High Pressure Knife Gate Valve

2" - 24" (DN50 - DN600)

Class 300 - 900 (up to 150 bar / 2200 psi)

A216 WCB, A217 WC6/WC9, A182 F316, A182 F51/F53

Metal-to-metal (Stellite 6 overlay), reinforced PTFE for lower pressure configurations

Flanged or welded body, heavy-wall construction, pressure seal bonnet above Class 600, rising stem with OS&Y indicator, bidirectional sealing

This Valve Exists Because Wafer Designs Blow Out

Standard knife gate valves top out at Class 150. Push them past 10 bar and the thin wafer body starts to flex. Push them to 50 bar and you're gambling. At 150 bar? You're not gambling—you're planning a failure.

The high-pressure knife gate valve solves this by being built like a block valve with a knife edge. Heavy-wall body casting. Flanged or welded ends—no wafer sandwich here. Above Class 600, the bonnet switches to a pressure seal design, where internal pressure actually compresses the bonnet seal ring tighter. Higher the pressure, tighter the seal. It's the same bonnet concept used on high-pressure gate valves in power plants and petrochemical steam systems.

Stellite Seats Are Not Optional At This Level

Metal-to-metal seating with Stellite 6 overlay is standard on the high-pressure configurations. Stellite resists galling, handles temperature cycles, and maintains seat integrity when the gate slams shut under full line pressure. Reinforced PTFE seats are available on Class 300 configurations for services where chemical resistance matters and pressure is moderate—but once you cross Class 600, it's metal seats all the way.

I've replaced seats on knife gates that cycled twice daily on a high-pressure steam bypass line for three years without measurable wear on the Stellite overlay. That's the kind of longevity you pay for when you spec this valve.

The OS&Y Stem Tells You What You Need To Know

Rising stem with outside stem and yoke (OS&Y) indicator. You can look at the valve from across the plant floor and see whether it's open or closed—the stem position is visible, not hidden inside the body. On high-pressure lines, that visual confirmation matters. You don't want to guess whether a valve holding 100 bar of pressure is open or shut. The rising stem gives you that answer at a glance.

Material Selection Matches The Service

A216 WCB handles standard hydrocarbon and steam service up to about 425°C. WC6 and WC9 creep into higher temperature territory—creep-resistant alloys for sustained high-temp operation. A182 F316 gives you corrosion resistance on sour service or chloride environments. F51 and F53 duplex alloys bridge the gap between strength and corrosion resistance, particularly useful on offshore and subsea process lines where both properties matter simultaneously.

A: At Class 900, rated pressure depends on the body material and temperature. Check ASME B16.34 pressure-temperature tables for your specific material and operating temperature. Some configurations reach 150 bar; not all go to 200 bar.

A: Bolted bonnets rely on bolt tension to keep the bonnet gasket compressed. As pressure rises, internal force pushes the bonnet upward, working against the bolts. Pressure seal designs use internal pressure to compress the seal ring—higher pressure means a tighter seal. Above Class 600, pressure seal is the reliable choice.

A: Yes. High-pressure knife gate valves use dual-seat or wrap-around seat designs that hold pressure from both directions. Unidirectional sealing is not acceptable at these pressure levels.

A: Electric motor actuators are common on high-pressure knife gates for precise, repeatable positioning. Pneumatic cylinders work on Class 300-600 sizes. At Class 900, electric actuators with torque limiting are preferred—you need controlled seating force, not a pneumatic hammer stroke.

A: Knife gate valves cut through suspended solids and pulp that would jam a standard gate valve's wedge. If your media is clean fluid, a standard gate valve is fine. If there's solids in the line, the knife gate's sharp edge is the functional advantage.