Flat Gate Valve

Product Overview

The Flat Gate Valve without Diversion Hole is a parallel‑type gate valve with a solid slab gate (no hole in the gate). It is designed only for ON‑OFF (open/close) service – not for flow regulation. Compared with flat gate valves that have a diversion hole, the no‑hole design prevents media from stagnating, crystallizing, or clogging inside the gate opening. It is particularly suitable for applications involving easily crystallizing media, high‑viscosity fluids, particle‑laden slurries, or services requiring strict bidirectional sealing.

The valve uses a floating or fixed seat design, relying on media pressure to press the gate against the downstream seat for sealing. It features bidirectional zero leakage, full‑bore flow path, and fast open/close action. The valve has flanged connections, with nominal diameters from DN50 to DN600, pressure ratings PN16 to PN160 (Class 150–900), and body materials including carbon steel and stainless steel. It is widely used in oil & gas, chemical, coal chemical, slurry transport, and other pipelines.

Product Structure

The Flat Gate Valve without Diversion Hole mainly consists of the following parts:

1. Body: Cast or forged body in carbon steel (WCB), stainless steel (CF8/CF8M), alloy steel, etc. Flanged ends conforming to GB/T 9113, ANSI B16.5, EN 1092‑1, etc. Full‑bore flow path with no restriction.

2. Gate (Slab): One‑piece or split slab gate made of stainless steel (304, 316, 17‑4PH) or alloy steel, with optional Stellite hardfacing or chrome plating. No diversion hole – the gate is solid.

3. Seats: Floating or fixed seats, typically metal‑to‑metal sealing, with soft sealing (PTFE, PEEK) optional. Floating seats are pressed against the gate by media pressure, providing bidirectional sealing.

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4. Stem: Stainless steel trapezoidal‑thread stem, moving the gate up and down. Available in rising stem or non‑rising stem design.

5. Bonnet: Bolted or pressure‑seal bonnet, housing the packing box.

6. Packing Box: Contains PTFE or flexible graphite packing, compressed by a packing gland to prevent external leakage. Low‑emission packing optional.

7. Spring or Preload Mechanism (optional): Springs behind the seats provide initial sealing force.

8. Drain / Vent Ports (optional): Provided on the top and bottom of the body to drain accumulated media or balance pressure.

9. Actuator: Handwheel, bevel gear, electric, pneumatic, or hydraulic.

Because there is no diversion hole, the valve completely isolates upstream from downstream when closed, preventing media buildup inside the gate. However, pressure equalization (via a bypass or vent valve) may be needed before opening.

Function

1. Bidirectional Zero Leakage Sealing: The solid gate combined with floating seats ensures that media pressure presses the seats against the gate, achieving bidirectional zero leakage (soft seal meets ANSI Class VI).

2. No Media Stagnation: With no hole in the gate, media cannot stagnate, crystallize, or solidify inside the gate – ideal for crystallizing, high‑viscosity, particle‑laden, or polymer‑containing media.

   

3. Full‑Bore Low Flow Resistance: When fully open, the gate is completely out of the flow path, and the bore matches the pipe inner diameter, providing minimal pressure loss and significant energy savings.

4. Fast Open/Close: Short gate stroke (equal to the port height) allows quick operation, suitable for frequent cycling.

5. Wear and Corrosion Resistance: The gate and seat sealing faces can be hardfaced with Stellite or other hard alloys for abrasive or corrosive media.

6. Bidirectional Pressure Capability: The body and sealing construction withstand media pressure from either side; flow direction is not restricted.

7. Optional Drain / Vent Ports: Bottom drain ports remove accumulated solids; top vent ports equalize cavity pressure for easier opening.

8. Multiple Actuator Options: Manual, electric, pneumatic, or hydraulic actuators to meet different automation requirements.

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Working Conditions

1. Applicable Media: Easily crystallizing media (urea, salt solutions, caustic), high‑viscosity fluids (heavy oil, syrup, resin), particle‑laden slurries (mineral slurry, coal slurry, pulp), corrosive liquids, natural gas, crude oil, etc.

2. Temperature Range: –29°C to +200°C (soft seal); –29°C to +550°C (metal seal).

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

4. Nominal Diameter: DN50 – DN600 (2″ – 24″); larger sizes available on request.

5. Installation Orientation: No strict limitation (bidirectional sealing), horizontal installation with stem vertical recommended.

6. Typical Applications:

   1. Easily crystallizing media pipelines in coal chemical and fertilizer plants (urea, ammonium bicarbonate)

   2. High‑viscosity oil lines (residue, asphalt) in refineries

   3. Pulp and coating lines in paper mills

   4. Mine tailings and concentrate slurry transport

   5. Chemical corrosive and polymer slurry lines

   6. Main line shut‑off in long‑distance natural gas pipelines (bidirectional sealing requirement)

   7. FGD gypsum slurry lines in power plants

Summary

The Flat Gate Valve without Diversion Hole, with its solid slab gate (no hole), bidirectional floating seat zero‑leakage sealing, and full‑bore low flow resistance, is an ideal bidirectional shut‑off valve for pipelines handling easily crystallizing, high‑viscosity, or particle‑laden media. Compared with flat gate valves that have a diversion hole, the no‑hole design completely eliminates the risk of media crystallization or clogging inside the gate – particularly suitable for urea, caustic, heavy oil, pulp, and similar services.

However, before opening, pressure equalization (via bypass or vent valve) is recommended to reduce operating torque. With flanged connections, a full‑bore flow path, and optional manual or automated actuators, the Flat Gate Valve without Diversion Hole is a safe, durable, non‑clogging professional solution for ON‑OFF pipeline systems that require reliable bidirectional shut‑off and handle easily crystallizing, viscous, or slurry media.