¿Qué es una válvula de compuerta? La guía completa

A válvula de compuerta is a type of valve used to start and stop fluid flow in pipes and pipeline systems. This versatile valve functions like a gate, closing to stop flow and opening to allow flow.

But what exactly are gate valves? How do they work? And why are they one of the most ubiquitous valves across various industries?

This complete guide on gate valves will answer all those questions and more. By the end, you’ll have a solid understanding of gate valve types, parts, design, operation, applications and advantages.

¿Qué es una válvula de compuerta?

A gate valve refers to a linear motion valve designed to start and stop fluid flow. It’s aptly called a gate valve because it uses a flat gate-like barrier that lifts in and out of the flow stream to shut off or allow passage.

Gate valves are mainly used as isolation valves o on-off valves in pipelines to achieve:

• Complete flow shut-off required during maintenance
• Flow rerouting procedures
• Regulating flow in branch lines

Unlike globe valves and ball valves, gate valves are not built for throttling or frequent operation. The absence of flow restriction allows full flow with little pressure drop.

Entonces en resumen:

A gate valve is used to isolate sections of a piping system by fully stopping or opening the flow path. The name comes from the gate-like disk that opens/closes against seats to control flow.

Now let’s get into the intricate details of gate valve design, working mechanism and applications.

¿Cómo funciona una válvula de compuerta?

All gate valves have the same simple yet efficient mechanism consisting of:

• Cuerpo de la válvula
• Capó
• Gate/wedge
• Packing seal
• Vástago de válvula

The primary purpose of all these components is to accurately lower and lift the gate/wedge against the seats for positive shutoff.

When the valve is open, the gate/wedge is fully lifted, allowing unrestricted flow through the valve. Closing the valve brings the wedge down on the seat, blocking flow in minutes.

The valve stem connects the gate and handwheel. Rotating the handle turns the stem, lifting the gate off the seat or lowering it onto the seat surface. The directional fluid control makes it suitable to isolate flow in either direction.

Now that you know what a gate valve looks like and how it controls flow, let’s get into some key gate valve design fundamentals and terminology.

Gate Valve Design Types

Gate valves come in different designs based on the wedge and seat orientation. The most common designs include:

Válvulas de compuerta corredera paralela

In parallel slide gate valves, the gate/wedge has flat, parallel faces that fit between two parallel seats. There is no wedge-effect on the seats. These valves are compact and generally preferred for handling slurries.

Parallel slide gate valves are best suited for regulating flow of abrasive media as the gate/seats are self-cleaning. Their drawback is the high fluid turbulence that causes seat wear.

Wedge Gate Valves

Wedge gate valves are the most common type that use a wedge-shaped gate. The tapered gate matches with inclined seats to achieve tight shutoff even at high pressures.

Based on the wedge flexibility, wedge gate valves have sub-types:

Solid wedge valves have a solid gate with no moving parts. The single-piece robust wedge provides tight shutoff.

Flexible wedge valves have a gate with flexible material around stem holes to match the seats. This self-adjustability prevents jamming.

Split wedge valves feature a two-piece gate with a spring between faces. The independent action seats both gate pieces evenly for reliable tight shutoff.

Wedge gate valves offer bidirectional shutoff suitable even for high pressure applications. The wedge-effect on the seats enables high strength fluid control.

Main Parts of a Gate Valve

As seen in the diagram earlier, a gate valve comprises:

Cuerpo de la válvula

The body forms the basic framework holding all parts together. Standard gate valve bodies conform to MSS SP-70 and are made of materials like bronze, cast iron, ductile iron or steel.

Gate valve bodies have flanged or threaded ends to connect pipes. They may be coated internally and externally to prevent corrosion.

Valve Bonnet

The bonnet is the top section attached to the valve body using bolts. It holds the packing and allows access to internal parts for repair.

Based on construction, gate valves have:

• Bolted bonnet
• Pressure seal bonnet
• Screwed bonnet
• Union bonnet

Bolted bonnets are preferred for large valves used in high pressure applications.

Valve Gate/Wedge

The gate/wedge is the closure element that provides actual flow control. In its shut position, the gate presses against seats for tight sealing.

Gate valves have either:

• Parallel faced gate
• Cuña cónica sólida
• Split wedge

Gate materials include brass, stainless steel or cast alloy suited for particular applications.

Valve Seat

The seat refers to the inside body surface that the gate presses against for positive shutoff. Gate valves have threaded-in or integral cast seats.

Based on resilience, gate valves have:

• Metal seats: Here a gate wedge presses against body seats usually made of bronze or stainless steel.
• Resilient seats: These have body seats overlaid with elastomers like Nitrile rubber. The rubber coating enables tight shutoff while allowing small solids to pass through partially open valve.

Resilient seat gate valves are often preferred due to their exceptional leak-tight closure.

Valve Stem

The valve stem connects the handwheel or actuator to the gate. Based on stem movement, gate valves are:

Rising stem: Stem is attached to the gate and rises out of the bonnet as the valve opens. Rising stems have position indicators.

Non-rising stem: Stem is fixed to the actuator. It causes the gate/wedge to raise or lower without any stem movement. Non-rising stems are compact.

Embalaje

Packing refers to the seal preventing fluid leakage from where the stem enters the bonnet. Valve packing contains resilient materials that allow smooth stem operation.

¿Por qué utilizar válvulas de compuerta? Ventajas y aplicaciones

Gate valves provide reliable on/off control suitable across various industrial applications, especially pipelines.

Water lines: Gate valves have long service life cycles when used to isolate municipal/industrial water lines for maintenance.

Plantas de proceso: Gate valves isolate vessels, equipment or branch lines from the main header in process plants.

Steam lines: Resilient wedge gate valves enable efficient on/off control in high temperature steam lines.

Chemical lines: The bidirectional sealing and corrosion-resistant coatings make gate valves ideal for corrosive chemical lines.

Fire prevention: Gate valves easily integrate with sprinkler/deluge systems for fire protection.

Petroleum lines: Oil refineries depend on heavy-duty carbon steel gate valves to block large diameter petroleum pipes for cleaning.

Wastewater lines: Utilities use underground non-rising stem gate valves arranged in concrete pits for accessing wastewater pipes.

Branched lines: Compact, non-rising gates conveniently regulate flow in pipeline branches and smaller process lines.

Buried service lines: Corrosion-proof gate valves suitable for buried underground access avoid excavations.

Tank draining: Quick full bore gate valves rapidly empty large tanks into drainage ditches.

In essence, gate valves reliably:

• Stop fluid flow including wastewater, chemicals and petroleum
• Separate equipment, pumps and vessel sections from main lines
• Enable pipe access when required while minimizing flow disturbances
• Drain media from tanks, basins or low points in piping

Ventajas de las válvulas de compuerta

Gate valves have inherent advantages making them a convenient flow control element:

1. Bidirectional sealing

Gate valves isolate flow in either direction, enabling flexibility in flow control.

2. Minimal flow restriction

The unobstructed gate valve flow path causes little pressure drop, saving pumping costs.

3. Low torque operation

Large gate valve openings combined with highly finished parts allows easy actuation.

4. No flow cavitation

Gate valves avoid flow cavitation that causes pitting and corrosion in globe valves under high pressure drops.

5. Pigging capability

Full openings enable cleaning pipeline interiors by passing a “pig”, avoiding flowshut downs.

6. Tight shutoff

Gate/seat contact force amplification in wedge gate valves enables reliable positive shutoff even against high Δ pressures.

7. Smaller size

Compact gate valve flange-to-flange dimensions fit restricted space installations.

8. Bidirectional dead-end service

Gate valves positively seal lines with single direction flow or liquid filled on one side during repair.

9. Safety against over-pressurization

The sturdy body-bonnet joint handles occasional pressure surges without leaking.

10. Easy maintenance

The bonnet separation allows fast access and removal of internal parts without removing the valve.

Desventajas de las válvulas de compuerta

Gate valves also have certain limitations that must be considered when selecting them for particular applications:

1. Not suitable for throttling

The wedge or gate causes turbulence and vibration when partially open, damaging seats and wedge/gate.

2. Slam closure can cause transients

Rapid gate closure against high differential pressures induces damaging water hammer transients within pipelines.

3. Not ideal for frequent operation

Due to the large number of moving components involved, gate valves may need early maintenance when actuated often.

4. Heavier than other valve types

The sturdy body and bonnet to allow high pressure service makes gate valves heavier than other valves.

5. Position indication not standard

Unlike rising stem gate valves, position indicators involve additional cost for underground non-rising stem valves.

Gate Valve Position Indicators

Gate valves with non-rising stems have no external visual indication showing open/close status. Position indicators overcome this, signaling valve status.

Gate valve indicators use:

• Targets: Brightly colored targets on rising stems signal open status.Targets dyeing, catching debris or stem movements out of sight easily compromise indication reliability.
• Proximity sensors: These electronically detect gate position, transmitting real-time data. However, electronics may fail in harsh environments.
• Mechanical indicators: Simple mechanisms with color bands or arrows show valve position through bonnet penetrations. Mechanical indices externally visible in all conditions provide straightforward gate position feedback without electronics.

Reliable indication avoids operating shut gates that can break stem/gates. Position feedback also prevents leaving gates slightly open that may pass debris leading to seat leakage.

Key Considerations When Selecting Gate Valves

Choosing suitable gate valves require assessing:

• Pressure rating
• Temperature rating
• Dirección del flujo
• Closure requirements
• Corrosion resistance needs
• Accessibility
• Throttling needs
• Automation requirements
• Initial/maintenance costs

Consider operating conditions, line media properties and installation location when picking valves. Consulting valve specialists also helps select optimum gate valve configurations.

Properly sized gate valves with pressure classes suiting max pressures provide long working life. Getting appropriate coatings for corrosion resistance prevents early valve failure.

Gate Valve Sizing

During sizing, gate valve flow passage diameter should match piping to prevent flow bottlenecks.

Oversized valves can settle debris around gates causing leakage. Undersized valves lead to erosion, leakage and flow losses from high velocities.

The valve connection end type also needs matching piping. Flanged ends suit frequent dismantling needs while threaded ends easily fit medium pressure applications.

Installation Position

Ideally, gate valves should be vertical allowing free fall of gate to reduce sliding friction. This prolongs seal life in high-cycle or throttling applications.

Horizontal positions need occasional opening/closing to prevent gate sticking to seats.

Configuraciones

Gate valves feature different bonnet joints, stem designs (rising/non-rising), seat types (metal/resilient) and end connections (flanged, socket weld, butt weld etc.) to suit particular installation needs. Getting suitable configurations prevents early failures.

Choosing the right gate valve configuration along with smart sizing results in reliable application performance. This minimizes unplanned shutdowns enabling increased uptime and operational productivity.

Conclusión

From the above detailed discussion, you now have a solid grasp on gate valve meaning, working, designs, applications and advantages.

To quickly recap:

• Gate valves provide on-off control using a gate/disk element moving normal to flow
• The gate presses against seat rings to achieve tight shutoff in both flow directions
• Gate valves are mainly used as isolation valves fully stopping or opening flow

Multiple design configurations with wedge, parallel slide or expanding gates are available. This allows reliable application across various industrial scenarios like chemical lines, process plants, steam lines etc. where frequent isolation is necessary.

I hope you enjoyed this ultimate guide explaining everything about gate valves. Please share it if you found it helpful. If you have any other gate valve questions, let me know in the comments section below!