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Idea to know Pneumatic Valve Materials

Pneumatic valves control the rate, pressure, and flow direction of compressed air and gasses in industries. These valves control the air or gas at the source and regulate its movement into hoses, tubes, or devices as needed in an automated pneumatic system. Pneumatic valves are commonly available in various housing materials like stainless steel, brass, aluminum, and industrial-grade plastics like PVC and have seal materials like NBR, FKM, and EPDM. Selecting the suitable material for a valve is crucial for its working. This article discusses the various types of materials used in pneumatic valve

What is a pneumatic valve?

Pneumatics is the technology that makes use of gas or pressurized air. A pneumatic system utilizes a compressor to reduce the air volume to increase its pressure. The air (or gas) is filtered and passed through pneumatic hoses, pipes, or tubes. During this transit, the air is controlled by valves, after which it reaches an actuator like a cylinder or a device that performs a function, for example, moving, lifting, or gripping.

A pneumatic valve controls the pressure, flow rate, and direction of air and gasses. According to these applications, a pneumatic valve is classified into the following categories:

  • Pneumatic pressure relief valves: Pressure relief valves keep the system pressure below a preset maximum value.
  • Pneumatic flow control valves: Flow control valves are used in pneumatic systems to govern the rate at which a media (liquid or gas) is allowed to flow. Flow control valves can typically be unidirectional or bidirectional.
  • Pneumatic directional control valves: Directional control valves like solenoid valves are used to start, stop, or direct airflow in a pneumatic system. By directing the flow of air, these valves control the action of other pneumatic devices like motors, cylinders, pumps, or other valves.

Know your process media

Pneumatic valves have two distinct contexts of use in general:

  1. A pneumatic valve is a device used to control the flow of air or other gasses in a pneumatic system. The valve can be actuated manually, electrically through a solenoid, motorized, or pneumatically. In this case, the media being controlled is air or gas, and hence the materials chosen for the valve body and seal should be compliant with these media. Possible options include aluminum, stainless steel, brass, and industrial-grade plastics
  2. Air can be used as a control mechanism for the valve, but in this case, the media flowing through the valve may be something other than air like oil, water, or other fluids. Here it is necessary to check how compliant the valve housing material is with respect to the various media. Read our article on the chemical resistance of materials to check the compatibility of various housing and seal materials with the media and environment used.

Driving pneumatic media or gas

The pneumatic media or gas (like an inert gas or CDA air) used in an automation control process is high conditioned, dried, and filtered. Therefore the valve design need not consider the aggressive media nature or account for the high purity level of the media. Industrial grade plastics (like PVC) can be used for these highly conditioned media.

Process fluids

Pneumatic valves for process fluids deal with highly acidic, corrosive, alkaline, or high purity media. Therefore, it is mandatory to select the construction materials suitable for protecting the media and the valve. Stainless steel is a great option for the valve housing material for aggressive and corrosive media. For neutral and non-corrosive media, brass is commonly used as the housing material.

Pneumatic valve housing materials

Always select the housing material suitable for the medium and the working environment. The housings of pneumatic valves for automation control are typically manufactured with a mix of different materials discussed below:

Industrial grade plastics (like PVC and nylon)

Plastic valves are lightweight, durable, and cost-effective. The material is suitable for pneumatic applications involving air and corrosive chemicals. But plastic valves have a low pressure and temperature rating compared to brass and stainless steel valves.

Brass

Brass is an alloy of copper and zinc, and it is an excellent forgeable and robust material. Brass is used in pneumatic applications involving non-corrosive gases. The material can withstand more heat compared to PVC but comes at a higher price. Brass can be easily welded, and it is more versatile when compared to stainless steel. Brass is commonly used to construct pneumatic valve bodies and end pieces.

Stainless steel (304/316)

Stainless steel is a very durable and resilient material, but it is more expensive than brass. Valves made out of stainless steel effectively resist leaks, and these valves can be operated at very high temperatures when compared to brass. Stainless steel is corrosion-resistant and lasts much longer compared to brass, and it is an ideal choice for high temperature and high-pressure pneumatic applications. Stainless steel is commonly used in the pneumatic valve bodies and trim materials like seats, discs, and wedges.

Aluminum

Aluminum is a lightweight metal that has approximately one-third the weight of steel. Aluminum is corrosion-resistant to atmospheric gases and hence suitable for pneumatic valve applications. The material is mainly used to construct the exterior components of the pneumatic valve, like the identification tags or handwheels.

Pneumatic valve housing material comparison table

Table 1: Comparison of different materials for pneumatic valve housings

PVC Brass Stainless steel Aluminum
Cost Low High Very high High
Durability Average High Very high High
Corrosion resistance High Average Very high Low-average
Operating temperature and pressure Low High Very high High
Weight Light Heavy Heavy Light

Pneumatic valve seal materials

Seals in pneumatic valves help prevent the escape of volatile and hazardous gasses into the atmosphere. The various types of seal materials used in pneumatic valves are the following:

NBR (Nitrile-butadiene rubber)

NBR has good resistance to compression and general wear and tear but is highly sensitive to weather changes. NBR is suitable for air and inert gasses but has poor resistance to ozone, ammonia, and steam. NBR seals can provide continuous sealing for gaseous media only at low temperatures compared to the sealing properties of FKM.

FKM (Viton)

FKM is typically used to manufacture O rings, gaskets, and seals for pneumatic valves. FKM seals have excellent resistance to the media, aging, and ozone. FKM is suitable for medium-high temperature pneumatic applications and has higher thermal resistance than PTFE. Also, FKM has superior strength, sealing capabilities, and flexibility when compared to PTFE. The material has excellent overall chemical resistance making it suitable for gaseous fuels, and the material shows more chemical resistance universally compared to NBR.

PTFE (Teflon)

PTFE is suitable for high temperature and pressure pneumatic applications. The material is non-elastic and has good resistance to wear and tear abrasion and most chemicals. PTFE offers superior resistance to gaseous chemicals as compared to FKM.

Materials for specific pneumatic valves

Directional control valves

Directional control valves are used in pneumatic systems to stop or direct the flow of compressed air or oil to their connected appliances. However, it is not recommended to use these valves for media other than air for most applications. Many pneumatic solenoid valves are piloted internally, and these valves vent a minimal amount of air required to actuate the valve. A small loss of air into the surroundings is acceptable in most applications but not in the case of oil, water, or other types of media. A few examples of materials for these valves that are compatible with the media and environment are:

  • Valve body: Aluminium, Plastic, Brass, Stainless steel
  • Seal: NBR, FKM, EPDM

Flow control valves

Pneumatic flow control valves are used to control the flow of media like a liquid or gas. These valves consist of a pneumatic actuator part and the valve part like a ball valve or butterfly valve. The actuator is mounted to the valve using a standard flange, allowing both the actuator and the valve portions to be swapped out with another one using the same flange size. Always choose the valve housing and seal materials to be compatible with the media used. A few options are:

  • Valve body: Cast iron, Stainless steel
  • Seal: EPDM

Pressure control valves

Pressure control valves reduce the pressure of incoming air to a set value at the output port. Brass is a viable choice for the valve’s body material, with a surface coating of nickel for added protection.

The material chosen for the connection cables and plugs used for transmitting the media to and from the valves should be compatible with the media chosen. Example:

  • Valve body: Polyurethane (for media like air, carbon dioxide, nitrogen, fuels, and oils)
  • Seal: EPDM

Pneumatic valve specifications

Knowing the valve materials is only one part of selecting a pneumatic valve. Some other factors to consider are discussed below.”

  1. Operating medium: The media types that the pneumatic valve can effectively control (compressed air in most cases)
  2. Flow capacity (Cv): Cv gives a measure of the valve capacity to move air through it
  3. Operating pressure: The range of pressure (in Pa, bars, or psi) that the valve is rated to handle
  4. Port size: The physical dimensional parameters that define the port sizes on the valve and the thread style
  5. Rated voltage of coil: For electrically actuated valves, the required voltage rating may be given in AC or DC volts.
  6. Response time: The amount of time required for the valve to switch states or positions once actuated.

Note: The discussed parameters are for general guidance only, and the individual valve suppliers and manufacturers may specify their valves differently.

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The different Stainless Steel 304 and 316

When selecting a valve’s housing material, it is important to know the differences between stainless steel 304 (EN steel number 1.4301) and stainless steel 316 (EN steel number 1.4401, 1.4436). Selecting between the two typically depends on an application’s corrosion resistance requirements. This article discusses the nature of each type of steel, how to choose between them, and how to determine which to use for a stainless steel valve.

What is stainless steel?

Steel, in general, consists of iron and carbon. Stainless steel, on the other hand, encompasses various steel blends containing at least 10.5% chromium by weight. These blends are primarily made to withstand corrosion or oxidation, which occurs when metals react with oxygen (in air or water) and form rust. Stainless steels are 100% recyclable.

When chromium (Cr), a durable metal, comes into contact with water or air, it undergoes a chemical reaction with oxygen. In stainless steel, chromium oxide forms a thin, stable film on the surface (Figure 2 labeled A), protecting the metal from corrosion by limiting oxygen exposure. This corrosion resistance process is known as passivation. The protective film can self-repair (Figure 2 labeled C) if scratched or disturbed (Figure 2 labeled B).

Stainless steel with a chromium oxide surface film. Chromium oxide intact (A), chromium oxide damaged (B), and chromium oxide self-reformed (C). The blue spheres are oxygen.Figure 2: Stainless steel with a chromium oxide surface film. Chromium oxide intact (A), chromium oxide damaged (B), and chromium oxide self-reformed (C). The blue spheres are oxygen.

Types of stainless steel

Varying the ratios of different elements has led to many kinds of stainless steel. Beyond chromium, other alloying elements are added to stainless steel, for example, molybdenum, nickel, and titanium. These elements enhance stainless steel’s formability, strength, and chemical resistance.

Austenitic stainless steel is the most widely produced family of stainless steel. It is created by alloying nickel, which gives it excellent formability and weldability. Stainless steels 304 and 316 are members of this family.

Stainless steel 304 vs 316

When selecting a specific grade of stainless steel for a given application, the first and foremost criterion is corrosion resistance. Other mechanical or physical properties may also need to be considered to meet service performance.

A stainless steel 304 pipe end stamped to indicate its steel gradeFigure 3: A stainless steel 304 pipe end stamped to indicate its steel grade

Corrosion resistance

Stainless steel 304 (EN steel number 1.4301) and stainless steel 316 (EN steel number 1.4401, 1.4436) have very similar physical and mechanical properties, but their primary difference remains in their resistance to corrosion in different environments:

  • 304 Stainless Steel
    • Contains 18% chromium and 8% nickel
    • Cost-effective choice if high concentrations of chloride are not present.
  • 316 Stainless Steel
    • Contains 16% chromium, 10% nickel, and an additional 2% molybdenum
    • The added molybdenum provides greater corrosion resistance to acids and localized pitting attack by chloride solutions such as seawater and de-icing salts.

The corrosion resistance of stainless steel in acidic or basic solutions depends on the kind and concentration of acid or base and the solution temperature.

A stainless steel 316 tee pipe fitting stamped to indicate its steel gradeFigure 4: A stainless steel 316 tee pipe fitting stamped to indicate its steel grade

Corrosion resistance to acids

Stainless steel type Resistance to acids
Stainless steel 304
  • Good resistance to moderately aggressive organic acids, such as acetic acid and formic acid
  • Prone to corrosion (e.g., pitting and crevice corrosion) by strong acids such as sulfuric or hydrochloric acids
  • Resistant to most concentrations of phosphoric acid and nitric acid but may have stress corrosion cracking in hot concentrated solutions
Stainless steel 316
  • Better acid resistance than stainless steel 304, especially if chloride ions are in the system
  • Better resistance to sulfuric acid than stainless steel 304. Can experience corrosion at concentrations above 20% or temperatures above 50 °C (122 °F)
  • Prone to corrosion by hydrochloric acids
  • Better resistance to phosphoric, acetic, formic, and tartaric acid solutions at a wide range of concentrations and temperatures

Table 1: Stainless steel 304 vs 316 resistance to acids

Corrosion resistance to bases

Stainless steel type Resistance to bases
Stainless steel 304
  • Good resistance to alkalis
  • Can withstand exposure to weak bases, such as sodium hydroxide or potassium hydroxide
  • May experience localized corrosion in the presence of strong bases at high temperatures
Stainless steel 316
  • Higher resistance to bases than stainless steel 304
  • Can maintain corrosion resistance to strong bases, such as sodium and potassium hydroxide, even at elevated temperatures

Table 2: Stainless steel 304 vs 316 resistance to bases

Other factors

As mentioned in the above section about corrosion resistance, most of the other properties of stainless steel 304 and 316 are similar. Understanding the following properties can help select the right stainless steel, but does not need a lot of focus unless the application has very precise demands:

  • Mechanical properties: 304 and 316 have similar tensile strength, yield strength, and elongation. 316 has slightly higher strength and toughness due to molybdenum.
  • Cost: 304 is less expensive than 316 due to the absence of molybdenum. The lower cost can be significant for large materials or projects.
  • Heat resistance: 316 has a slightly higher heat resistance than 304.
  • Fabrication and formability: 304 is slightly easier to work with than 316 when fabricating, welding, and forming.
  • Weight: 316 is slightly denser than 304 due to molybdenum.

Stainless steel valves

Stainless steel valves are widely used primarily due to their corrosion resistance. With everything else equal, 304 and 316 valves have a negligible difference in temperature and pressure rating. Look for a stamped number on the valve’s body to determine if it’s 304 or 316, similar to the objects in Figures 3 and 4. The following table describes factors to consider when selecting between stainless steel 304 and stainless steel 316 valves.

Property Stainless steel 304 valve Stainless steel 316 valve
Corrosion resistance Good resistance but inferior to 316 Superior to 316 due to the addition of molybdenum
Applications Food processing, water treatment, general plumbing and other applications that require moderate corrosion resistance Marine environments, chemical processing, pharmaceutical industries, and other applications with high corrosion resistance demands
Cost Less expensive More expensive

Table 3: Selecting between stainless steel 304 and stainless steel 316 valves

FAQs

How do I tell the difference between stainless steel 304 and stainless steel 316?

Unless stamped, the only way to tell the difference between these two types of stainless steel is to test them chemically. There are no visual markers or mechanical properties that make them easy to differentiate.

How do I choose between stainless steel 304 and stainless steel 316?

Choosing between these two stainless steel types typically comes down to understanding how much corrosion resistance is necessary. Stainless steel 316 has superior corrosion resistance but is also more expensive.

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Gate Valve vs Butterfly Valve

At first glance, it is not simple to decide between a gate valve and a butterfly valve for an application. Therefore, it is important to understand the differences between these two valve types to avoid unnecessary setbacks in an operation. This article lays out the fundamental similarities and differences between a gate valve and a butterfly valve, which can be seen in Figure 1, and looks at their application suitability, advantages, and disadvantages.

Gate and butterfly valves are both used to turn on and off the flow, but butterfly valves can also regulate flow via partial disc closure. Butterfly valves are part of the quarter-turn family of valves and can be shut off much faster than gate valves, which are multi-turn valves. Gate valves are preferable for high-pressure systems whereas butterfly valves are preferable for larger port sizes.

Gate valves

How does a gate valve work?

A gate valve is named after its disc, which behaves like a gate by either stopping or allowing media flow. It has a simple operation compared to other control valves, which makes it one of the most commonly used valves. Because a gate valve is a full-port valve, which means that the valve’s ports are the same size as the inner diameter of the connecting pipes, there is very little resistance to liquid or gas media that flows directly through it. Therefore, the pressure drop through the valve is quite low. For a more extensive understanding, read our article on gate valves.

Operating a gate valve

Gate valves are multi-turn valves, meaning the handwheel must turn more than 360° to fully open or close the valve. Turning the handwheel in one direction or the other moves the gate up or down via the stem. When the gate is completely up, the passageway is unobstructed, and media can flow. When the gate is down, media is blocked and cannot flow. Gate valves cannot modulate or throttle flow because there is a nonlinear relationship between the gate’s travel and flow rate. If the gate is partially open, the flow will crash into it while traveling through the valve, causing the flow to move at a higher velocity and create turbulence, both of which lead to increased wear on the disc and seats.

The three common means for actuating a gate valve are manually, pneumatically, or electrically. The manual method requires an on-site user to spin the handwheel to open or close the valve. This method is the most cost-effective since gate valves are not typically opened or closed often. The pneumatic and electric solutions allow for remote operation of a gate valve. Pneumatic actuation requires a pneumatic system on-site and electrical actuation requires electrical power on-site.

Gate valve types

As mentioned above, there exist different styles of gate valves. Three factors typically determine a gate valve’s style: the gate type, the bonnet type, and the stem type.

Gate type refers to the disc that blocks the flow when the valve is closed, for example:

  • Wedge disc: The gate is shaped like a wedge and it sits on two inclined seats. This provides a high wedging force which assists with sealing.
  • Knife disc: The gate is a piece of metal with a beveled edge like a knife. It can be used to cut through thick fluids and dry solids.
  • Double disc: The gate is two discs which sit on two seats. The discs expand away from each other to provide a tight seal.

Bonnet type refers to how the bonnet is attached to the valve body. It can be:

  • Screwed: This is the simplest type of bonnet construction and is normally used in small size valves.
  • Bolted: These bonnets are used in larger valves and high-pressure applications.
  • Welded: The bonnet is threaded in and the body-bonnet joint is welded. This offers extra protection against leaking.
  • Pressure sealed: The body-bonnet joint seal enhances as pressure within the valve increases. Used typically for high-pressure applications above 100 bar.

Stem type refers to the position and action of the stem

  • Rising vs non-rising: Rising stem gate valves require more space above the valve than non-rising.
  • Remains within the valve vs rises out of the valve upon opening: Rising out of the valve makes the stem easier to lubricate.

Materials

The correct material depends on the application’s fluid service and temperature. Common materials used for a gate valve are:

  • Body and bonnet: cast steel, stainless stell, cast iron, gunmetal, bronze, brass, and PVC
  • Disc: stainless steel, polypropylene, Teflon, rubber lined (e.g., wedge disc)
  • Seal: EPDM, NBR, Teflon

  • Butterfly valves

    How does a butterfly valve work?

    The essential operation of a butterfly valve is achieved by turning its handle 90° or using a pneumatic or electric actuator. This turns the valve’s stem, which rotates the disc. In the fully closed position, the disc is perpendicular to the flow, and in the fully open position, the disc is parallel to the flow. Partial opening or closing of the disc can achieve proportional or throttled flow rates. In cases of a large butterfly valve or a valve used in a liquid application for which fast closure could produce water hammer, a butterfly valve can be gear operated via a gearbox (Figure 2, right). The gearbox’s handwheel must be turned more than 90°, though, which eliminates the butterfly valve’s relatively fast closing speed. For a more comprehensive understanding, read our article on butterfly valves.

    A zero offset butterfly valve with a lever handle on the left and an eccentric butterfly valve with a hand wheel on the rightFigure 2: A zero offset butterfly valve with a lever handle on the left and an eccentric butterfly valve with a hand wheel on the right

    Butterfly valve types

    There are two key topics when discussing types of butterfly valves: body and stem offset. Body refers to how the valve’s body connects with piping, and stem offset refers to whether the stem passes through the center of the disc or is offset.

    The butterfly valve body types are:

    • Double-flanged: This design is typically used for larger butterfly valves.
    • Wafer: Most cost-effective design; sandwiched between two pipe flanges.
    • Single flange: This design uses bolts and nuts passed through the valve’s holes to connect to both sides of the piping.
    • Lug type: This design has threaded inserts, and bolts are used to connect pipe flanges to each side. Suitable for removing piping from one side without affecting the other.
    • Flangeless: Like the wafer style, this design is sandwiched between two pipe flanges.
    • Butt-welding ends: Prepared for welding directly to piping.
    • U-section: Also clamped between pipe flanges and suitable for end-of-line service.

    The stem can pass through the centerline of the disc (concentric) or be offset behind the centerline (eccentric). Offset, which can be single-, double-, or triple-offset, is used to reduce how much the disc rubs against the seating while closing. The higher the offset, the more the disc moves towards fully closed before contacting the seal. Any rubbing against the seal can reduce the service life of the valve. High-performance butterfly valves are specifically designed to withstand more demanding applications in terms of pressure and temperature.

    The following compares a high-performance butterfly valve with a standard butterfly valve:

    • Maximum shutoff pressure: Approximately 50 bar (725 psi) vs approximately 14 bar (203 psi)
    • Tight shutoff: Below 260°C (500°F ) vs below 120°C (248°F)
    • Shutoff with allowable seat leakage: Below 538°C (1000°F) vs below 425°C (797°F)

    Read our article on butterfly valve design differences article for more details on the features of each design type.

    Materials

    The valve’s body and seat materials should be chosen carefully based on the needs of the application. Common body materials are iron, stainless steel, carbon steel, nickel alloy, titanium alloy, and nickel aluminum bronze. These materials vary in weight and resistance to corrosion and extreme temperatures.

    Common seat materials are EPDM, EPDM white, FKM, XNBR, and NBR. Depending on the seat material, a butterfly valve can be used in temperatures ranging from -10°C to 180°C. Resilient and metal seated butterfly valves are also available, using the same materials listed here, and are designed to operate under more extreme temperatures and pressures.

    Gate valves vs butterfly valves

    There are many factors to consider when deciding whether a gate or butterfly valve is correct for a given application. Below are some of the most important:

    • Cost: A butterfly valve is typically less expensive than a gate valve, especially at larger port diameters.
    • Installation space: A butterfly valve takes up less installation space than a gate valve.
    • Weight: A butterfly valve weighs less than a gate valve; the latter may need support structures at larger port diameters.
    • Maintenance: While a butterfly valve is relatively easy to maintain, repair, or install due to its small size and low weight, its center disc makes it not suitable for systems that use pigging and swabbing for cleaning purposes. On the other hand, a gate valve is ideal for such maintenance.
    • Operation: A butterfly valve can close faster than a similar port diameter gate valve. However, this fact means that butterfly valves are more susceptible to water hammer.
    • Flow regulation: A butterfly valve can modulate or throttle flow, whereas a gate valve can only be on/off.
    • Flow resistance: A gate valve offers less flow resistance and, therefore, less pressure drop than a butterfly valve.
    • Pressure: Gate valves can handle higher pressures than butterfly valves.

    Applications

    • Gate valves have a higher sealing tightness, and therefore are more suitable for applications that require zero leakage.
    • Butterfly valves are more suitable for applications that require flow modulation or throttling.
    • If a slurry flow does not need to be modulated, gate valves are preferable to butterfly valves.
    • Gate valves are more suitable for systems that require bi-directional, uninterrupted flow.

    FAQs

    Which is better, a gate valve or a butterfly valve?

    A gate valve has a stronger seal and is more suitable for high-pressure applications. A butterfly valve is less expensive and available in very large sizes.

    Can a butterfly valve be used instead of a gate valve?

    A butterfly valve can be used instead of a gate valve in low-pressure systems for which some leakage is not a major concern.

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How to replace a ball valve

Ball valves are an integral part of plumbing and piping systems. These valves are highly durable and leak-resistant by and large, but they are not immune to damage. Replacing a damaged ball valve is relatively simple if the correct sequence of steps is followed. This article discusses how to replace a ball valve connected to a copper pipe or PVC pipe in case the valve doesn’t work properly.

Ball valve issues

A ball valve is a shut-off valve that directs the flow of a fluid by means of a rotary ball having a hole. There are a few potential ball valve failures like getting stuck, fluid leakage, corrosion, and overheating, resulting in the valve not functioning properly. Typically, there are three cases:

  1. Ball valve issues that can be fixed manually: Issues like a stuck ball valve that prevents fluid flow, sediment and dirt buildup that makes the valves difficult to open and close, or actuator issues can be easily solved by manual intervention as discussed in our article on ball valve issues and troubleshooting.
  2. Ball valve issues that can be fixed by replacing a part: Issues like a partially closing ball valve, worn-out O-ring, and stem may require certain parts of the ball valve to be replaced with new ones rather than ordering a whole new valve.
  3. Ball valve issues that require a total replacement: Certain issues like a leaking ball valve may require the whole valve to be replaced with a new one.
A rusted ball valveFigure 2: A rusted ball valve

How to replace a ball valve

The following is an example on how to replace a ball valve on a water line with a new one. The same principles apply for other applications.

Step 1: Turn off the water

Turn off the main water supply to all the pipes being worked on. Then, drain the existing water pressure in these pipes by turning on the connected faucet.

Step 2: Access the pipes

Accessing the pipes is necessary to replace an existing ball valve. For example:

  • A sink: Try to access the ball valve underneath the sink.
  • Shower pipe/bathtub faucet: Either via the basement crawlspace or via breaking the wall that has the pipe attached.

This step helps plan in advance whether to break the wall for replacing the required valve.

Three-dimensional representation of copper and PVC pipes within a wallFigure 3: Three-dimensional representation of copper and PVC pipes within a wall

Step 3: Cut the old valve out

Once there is full access to the pipes, use a hacksaw to cut off the old ball valve residing in the pipe (marked in red circles in Figure 4). For this, cut the two sides of the pipe where the valve is placed, and get the valve removed from its position. In case the old valve can be unscrewed from its position, remove the valve and skip to Step 8.

A ball valve connected in a pipe system. The red circles show the points where the pipe needs to be cut to remove the valve.Figure 4: A ball valve connected in a pipe system. The red circles show the points where the pipe needs to be cut to remove the valve.

Step 4: Disassemble the ball valve

Disassemble the ball valve parts and make sure to keep all the parts together. This ensures that if any of the individual parts are salvageable, the reassembling process can be done with ease.

Step 5: Inspect the ball valve parts

Inspect the ball valve parts for any cracks or wear and tear that might have led to the leaking or nonfunctional ball valve. If a specific part of the valve seems faulty while the rest of them seem normal and function well, the best option would be to order a replacement part. Read our ball valve leakage troubleshooting article for more details on the causes of ball valve leakage and how to troubleshoot them. After getting the damaged part replaced, use lubricating oil and screws to reassemble the ball valve parts. If there is damage to multiple parts of the valve, or if the ball valve seems damaged beyond repair, it is a better option to get a completely new ball valve.

Step 6: Buy a new valve/valve part and other supplies required

Have an idea about the type of pipes installed so that it is easy to buy a new pipe section and seals required.

  • Copper pipe: A plumber’s tape or sweat pipe joints
  • PVC pipe: Pipe cement

Also, get a spackle and a new valve or valve part(s) based on the needs.

Step 7: Splice the pipe

Splice the new pipe section onto the pipe where the valve was cut. Allow enough space for the new ball valve to fit in.

  • PVC pipe: Apply PVC glue to the existing pipe where the cut was made and on one end of the new pipe. Push the new pipe onto the existing pipe and hold for approximately 30 seconds. Connect a coupler to one end of the new pipe if needed.
  • Copper pipe: Two copper pipes can be connected together by soldering their ends or by using a coupler. Read our article on ball valve soldering for the detailed soldering process employed in the plumbing industry.

  • Step 8: Install the new/repaired ball valve

    Install the new/repaired ball valve properly into the pipe.

    • Copper pipes typically need to be soldered to the valve. Read our article on ball valve soldering for detailed instructions on how to solder a ball valve to a copper pipe.
    • For installing a ball valve to a PVC pipe, cover one end of the pipe using pipe dope and insert the ball valve into the pipe. Then brush pipe dope to the other connecting end of the pipe and insert the other port of the valve.
    • Welded connections are used for ball valves where zero leakage is crucial for high-pressure and high-temperature applications. Welded connections are permanent and should be carried out only by trained professionals.
    • Threaded connections are useful to install small valves to pipes. Typically, the valve has female threaded ends that connect to a male threaded component. In some cases, the valve has male threaded ends or one male threaded end and the other a female threaded end. Threaded connections can either be straight or tapered. Straight connections often require an O-ring that compresses to ensure a tight seal between the valve and the pipe. The tapered thread does not require an O-ring to achieve a tight seal. Both types of thread can use pipe tape or a sealant between the male and female thread, which serves as a lubricant, provides sealing, and prevents metal-to-metal contacts that cause wear.
    • Ball valves with flanged connections are quite easy to install and can be easily removed for cleaning and maintenance without affecting other parts of the pipe network. They are very common in industrial applications. The flanges are solid metal plates with holes through which bolts and nuts are placed to tighten the valve to the pipe.

    Step 9: Test the ball valve installation

    Turn on the water supply and faucets that were previously turned off for the installation. Check for leaks in the pipes. If there are no leaks, the broken walls that contain the pipes can be closed. If the pipes leak, go back into the steps and make the proper connections required.

    If the wall had to be cut into, place the part back and paint over it with spackle. If the valve was below the sink, just close the cabinets.

    FAQs

    Can you replace a gate valve with a ball valve?

    Yes, a ball valve is superior in terms of performance compared to a gate valve; hence, it is a good idea to replace a gate valve with a ball valve if needed.

    Can ball valves fail?

    Yes, a ball valve can fail due to a damaged seal (the valve won’t close fully) or foreign particles entering the valve (the valve gets stuck).

    What is the life expectancy of a ball valve?

    The average life expectancy of a ball valve is 8-10 years. Ball valves get worn out due to continuous rotation.

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ISO 5211 For Industrial Valves

ISO 5211 is an international standard that specifies the flange dimensions, driving component dimensions, and torque reference values for part-turn actuators that connect to industrial valves like butterfly and ball valves. The standard also defines the different types of drive inserts used for these actuators. This article concentrates primarily on ISO 5211 standard and the other relevant ISO standards used for ball valves and butterfly valves.

ISO 5211 standard

Modern valve designs are compliant with an ISO mounting interface. The actuator can be mounted directly to the valve without a bracket and drive log, thus saving time, hassle, and money. The highlight of following a standard like ISO 5211 is that the user can buy the parts from any manufacturer and then mix and match the valve and actuator and replace a single part if needed.

ISO 5211 is an international standard that specifies requirements for the attachment of part-turn actuators (with or without gearboxes) to industrial valves. ISO 5211 specifies the following parameters:

  1. The flange dimensions necessary for attaching part-turn actuators to industrial valves or intermediate supports.
  2. The driving component dimensions of part-turn actuators necessary to attach them to the driven components.
  3. The reference values of torques for interfaces and couplings.

Flange dimensions

Flanges for part-turn actuators (Figure 2 labeled 1) comply with the dimensions shown in Figure 2 and Table 1. The flanges can be attached by screws, studs, or bolts. Holes for the studs, screws, or bolts are equally spaced apart and positioned off-center (see Figure 3 and Table 3), and conform to the requirements of ISO 273. ISO 273 specifies the clearance hole diameters for general purpose applications. These values are from bearing area calculations connected to ISO bolt and nut product standards.

Flange dimensions of a part-turn actuatorFigure 2: Flange dimensions of a part-turn actuator

Table 1: Flange dimensions (in mm)

Flange type d1 d2 d3 d4 h1max h2min No. of bolts/studs
F03 46 25 36 M5 3 8 4
F04 54 30 42 M5 3 8 4
F05 65 35 50 M6 3 9 4
F07 90 55 70 M8 3 12 4
F10 125 70 102 M10 3 15 4
F12 150 85 125 M12 3 18 4
F14 175 100 140 M16 4 24 4
F16 210 130 165 M20 5 30 4
F25 300 200 254 M16 5 24 8
F30 350 230 298 M20 5 30 8
F35 415 260 356 M30 5 45 8
F40 475 300 406 M36 8 54 8
F48 560 370 483 M36 8 54 12
F60 686 470 603 M36 8 54 20
Positions of holesFigure 3: Positions of holes

Table 2: Position of holes

Flange type ⍺/2
F03 to F16 45°
F25 to F40 22.5°
F48 15°
F60 9°

Drive inserts

Drive inserts allow the actuators to directly mount to the valve in accordance with ISO 5211. Direct mounting eliminates the need for a coupling-type mounting kit and significantly cuts the valve/actuator assembly cost. ISO 5211 covers parallel and diagonal square drives, flat head drives, and single and two key drives. These drive inserts are on factory-built actuators or come as separate units. Also, these inserts are easily replaceable at the distributor or end-user level.

Drive inserts for connecting ISO 5211 actuator to butterfly valves: Actuator (A), drive insert (B), Butterfly valve (C)Figure 4: Drive inserts for connecting ISO 5211 actuator to butterfly valves: actuator (A), drive insert (B), butterfly valve (C)

ISO 5211 torque chart

As per the ISO 5211 standard, the maximum torque transmitted through the mounting flange of a butterfly or ball valve should comply with the values listed in Table 3. The values specified in Table 3 are based on bolts in tension at a stress of 290 MPa and a coefficient of friction between the mounting interface of 0.2. Any variation in these defined parameters can lead to variations in the values of torque transmitted. Hence, while selecting a flange type for a particular application, the additional torque that inertia or other factors may generate should be considered.

Table 3: Maximum flange torque values as per ISO 5211 standard

Flange type Maximum flange torque (in Nm)
F03 32
F04 63
F05 125
F07 250
F10 500
F12 1000
F14 2000
F16 4000
F25 8000
F30 16000
F35 32000
F40 63000
F48 125000
F60 250000
F80 500000
F100 1000000

Designation

Part-turn valve actuators that comply with ISO 5211 standard can be designated as shown in Table 4.

Table 4: ISO 5211 valve designation

Flange designation Spigot identification Drive identification Drive dimensions (in mm)
Flange types given in Table 1 Y: with spigot 

N: without spigot

 V: Single key drive 

W: Two key drive

L: Parallel square drive

D: Diagonal square drive

H: Flat head drive

 The actual dimensions of the drive in mm

Example

Consider a part-turn actuator with the following designation:

EN 150 5211 – F07 – Y – V – 22

The designation can be decoded as follows:

  • F07: Flange type
  • Y: With spigot
  • V: Single key drive
  • 22: 22 mm drive diameter

Therefore, EN 150 5211 – F07 – Y – V – 22 identifies a part-turn actuator attachment in accordance with ISO 5211 standard with F07 flange type, spigot and single key drive with a 22 mm diameter. Please note that marking the designation on the actuator is not mandatory. Refer to the ISO 5211 document for more information on the dimensions of drive components for different types of drive inserts.

Additional features of ISO 5211 actuators

ISO 5211 direct-mounted valves come with additional features like a blow-out proof stem design, handles with an inherent locking device, or an anti-static design. In a ball valve, an anti-static design eliminates the static charge generated on the ball due to friction. The design protects the valve against sparks that can ignite the fuel flowing through the valve. ISO 5211 actuator options for modulation DPS (Digital Positioning System) or fail-safe BSR (Battery Safety Return) are also available.

Other ISO standards for butterfly valves

ISO 5752

ISO 5752 standard for butterfly valves specifies the basic series of face-to-face and center-to-face dimensions for two-way metal butterfly valves. Each basic series applies to flanges of mating dimensions conforming to the equivalent EN or ASME flange series.

The face-to-face dimension is the distance between the two gasket contact surfaces. (Figure 5 left side). The center-to-face dimension is the distance between the plane at the extremity of either body end port and perpendicular to its axis and the other body end port axis (Figure 5 right side).

Face-to-face dimension of butterfly valve denoted by ‘a’ and center-to-face dimension denoted by ‘b.’Figure 5: Face-to-face dimension of butterfly valve denoted by ‘a’ and center-to-face dimension denoted by ‘b.’

ISO 10631

ISO 10631 specifies the general requirements for design, materials (e.g., steel, cast iron, ductile iron, copper alloy), pressure/temperature ratings, and testing for butterfly valves having metallic bodies for use in flanged or butt-welding piping systems.

IS0 16136

ISO 16136 specifies the requirements for the design, functional characteristics, and manufacture of butterfly valves made of thermoplastic materials intended for isolating and control service, their connection to the pipe system, the body materials, and their pressure/temperature rating between − 40 °C and + 120 °C, for a lifetime of 25 years, and also specifies their tests after manufacturing.

Other ISO standards for ball valves

ISO 7121

ISO 7121 specifies the requirements for a series of steel ball valves suitable for general-purpose industrial applications. The standard covers ball valves of nominal sizes and is applicable to Class 50, 300, 600, 800, and 900 pressure designations. It includes provisions for ball valve characteristics as follows:

  • flanged and butt-welded ends in sizes 15 ≤ DN ≤ 600 (1/2 ≤ NPS ≤ 24)
  • socket welding ends in sizes 8 ≤ DN ≤ 100 (1/4 ≤ NPS ≤ 4)
  • threaded ends in sizes 8 ≤ DN ≤ 50 (1/4 ≤ NPS ≤ 2)
  • body seat openings designated as full bore, reduced bore, and double reduced bore
  • materials
  • testing and inspection.

ISO 17292

ISO 17292 specifies the requirements for a series of metal ball valves suitable for petroleum, petrochemical, natural gas plants, and related industrial applications. It includes provisions for testing and inspection and for valve characteristics as follows:

  • flanged and butt-welded ends, in sizes 15 ≤ DN ≤ 600 (½ ≤ NPS ≤ 24)
  • socket welding and threaded ends, in sizes 8 ≤ DN ≤ 50 (¼ ≤ NPS ≤ 2)
  • body seat openings designated as a full bore, reduced bore, and double reduced bore
  • materials

ISO 23826

ISO 23826 specifies the design, type, testing, marking, manufacturing tests, and examination requirements for ball valves used as:

  • closures of refillable transportable gas cylinders, pressure drums and tubes
  • main valves for cylinder bundles
  • valves for cargo transport units [e.g. trailers, battery vehicles, multi-element gas containers (MEGCs)], which convey compressed gasses, liquefied gasses, and dissolved gasses.

However, the standard does not apply to ball valves for oxidizing gasses, toxic gasses, and acetylene for single gas cylinders, pressure drums, and tubes.

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The floating ball valve vs the trunnion mounted ball valve

‘’Floating ball’’ and ‘’trunnion ball’’ are concepts which are used generally. But what are the exact difference between these two designs and when to use which one?

The most important difference between these two design is the construction of the ball and the way in which it is assembled inside the valve body. A trunnion ball is attached and centred inside the valve body through both a top shaft -the valve stem- and a bottom shaft – the trunnion. A floating ball is attached to the valve body only through the valve stem. As a result, the floating ball ‘’floats’’ in the valve seats.

In a floating ball design the ball is pushed against the downstream seat by the in-line pressure, resulting in tightness. When operated from closed to open position, the ball is to be rotated against both the in-line pressure (∆p) and the friction of the seats. In other words: the torque needed to operate the valve is created by both in-line pressure and the nature of the valve seats. The amount of torque required increases significantly when operating pressure (∆p) and/or valve size increase, and/or whenever the nature of the seat is made more robust. The latter applies in case of a metal seated valve design.

Floating ball
Trunnion ball

In a trunnion design, the ball is inserted in a central bottom shaft which is called the trunnion. The ball is fixed between the stem and the trunnion, which inclines that the ball is not floating but fixed and centred. The inline pressure presses the seats against the ball, causing the tightness. This inclines that during operation, the ball does not have to be rotated against the in-line pressure (∆p) and the valve seats, but that is solely needs to be rotated against the pressure of the seats.

 

Floating ball & trunnion ball

As a result, the required torque of a trunnion mounted ball valve is generally lower than the torque required of a comparable floating ball valve. For example: a DN200 metal-seated floating ball valve would require a significantly larger actuator than a DN200 comparable trunnion valve, leading to significantly lower costs of the overall package. Also, in general the trunnion seat design offers higher stability which makes it more suitable for extreme conditions and especially varying pressure levels.

So, the trunnion-mounted ball valve is more suitable for high pressure applications and bigger dimensions compared to the floating ball. Another advantage of the trunnion design vis-à-vis the floating design is the fact that a trunnion generally is included with a drain or bleed connection, making it suitable to function as a dual safe device. Furthermore, it functions as an relief valve automatically whenever the pressure in the central cavity is higher than the spring force of the seats. When this happens, the seat springs relieve automatically in order to drain the excess pressure back into the main line. Because of these reasons, the trunnion is commonly used in offshore- & oil & gas applications, where extreme conditions pose the standard.

Off course, a large disadvantage of the trunnion compared to the floating design is associated with its costs; which are significantly bigger. Because of these costs, trunnions are used solely when they have to be used.

Our specialist happily assist you in advising the right ball valve design for your application.

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Pressure seal Gate Valves

The high pressure gate valve, also called pressure seal gate valve, is designed and manufactured according to ASME B16.34, API600, and the valve has the characteristics of beautiful appearance, compact structure and reliable seal. It is suitable for various pipelines of Class900 to Class4500.

 

Operating principle pressure gate valve:
Before the high pressure gate valve is boosted, turn the tightening bolt to raise the bonnet, so that the initial formation between the bonnet, the segment ring, and valve body created sealing condition – preload pressure on the sealing surface. When the media pressure increases, the sealing pressure between the bonnet, segment, valve body increases gradually with the increase of medium pressure. In self-tight sealing, the working seal pressure on the sealing surface is synthesised by two parts: one is the pre-tight seal pressure, and the other is the pressure formed by the pressure of the medium. It should be emphasised that: the media pressure in a self-tightening seal always tends to increase the preload seal pressure to increase sealing performance. The higher the media pressure, the greater the operating seal pressure and the better the sealing performance.

 

The main features of the high pressure gate valve:
①    The self-sealing structure can make the connection between the valve body and bonnet of the high-pressure valve tightly structured, labor and material saving, safe and reliable.
②    The high pressure gate valve uses a combined structure at the bonnet pressure self-sealing, to achieve a linear seal, while its seal ring uses Austenitic stainless steel, anti-corrosion, extends the life of the use, thus ensuring that the valve seal is not leaking under high pressure difference.
③    When the high pressure gate valve is in the 2500LB and above, the inner cavity of the valve body and the contact area of the sealing ring are welded with stainless steel material to avoid the valve body sealing area being eroded by air and water under high pressure difference, which may cause pitting leakage, thus ensuring the safe and long-term operation of the valve.

 

Self-sealing structure of the high pressure gate valve:
The pressure seal gate valve uses a sealing structure combined with the packing outer seal and the internal pressure self-sealing at the stem seal to ensure that the medium does not leak. The outer seal of the stem is filled with polytetrafluorene or O-ring packing, which is pressed tightly with packing gland. Under the action of media pressure, the upward pressure is generated, the greater the pressure of the medium, the greater the sealing force, this structure is suitable for high media.

Gate Valves

 

Gate Valves – Pressure-seal

Size 3″ to 42″ (80 mm to 1050 mm)
ASME Class Class 600 to 2500
Design Standard ASME B 16.34, API 600

Beyond Standards:

  • Pressure-seal Gate Valve design conforms to ASME B 16.34.
  • The design was successfully validated by conducting in-house High Pressure High Temperature (HPHT) Gas Tests on ultra-high pressure valve prototypes.
  • Flow Interruption Test successfully conducted on 8″ Class 600 Pressure-seal Gate Valve suitable for Main Stream Isolation Valve (MSIV) service in nuclear power plants – at Areva, Germany.
  • Fugitive Emission – 14″ Class 2500 Pressure-seal Gate Valve (test pressure of 431 bar at ambient and 289 bar at 400 degree C) has been tested successfully as per ISO 15848-1, endurance Class CO2 and Tightness Class BH
  • CE Marking – Meets requirements of Pressure Equipment Directive 2014/68/EU, Annexure III, Module H
  • Atex – Meets requirements of Atex Directive 94/9/EC (ATEX), category 2 non-electrical equipment
  • SIL3 Safety Integrity Level for Automated Valves
  • Pressure-seal Gate Valves (up to Class 2500) used in Oil & Gas industry tested to ISO 15848-1 Class BH
  • Pressure-seal Gate Valves successfully tested to Shell Design Validation Test 77/300 and witnessed by Shell Inspectors

Features that Add Value:

  • Valves in intermediate classes reduce total cost of ownership
  • Pressure-Seal mechanism utilizes line pressure to enhance seal; ensures sealing integrity at higher operating pressures.
  • Higher hardfacing thickness (3 mm) to ensure consistent hot hardness
  • Disc guides hardfaced for longer life
  • Customised deposition process in F91/ C12A valves to avoid delamination of hardfaced surfaces
  • Live loading of bonnet bolts for F91/ C12A valves
  • Special high purity graphite packing (seven rings) provided for pressure rating > Class 2500 in Power applications
  • Live loading of bonnet bolts and gland bolts for all valves in F91/ C12A construction

Versatile Solutions:

  • Available in a cast and forged steels and exotic metallurgies for a wide variety of applications
  • By-pass arrangement provided for over-pressure protection based on customer requirement
  • Accessories: Heat Dissipation Bonnets, Dashpot Arrangement, Limit Switches, Extension Spindles and Position Indicator
  • STV Valve Technology Group Co., Ltd is a professional leader China 1500Lb cast steel Pressure Seal Gate valve,CAST STEEL GATE VALVE 1500Lb ,1500 lb Cast Steel Gate Valve Pressure Seal ,Flange Gate Valve,High Pressure Gate Valve,Pressure Seal Gate Valve Manufacturer with high quality and competitive price.
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What is a segment ball valve?

A segment ball valve is a type of ball valve with a V-notch contour segment in the ball. Segment ball valves are control valves that have good control, rangeability, and shutoff capability. This valve is capable of producing high capacity and non-clogging flow control. Segment ball valve manufacturers design the ball with special contours to enhance capacity and shutoff integrity and seal life. Segment ball valves are known to be economical and of high performance. These valves can be of a wide variety such as from small and lightweight valves to large heavyweight valves. The lightweight valves are easy to mount and handle. The heavy-weight segment ball valves are used in harsh environments to deliver optimized control and for on/off applications. Due to such features, segment ball valves find use in many industries such as paper and pulp industries, refinery, and petrochemical services among others. These valves are durable and reliable even when used in harsh environments.

Figure: Segment Ball Valve Torque

Figure: Segment Ball Valve Material

Components of segment ball valve

Some of the main components of segment ball valve are:

Valve housing 

This is the component that is used to house all internal components of the segment ball valve. This part is made using rigid and hard materials, thermoplastic lined metallic materials, or thermoplastics to protect components of the valve. This part also allows for the external components to access the controlling mechanism to rotate the ball thus opening or closing the flow.

Segment ball 

This is a V-shaped contoured ball. This segment ball has is used as the opening for the fluid to flow. The segment ball provides shear action to produce flow characteristics.

Shafts 

The shafts are used to connect the segment ball valve control mechanism to rotate the segmented ball. The shafts are made with packing rings and O-rings that help to seal the shaft as well as a bonnet to prevent leakage. The shaft can be operated manually, using a pneumatic or electric actuator.

Seat 

The seat is used to provide sealing between the segment ball valve body and segment ball.

Bearing seals

These seals protect metallic bearings from fluid ingress.

 

How does a segment ball valve work? 

A segment ball valve is a quarter-turn ball valve. It operates similarly to an eccentric plug valve. The valve has shafts that help to enlarge the center flow path. A driving shaft connects to one side of the ball and a follower shaft connects to the opposite side. When the driving shaft rotates, the segmented ball rotates exposing the flow path via the V-notch. The use of V-notch enhances a large range of fluid flow because of a small area of flow at low travel and maximum travel allows a large flow area. Segment ball valves can have two end connections for the body that is the flanged and flangeless connections.

 

Types of segment ball valves

Side entry segment ball valve 

The side entry segment ball valve is a valve of high performance. This valve is made based on the O type of ball valve. Side entry ball valve helps to convey solid-gas and solid-liquid two-phase medium. This means that this valve can control the flow of solids and liquids or gases and solids conveniently.

Features of side entry segment ball valves are:

  • Easy operation. This is because the segment ball valve can be moved away from its seat with no contact thus having small starting torque.
  • The side entry segment ball valve has a straight-through valve body which makes it keep the medium flow linear when it is fully opened. This helps to reduce energy loss compared to other valves.
  • The side entry segment ball valve has a double eccentric structure making the segment ball valve perfectly sealed and tightly closed.
  • When the side entry segment ball valve is closed, its shear force can remove foreign matter thus it is known for anti-scaling performance.

 

Figure: Segment Ball Valve Flow Rate

Top entry segment ball valve 

The top entry segment ball valve is a valve suitable for use in pharmaceutical, chemical, and food processing where excellent and fast cleaning is needed. This segment ball valve has certain advantages which make it preferred in industries that need clean products such as:

  • Easy and quick cleaning of the interior and piping parts without removing the valve.
  • Quick and easier replacement of worn out parts.
  • It does not have spare parts inside the body

 

Features of segment ball valves 

Integrated valve body 

Segment ball valve manufacturers design the valves in a one-piece body. This helps to provide greater rigidity against fluctuations in pipe loads. These valves have a side entry structure that enhances rigidity and makes it hard for leakage and deformation despite high stress due to fluid and closing torque.

Segment ball 

Segment ball valve manufacturers make the valve with a V-port segment ball. This helps to provide a wide range of abilities to control fluid flow. This makes the valve suitable for throttling applications with high consistency and syrup services. The segment is designed so that it can provide optimum flow and its hard-coated spherical face prevents galling.

Self-lubricated bearing 

A segment ball valve designs employ double bearings on the lower and upper valve stems to provide good stability. This makes the contact surface with stem bigger and enhances low coefficient of friction and high carrying capacity as well as reduce operating torque.

Soft and metal sealing seat 

Segment ball valve manufacturers make the valves with either PTFE or metallic seats. The material depends on the intended medium of flow. Metal seats sealing faces are overlaid with hard and strong alloy while the surface of the ball is hardened using hard chromium plated, plasma nitriding among others. This helps to enhance the service life of the sealing face as well as improve temperature resistance. Seats made of PTFE or RPTFE have excellent seal performance, have good resistance to corrosion, and are of wide applications.

Economical practicality 

Segment ball valves manufacturers aim to make these valves as lightweight as possible and of small stem torque. Such critical design parameters make the valve be installed with small electric or pneumatic actuators, and be cost-effective relative to small size or other class of regulating valves.

 

Selection of segment ball valves 

Type of operation 

This is the case where one is supposed to decide the type of mechanism to power the actuator. The actuator can be manual, pneumatic or electric. The actuator type depends on the power source available for example, electricity or compressed air as well as required torque. Pneumatic actuators provide high torque values while the electric actuators have a high initial cost but their operating cost is lower relative to pneumatic ones.

Housing material 

The segment ball valve should be such that the material used to make the housing is compatible with the media being controlled. Different materials have different properties such as:

Brass is suitable for non-corrosive and neutral media, durable, resists high temperatures, not suitable for salty water, acids and chlorides.

Stainless steel is resistant to chemicals, abrasion-resistant, resistant to high temperatures, but not good to chlorides, hydrochloric acids, bleach, and bromine.

PVC material is good for corrosive fluids like acids, salty water, bases, and organic solvents. However, it is not resistant to chlorinated and aromatic hydrocarbons. PVC temperature and pressure resistance are lower relative to that of brass and stainless steel.

Pressure rating 

The segment ball valve selected should be able to withstand maximum and minimum fluid pressure during operation. The pressure rating of the segment ball valve will be determined by the material used to make the housing. Strong materials like stainless steel can withstand high pressure compared to PVC material.

Working temperatures 

Different segment ball valve materials can withstand different levels of temperature from minimum to maximum values. The temperature range of the segment ball valve is determined by the seal and housing material. Brass material can withstand temperatures in the range 20°C to 60°C, stainless steel material can withstand temperatures in the range of -40°C to 220°C, while PVC segment ball valve can withstand temperatures between -10°C to 60°C.

Standards and approvals 

Depending on the use of the segment ball valve, the valve manufacturers may need to follow certain standards from regulatory bodies. This is often required for valves to be used in drinking water, food products, pharmaceuticals, or gas.

 

Segment ball valve actuators 

The segment ball valve can use different types of actuators to open and close. The types of actuators that can be used by these valves include manual, pneumatic actuators, and electric actuators.

Manual segment ball valve actuator 

This is a segment ball valve actuator that is powered by a human hand. This type of actuator has a handle where the operator applies torque to turn the handle and thus turn the valve mechanism to open or close the valve.

Rack and pinion pneumatic actuator 

Rack and pinion pneumatic actuators are actuators used in segment ball valves for opening, turning, and closing the valve as it may be needed. These actuators convert the energy of compressed air by using pneumatic cylinders to oscillating rotary motion. These actuators require dry, clean, and processes gas to provide by a central compressed air station.

Electric actuator

These actuators are used in segment ball valves to control the closing and opening of the valve. These actuators can provide rotary or linear motion. As the name suggests, these actuators use electricity to enhance their work. The torque to open/close the valve is transmitted using a shaft to open or close the valve.

 

Applications of segment ball valves

  • Segment ball valves are used to control flow in paper and pulp industries.
  • These valves are used to control the flow of chemicals in chemical plants.
  • They are used in sewage treatment plants as they can work on solid particles.
  • They are used in power industries to control the flow of heating and cooling fluids.
  • They are used in petroleum industries as they can withstand flammable products.
  • Segment ball valves are used in pharmaceutical industries to regulate the flow of production compounds.
  • They are used in food industries because of their ease to clean and maintenance.

 

Advantages of segment ball valves 

  • Segment ball valves have high efficiency.
  • These valves are simple in design.
  • Segment ball valves design makes them of small weight and volume.
  • These valves are easy to disassemble and repair.
  • Segment ball valves design makes them have a perfect seal.
  • They can provide low-pressure drop and high flow rates.
  • The segment ball valve opens and closes quickly.
  • These valves are easy to clean.

 

Disadvantages of segment ball valves 

  • Cavities around the seat tend to cause blockage.
  • When used in solid particles it can get eroded and thus start leaking fluid and failing.

 

Troubleshooting segment ball valve 

Gland packing leakage 

  • Loose gland nuts. Tighten the loose gland nuts.
  • Worn out gland packing. Replace gland packing.
  • The stem is corroded or scored. Clean stem or replace it as well as gland packing.
  • The stuffing box is corroded. Clean it and replace gland packing. The segment ball valve can be replaced if it has excess corrosion.

Leakage on the bottom plate gasket 

  • Loose nuts. Tighten the nuts.
  • The gasket is damaged. Replace the gasket.
  • Corrosion/damage in the seal area. Clean corrosion or replace the plate and body depending on the level of damage.

Through bore leaking fluid 

  • The segment is not in the full closing position. Fix close limit travel in the actuator.
  • Misalignment between seat and segment. Loosen gland packing to center the segment. Make sure to tighten the gland packing again after alignment so it has enough torque.
  • Entrapped or solidified media. Clean seat spring and sealing surfaces.
  • Seal seat damaged. Replace the damaged seals.
  • The segment or seat is damaged. Replace as necessary.

High segment ball valve torque 

  • Over tightened gland nuts. Reduce the torque on the gland nuts to the levels recommended by the segment ball valve the manufacturer.
  • Operating segment in the reverse direction thus disengaging it from the seat. Make liner retainer lose to re-engage the seat and the segment in a closed position. Enhance the liner retainer torque after segment and seat are aligned.
  • Actuator/operator misaligned with the valve stem. Loosen fasteners and modify the mounting base to be parallel and ensure the operator is centered. Tighten the fasteners.
  • Damaged bearing. Replace it.
  • Damaged segment or seat. Replace as necessary.
  • Accumulated or solidified media. Remove the media from the valve cavity, seat, segment, and clean sealing surfaces.
  • The segment ball valve was installed in the wrong orientation. The valve needs to be installed according to the flow indicator tag.

Summary 

A segment ball valve is a ball valve that makes a quarter turn to open/close the fluid flow. This valve has a hollow spherical ball segment supported by bearing and shaft at the actuator side of the valve. The other end of this valve has a bearing and a post. The segmented ball rotates about a pivot to make a continuous single upstream seal in a closed position. The seal of this segment ball valve is obtained through a flexible elastomer or flexible seat ring that presses against the spherical segment. Segment ball valves body is made of strong materials mostly stainless steel with flangeless or flanged construction.

Segment ball valves can be classified as side entry segment ball valves and top entry segment ball valves. These valves employ a design and technology that helps them to work even in viscous fluids and slurries. These valves are used in many industries such as petrochemical, pharmaceutical, food processing, sewage treatment, chemical processing among others. The segmented ball valves have many applications due to their superb features such as ease of cleaning, ease of repair and maintenance, simple design, small size and weight, corrosion resistance, and high strength to stand slurries. Important parameters to consider when purchasing a segment ball valve are actuator type, pressure rating, working temperatures, housing materials, standards and approvals.

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what is check valve working principle of check valve

A check valve is a type of valve which are designed to allow the flow of fluid in one directions by raising the disc by a pressure of fluid or it interrupt the flow in reverse direction by automatic lowering a disc. Definition of valve is,it is a mechanical device which are designed to control or interrupt […]

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What is the different Plug valve and Ball Valve?

Any production arrangement where one needs to monitor, regulate, or alter the flow of a liquid media through various piping sections of a system must include control valves. Every piping system needs control valves as a crucial component.

Control valve types include ball and plug valve models that carry out comparable functions and are frequently used interchangeably. They remain unique in terms of the overall structure, function, and applied applications. This guide lists all the major differences between plug vs ball valve and other relevant information that can help people in choosing the ideal valve type for the desired applications from reliable industrial valve suppliers.

What Is Plug Valve ?

China Plug valve

A plug valve rotates in a 90-degree turn and it regulates flow using a tapered or cylindrical stopper. The disc has a path for the flow to pass through and is shaped like a plug. The bore passage is in the flow while it is open. The heavy part of the stopper restricts the flow when it is swiveled 90 degrees from the open position.

In situations where speedy operation is necessary, it is utilized in place of a gate valve. Typically, plug valves are chosen for low-pressure and low-temperature applications. For usage with corrosive chemicals, plug valves that have body linings made of polytetrafluoroethylene (PTFE) can be utilized.

What Is Ball Valve ?

Ball valves are on or off mechanisms with a quarter-turn. The valve’s movable ball, which is located in the center, regulates the flow of gas or fluid media. The rotary ball, which serves as the pivot, is made with a hole in the middle. The ball is swiveled to open or shut down the valve via a stem on its top. The stem can be swiveled manually or automatically using levers.

Steel, bronze, iron, brass, or PVC are the materials that ball valves are most frequently composed of. Multiple ports, or apertures in the valve, are possible with ball valves. Two-port ball valves are utilized for conventional on or off control and retain double ports. Applications that need more than one media source or that require diverting media in various directions employ multi-port valves, such as 3-way valves, 4-way valves, etc.).

Plug Valve Vs Ball Valve: Major Differences

Check out the main differences between ball valves and plug valves.

Different Types of Valve

The different types of plug valves vs ball valves are listed below.

  • Plug Valves

Most plug valves are full bore, especially rectangular port valves. Round port and diamond port valves can also be used, but their usage is quite limited to low-pressure applications. Lubricated plug valves and non-lubricated plug valves are the two types of plug valves.

The plug of lubricated plug valves is typically made of metal and possesses a lubricant chamber that maintains lubrication all the time. The lubricated plug moves more easily, experiences less friction, and is corrosion-resistant. Lubricated plug valves can deal with larger and high-temperature applications.

  • Ball Valves

A form of control valve that has numerous applications is the ball valve. In accordance with their construction and purpose, they are available in a variety of sizes and shapes. Because of this, they are currently among the valves used most frequently in the pipe industry. There are ball valves with full and reduced bores.

Full bore ball valves enable unrestricted medium flow. As the bore is less than the diameter of the pipeline, reduced bore or reduced port valves restrict the media flow. Ball valves can be mounted on a float or trunnion. Floating ball valves are utilized in applications where a bi-directional shut-off is necessary. High-pressure, high-temperature applications use ball valves with trunnion installation.

Structure Of The Valves

The structural difference between plug and ball valve is mentioned here.

  • Plug Valves

A plug valve, which has a conical tapering or cylindrical disc, regulates the flow of liquid through one or additional sideway-moving passageways. The hollow tunnel aligns with the flow when the valve is open, enabling the liquid to flow freely. The plug is realigned to restrict the flow after a 90-degree rotation shuts down the valve.

The plug valve is a compact, straightforward device that alters the flow of media by cutting or dispersing. Although some specialized varieties of plug valves can function in high-temperature situations, their primary applications are in medium or low-pressure and low-temperature environments.

  • Ball Valves

The ball valve is an altered plug valve that has a spherical disc and a circular bore channel. The port is a hole that exists in the disc. The valve is open, and the medium seeps through it when the port is in line with the dual ends of the valve. The flow ceases when the port is vertical to the valve ends.

Ball valves are useful for a range of systems due to their small structure, simple use and upkeep, and compatibility with water, acids, natural gas, and solvents. Even in the extreme operating environments of media like hydrogen peroxide, oxygen, methane, or ethylene, ball valves are an excellent choice. Traditional gas shutdown ball valves are best suited for open and close operations, while more sophisticated or customized models also deliver flow control and throttling features.

Function

The plug valves and ball valves operate with a rapid 90-degree rotation of the actuator, making them quarter-turn valves that open and close. Their main function is sealing and shut-off procedures. The plug valve’s sealing surface is substantially greater than a ball valve. Better sealing properties result from this, but it also entails greater torque and more work during operation.

Ball valves are somewhat simpler to regulate than plug valves because of their torque-free functioning and lightweight feature. Despite the possibility that their tiny sealing surface may result in poor sealing performance, developments in chemical sealants and seal injections have helped to address this flaw.

Construction

Both plug and ball valves have bored discs in the middle. A ball valve features a spherical disc with a hollow center. A plug valve is composed of a conical or cylindrical disc with drilled apertures. The disc or ball in a plug valve is larger than the disc or ball in a ball valve, and it enables a plug valve to provide a tighter shut-off than a ball valve. Plug valves are also more compact than ball valves. Plug valves can be effortlessly positioned in tinier departments because of their low footprint.

Distinct Principle

The plug valve gave rise to the ball valve. They both rotate at 90 degrees, and based on whatever “plug” is being used, it can be a plug or a ball with a circular through hole or channel running through its center. The ball and ports should be arranged so that the sphere will appear as a sphere at the intake and outlet to stop the flow when rotated by 90 degrees.

The upper components of the plug valve, the conical plug, and the body surface created by the conical pressure are sealed with packing in the space between the plug and the body. Since plug valves typically do not retain bonnets and the handles are exposed outdoors at the end, they are easy to use and frequently inexpensive.

Control Capacity

A number of actuators, such as manual, pneumatic, hydraulic, electric, and other types, can be used to operate ball valves. They are easy to open and shut down and need little force, even while functioning in high-pressure circumstances.

Plug valves can be opened and closed manually or electrically using actuators. Despite being relatively expensive to install, pneumatic actuators can also be utilized to regulate them. Plug valves in high-pressure applications may be challenging to open and stop due to the substantial amount of torque. Because of this, plug valves are rarely used in larger applications.

Cost

The plug valve costs considerably less than ball valves. The “plug” is completely covered by the bushing, which deters wear on the valve body and plug. By changing the bushing and top seal, which can withstand 300°C of continuous use, the valve can be updated and repaired.

All other components of the plug valve are cast in a single step, and only the top face and flange need to be processed. However, the internal body does not need processing. Comparing the plug valve to the ball valve, there is a clear cost advantage of choosing plug valves.

Lifespan

In general, ball valves last longer than plug valves. A plug valve possesses a bigger surface area in contact with the medium and is required to deal with more torque. It shows that the valve has undergone greater deterioration and is more vulnerable to corrosion.

Ball valves have unique features that stop the medium from constantly contacting the disc. Even though there will be more moving parts, the low torque ensures that it will last longer with little to no wear and tear.

Customization

  • Check Valves

Even though it is only partially achievable, plug valve customization is also an option. It is possible because of their basic design, which offers little potential for development. There are many sizes of multi-port plug valves, varying from two to five ports.

Multiport valves need to be used carefully because they might not create a very tight shut-off. The expense of all additional plug valve modifications, like the addition of electric or pneumatic actuators or anti-friction components, is relatively expensive.

  • Ball Valves 

Compared to plug valves, ball valves offer a significant increase in adjustability. It is because there are so many different types of ball valves accessible in the marketplace. Ball valves come in unidirectional, bidirectional, and multidirectional varieties.

They can retain one, two, or three pieces with one or more ports. Ball valves with split-body, top-entry, end-entry, and side-entry options are accessible. Ball valves can also be equipped with double block and bleed capacities.

Maintenance

Both ball and plug valves require routine upkeep to operate effectively. Plug valves contain fewer moving components and simpler construction, making them relatively easy to maintain. Additionally, you can simply reach the remaining valve body for easy cleaning after eliminating and cleaning the plug.

Ball valves are more difficult to clean since the ball or disc is buried deep inside the valve and is hard to access. The ball valve’s body chamber may gather significant debris over time, adding to the problems of cleaning and maintaining it.

In comparison to ball valves, plug valves provide low-cost operations. It is so that the valve body and plug would not wear out as the plug fits underneath the bushing with a plug valve. In order to update and maintain the valve’s optimal function and

Are Plug Valves Better Than Ball Valves

manual Ball Valve
Source: Unsplash

Here are the top three primary reasons that explain why the plug valves are better compared to ball valves:

  • Plug valves cannot be replaced by ball valves, but the plug valves have the capacity to replace ball valves.
  • Plug valves are simpler to use. Contrarily, ball valves have a space between the body and the ball. Some medium stays in the void after the ball valve is placed and is shut down. The medium must be cleaned before the machine is put back into operation. It is a common issue in chemical and food manufacturing facilities. Ball valves become worthless in critical situations where the medium cannot be thoroughly cleaned due to a prolonged stop period.
  • Plug valves have a full port, meaning that the entire flow is permitted. However, ball valves can have a full port or a limited port.

Plug Valve Vs Ball Valve: How To Choose

By understanding the type of valve application, it can become easy to choose between ball valves and plug valves.

  • When To Acquire Plug Valves 

For bubble-tight shut-off, plug valves are used in liquid applications like vapor, air, gas, hydrocarbon, and others. Since they have a larger surface area and provide unrestricted medium flow, plug valves are frequently employed in slurries, sewage, and mud applications.

In order to ensure good sealing while working with corrosive or hard materials, strengthened plug valves are used. Because of their straightforward operational structure and anti-corrosion qualities, they are the most dependable shutdown option in sensitive applications.

  • When To Acquire Ball Valves

There are many applications for ball valves, and they are used in a variety of equipment, including generator skids, compressor skids, gas feed lines, crude oil plants, LNG plants, industrial gas processing plants, polymer plants, field gas plants, hydrocarbon processing, oil refinery feedstock lines, tank farms, separator skids, and automated process applications.

High-pressure ball valves are necessary for cryogenic, subterranean, and subsea applications. In addition, ball valves made of stainless steel are necessary for brewing, desalination, feedwater, cooling water, and petroleum refining.

Conclusion

Valves come in a variety of types, sizes, lifetime, purposes, and control capabilities. Plug valves and ball valves have the same purpose. They both regulate the flow of gas or fluid using either a straightforward on or off function or a multipath feature.

Due to their flexibility in high-pressure applications, ball valves are excellent choices. Whereas the plug valves can be maintained easily since they have easy construction and not too many moving components. It is possible to acquire ball valves and plug valves in bulk orders from a professional valve manufacturer.

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