What is a Bellows Seal Gate Valve？

A Bellows Seal Gate Valve is a high-performance valve improved on the basis of ordinary gate valves. Its core feature is the adoption of bellows sealing technology to replace or assist the traditional packing seal, achieving zero leakage sealing at the valve stem. It is particularly suitable for pipeline systems handling flammable, explosive, toxic, and valuable media.

I. BASIC DEFINITION AND STRUCTURAL CHARACTERISTICS

A Bellows Seal Gate Valve is a valve used for fully opening and closing to control fluid flow in pipeline systems. Its opening and closing element is a gate (or disc) with a flat or conical sealing surface, and the gate moves linearly along the centerline of the fluid.

Main structural components:

• Valve body, bonnet, valve stem, gate, handwheel (basically the same as ordinary gate valves)

• Core component: Metal bellows (made of laminated multi-layer stainless steel sheets, with high elasticity and flexibility)

• Dual sealing system: Bellows seal + packing seal (forming safety redundancy; if the bellows fails, the packing can still prevent leakage)

Bellows installation method:

• Lower end: Welded to the valve stem assembly using automatic girth welding technology

• Upper end: Welded to the connecting plate or bonnet using automatic girth welding technology

• Function: Form a metal barrier between the fluid medium and the atmosphere to ensure zero leakage of the valve stem

II. WORKING PRINCIPLE

The working principle of a Bellows Seal Gate Valve is similar to that of an ordinary gate valve:

1. Rotate the valve stem through a handwheel or other actuators (pneumatic, electric, etc.)

2. The valve stem moves axially, driving the gate (or disc) to move up and down

3. When the gate rises, the valve opens and fluid passes through; when the gate descends, the valve closes and blocks fluid flow

4. Key difference: The bellows expands and contracts synchronously with the valve stem, maintaining a sealed state at all times to prevent medium from leaking outward through the gap of the valve stem movement

III. MAIN ADVANTAGES AND APPLICATION SCENARIOS

Typical application scenarios:

• Nominal pressure: PN1.6～16MPa

• Operating temperature: -29～350℃

• Applicable industries: Petroleum, chemical, pharmaceutical, chemical fertilizer, power, metallurgy, etc.

• Applicable media: Flammable, explosive, toxic, valuable, radioactive, high-temperature, high-pressure and other dangerous or special media

IV. DIFFERENCES FROM ORDINARY GATE VALVES

V. SUMMARY

A Bellows Seal Gate Valve is a high-performance valve designed to solve the problem of valve stem leakage in traditional gate valves. Through its unique bellows sealing technology, it achieves zero leakage at the valve stem, making it particularly suitable for industrial application scenarios with extremely high sealing requirements. With its simple structure, long service life, and reliable sealing performance, it has become an important equipment choice in pipeline systems handling dangerous media.