Flange globe valve is a commonly used shut-off valve, mainly used to connect or cut off the medium in pipelines, and is not suitable for throttling. It has the following characteristics:
1. Working principle: By relying on the pressure of the valve stem, the sealing surface of the valve disc is tightly adhered to the sealing surface of the valve seat, preventing the flow of the medium. Due to its usual top-down flow, the force required to close the valve is relatively small, while the force required to open the valve is relatively large, which is beneficial for improving sealing performance.
2. Advantages:
-Simple structure, easy to manufacture and maintain.
-The sealing surface is not easily worn or scratched, so it has a longer service life.
-The small stroke of the valve disc during opening and closing results in a relatively small height of the shut-off valve.
-Has good sealing performance and is suitable for high-pressure systems.
3. Disadvantages:
-The fluid resistance is high because the medium channel inside the valve body is relatively tortuous.
-The medium can only flow in one direction and has directionality during installation. It is not suitable for media with particles, high viscosity, and easy coking.
-The opening and closing torque is large, the opening and closing process is laborious, and the opening and closing time is relatively long.
4. Application scenarios:
-Industrial manufacturing: fluid control in industries such as petroleum, chemical, metallurgy, and energy.
-Tap water supply system: controls the inflow and outflow of water, maintains water supply pressure and flow rate.
-Oil and gas transmission pipelines: quickly cut off fluid flow in emergency situations.
-Fire protection system: Control the shutdown of water sources to ensure the safe operation of the fire protection system.
5. Sealing performance: The sealing performance of flange globe valves usually depends on the design and material of the sealing surface. There are three common types of seals: flat seal, conical seal, and spherical seal. Each type has its specific application scenarios and advantages and disadvantages. For example, the advantage of planar sealing is that the valve disc can automatically align and match the sealing surface of the valve seat, but solid particles and sediment in the medium can easily damage the sealing surface. Cone and spherical seals provide higher sealing stress and are easier to achieve sealing, but require higher abrasion resistance of the sealing material.
6. Maintenance: In order to ensure the sealing performance of the flange globe valve, regular maintenance is required. This includes checking the wear of the sealing surface, the trapezoidal thread wear of the valve stem and valve stem nut, whether the packing is outdated or ineffective, and making necessary replacements. In addition, it should be ensured that the opening and closing of the valve are both within the limit device to avoid exceeding the ultimate tension or compression of the bellows, which may cause seal failure.
7. Installation and maintenance: The installation of flange globe valves should ensure that the flow direction of the medium is consistent with the direction of the arrow shown on the valve body, avoid the handwheel turning downwards, and do not install underground to prevent moisture from corroding the valve stem. Valves should be stored in a dry and ventilated room, and both ends of the valve passage should be sealed with dust covers. Valves stored for a long time should be regularly inspected, with special attention paid to the cleanliness of the valve sealing surface to prevent damage to the sealing surface.
In summary, the sealing performance and service life of flange globe valves are affected by various factors, including valve design, material selection, operating environment, frequency of operation, and maintenance. Proper installation, use, and maintenance can significantly improve the sealing performance and service life of valves.
