Gate Valve Design Variants and Applications

Gate valves are primarily used for full-bore, low-pressure-drop isolation in pipelines. Various design variants have been developed to address specific service requirements including corrosive media, high-pressure applications, and slurry services.

Gate Valve Design Types

• Solid wedge: Most common, robust, suitable for most services

• Flexible wedge: Accommodates thermal distortion in steam services

• Split wedge (double disc): Self-adjusting, reduces stem torque

• Parallel slide: Two parallel discs with spring between, used in steam and high-temperature service

• Slab gate (through-conduit): Full-bore passage, common in pipeline pigging services

Rising vs. Non-Rising Stem

Rising stem gate valves provide visual indication of valve position through stem travel. Non-rising stem designs are preferred where headroom is limited. Inside screw (IBBM) design protects threads from the process fluid. Outside screw and yoke (OS&Y) design makes stem threads accessible for maintenance.

High-Pressure Gate Valves

• Pressure seal bonnet: For Class 900 and higher pressure classes

• Bolted bonnet: Standard for Class 150-600

• Welded bonnet: Permanent installations requiring no future disassembly

• Integral flanges: Forged body with integral end flanges for compact design

Knife Gate Valves

Knife gate valves feature a sharp-edged gate that cuts through slurries, fibrous materials, and paper pulp. Used in mining, pulp and paper, and wastewater treatment. Wafer body style reduces weight and installation cost. Packing must be replaceable online due to abrasive service demands.

Common Gate Valve Applications

Gate valves are standard for pipeline isolation, block valve service, pump and compressor isolation, and tank outlet valves. They are not suitable for throttling service due to vibration and erosion risk at partial-open positions. Full open or full closed operation extends valve life.