This essay will outline the fundamental distinctions between ball valves and gate valves. “THINKTANK,” a leading China-based provider of industrial valves, will explain all you need to know about these valves.
Click here to get more.
Selecting the correct valve may have a significant impact on the success or failure of a pipeline system. Today, there is a vast selection of valves on the market, and it may be quite challenging to choose the ideal valve for a certain application. Ball and gate valves are the most popular valves used in pipeline systems and industrial applications.
In the industrial process, ball valves and gate valves can be seen everywhere in the pipeline, they both have the function of closing and opening the flow channel, but the same shut-off function, when to use the ball valve, when to use the gate valve? I know you need some expert advice for your application, and in this post, I will walk you through the expanded definition of ball valves and gate valves, How do they work, what’s pros and cons them, which typical types are they, and what’s the exact application they used for?
Expanded Definition
Ball valves use a rotating ball to control the flow of a liquid or gas. The medium travels through a hole (or holes) in the ball, and its location determines whether the valve is open or closed.
Ball valves may have several ports. For typical on/off control, two-way ball valves feature two ports. Multi-port ball valves are also available and are utilized in situations where media must be transmitted in several commands or when more than one media source is required. Ball valves are faster on/off control alternative than gate valves since they need just a 90° dependency on regulating the position of the ball. Ball valves with manual or pneumatic/electric actuators are widely available.
The ball valve belongs to the family of quarter-turn valves. It requires a 90-degree rotation to open or close. The disc of a ball valve is a ball that has been hollowed down to facilitate the passage of media. Ball valves are mostly used for non-slurry applications, although they are also suitable for applications requiring a tight shut-off.
The fast opening and closing of the ball make it essential for some media isolation applications.
Gate valves are used to completely start or block the flow of fluid via a pipeline by raising or lowering a solid gate. A valve body, seat, disc, actuator, shaft, and gland are all components of gate valves.
Gate valves are only used to completely open or completely close lines; they are not utilized to manage flow or pressure. These valves require more than 360° of multi-turn motion to change the position of the valve, whereas ball valves only need 90° of action to go from open to closed or from closed to open, which means gate valves are needs more time to shutoff or full open valve. Because of this, gate valves might not be the ideal option for applications requiring frequent operation or quick cycling. Gate valves are most commonly operated with a manual handwheel, but pneumatic and electric actuation options are also available.
Furthermore, gate valves are a member of the linear motion valve family. The gate valve features a flat or wedge-shaped disc that serves as a gate. The flow of fluid within the valve is controlled by this gate. The gate valve works well when linear media flow with little pressure drop is desired.
The ball valve developed from the plug valve, it has a ball as its opening and closing component and rotates the ball 90 degrees around the stem’s axis to accomplish opening and closing. Ball valves are mostly used in pipelines to distribute media flow, stop, and change its direction.
They are built with an O-type or V-shaped orifice. Ball valves are effective in controlling flow. Ball valves are one of the valve types that have grown the fastest over the past ten years. They have a straightforward structure, good sealing performance, compact design, lightweight, less material consumption, small installation size, and little driving torque. Ball valves are used for a variety of applications including high temperature, high pressure, wide range size, high sealing, long service life, and multi-functional.
The ball valve can be categorized in three different ways.
First, Let’s learn the main components of the gate valve through the following figure.
The operation of gate valves involves raising the gate or disc to enable the media to flow through. These valves permit only unidirectional flow with little pressure loss.
There are two types of stem designs for gate valves. One is the rising stem gate valve, this handwheel raises the stem to the outside environment and simultaneously raises the gate when turned. The second kind of stem is a non-rising gate valve. This is distinguished by a stem that is inserted into the wedge, exposing it to the media.
When you open a gate valve with a rising stem, the stem moves up and the stem will rise above the handwheel, when you close the valve, the stem moves down. It is depicted in the picture. The OS&Y design means outside stem and york, it’s more frequently described as the rising stem gate valve.
The above figure is the non-rising stem gate valve, you can see when the valve is closed or opened, the valve stem is not rising.
When the gate valve is opened, the passageway expands. As seen in the diagram below, the flow route is not linear in the sense that the medium may fill the vacuum. If the gate valve is employed as a throttle, the flow rate would be inconsistent. This will result in a vibration. These vibrations might cause gate damage.
The gate valve can be categorized in three different ways.
The flexible wedge is a solid, one-piece disk with a perimeter incision. The size, form, and depth of these incisions vary. Less flexibility is provided but strength is maintained via a shallow, thin cut across the wedge’s perimeter. Although it reduces strength, a cast-in recess or a broader and deeper cut on the wedge’s perimeter increases flexibility.
This layout offers improved leak tightness and seat alignment. Additionally, it enhanced performance when heat binding was a possibility. adjustable wedges Steam systems employ gate valves.
The deformation of valve bodies caused by the thermal expansion of the steam line can occasionally result in thermal blindness. The flexible gate eliminates thermal blindness by allowing the gate to stretch as the valve seat contracts as a result of the steam pipeline’s thermal expansion.
Line fluid has a propensity to gather in the disc, which is a drawback of flexible gates. These may cause corrosion, which would degrade the disc in the end.
The most popular and extensively utilized variety of discs is a solid wedge because of its strength and simplicity. A solid wedge valve may be fitted anywhere and is appropriate for practically all fluids. Additionally, it applies to turbulent flow.
A split wedge disc is made up of two solid sections that are held together by a unique mechanism. The disk is free to align itself with the sitting surface in the event that one half of the disk is out of alignment. The split disk may have a wedge shape or take the form of a parallel disk.
Since parallel discs are spring-loaded, they always make contact with the seats and provide sealing in both directions. At both normal and high temperatures, the split wedge can handle noncondensing gases and liquids.
Even if the valve was closed when the line was cold, the disc’s freedom of movement avoids thermal binding. This indicates that when a line is heated by a fluid and expands, thermal blindness is not produced.
This is the most widely used design and is seen in many gate valves. The bonnet and body must be sealed with a gasket.
This is the most basic design that is utilized for low-cost valves.
This is a common design that doesn’t need disassembly, and compared to the bolted-bonnet gate valve, the welded-bonnet gate valve is lighter than theirs.
The pressure seal bonnet gate valves are widely used for high-pressure and high-temperature applications. The force on the gasket of a pressure seal gate valve increases with the body cavity pressure.
But it doesn’t make up for changes in the alignment of the seat caused by pipe loads or thermal expansion. As a result, this kind of disk design is most prone to leakage. Thermal locking occurs when a solid wedge is applied in high-temperature conditions.
If it’s used for high temperatures, it will cause the metal expansion, and that thermal locking makes a wedge stuck between the seat. So the solid wedge gate valve is commonly serviced for low-pressure and moderate-temperature conditions.
The kind of fluid running through your pipeline will determine whether you select a ball valve or a gate valve. We also take into account the cost budget. Careful evaluation of the advantages and disadvantages will help you choose the best valve for your circumstance. If you have any other questions, just feel free to contact us for a free consultation.
A cutaway of a quarter-turn ball valve. (A) indicates the stem and (B) indicates the rotary ball.
One of the most reliable valve designs used in industrial and OEM applications is the ball valve, a quarter-turn on/off valve with a pivoting ball that controls the flow of gas or fluid media. Ball valves feature a fairly simple design: A hollow ball pivots inside the valve body to allow media to pass through and is controlled by a levered stem that is turned manually or automatically. Compared to gate valves or globe valves, ball valves are often preferred for their:
Ball valves are designed for gas and fluid handling in process systems servicing the oil and gas, chemical processing and agriculture industries. They also are commonly used in food and beverage equipment, mechanical engineering and automotive manufacturing and maintenance. Any ball valves present in processing plants should adhere to the American Society of Mechanical Engineers (ASME) standards for process piping (ASME B31.3), which govern the materials, components, design, assembly and more present in the piping system.
In spite of their durability — or perhaps because of it — ball valves experience significant wear and tear over their lifetime. Most ball valves are designed to be maintenance-free and are intended to eventually be replaced rather than repaired. For this reason, three-piece ball valves are often a good option in high cycle or high-pressure applications where valve seals are likely to experience wear and tear at an accelerated rate. In such applications proper preventative measures can significantly extend the life of your ball valves.
RKS supply professional and honest service.
Longevity
Valves that last longer and require few to no repairs help save money, prevent downtime and keep plant production on schedule. Without routine maintenance and quality checks, any issues with your ball valves may be missed, leading to equipment failures, damaged parts or injured workers.
Security and safety
The worst-case scenario on a plant floor is a preventable accident that causes injuries or costly repairs. Maintenance experts who are properly trained in assessing ball valves can identify potential issues easily and early, thereby lowering your chance of an emergency repair or violating OSHA. When it comes to plant safety, properly installed and maintained ball valves can prevent any hazardous leaks in a piping or processing system.
Reduced need for shutdowns
Downtime is expensive, since any time your plant is not producing is money wasted or revenue missed. Some ball valve maintenance can even be performed while the valve is in operation, allowing plant production to continue uninterrupted.
Cost savings
Just as increased uptime means increased revenue, fewer maintenance issues keep more money in your pocket. If ball valves are regularly inspected, maintained and replaced on a projected schedule, there will be less need to allocate funds to unexpected repairs or replacements.
Many ball valve manufacturers will provide an estimate of the expected lifespan of a ball valve, and proper maintenance can certainly extend this range. However, ball valve lifespan can be influenced by a variety of other factors.
Actuation
While some ball valves are powered manually, many are operated via automatic actuator. Depending on your system’s intended cycle speed, you have your choice between pneumatic (air-powered), electric (motorized) or hydraulic (fluid-powered) actuation. By choosing the appropriate power source for your application, you can reduce maintenance expenses, increase uptime and maximize safety. Pneumatic actuated ball valves are the most durable option in high-pressure environments, provided you have access to compressed air. In most cases, actuators will far outlive the ball valves they control.
Two examples of pneumatic actuated ball valves. The actuator sits on top of the valve body and operates the valve via compressed air.
Design
Ball valves come in one-, two- and three-piece designs, the first two of which do not allow for maintenance and must be replaced when components fail. Three-piece ball valves, however, are designed so that the seats and seals can be removed and replaced quickly and easily without removing the entire valve from the system. Provided the valve is made of durable material, the ability to replace components means that three-piece ball valves can long outlive their one- and two-piece counterparts. For this reason, three-piece ball valves are favored for high-cycle and high-pressure applications that subject the seal components to lots of wear and tear.
Left: A manual two-piece ball valve; Right: A manual three-piece ball valve.
Serviceability
Seals are typically the first component to fail in a ball valve, since they are made of much softer material than the valve body. While one-piece and two-piece ball valves must be replaced when their seals expire, three-piece ball valves allow for easy replacement of seals without removing the valve entirely.
Temperature and pressure rating
Ball valves used in high-pressure or high-cycle settings will need to be serviced or replaced more frequently than those in lower-pressure applications. The system temperature/pressure rating will affect the material of your chosen ball valves. Be aware that the closer the media’s temperature/pressure rating is to the ball valve’s rating, the more frequently the valve will need to be replaced.
The good news is that the actuator (which is typically the more expensive component in an actuated valve assembly) will normally outlast the ball valve. This means that in most cases the valve can be replaced without replacing the existing actuator.
Media
Ball valves are generally intended for the on/off control of fluids and gases without solid particulates. Any particles in the media can abrade the valve seals, leading to repairs, valve failure or actuator failure. Conversely, lubricative medias such as oils can reduce seal wear and extend the life of the valve even further.
Valve materials
Media is a major determinant of the materials for ball valve bodies and accessories. Ball valves can be made of stainless steel, brass, bronze, or plastic (PVC). While PVC offers flexibility and cost savings, metal ball valves are more durable and able to withstand higher temperatures and pressures. Overall, metal ball valves have a longer lifespan than those made with PVC or other synthetic materials. When in doubt regarding the appropriate valve material, use the Cole-Parmer Chemical Compatibility Database to ensure valve materials are compatible with your specific media.
Left: A manual two-piece brass ball valve; Right: A manual two-piece stainless steel ball valve.
Source
If your plant contains processing equipment made in the U.S., you’ll want to source ball valves from domestic manufacturers and suppliers. Some valve retailers source their products from all over the world, but products from overseas carry the risk of incompatibility with products made Stateside. Quality aside, it’s best to buy ball valves from domestic sources to ensure longevity and prevent premature replacements.
Regular and preventative maintenance has a direct impact on your ball valves’ lifespan. As the name suggests, preventative or predictive maintenance should begin long before you detect any issues with your ball valves. Build the following steps into your maintenance program.
Proper installation
Ball valves that are installed correctly have a much lower chance of needing repairs or replacement. Make sure the engineer installing your valves is experienced and knowledgeable in ball valve installation and maintenance.
Regular cleanings
Clean valves last longer, since there’s little chance for debris to build up and negatively impact the performance of your piping system. Use a towel to wipe dirt, oil or dust from the valve casing and a wire brush to clear any build-up from the valve stem or other moving parts. Be sure you use cleaning agents that won’t react negatively with the valve materials: Gas-based or compressed air cleaners work well for metal components, and alcohol- or water-based cleaners are ideal for non-metal parts. Clean your ball valves at least once a year, and more frequently if the plant environment contains lots of dirt or dust.
Valve lubrication
Lubrication keeps your ball valves operating smoothly and prevents abrasion. Lubrication also helps increase the effectiveness of the valve seals, provided it’s applied properly. Stick to synthetic, water-insoluble, oil-based lubricants; avoid any clay- or solid-based lubricants that may build up inside the valve cavity. Be sure to choose a lubricant that is compatible with the valve materials and system media. Many manufacturers (such as Gemini Valve) permanently lubricate their ball valves before shipment, meaning that additional lubrication later in the valve’s life is unnecessary.
Routine inspections
Have your valves checked by a skilled inspector on a routine basis. For most applications, once a year is ideal, but ball valves in high-pressure and high-cycle applications should receive more frequent inspections. Inspections should address the following:
Scheduled plant shutdowns
Annual shutdowns are an ideal time to perform ball valve inspections. Remove valves from the piping system, disassemble them, clean the interiors and replace any broken or worn components, paying particular attention to seals or other rubber parts.
With a history spanning over a century, the team at Gemini Valve leverages our years of valve design and manufacturing expertise to help our customers identify the right solutions for their applications. Our primary goal is 100% customer satisfaction — if you have any questions about keeping your ball valves up and running for years to come, we’re your go-to source. Start a conversation with the team today, and we’d be happy to help.
The company is the world’s best Welded Ball Valve supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.