Introduction to the Basic Advantages and Disadvantages of Slurry Valves, along with Some Common Sense on Their Classification

A slurry valve is a type of valve in which the gate (or disc) moves vertically along the centerline of the flow passage. In piping systems, slurry valves are primarily used for on-off service. Slurry valves are widely employed and generally find application in cutting devices with nominal diameters of DN≥50mm; even smaller-diameter cutting devices may also utilize slurry valves. Now, let’s take a closer look at the basic advantages and disadvantages of slurry valves, as well as some handy classification tips!

　　A slurry valve is a type of valve in which the gate (or disc) moves vertically along the centerline of the flow passage. In piping systems, slurry valves are primarily used for cutting applications. Slurry valves are widely employed and generally found in cutting devices with nominal diameters of DN≥50mm; even smaller-diameter cutting devices may also utilize slurry valves. Now, let’s take a closer look at the basic advantages and disadvantages of slurry valves, as well as some handy classification tips!

　　I. Advantages of Slurry Valves

　　1. Low fluid resistance.

　　2. The switch requires little external force.

　　3. Media flows are unrestricted.

　　4. When fully open, the working medium causes less erosion on the sealing surfaces compared to a globe valve.

　　5. The shape is relatively simple and has good castability.

　　II. Disadvantages of Slurry Valves

　　1. It has large external dimensions and a significant open height. The installation requires a substantial amount of space.

　　2. During the switching process, relative friction occurs between sealing surfaces, making them prone to scratches.

　　3. Slurry valves typically have two sealing surfaces, which pose challenges for machining, grinding, and maintenance.

　　III. Types of Slurry Valves

　　1. Classified according to the gate structure

　　1) Parallel-type slurry valve: A slurry valve whose sealing surfaces are parallel to the vertical centerline—that is, the two sealing surfaces are parallel to each other.

　　In parallel-type slurry valves, a structure featuring thrust wedges is commonly used. Between the two gate plates, there are double-sided thrust wedges. This type of slurry valve is suitable for low-pressure slurry applications with small to medium diameters (DN40–300 mm). In some designs, springs are installed between the two gate plates; these springs generate preload pressure, which helps ensure tight sealing of the gate plates.

　　2) Wedge-type slurry valve: A slurry valve in which the sealing surfaces are inclined at a certain angle relative to the vertical centerline, meaning the two sealing surfaces form a wedge shape.

　　The inclination angle of the sealing surface typically ranges from 25° to 33°. The specific values—such as 5°, 8°, or 10°—primarily depend on the temperature of the medium. Generally speaking, the higher the operating temperature, the greater the inclination angle needed to reduce the likelihood of wedge formation caused by temperature fluctuations.

　　Wedge-type slurry valves are further classified into single-gate, double-gate, and elastic-gate types. The V-shaped ribbed wedge valve boasts a simple structure and reliable performance; however, it demands high angular precision of the sealing surfaces, making machining and maintenance challenging. Moreover, temperature fluctuations can easily lead to wedge formation. Double-gate wedge valves are commonly used in pipelines conveying water and steam. Their advantage lies in their lower angular precision requirements for the sealing surfaces, which makes them less prone to wedge formation caused by temperature changes. Additionally, when the sealing surfaces wear down, they can be compensated for using shims. Nevertheless, this design features numerous components, making it susceptible to sticking in viscous media and compromising the seal. Furthermore, the upper and lower gates tend to rust over prolonged use, increasing the likelihood of gate detachment. The wedge-type elastic-gate slurry valve combines the simplicity and usability advantages of the single-damping wedge valve while also allowing for slight elastic deformation. This feature helps compensate for deviations arising during the machining of the sealing surface angles, thereby improving machinability. As a result, this type of valve is now increasingly widely adopted.

　　2. According to the different valve stem structures, the slurry valves can be further classified into:

　　1) Rising stem slurry valve: The valve stem nut is located on the valve bonnet or bracket. When opening or closing the gate, rotating the valve stem nut causes the valve stem to move up and down. This design facilitates lubrication of the valve stem and provides clear indication of the valve’s open and closed positions, making it widely adopted.

　　2) Submerged-stem slurry valve: The valve stem nut is located inside the valve body and comes into direct contact with the medium. When opening or closing the valve, this is achieved by rotating the valve stem. The advantage of this design is that, since the height of the slurry valve remains constant, it is particularly suitable for applications where installation space is limited, pipe diameters are large, or installation space is restricted. This design must be equipped with a switch indicator to show the degree of valve opening or closing. However, the disadvantage of this design is that the valve stem screw not only cannot be lubricated but also directly suffers from medium corrosion, making it prone to damage.

　　4. Contraction of the slurry valve bore diameter

　　When the flow paths within a valve body differ, the diameter of the seat section is often smaller than that of the flange connection section. This phenomenon is known as diameter reduction. Diameter reduction can minimize part dimensions, thereby reducing the force required to operate the valve. At the same time, it broadens the range of applications for the component. However, after diameter reduction, fluid resistance losses increase.

　　The above is an introduction to the basic advantages and disadvantages of slurry valves, as well as some handy tips on their classification. If you’d like to learn more, feel free to contact us anytime!