Structural Features Of Bellow Seal Globe Valve

Structural Features Of Bellow Seal Globe Valve

Structural features of bellows globe valve

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The intercepting steam globe valve, also known as the "bellows globe valve," features a double-layer bellows design welded to the stem. This design maintains stable operation and prevents stem vibration caused by valve plug movement.

In high-temperature settings, the stem remains isolated from the medium, ensuring zero leakage. The valve can be opened and closed tens of thousands of times due to its robust construction. The handwheel is ergonomically designed for extended service life and effortless operation. The opening and closing mechanism involves plug-shaped valve flaps with flat or tapered sealing surfaces, moving in a straight line along the fluid's centerline. Known as a shut-off valve, it is widely used due to its minimal sealing surface friction during operation, durability, small opening height, easy manufacturing, and convenient maintenance. It is suitable for low, medium, and high-pressure applications, making it ideal for industries such as food, medicine, petroleum, chemical, natural gas, steel, environmental protection, and paper for media cut-off or circulation.

Features of Bellows Disconnecting Valve

• Double sealing design (bellows + packing): If the bellows fail, the stem packing will still prevent leakage.
• Reasonable structure with reliable sealing, excellent performance, and appealing aesthetics.
• No fluid loss, reducing energy waste and enhancing plant equipment safety.
• Overlaying cobalt-based hard alloy, featuring a dense, wear-resistant, and corrosion-resistant layer for long service life and low maintenance costs.
• Sturdy bellows seal design ensures zero stem leakage and maintenance-free conditions.
• Stem tempering and surface nitriding treatment provide excellent anti-corrosion and anti-friction properties.
• Clear indication of stem lift position.
• Double sealing offers more reliable performance and zero leakage.
• Choice of materials, flange, and butt welding sizes according to actual working conditions or user requirements to meet diverse engineering needs.

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Principle of Operation

Relying on the steam pressure, the valve's sealing surface and seat sealing surface fit closely together to stop the flow of media.

Note on selecting a bellows disconnecting valve:

• Suitable for small diameter pipelines to adjust flow and pressure where accuracy requirements aren't high or for sections that frequently close to cut off one-way flow.
• Due to its significant resistance, it is more suitable for pipelines where high flow resistance isn't a concern.
• Not suitable for media with high viscosity or particles that may precipitate easily.

Construction and Installation Guidelines

• Installation location, height, and import/export direction must meet design requirements, ensuring solid and tight connections.
• For all types of manual valves on insulated pipelines, the handle should not be facing downward.
• Before installation, steam shut-off valves should undergo an appearance check. For valves operating at pressures greater than 1.0 MPa and used to cut off main pipelines, a performance test for strength and tightness should be conducted. The strength test pressure should be 1.5 times the nominal pressure for a duration of at least 5 minutes. The valve shell and packing should show no leakage to be qualified, with a tightness test pressure of 1.1 times the nominal pressure.
• The handwheel, handle, and transmission mechanism are not designed for lifting.
• The medium flow direction should match the arrow direction indicated on the valve body.

Application Areas

Bellows seal globe valves are widely used in sectors such as petroleum, petrochemical, chemical, metallurgy, electric power, water conservancy, urban construction, machinery, coal, food, and other industrial applications. These include main steam trapping, boiler drainage, blast furnace systems, hot air furnaces, thermal systems, and steam systems.

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