What Is A Slab Gate Valve?

Plane gate valve is a valve that controls or cuts off the flow of medium by linear lifting and fall of parallel gate ( "flat"). It is a special type of gate valve. Its core design features the gate parallel to the valve seat sealing surface, the gate moving up and down to realize switching. It has the advantages of simple structure, small flow resistance and reliable sealing. Widely used in petroleum, gas, chemical industry, metallurgy, water treatment and other fields.
1.Core structure and working principle of slab gate valve
Structure composition
Valve body: usually a integral casting or forged structure, providing dielectric piping and supporting components;
Gate: a flat plate parallel to the seat cover and connected to the actuator through the valve stem;
Seat: with the gate to form a sealed cover, material must be abrasionresistant, corrosion resistant;
Valve stem: Transmission of actuator power, driving gate lift;
Seals: including valve seat seals and gate sealing ring (e.g. rubber, metal hard seal);
Execution: Manual, pneumatic, electric or hydraulic device that controls gate movement.
Principles of work
Opening process: The actuator lifts the gate through the stem, separates the gate from the valve seat, and media flows through channels on both sides of the valve body.
CLOSE PROCESS: The gate is tightly affixed to the valve seat and the media flow is blocked by the sealing pressure.
Bidirectional sealing: The gate can be designed as a two-way seal structure, suitable for frequent changes in media flow.
2.Classification of planar gate valves
By Seal Type
Soft Seal Flat gate valve:
The sealing surface is made of flexible materials such as rubber (such as NBR, EPDM) or polytetrafluoroethylene (polytetrafluoroethylene);
Advantages: good sealing performance, small opening and closing torque;
Limitations: limited resistance to temperature and pressure, suitable for ambient or low temperature media.
Hard Sealed Flat gate valve:
The sealing surface made of metal (such as stainless steel, carbide) or ceramics.
Strengths: High temperature, high pressure, wear resistance, suitable for high temperature, high pressure or granular media;
Weaknesses: High opening and closing torque, high precision processing required.
By Structural Form
Open Stem Flat Valve:
The stem nut is located on the outside of the valve body and is exposed when the valve stem is raised or lowered, which makes it easy to observe the state of the switch.
Suitable for situations (such as pipeline systems) where the position of the switch needs to be clearly displayed.
No hidden stem flattened valve:
The stem nut is located inside the valve body, and the valve stem only rotates and does not rise or fall, making the structure more compact.
Suitable for limited space or buried installation.
By functional extension
Flat gate valve with diversion hole:
There are holes in the gate, and the media can flow in both directions when the gate is opened and in both directions when the gate is closed.
Suitable for pipelines that require two-way flow (e.g. pipeline / pipeline).
Flat gate valve with no guide hole:
The gate is a solid slab, which is only used for one-way truncation of media.
Simpler structure, lower cost.
III. Core advantages of flat gate valve:
Low flow resistance
The gate is parallel to the valve seat, the dielectric channel is straight, the flow resistance is close to the pipe itself, the pressure drop is small, suitable for long distance transport or pressure drop sensitive working conditions.
Reliable sealing
The hard sealing structure achieved by the extrusion of metal and metal or metal and ceramics, high temperature and high pressure resistance;
The soft sealing structure has zero leakage through the elastic deformation of rubber or PTFE and is suitable for cleaning media.
Effortless opening and off
The gate runs in parallel with less friction and less opening and closing torque than the wedge gate, especially for large caliber valves.
Bidirectional sealing
Sealing rings can be formed on both sides of the gate, suitable for pipelines with frequent media flow (such as pump outlets, compressor inlets outlet, etc.).
Compact structure
Dark rods are designed to save space and are suitable for buried or compact equipment installation.
Wearability
The hard sealing structure can adapt to granular media (such as sand and coal powder), long service life.
IV. INTRODUCTION Typical application scenarios of Plane gate valves
Oil and gas industry
Interception or adjustment of oil and gas pipelines;
wellhead devices, Christmas tree, metering stations and other key equipment;
LNG (liquefied natural gas) storage tanks import and outlet control.
Chemical industry
Corrosive media (e.g. acid, alkali) piping system;
Import and outlet control of high temperature and high pressure reactor.
Metallurgical industry
Blast furnace gas, converter gas and other high temperature media transmission;
Controlling solid particle media such as ore pulp and coal powder.
Water treatment Industry
Sewage treatment plant sludge, sewage pipes;
Media control of seawater desalination systems.
Power industry
Cutting of boiler feed water and steam pipelines;
Control of cooling water systems in nuclear power plants.
V. selection point of planar gate valves.
Moderate characteristics
Temperature: Soft seal suitable for ≤120°C, hard seal resistant to high temperature (e.g. above 600°C);
Pressure: Nominal pressure selected according to working conditions (e.g. PN16, PN40, PN100, etc.);
Corrosion resistance: use of corrosion resistant materials (e.g. stainless steel, Hastelloy).
Requirements for working conditions
Two-way flow: Select the design with guide holes;
Frequent opening and closing: Prioritize hard seal structure (abrasion resistance);
Quick opening and closing: Optional pneumatic or electric actuators.
Installation environment
Space is limited: choose dark rod structure;
Buried site installation: embalming is required (e.g. epoxy coating, 3PE embalming). VI. INTRODUCTION Maintenance and troubleshooting of planar gate valves
Regular inspections
Check for wear and tear on sealing surface and replace valve seat or gate if necessary;
Lubricate stem nuts to prevent adhesion.
Common Faults and Treatment Methods
Leaks:
Soft seal: replace the sealing ring;
Hard seal: Grind the sealing surface or replace valve seat.
Difficulty opening and closing:
Remove impurities from the valve cavity;
Check the actuator pressure or power supply.
Stem corrosion:
Replace corrosion resistant valve stem or coating protection.
VII. Development trend in Flat gate valves
Intelligent?
Integrate sensors (such as pressure sensors, temperature sensors, position sensors, etc.) for remote monitoring and fault warning;
Use intelligent actuators,such as electric control valves, to support automatic control.
Material innovation
Development of new corrosion-resistant and high-temperature alloy materials (such as dual-phase stainless steel and nickel-base alloys);
Study nano-coating technology to improve the abrasion resistance of sealing cover.
Environmental protection requirements
Reduce valve leakage rate of valves (if ISO 15848 compliant);
Reduce the amount of harmful substances in materialssuch as lead and mercury.
Lightweight design
topological optimization technology is used to reduce valve body weight and reduce cost.