Valve Selection Best Practices - Swagelok Chicago

Author: Sam

Jul. 28, 2025

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Valve Selection Best Practices - Swagelok Chicago

When selecting a valve for an instrumentation system, your choices may seem overwhelming. Just to name a few, there are ball valves, diaphragm and bellows valves, as well as check valves, excess flow valves, fine metering, gate, multi-port, needle, plug, relief, rising plug, and safety valves. Furthermore, each of these valves comes in many sizes, configurations, materials of construction, and actuation modes. To make the best choice, it is always good practice to ask the first question in valve selection: What do I want the valve to do?

Most valves fulfill one of five primary functions:

on-off
flow control
directional flow
over- pressure protection
excess-flow protection

Matching valve type to function is the first and most important step in the valve selection process. It is not unusual in the field to see the misapplication of valves, such as a ball valve used for throttling flow. In some cases, the mismatch can be catastrophic, say, if a ball valve were used in a high-pressure oxygen system. With a source of ignition, the sudden burst of oxygen – enabled by the fast opening of the valve – could lead to an oxygen fire. Here is a tutorial reviewing the basic types of valves, how they work, what functions they fulfill, and what to think about when choosing one.

On-Off Valves

On-off control is the most basic valve function. Valves in this category stop and restart system fluid flow. Primarily on-off valves are ball, gate, diaphragm and bellows valves.

Perhaps the most common of all valve types, ball valves are designed for on-off control. Quarter turn actuation starts or stops flow by positioning a metallic ball in a straight-through flow path. The ball has a large hole through the center of it. When the hole is lined up with the flow path, it enables flow. When it is turned 90 degrees from the flow path, it stops flow. If you are seeking an on-off valve with quick shutoff and high flow capacity, then a ball valve is a good choice. The position of the handle provides a quick indication of whether the valve is open or closed, and, for safety purposes, ball valves are easy to lock out and tag. They are most practical and economical at sizes between 1/4 inch and 2 inches.

Typically used for process control rather than instrumentation applications, gate valves are commonly chosen for on-off control, particularly for lines above 2 inches. They are also used as the first valve off the process line for process instrumentation, often in a double block and bleed configuration. Among the oldest types of on/off valves, they are typically specified in general industrial applications, such as large process or transmission lines. Some can even be larger than 100 inches ( mm). Multiple rotations of the handle raise and lower a sealing mechanism in and out of a straight flow path. Shutoff is gradual. Packing surrounds the stem, preventing system media from escaping to atmosphere where the stem meets the valve body. Valves that seal to atmosphere with metal-to-metal seals are referred to as “packless” because they do not contain the soft packing material, e.g. gaskets and O-rings, normally found around the stem in other valves. The valve stem is the cylindrical part that connects the handle (or actuation) with the inner mechanism for shut-off, flow control and directional control. Usually, the stem turns and/or moves up and down. All stem seals or packing are subject to wear, and wear can lead to leakage. Valves with packing must be serviced or replaced at regular intervals, although some types of packing create more effective seals and last longer than others, such as the two-piece chevron design. Contrary to packed valves, diaphragm valves are packless, and provide rapid shutoff and precise actuation speeds. In some cases, they may also deliver consistent quantities of process fluid. Typically, diaphragm valves are employed in high purity applications in the biopharmaceutical and semiconductor industries. Among all valve types, they provide the highest cycle life, a product of the valve’s highly engineered anatomy. Each valve contains a thin metal or plastic diaphragm, which flexes up and down, creating a leak-tight seal over the inlet. This robust valve is usually small, with the largest orifice — or internal pathway — typically less than two inches.

Like the diaphragm valve, bellows valves are packless, making them a good choice when the seal to atmosphere is critical and access for maintenance is limited. Frequently, they are specified for the containment area in nuclear power plants. A welded seal divides the lower half of the valve, where the system media resides, from the upper parts of the valve, where actuation is initiated. The stem, which is entirely encased in a metal bellows, moves up and down without rotating, sealing over the inlet.

Bellows valves and diaphragm valves are said to have a globe-like flow path. In globe valves, fluid does not flow straight through on a level plane as it does with a ball valve. The flow path enters the valve under the seat and exits above the seat. Globe valves will have lower flow rates than valves a straight-through flow path of the same orifice size.

Flow-Control Valves

Flow-control valves enable the operator to increase or decrease flow by rotating the handle. The operator can adjust the valve to a desired flow rate, and the valve will hold that flow rate reliably. Some flow control valves also provide very reliable shut-off, but many turns of the handle are necessary to move from the fully open to the fully closed position. The most common flow-control valves are needle, fine metering, quarter-turn plug, and rising plug. Needle valves provide excellent flow control and, depending on design, leak-tight shut-off. They consist of a long stem with a highly engineered stem-tip geometry (e.g., vee- or needle-shaped) that fits precisely into a seat over the inlet. The stem is finely threaded, enabling precise flow control. Stem packing provides the seal to atmosphere. Some designs contain a metal-to-metal seat seal; consequently, needle valves may be a good choice for high-temperature applications. As discussed earlier, flow is limited because of the globe-style flow path. Needle valves are a good choice with lighter, less viscous fluids. For the most precise flow control, consider fine metering valves, typically found in laboratory settings. Fine metering valves are a type of needle valve, with a long, fine stem that lowers through a long, narrow channel. This anatomy makes for a pronounced globe pattern, ideal for marking fine gradations of flow. Some fine metering valves are not designed to shut off.

Quarter-turn plug valves are utility valves, economically priced. Quarter-turn actuation rotates a cylindrical plug in a straight-through flow path. The plug contains an orifice to permit flow. Plug valves are commonly used for low-pressure throttling applications, in addition to shut off. Another type of plug valve is the rising plug valve. Like a needle valve, a tapered plug lowers into an orifice to reduce flow. It differs from a needle valve in its flow path, which is straight-through rather than globe patterned. Because of the straight path, the valve is not as effective at providing fine gradations of flow. The rising plug is roddable, which is a good choice if the valve becomes clogged with system media.

Directional Flow Valves

A third type of valve directs fluid flow. Check valves ensure flow in one direction only. In most designs, the upstream fluid force pushes a spring-loaded poppet open, allowing flow. In the case of an increase in downstream or back-pressure force, the poppet is forced back into the seat, stopping reverse flow. Check valves are available with fixed or adjustable cracking pressures.

Some ball valves and diaphragm valves are designed with multiple ports. In most multi-port valves, fluid enters through a single inlet but may exit through one of many outlets, depending on the position of the actuator. Multi-port valves may or may not have a shut-off position.

Overpressure Protection Valves

Valves in this category prevent the buildup of system pressure beyond a certain pressure setting. They are available in two types: relief valves and rupture discs. One type of relief valve is a proportional relief valve. It contains a vent to atmosphere that opens when pressure in a system exceeds a certain point set by the operator. A spring-loaded poppet enables the measured release of fluid.The vent closes when pressure returns to a point below where it was set. A safety relief valve is designed to open very quickly, releasing a large amount of system media. Due to their critical safety function, safety relief valves are required by code in certain applications. Safety relief and proportional relief valves are not to be used interchangeably with check valves, since the three have different functions.

Rupture discs are used mainly on sample cylinders to protect against overpressurization, which may occur, for example, when temperatures rise during transport. Similar to relief valves, rupture discs vent to atmosphere. A metal diaphragm bursts when pressure reaches a set point. This value is preset by the manufacturer. Once activated, the rupture disc must be replaced. Transportation codes require that compressed gas cylinders be equipped with a pressure relief device. A rupture disc is an economical choice for this application.

Excess Flow Valves

Excess flow valves stop uncontrolled release of system media if a downstream line ruptures. Under normal conditions, a spring holds a poppet in the open position. In an excess flow condition downstream, the poppet moves to a tripped position stopping almost all the fluid flow. When the system is corrected, the valve resets automatically. These valves are available with fixed tripping values.

Conclusion

Once you have matched valve type to function, you are well on your way in the valve selection process. Many details remain, though. You will need to give detailed attention to each of the following, if you have not had occasion to so far in the process: Installation issues, maintenance schedules and access:

Installation issues, maintenance schedules and access
Safety and code requirements
System parameters, such as pressure, temperature, flow rates, and system media

Ultimately, you will need to determine:

Valve size and actuation types
Materials of construction (including O-rings and seals), which must be compatible with the chemical composition of the system media, pressures, and temperatures.

Ball Valve Types Decoded: Expert Guide to Smart Selection

I first need to check the application requirements. Then, I can choose a ball valve type. This step will help me pick a valve that works well under the conditions. It will also stop early failure or poor performance.

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Process Parameters Assessment: Pressure, Temperature, and Flow Rate

A ball valve's pressure rating affects its performance and safety. My system's least and most pressures are key in valve selection. Stainless steel housings have the highest pressure ratings. Brass and plastic materials, like PVC, follow closely. The seal material also plays a vital role in handling pressure. FKM (fluoroelastomer) resists high pressures well and works with many chemicals.

Temperature requirements play an equally crucial role. Ball valves made from different materials work in these temperature ranges:

Brass ball valves typically handle -20°C to 160°C (-4°F to 320°F)
PVC ball valves generally operate within -10°C to 60°C (14°F to 140°F)
Stainless steel ball valves offer a broader range from -40°C to 220°C (-40°F to 428°F)

Flow requirements need accurate assessment. The valve's flow coefficient (Cv) shows its flow capacity and should match system needs. Valves that are too big or small can cause inefficiencies, pressure drops, or poor control. Larger pipes that must handle higher flows may need bigger bore diameters. Meanwhile, standard port valves are suitable for smaller systems.

Media Characteristics: Corrosiveness, Viscosity, and Particulates

My system's media type significantly influences valve selection. Material compatibility becomes crucial for corrosive applications. Grade 316 stainless steel valves are ideal for very corrosive environments. In contrast, grade 304 performs effectively in conditions with mild corrosion. PVC and CPVC plastic ball valves resist corrosion. But, they can't handle extreme temperatures.

Viscous media create unique challenges. They increase friction and resistance, which make valves harder to operate. This leads to slower responses and less accurate flow control. Ball valves are great for viscous fluids. They have high flow coefficients and cause little pressure drop.

Fluids with particles need special attention. Solid particles in media can wear down valve surfaces faster. Research shows bigger particles moving at higher speeds cause more erosion. Erosion peaks at a 30° impact angle. My valve choice must include materials and designs that can handle this wear.

Space Constraints and Installation Considerations

Available space shapes ball valve selection and installation choices. The installation plan must account for physical space, nearby pipes, equipment, and obstacles. Exact measurements help us understand everything. This way, we can choose the best installation method.

Ball valves are great for tight spaces, like ship engine rooms and plane systems. Their compact design makes them a perfect fit. Proper valve orientation remains essential.

You can install 2-way ball valves either horizontally or vertically. Just make sure the handle points in the flow direction when it’s open. This setup removes any doubt about flow direction.

Setting the valve stem vertically works best for easy operation. An upside-down installation might let dirt and sediment build up on the stem packing. Good pipe support is crucial. Bad support can void warranties and lead to structural failure.

Ball valves operate effectively due to their unique construction types. Each type serves specific operational needs. Let me help you understand these core variants to pick the right valve for your applications.

Floating Ball Valves: Design and Applications

Floating ball valves have a hollow ball with holes. This ball floats in the flowing medium. Two seats hold it in position by compression. The design uses natural line pressure to press and seal the ball against the downstream seat. This creates a tight seal. The stem has a loose connection to the ball, which lets it "float" slightly as pressure pushes it against the seat.

These valves perform well even after many cycles. They remain reliable during long breaks without use. They excel at bi-directional shut-off applications in moderate pressure systems. You can use them instead of gate and globe valves. Large sizes or high-pressure systems make them less effective. The seats can't support the ball well.

Trunnion-Mounted Ball Valves for High-Pressure Systems

Trunnion-mounted ball valves are perfect for tough applications. They anchor the ball at both the top and bottom for better performance. The trunnion design features a solid ball. It has supporting mounts that manage the pressure load. This reduces stress on the ball and seats. The stem connects firmly to the ball, so it only moves around its axis.

This design reduces the torque needed for high-pressure operations. It seals well on both the upstream and downstream sides. These valves provide vital double block and bleed functionality. Oil and gas industries use them for large-bore and high-pressure operations.

V-Port Ball Valves for Precise Flow Control

V-port ball valves come with a special design. They have a V-shaped notch in the ball or seat instead of a regular round port. This unique shape offers great flow control. It also keeps the tight shut-off benefits of regular ball valves. The V-shaped geometry creates more linear flow characteristics during valve opening. This is a big deal as it means that these valves control flow better than standard ones. Quality actuators and positioners help these valves achieve control accuracy above 0.5%. They work well with fibrous suspensions, clean or dirty liquids, thick fluids, and corrosive materials.

Multi-Port Ball Valves for Flow Direction Management

Three-way multi-port ball valves let you control flow direction through additional ports. The ball has either an "L" or "T" shaped bore for different flow setups. Three-way designs offer flexibility. You can stop flow completely. You can also switch between two sources. Mixing flows from different sources is possible too. You can change destinations or split one flow into many paths. Complex systems that need flow diversion or combination capabilities enjoy this flexibility. The valve works based on your piping setup and handle rotation. You get cheap solutions that combine shut-off and flow direction control in one unit.

Body Configurations and Their Impact on Performance

Ball valve performance, maintenance needs, and lifespan depend on their body configuration. I've learned that choosing the right ball valve type is key. It helps to meet current needs and prepares for future demands.

One-Piece Ball Valves: Compact and Cost-Effective

One-piece ball valves come with a single, solid cast body that contains all internal parts. These valves cost 30-40% less than two-piece versions. The lower price comes from easier manufacturing and fewer components. Their small, lightweight build works great in tight spaces with limited access.

The design has its drawbacks. These valves earned the nickname "throwaway valves" because you can't fix them. A failed component means replacing the whole valve. That's why we used them mostly in non-critical spots like food service equipment. They work best where simple operation matters more than repairs.

1PC Threaded Steel Ball Valve

Two-Piece Ball Valves: Balance of Maintenance and Durability

Two-piece ball valves consist of a main body and one end connection. This connection can be made with threads or a bolt-flange assembly. You can repair these valves after taking them out of service. Removing the end plug can damage the threads, making maintenance tricky.

These valves seal better than one-piece models and work in more applications. They do not fit high-pressure systems because the connection between sections might leak. These valves work best in systems that require little maintenance. They are ideal for moving non-corrosive materials at low pressures and temperatures.

2 Piece Threaded Steel Ball Valve

Three-Piece Ball Valves: Greatest Serviceability

Three-piece ball valves use a split body design. The middle section holds the ball, stem, and seats, with two end caps linking to the pipeline. The biggest advantage? You can keep them connected. Just take out the center part while the ends stay connected to the pipes.

This setup shines in tough applications. You can easily replace parts and clean by fixing the valve body. You won't need to touch the pipe connections. That's why three-piece valves excel in high-cycle and high-pressure jobs with lots of wear. The higher upfront cost leads to less downtime and lower maintenance costs later.

Choosing the right ball valve—floating or trunnion—depends on your needs and budget. These two designs may appear similar, but they have different purposes. Each one has its own strengths.

When to Select Floating Ball Valves

Floating ball valves are common in industrial piping. They are effective and more affordable. These valves are ideal for low to medium pressure systems. They typically work well in sizes below 6 inches for Class 150-300. For Class 600 ratings, they are best under 2 inches. The ball floats freely and forms a tight seal in both directions. Pressure pushes it against the downstream seats.

These valves are perfect for:

Chemical processing
Water treatment
Industrial jobs with moderate pressure.

The best part? They cost much less than trunnion valves.

Trunnion-Mounted Advantages for Critical Applications

Trunnion-mounted designs work differently. They hold the ball with fixed shafts at the top and bottom, which makes them more stable and easier to operate. You'll find them everywhere in oil and gas, power generation, and petrochemical operations. The fixed ball stays aligned with the seats, even in tough conditions. This helps it seal well on both the upstream and downstream sides. Multi-port valves or low-pressure systems need trunnion designs. They don't use line pressure for sealing. Their strong performance under pressure makes them the top choice for safety.

Pressure Ratings and Size Limitations

The rules for valve selection are clear in industry standards.

EEMUA 182 states that trunnion designs are required for:

Class 150-300 valves at DN 150 (NPS 6") and larger.
Class 600- valves at DN 50 (NPS 2") and larger.
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Floating designs work well at moderate pressures. But they have limits as they grow larger. Bigger balls are more difficult to seal. Trunnion valves can handle up to 500 bar (7,250 psi) when made of steel. This strength makes them the best option for high-pressure tasks. Only at DN 50 (NPS 2") size can you choose either design, depending on what your system needs.

Ball valve design greatly affects how fluids flow and how well different types work. The internal bore shape affects how well media flows through the valve. This directly affects pressure drops and system performance.

Full Port vs. Reduced Port: Flow Efficiency Trade-offs

Full port ball valves have a bore diameter that matches the pipe size. This creates an unobstructed flow path. The straight-through design allows liquids and gases to move easily. This means there’s almost no pressure drop when it’s fully open. Flow rates remain steady, which significantly reduces the risk of cavitation. Cavitation is the formation of damaging air bubbles due to pressure drops. These designs shine in places where flow rate matters. They are great for handling both solids and liquids together.

Reduced port ball valves have a smaller internal bore. They are typically one pipe size smaller than the connecting pipeline. A 3/4" reduced port valve might have only a 1/2" ball opening. This design restricts flow more. As a result, it causes higher velocity, energy loss, friction, and a pressure drop across the valve. Reduced port designs offer real advantages. Their small size uses less material. This makes them about 30% lighter and cheaper than full port options.

Cavity-Filled Designs for Sanitary Applications

Cavity-filled ball valves address a big issue in standard ball valve designs. They fill the empty spaces behind the ball and inside the valve body. These cavities can trap media and create potential contamination points and operational issues. Cavity fillers get rid of these spaces and prevent media from getting stuck after flow.

These specialized valves are ideal for pharmaceutical, food, and beverage uses. Sanitation is key in these applications. Their design prevents medium from collecting. This reduces the risk of cross-contamination between different process fluids. Cavity-filled designs benefit companies using paint, pigments, or chemicals such as sodium hypochlorite. They prevent product buildup.

We make these valves with sanitary tri-clamp ends. They use FDA-compliant materials like PTFE (Teflon) and silicone or FPM (Viton). This ensures they meet strict regulatory standards. They are crucial for dealing with thick materials, slurries, and sticky substances. Standard ball valves would fail quickly in these situations.

Material Selection for Optimal Valve Performance

The materials you choose for ball valves affect their lifespan, reliability, and performance in different settings. Choosing the right parts means balancing performance with your budget

Metal Body Options: Brass, Bronze, and Stainless Steel

Brass is made of copper and zinc. It has good mechanical properties, so you can shape it easily. It won’t crack or rupture. This budget-friendly material works up to 204°C (400°F) and handles pressure ratings up to psi. We successfully used brass for water, gas, oil, and air. Yet, it doesn't resist chloride solutions well because of dezincification.

Bronze, made from copper and tin, stands up better to corrosion than brass and cast iron. Stainless steel takes durability even further for extreme conditions. You'll find two main grades—304 (18% chromium, 8% nickel) and 316 (18% chromium, 10% nickel). The 316 grade resists corrosion better, which makes it ideal for marine environments. Stainless steel handles impressive temperatures up to 926°C (°F) and pressures up to 10,000 psi.

Plastic Valve Bodies: PVC, CPVC, and PVDF

PVC (polyvinyl chloride) valves are a budget-friendly choice for corrosive applications. These valves can handle many salt solutions, acids, bases, and organic solvents. But, they don’t work well above 60°C or with aromatic and chlorinated hydrocarbons. CPVC becomes your best bet when temperatures run higher.

PVDF (polyvinylidene fluoride) serves as a premium option for tough chemical service. Models come in sizes from 1/4" to 2" with a full-port design and reversible PTFE seats.

Seat Materials: PTFE, PEEK, and metal seats

PTFE (Teflon) seats never need lubrication and keep seals "bubble-tight." This material has the lowest friction coefficient of all thermoplastics. It can work in temperatures from -429°F to 400°F. Plus, it resists nearly every chemical. You can boost PTFE seats' performance by adding glass or carbon-fiber reinforcement.

PEEK (polyetheretherketone) seats take performance to another level in extreme conditions. They work from -70°F to 500°F and handle pressures up to psi. PEEK handles radiation better than PTFE. This quality makes it ideal for nuclear uses.

Material Compatibility with Process Media

The right match between valve materials and process media prevents early failures. For example, stainless steel 316 works well in seawater and chlorine-rich areas. PTFE works with most chemicals except fluorine and liquid alkalis. PEEK handles most chemicals well but struggles with sulfuric acid.

Your material selection should account for all service conditions. Review chemical compatibility charts for your media. Consider concentration, temperature, and exposure time.

Conclusion

Choosing the right ball valve means considering several factors. First, understand the application fully. This piece covers everything from basic construction types to material compatibility. This helps achieve the best performance.

Floating ball valves work great in low to medium pressure applications. Trunnion-mounted versions become crucial for high-pressure environments where you cannot compromise on reliability.

The valve's body shape greatly impacts maintenance choices. You can choose simple one-piece designs or more complex three-piece builds. These can be serviced easily. A valve's port design and material choice help you select the right option. This depends on your flow needs and media compatibility.

A ball valve works best when its specs match the application perfectly. Test the operating conditions, space limits, and maintenance needs first. Then, make your choice. This prevents mistakes that can get pricey and will give you long-term reliability. Match the right materials using this selection method. You’ll achieve better performance and a longer service life.

FAQs

Q1. What are the main types of ball valves? Ball valves have different types.

These are:

Floating ball valves
Trunnion-mounted ball valves
V-port ball valves
Multi-port ball valves

Each valve type has a specific use and pressure range. Floating ball valves work well in low to medium pressure systems. Trunnion-mounted valves are best for high-pressure situations.

Q2. How do I choose the right ball valve for my application?

To choose the right ball valve, think about these key factors:

Valve size
Material compatibility with your media.
Pressure and temperature ratings
We need flow control.
Actuation type

Before deciding, assess your application needs. Consider space limits and maintenance needs.

Q3. What's the difference between full port and reduced port ball valves?

Full port ball valves have an internal diameter that matches the pipe size. This design allows for minimal flow resistance and pressure drop. Reduced port valves have smaller internal diameters. They are usually one pipe size smaller than the connecting pipeline. This design limits flow more, but it’s also smaller and cheaper.

Q4. Why are trunnion-mounted ball valves preferred for high-pressure systems?

Trunnion-mounted ball valves are the top choice for high-pressure systems. They support the ball at the top and bottom, which cuts down stress on the ball and seats. This design seals both upstream and downstream at the same time. It needs less torque to work under high pressure. So, it is great for critical uses in the oil and gas industries.

Q5. What materials are frequently utilized in the construction of ball valves?

Ball valves are often made from metals like brass, bronze, and stainless steel. For corrosive uses, manufacturers can also make them from plastics like PVC, CPVC, and PVDF. Seat materials often include PTFE (Teflon), PEEK, and metal seats for extreme conditions. Choose materials that fit your chemical needs, temperature limits, and pressure levels for your project.

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