Pressure Seal Gate Valve

Pressure Seal Gate Valve is a high-pressure, high-temperature valve design where the bonnet joint seals tighter as internal pressure increases. Unlike bolted bonnet valves, this type uses a pressure-assisted seal, making it ideal for power plants, refineries, and steam service.
Pressure Seal Gate Valve is typically used for high-pressure service, often above 100 bar, and commonly in pressure classes like ANSI Class 600, 900, 1500, 2500.
They often must comply with ASME Boiler & Pressure Vessel Code, API, ISO, or similar international standards depending on region.
Materials: carbon steel, alloy steels, stainless steels are used depending on temperature/pressure/medium. Seat/hardface materials are important (e.g. CoCr-A alloys, etc.) for wear & sealing performance,
Testing: hydrostatic tests, pressure tests, and often hot-torqueing (i.e. bolt tightening after thermal/pressure conditions are such that the gasket & seating surfaces are “settled”)

1.Structure Of Pressure Seal Gate Valve

Body – pressure-containing housing.
Bonnet (Pressure Seal Bonnet) – designed to be pressed upward by fluid pressure, improving the seal.
Pressure Seal Gasket – usually metal or graphite, compressed by pressure.
Segmented Thrust Rings – hold the bonnet in position and transfer sealing load.
Gate/Wedge – the closing element, usually solid or flexible wedge.
Seat Rings – provide sealing surface (often hard-faced).
Stem & Packing – for opening/closing operation.
Key point: The higher the pressure, the better the seal between body, bonnet, and gasket.

2.Standards Of Pressure Seal Gate Valve

Pressure Seal Gate Valves are typically manufactured to:
ASME B16.34 – Valves, Flanged, Threaded, and Welding Ends
API 600 / API 602 / API 603 – Gate Valves (depending on type/size)
ASME Section VIII & ASME Section III – for pressure vessels and nuclear service
Pressure Classes: ANSI Class 600, 900, 1500, 2500
Materials: Carbon steel, alloy steel, stainless steel, depending on service.

Features Of Pressure Seal Gate Valve

Compact and lighter than bolted bonnet valves at the same pressure rating.
Metal-to-metal seating surfaces with optional hardfacing for wear resistance.
Rising stem design (outside screw and yoke, OS&Y).
Self-energizing bonnet seal improves as pressure increases.
Designed for high-pressure, high-temperature service.

3.Advantages Of Pressure Seal Gate Valve

Better sealing with higher pressure → reduces leak risk.
Smaller, lighter construction than bolted bonnet types.
High reliability under severe conditions (thermal cycling, steam).
Lower maintenance in continuous service.

4.Applications Of Pressure Seal Gate Valve

Power plants: main steam lines, boiler feedwater, turbine bypass.
Oil & Gas: refining, petrochemical high-pressure service.
Chemical plants: handling superheated steam, high-pressure fluids.
Pulp & Paper industry: steam and condensate lines.
Any high-pressure / high-temperature pipelines requiring shut-off.