Wedge Gate Valve

Product Overview

The Hard Seal Wedge Gate Valve is a wedge gate valve with both the seat and gate sealing faces made of metal (hardfaced with Stellite or other hard alloys). It relies on the wedge angle between the gate and seats to generate sealing pressure, achieving reliable shut‑off of the medium. Compared with soft‑seated gate valves, the hard seal version offers significant advantages including high temperature resistance, wear resistance, erosion resistance, and long service life.

It is particularly suitable for steam, high‑temperature oil, media containing particles, and corrosive services. The valve features a full‑bore design with extremely low flow resistance, making it ideal for applications requiring frequent fully open or fully closed operation. The valve has flanged connections, with nominal diameters from DN50 to DN1200, pressure ratings from PN16 to PN160 (Class 150–900), and body materials including carbon steel, stainless steel, and alloy steel. It is widely used in oil & gas, chemical, power generation, metallurgy, and district heating pipelines.

Product Structure

The Hard Seal Wedge Gate Valve mainly consists of the following parts:

1. Body: Cast or forged body in carbon steel (WCB), stainless steel (CF8/CF8M), alloy steel (WC6/WC9), etc. Flanged ends conforming to GB/T 9113, ANSI B16.5, EN 1092‑1, etc. Full‑bore flow path.

2. Gate: Wedge gate (single wedge or double wedge) forming a wedge sealing interface with the seats. The gate sealing face is hardfaced with Stellite 6, Stellite 21, or other hard alloys, then ground to a high‑hardness, wear‑resistant surface.

3. Seats: Integral or removable seats hardfaced with Stellite and lapped with the gate to achieve a tight metal‑to‑metal seal.

4. Stem: Stainless steel (2Cr13, 304, 316, 17‑4PH) or alloy steel stem with trapezoidal threads, converting rotary motion from the handwheel or actuator into linear lifting of the gate.

5. Bonnet: Bolted bonnet or pressure‑seal bonnet. The packing box contains PTFE or flexible graphite packing compressed by a packing gland to prevent external leakage.

6. Handwheel / Actuator: Manual handwheel, bevel gear (for large sizes), electric, pneumatic, or hydraulic actuator to drive the stem.

7. Yoke / Bearing: Supports the stem and transmission components.

8. Gasket: Spiral wound stainless steel + graphite gasket or metal ring gasket between body and bonnet.

Robust construction, full‑bore flow path with no restriction, metal‑to‑metal sealing faces for high temperature and wear resistance.

Function

1. Media Shut‑Off: The valve opens and closes by lifting and lowering the gate. Fully open, the gate is completely out of the flow path, providing near‑zero flow resistance. Fully closed, the wedge gate presses tightly against the seats, achieving zero leakage (metal seal meets ANSI Class V or higher).

2. Hard Seal High Temperature Capability: Metal sealing faces can withstand temperatures up to 550°C, suitable for steam, superheated steam, and high‑temperature thermal oil.

3. Wear and Erosion Resistance: Sealing faces hardfaced with Stellite provide high hardness, making the valve suitable for media containing solid particles (slurry, pulverized coal, ash, etc.).

4. Bidirectional Sealing: The wedge gate design provides equal sealing pressure in both directions; flow direction is not restricted.

5. Full‑Bore Low Flow Resistance: When fully open, the valve bore matches the pipeline inner diameter, resulting in minimal pressure loss – ideal for pressure‑sensitive lines.

6. Multiple Drive Options: Available with handwheel (manual), bevel gear (large sizes), electric, pneumatic, or hydraulic actuators to meet different automation requirements.

7. In‑Line Maintenance: Some designs allow replacement of packing and bonnet gasket without removing the valve from the pipeline.

Working Conditions

1. Applicable Media: Steam, high‑temperature water, thermal oil, crude oil, refined oil, natural gas, chemical media, fluids containing particles (slurry, pulverized coal, etc.), corrosive liquids (with stainless/alloy steel body).

2. Temperature Range: –29°C to +550°C (depending on body and sealing face materials).

3. Pressure Rating: PN16, PN25, PN40, PN63, PN100, PN160 (Class 150, 300, 600, 900).

4. Nominal Diameter: DN50 – DN1200 (2″ – 48″); larger sizes available on request.

5. Installation Position: Horizontal or vertical (stem upward), with vertical installation recommended for the stem.

6. Typical Applications:

   1. Main steam isolation in power plant boilers

   2. High‑temperature oil line isolation in refineries

   3. Corrosive media isolation in chemical plants

   4. Steam/hot water isolation in district heating networks

   5. Slurry lines in mining and metallurgy

   6. Main line isolation in long‑distance natural gas pipelines

   7. High‑temperature thermal oil systems

Summary

The Hard Seal Wedge Gate Valve, with its advantages of metal‑to‑metal hard sealing, full‑bore low flow resistance, high temperature and wear resistance, and bidirectional sealing, is one of the most reliable shut‑off valves for high‑temperature, high‑pressure, particle‑laden, and corrosive media services. Compared with soft‑seated gate valves, the hard seal version can operate continuously at temperatures up to 550°C, with sealing faces that resist wear and erosion, providing a long service life. The valve features flanged connections and complies with international standards such as API 600. It is widely used in power generation, oil & gas, chemical, and district heating critical pipelines. For pipeline systems that demand tight shut‑off, frequent operation, or severe media conditions, the Hard Seal Wedge Gate Valve is a trustworthy core component.