What is a Pressure Sealed Gate Valve

author: ATHENA GROUP

2026-06-22

A Pressure Sealed Gate valve is a gate valve specially designed for high-temperature and high-pressure working conditions. Its core feature is to use the medium’s own pressure to strengthen the sealing, achieving the effect of the higher the pressure, the tighter the seal. It is widely used in key pipelines of power stations, petrochemical and other industries.

1. Working Principle

Its core adopts a bonnet self-sealing structure, which is different from the conventional design of pressing gaskets by bolts:
a.Initial Sealing: Under low pressure, the basic sealing is formed by the thread pre-tightening force of the bonnet and the sealing ring (wedge / metal C-shape).
b.Pressure Self-reinforcement: The medium pressure acts on the inner side of the bonnet, pushes the bonnet upward to compress the sealing ring, makes it expand radially, and fits closely to the sealing surfaces of the valve body and bonnet.
c.Higher Pressure with Higher Reliability: The higher the pressure, the greater the sealing specific pressure and the better the sealing performance, suitable for high-pressure working conditions (Class 900–2500).
d.Bidirectional Sealing: The gate plate adopts a wedge design, and the medium pressure assists the sealing between the gate plate and the valve seat at the same time.

2. Structural Features

Bonnet Type: Adopt pressure self-tightening bonnet (threaded connection + internal pressure self-sealing ring), compact structure, fewer bolts, not easy to leak under high pressure.
Gate and Valve Seat: Wedge gate (single wedge / double wedge); the sealing surface is overlaid with cobalt-based hard alloy, featuring wear resistance and scratch resistance.
Stem Sealing: Packing (PTFE / flexible graphite) + upper sealing seat, with reliable sealing performance under high pressure.
Valve Body Material: Forged steel (A105, F304, F316), suitable for high temperature and high pressure conditions.
Connection Type: Butt Weld (BW), Socket Weld (SW), Flange (RF/RJ).

3. Main Advantages

a.Reliable High-pressure Sealing: Tighter with increasing pressure, zero leakage (ISO 5208 Class A), suitable for supercritical power stations, hydrogenation units, etc.
b.Compact Structure: No need for large-size bonnet bolts, small volume, light weight, convenient installation and maintenance.
c.High Temperature Resistance: Withstands -29℃ to 500℃ (stainless steel); thermal expansion will not affect sealing performance.
d.Low Fluid Resistance: Full bore design, straight medium flow and small pressure loss.
e.Easy Maintenance: No need to fasten bolts frequently; the sealing ring can be replaced conveniently.

4. Applicable Working Conditions

Pressure Class: Class 150–2500 (PN16–PN420)
Temperature Range: Carbon steel -29～425℃; Stainless steel -29～500℃
Medium: Steam, water, oil products, nitric acid, acetic acid, hydrogen, etc.
Industry: Thermal power generation (main steam, feed water), petrochemical industry (high-pressure hydrogenation, reforming), metallurgy, boiler, LNG, etc.

5. Comparison with Ordinary Gate Valves

Characteristic	pressure sealed gate Valve	Ordinary Bolted Bonnet Gate Valve
Sealing Principle	Medium pressure self-reinforcement	Gasket compressed by bolt pre-tightening force
High Pressure Performance	Excellent, more reliable at higher pressure	Prone to leakage, requires frequent bolt tightening
Structure	Compact with fewer bolts	Bulky with more bolts
Applicable Pressure	Class 900 and above	Class 600 and below