GEKO Metal Bellows Sealed Globe Valve

GEKO: A Dedicated Valve Brand for Highly Corrosive and Highly Toxic Chemical Media

GEKO is positioned as a specialized valve brand for chemical applications involving highly corrosive and extremely toxic media. Its core product is the metal bellows sealed globe valve, designed for zero fugitive emissions, zero external leakage, and long service life. It is an ideal valve solution for highly toxic media such as chlorine, phosgene, hydrogen fluoride, and other hazardous gases.

Compared with conventional packed globe valves, GEKO bellows sealed globe valves reduce fugitive emissions by more than 100 times and offer a service life 5 to 10 times longer. Compared with other bellows valve designs, GEKO valves feature a more compact structure, easier maintenance, and lower overall operating costs.

Product Series and Technical Parameters

Main Product Series: Bellows Sealed Globe Valves

• T-Type Straight-Through Globe Valve

This is the standard design, covering sizes from DN15 to DN600, pressure ratings from PN16 to PN160 or Class 150 to Class 2500, and operating temperatures from -20°C to +450°C.

• Y-Type Globe Valve

The Y-pattern design offers lower flow resistance and is suitable for high-viscosity media and fluids containing particles.

• Angle Type Globe Valve

With a 90-degree flow path, the angle type globe valve saves installation space and is commonly used for small-diameter, high-pressure applications.

• Chlorine Service Valve

GEKO chlorine valves are designed specifically for dry and wet chlorine service. They meet European chlorine industry standards and are among the products certified by only a limited number of qualified manufacturers. These valves provide excellent corrosion resistance and zero external leakage for chlorine applications.

Materials and Pressure Ratings

• Valve Body: WCB carbon steel, CF8M stainless steel 316, Alloy 20, Hastelloy C for highly corrosive applications.
• Bellows: Multi-layer stainless steel bellows, such as 316L or 321, with a fatigue life of no less than 10,000 opening and closing cycles.
• Disc and Seat: Stellite 6 hardfacing, hardness HRC40–50, providing excellent wear resistance and erosion resistance.

Core Structure and Sealing Principle

 Integral Structure: Three-Piece Design, Bellows Seal, No Packing

• Valve Body

The valve body is forged or cast in accordance with ASME B16.34 and can be supplied with flanged or butt-weld ends.

• Bellows Assembly

The multi-layer welded stainless steel bellows is connected to the valve stem at one end and to the valve body at the other end. This structure completely isolates the process medium from the atmosphere, eliminating the need for traditional packing and preventing external leakage.

• Valve Stem

The two-section rising stem design provides reliable sealing performance. The stem is Stellite-coated, anti-rotation, and designed for low-friction operation.

• Disc and Seat

The conical metal-to-metal sealing structure ensures tight shut-off and zero internal leakage. During opening and closing, the sealing surfaces are self-cleaned to maintain reliable sealing performance.

• Bonnet Flange

The bonnet flange adopts a tongue-and-groove design with a flexible graphite gasket, providing fire-safe performance in accordance with API 607.

Patented Sealing Mechanism for Zero External Leakage

• Absolute Isolation by Bellows

The process medium is sealed inside the bellows, achieving zero fugitive emissions in compliance with TA-Luft requirements. Since there is no packing wear, the risk of external leakage is eliminated.

• Elastic Preload Compensation

The bellows provides inherent elasticity, allowing automatic compensation for thermal expansion, contraction, and wear. This ensures stable sealing pressure during long-term operation.

• Conical Hard Sealing

The disc and seat are precision-lapped to a micron-level finish. When closed, the metal sealing surfaces fit tightly together, achieving zero internal leakage in accordance with API 598.

• Anti-Torque Design

The bellows is equipped with an anti-rotation limiting structure to prevent torsional fatigue during valve operation, significantly extending service life.

Application Conditions and Performance Limits

Recommended Applications

GEKO bellows sealed globe valves are especially suitable for the following severe service conditions:

• Media: dry and wet chlorine, phosgene, hydrogen fluoride, hydrogen chloride, toxic gases, high-temperature steam, hot alkali, and high-temperature media containing particles.
• Temperature Range: -50°C to +450°C; special alloy designs can reach up to 550°C. The valve maintains stable performance under alternating hot and cold conditions.
• Pressure Range: Class 150 to Class 2500, or PN16 to PN160, with reliable high-pressure sealing and no internal leakage.
• Industries: chlor-alkali chemical plants, coal chemical industry, petroleum refining, fertilizer production, fine chemicals, and pharmaceutical manufacturing.

Applications Not Recommended

• Strongly abrasive media with large particles, such as high-slag black water. In such cases, a hard-seated ball valve is recommended.
• Low-pressure, large-diameter applications, where soft-seated butterfly valves may offer better cost performance.
• Very frequent opening and closing operations, because bellows have a limited fatigue life. For high-cycle services, wear-resistant ball valves are recommended.

Maintenance Guidelines and Common Faults

Key Maintenance Principles for Toxic and High-Temperature Services

• Never disassemble under pressure.

The bellows is a thin-wall component and may rupture if disassembled under pressure. The valve must be fully depressurized to 0 MPa before maintenance.

• Protect the bellows from impact.

The bellows has a multi-layer thin-wall structure. Hammering, squeezing, scratching, or impact damage is strictly prohibited. Soft tools should be used during disassembly and assembly.

• Keep maintenance records.

All maintenance steps, including disassembly, cleaning, inspection, replacement, assembly, and pressure testing, should be recorded with written notes and photos for traceability.

Common Faults and Solutions

• Internal Leakage or Poor Shut-Off

Possible causes include coking on the sealing surface or particles stuck between the disc and seat. The valve should be disassembled, cleaned, and lapped. If the disc or seat is worn, the sealing components should be replaced. If the bellows is fatigued, the bellows assembly must be replaced.

• Sticking or High Operating Torque

This may be caused by ash accumulation in the valve cavity, bellows deformation, or stem corrosion. The valve should be disassembled and cleaned. Deformed bellows must be replaced, and corroded stems should be derusted and lubricated with high-temperature grease.

• Bellows Leakage, Rare Case

Possible causes include fatigue at the welded area or corrosion by the medium. The bellows should be replaced, and the material should be upgraded when necessary, such as using Hastelloy C for highly corrosive media.

Selection and Procurement Recommendations

• Operating Conditions First

For highly toxic, highly corrosive, high-temperature, and high-pressure applications, GEKO bellows sealed globe valves are the preferred choice. For media containing particles, GEKO hard-seated ball valves are recommended.

• Size and Pressure Selection

DN15 to DN200 and Class 300 to Class 600 are the most commonly selected and cost-effective ranges.

• Spare Parts Strategy

It is recommended to keep spare bellows assemblies, disc and seat sets, and bonnet gaskets of the same specifications in stock. This helps reduce maintenance downtime and overall repair costs.

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