What are the main features of knife gate valve products?

Release time:

2022-08-05

The upper part of the knife gate valve consists of a valve bonnet and a stuffing box, making it easy to disassemble and maintain on-site. The inclined valve stem design and the optimized flow path shape ensure that the medium flows in a nearly straight line. Compared with other types of valves, this valve exhibits a lower pressure drop for the same CV value. The valve body features a hard alloy sealing surface applied via specialized surfacing welding (with the entire sealing surface undergoing integral hardening treatment), resulting in a compact structure.

　　 Knife Gate Valve The upper part consists of a valve bonnet and a packing gland, making it easy to disassemble and maintain on-site. The design of the inclined valve stem and the flow passage shape ensures that the medium flows in a nearly straight line. Compared with other types of valves, this valve exhibits a lower pressure drop for the same CV value. The valve body features a hard alloy sealing surface applied via specialized surfacing welding (with the entire sealing surface undergoing integral hardening treatment), resulting in a compact structure. So, what are the main characteristics of knife gate valve products?

Knife Gate Valve

　　1. Knife Gate Valve The upper part consists of a valve bonnet and a packing gland, allowing for quick disassembly and on-site maintenance. The optimized design of the inclined valve stem and flow passage geometry ensures that the medium flows in a nearly straight line. Compared with other types of valves, this valve boasts a relatively high CV value and generates lower pressure drop.

　　2. The knife gate valve features a specially processed hard alloy sealing surface (with overall hardening treatment of the sealing surface), resulting in a more compact structure. The conical sealing surface design minimizes axial sealing force, ensuring reliable sealing and a long service life.

　　3. The knife-type gate valve features a valve disc guided by two guide rings in the valve chamber. The top and bottom of the valve disc are simultaneously guided, forming a piston-type valve disc that is fully guided throughout the entire length of the valve body chamber. This design effectively eliminates various issues caused by improper forces, such as sticking, surface scratches, stem bending, and valve-disc vibration. The guide ring at the bottom of the valve disc allows nearly 90% of the fluid to pass through it in a nearly linear manner, thereby effectively eliminating all adverse effects resulting from side impacts. These characteristics make this valve particularly well-suited for rapid “relief” and “discharge” systems in power plant steam applications.

　　4. Knife Gate Valve The sealing surfaces of valve discs are typically welded with hard alloys, which give them excellent mechanical properties, wear resistance, and erosion resistance. This ensures that the valve remains free from damage during prolonged use and significantly extends its service life.

　　5. The valve stem packing of the knife gate valve uses imported specialized packing material, which provides superior leak-proof performance, is highly durable, and easy to disassemble. The packing box and valve body are sealed with 316 high-mesh flexible graphite gaskets, assembled according to a predetermined torque for enhanced safety and reliability, effectively preventing leaks. In addition, the actuator of the knife gate valve employs a pneumatic device, enabling safe and efficient valve control. Meanwhile, the stuffing box features a specially designed structure that ensures sufficient strength and excellent thermal properties.

　　 Knife Gate Valve These characteristics make it well-suited for rapid “venting” and “discharge” systems in power plant steam applications. Moreover, the valve disc sealing surface is protected by a hard alloy, which enhances its mechanical performance and also provides it with good wear resistance and impact resistance. However, when using this product, given its relatively thin edges, careful maintenance is essential. It’s important to avoid collisions with hard objects as much as possible, to prevent surface damage that could compromise its performance in later use.

The vast majority of stainless steel knife gate valves employ forced sealing: that is, when the valve is closed, an external force is applied to forcibly press the gate against the high-pressure valve seat, thereby ensuring a tight seal on the sealing surfaces. Some gates can also be designed to undergo slight deformation, which helps improve their manufacturability and compensate for any misalignment in the sealing surface angles that may occur during the manufacturing process. Such gates are referred to as flexible gates. The majority of knife gate valves rely on forced sealing—meaning that when the valve is closed, an external force is used to press the gate firmly against the high-pressure valve seat, thus guaranteeing a secure seal on the sealing surfaces. Valves of this type are generally installed horizontally in pipelines.

2023-05-11

Next, let’s talk about several operating procedures for knife gate valves.

When a gate valve is closed, the sealing surfaces rely solely on the pressure of the medium to achieve a seal—specifically, the sealing surface of the gate is pressed against the valve seat on the opposite side by the medium’s pressure, thereby ensuring a tight seal. This type of sealing is known as self-sealing. In contrast, most gate valves employ forced sealing: when the valve is closed, an external force must be applied to press the gate against the valve seat in order to guarantee the sealing performance of the sealing surfaces. Such valves should be installed vertically in the pipeline.

2023-05-11

Next, let’s talk about whether knife gate valves have fire-resistant and anti-static requirements.

When an electrostatic knife gate valve is opened or closed, the sphere and the valve seat experience mutual friction. The static electricity generated by this friction tends to accumulate on the sphere—something that is unacceptable for ball valves used in gas, fuel, and chemical pipelines, as it could potentially lead to pipeline explosions. Ball valves with antistatic designs are equipped with static discharge devices.

2023-05-11

Next, let’s talk about some important considerations for the installation, operation, and maintenance of pneumatic knife gate valves.

Pneumatic knife gate valves have a wide range of applications, spanning from ordinary fields to more diverse industries—from coal preparation, gangue removal, and slag discharge in coal-fired power plants to urban wastewater treatment; from general industrial pipelines to pipeline systems used in food, sanitation, and pharmaceutical industries. So, what are the key considerations when installing, using, and maintaining pneumatic knife gate valves?

2023-05-11

Slurry Valve Manufacturer: How are stainless steel knife gate valves good?