Introduction to the Use of Plug Valves

Release time:

2022-03-22

The manufacturer, Higashi, introduces the applications of slide valves. As a shut-off valve, the slide valve can only be used in fully open or fully closed positions. When the slide valve is operated in the fully closed position, it must have a certain degree of sealing performance to prevent material leakage. After the slide valve is manufactured, a test of its shell’s sealing performance is conducted.

　　The manufacturer, Hidaka, introduces the application of slide valves. As a shut-off valve, the slide valve can only be used in fully open or fully closed positions. When the slide valve is operated in the fully closed position, it must have a certain degree of sealing performance to prevent material leakage. After the slide valve is manufactured, a test of its shell’s sealing performance is conducted.

　　For slide valves with a shell and sealing test medium of water (containing an anti-corrosion agent), kerosene, or other suitable liquids with a viscosity no greater than that of water, if the sealing pair is made of non-metallic materials, the shell sealing test and related requirements shall be conducted in accordance with relevant regulations. For slide valves whose sealing pair is made of metallic materials and which have sealing performance requirements, the same regulations apply.

　　The leakage rate for the sealing test shall be calculated as 1 × DN mm³/s. For slide valves driven by electric, hydraulic, or pneumatic actuators that have no specific sealing performance requirements, this test need not be performed. After the closing position has been set, perform the shell and sealing tests three times, in accordance with requirements 1 and 3. The cleanliness requirements for slide valves shall comply with relevant regulations. The number of static pressure endurance tests for slide valves shall be conducted according to specified standards, and other technical requirements shall follow relevant regulations.

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?