside Screw Non-rising Stem Wedge Gate Valve,Insulation Jacket Gate Valve,Lined Gate Valve,MZ44W Rising Stem Gas Quick Open&close ParallelMZ48W Manual Non-rising Stem City Gas Quick Gate Valve,Manual Knife-shaped Gate Valve,Manual Slurry ValveManual Wedge Copper Gate Valve,Manual Vacuum Isolated Wedge Gate Valve,Manual Welding Vacuum Wedge Gate Valve

Types of Flow Passages in Gate Valve Bodies

The flow passage of a gate valve body is mainly divided into two types: full bore and reduced bore.

Full Bore: The flow passage diameter is essentially the same as the nominal diameter of the valve, resulting in low fluid resistance. It is suitable for pipelines requiring full flow capacity.

Reduced Bore: The flow passage diameter is smaller than the nominal diameter. This type can be further categorized into uniform reduced bore and non-uniform reduced bore (e.g., conical taper). In conical reduced bore valves, the inlet diameter is close to the nominal diameter and gradually tapers to the minimum at the valve seat.

Advantages and Considerations of Reduced Bore Design

The reduced bore design offers the advantage of reducing the disc size, lowering the operating force, and decreasing torque for valves of the same specification. However, it also increases flow resistance, leading to higher pressure drops and energy consumption. Therefore, the reduction ratio should not be excessive.

For conical reduced bore valves, the ratio of the seat inner diameter to the nominal diameter is typically recommended to be between 0.8 and 0.95. Selection guidelines include:

Nominal Diameter < 250 mm: The seat inner diameter is usually one standard size smaller than the nominal diameter. 

Nominal Diameter ≥ 300 mm: The seat inner diameter is generally two standard sizes smaller than the nominal diameter.

A well-designed reduced bore can optimize manufacturing costs and operational efficiency while maintaining valve performance.

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