A ball valve does not always need to be fully open, but whether it should be fully open or not depends on the application and the design of the valve.

1. Designed for On/Off Control

Ball valves are typically designed for full on/off control, meaning they function best when they are either fully open or fully closed. This is because they allow for minimal resistance to flow when fully open and provide a complete seal when fully closed. Operating a ball valve in a partially open position for extended periods can lead to issues like:

(1) Turbulent Flow: Partial opening can create turbulence, increasing wear on the valve and pipe.

(2) Damage to the Ball and Seals: The high velocity and turbulence near the partially open ball can cause damage to the sealing surfaces.

(3) Vibration and Noise: A partially open ball valve may cause vibration or noise due to the irregular flow.

2. Throttling Applications

Although ball valves are primarily used for on/off applications, they can be used for throttling (controlling flow) in certain cases. However, for precise flow control, globe valves or other throttling valves are more suitable because they are designed to handle partial openings without causing damage to the valve or creating inefficiencies in flow control.

3. Special Ball Valves for Throttling

Some ball valves are specifically designed with V-port balls or multi-port designs, which allow for better flow control when partially open. These valves provide more precise control over the flow compared to standard ball valves and can be safely used in a partially open position.

While a ball valve can operate in a partially open position, it is generally recommended to use it fully open or fully closed for optimal performance and longevity, unless it is a specialized ball valve designed for throttling. For precise flow regulation, other types of valves may be more appropriate.

In the installation and maintenance of gas systems, selecting the appropriate valve is crucial for both safety and performance. Given the characteristics of gas and its application environments, ball valves and gate valves are widely recommended as ideal choices for gas pipelines due to their excellent sealing performance and ease of operation. However, their specific characteristics, suitable applications, and considerations for installation and maintenance differ. The following provides a detailed analysis of the advantages and disadvantages of these two valves, as well as the gas system scenarios in which they are best suited.

1. Ball Valve: Precise Control and Quick Shut-off

(1) Quick Opening and Closing Operation

The design of the ball valve allows for rapid opening or closing, which is especially crucial for emergency control in gas pipelines. By simply rotating the handle 90 degrees, the gas flow can be quickly cut off, making it highly effective in handling emergencies such as leaks.

(2) Reliable Sealing Performance

The ball valve opens and closes through the rotation of its spherical element. When closed, a tight seal forms between the ball and the valve seat, reducing the risk of gas leakage. This sealing advantage is particularly prominent in high-pressure pipelines, where the ball valve can effectively ensure system safety.

(3) Corrosion Resistance and Broad Applicability

Ball valves used in gas pipelines are often made of materials such as stainless steel and brass, offering strong corrosion resistance and suitability for various gas types, including natural gas and liquefied gas. Whether in outdoor exposed environments or enclosed indoor settings, the materials and design of ball valves ensure their durability and stability.

(4) Low Maintenance Cost

The simple structure of ball valves results in minimal wear and low maintenance requirements, making them suitable for long-term use. Particularly in commercial and industrial pipeline systems, the low-maintenance nature of ball valves can reduce downtime and enhance cost-effectiveness.

These characteristics make ball valves a preferred choice for residential, commercial, and industrial gas distribution systems.

2. Gate Valve: Suitable for Flow Control in Long-Distance Pipelines

The gate valve controls flow through a rising and lowering gate mechanism. Unlike ball valves, gate valves open and close more slowly, making them more suitable for applications where frequent operation is not required.

(1) Suitable for Flow Regulation in Long-Distance Pipelines

When fully open or fully closed, the internal passage of the gate valve is nearly unobstructed, reducing pressure drop within the pipeline. This is particularly important for long-distance gas pipelines, as it helps maintain stable pressure and flow rate over extended distances.

(2) Gradual Opening and Closing to Reduce Pressure Shock

During closure, the gate valve gradually lowers the gate, making it suitable for pipeline systems that require controlled flow variation. This gradual operation effectively reduces the impact of fluid on the valve and pipeline, extending the system's service life.

(3) Versatile Pressure Ratings for Flexible Application

Gate valves are suitable for gas pipelines with various pressure ratings, meeting diverse flow requirements. Whether in low-pressure residential pipelines or high-pressure industrial systems, gate valves can provide relatively stable control.

3. How to Choose the Right Valve?

(1) Quick Switching and Emergency Handling

If a gas pipeline requires rapid opening or emergency shutdown, such as in response to a gas leak or emergency situation, a ball valve is more suitable.

(2) Stable Flow Control and Long-Distance Transportation

If a gas pipeline requires gradual flow control, such as in adjusting pressure variations during long-distance transportation, a gate valve is the better choice.

(3) Characteristics of Different Gases

Select suitable materials based on the corrosiveness and flammability of the specific gas to ensure the durability and safety of the valve.

In industrial pipeline systems, ball valves and other regular valves each have distinct characteristics, making the selection process crucial for different operating conditions.

 

1. Structure and Operating Principle

Ball Valves use a spherical closure element to control fluid flow by rotating 90°. With a straight-through flow path, they offer minimal flow resistance and quick operation.

Conventional Valves include gate valves, globe valves, butterfly valves, and others, each with different closure elements such as a gate, disc, or plate. Most conventional valves regulate flow through linear or rotational stem movement, resulting in a relatively more complex structure.

 

2. Seal Performance Comparison

Ball valves typically use soft seals (such as PTFE) or metal seals, providing excellent zero-leakage performance, making them ideal for applications requiring high sealing integrity.

Conventional valves employ various sealing methods, such as wedge seals in gate valves and conical seals in globe valves. Some conventional valves, like butterfly valves, may experience minor leakage under low-pressure conditions.

 

3. Operation Method and Flow Control

Ball valves enable quick opening and closing with just a 90° turn, making them suitable for applications requiring frequent operation. Conventional valves vary in operation depending on the type. For example, gate valves typically require multiple turns for full operation, making them slower but well-suited for large-diameter, fully open or fully closed control. Globe valves, on the other hand, are more suitable for flow regulation.

 

4. Application Scenarios

Ball valves are widely used in industries such as oil and gas, chemical processing, and water supply and drainage, especially in applications requiring rapid switching and high sealing performance.

Conventional valves are suitable for a broader range of conditions, such as high-temperature and high-pressure pipelines (gate valves), flow regulation (globe valves), and large-diameter, low-pressure transportation (butterfly valves).

 

5. Maintenance and Service Life

Ball valves have a compact structure with minimal wear on the sealing surfaces, resulting in low maintenance costs and a long service life. Conventional valves, such as gate valves, may experience wear on the disc or sealing surfaces due to prolonged friction and corrosion, making maintenance more complex in some cases.

Ball valves are widely used in various industrial sectors due to their simple structure, excellent sealing performance, and ease of operation. However, during long-term use, ball valves may develop leaks. Leaks not only lead to the waste of media but can also disrupt the normal operation of the system and even pose safety risks.

Common Reasons

1. Aging or Damage of Sealing Materials

The sealing performance of a ball valve primarily relies on the tight fit between the valve seat and the ball. These sealing components are typically made from materials such as rubber or polytetrafluoroethylene (PTFE). Over long-term use, the sealing materials may experience aging, deformation, or damage due to medium corrosion, high-temperature and high-pressure environments, or friction, leading to leaks. This issue is particularly common in applications involving high temperatures and highly corrosive media.

2. Wear of the Ball or Seat

The core components of a ball valve are the ball and the seat, which continuously contact and rub against each other during opening and closing. If the medium contains solid particles, or if the ball valve operates for an extended period in high-pressure, high-flow environments, wear can occur on the surfaces of the ball and seat. Worn surfaces struggle to form a tight seal with the sealing components, leading to inadequate sealing and resulting leaks.

3. Seal Failure of the Stem

The operation of a ball valve is facilitated by the stem, which connects to the valve body through the packing gland, providing a sealing function. Due to frequent operation, aging of the packing, or improper installation, the packing gland may experience seal failure, allowing the medium to leak along the stem. This type of leak is classified as external leakage, which can lead to environmental pollution and energy waste.

4. Improper Installation

If a ball valve is not correctly installed or tightened at the flange or threaded connections, gaps may occur, leading to leaks. Additionally, if factors such as thermal expansion and vibration of the pipeline are not considered during installation, the ball valve may experience stress during operation, resulting in leakage at the interface between the valve body and the pipeline.

5. Medium Factors

Certain special media, such as high-temperature, high-pressure fluids, highly corrosive substances, or fluids containing suspended particles, can accelerate the wear and corrosion of ball valves, leading to leaks. For example, acidic media can hasten the corrosion of metal components, while particulate matter may cause wear on the seat and ball, both of which can diminish the sealing performance of the ball valve, ultimately resulting in leakage issues.

How to Prevent and Handle

1. Choose Appropriate Sealing Materials

Selecting the right sealing materials for different operating conditions is crucial. For example, in high-temperature environments, high-temperature resistant sealing materials should be chosen, while chemical-resistant seals are necessary for highly corrosive media. Regular inspection and replacement of seals can also effectively prevent leaks caused by aging or wear.

2. Regular Maintenance and Care

Routine maintenance and regular servicing of ball valves help extend their lifespan and reduce the risk of leaks. The wear of the ball and seat should be regularly checked, and impurities and particles in the medium should be promptly removed to prevent further wear. Additionally, the packing should be inspected to ensure good sealing, and aging packing should be replaced in a timely manner.

3. Proper Installation and Operation

Installation should strictly adhere to the technical specifications of the ball valve, ensuring that flange or threaded connections are tight to avoid leaks caused by thermal expansion, vibration, or stress. Additionally, during operation, frequent opening and closing should be avoided, especially under high-pressure conditions, to reduce wear on the valve.

4. Special Treatment for Media

For applications involving fluids with suspended particles or strong corrosive properties, it is advisable to install a filter upstream of the ball valve to reduce solid particle damage to the valve. Additionally, choosing ball valves made from corrosion-resistant materials can effectively slow down the corrosion process and lower the risk of leakage.

A gate valve is considered better than a ball valve in certain applications due to its design and functional advantages in specific conditions. Here are some key reasons why a gate valve might be preferred over a ball valve:

1. Flow Control

Gate Valve: Designed for full, unobstructed flow when fully open, allowing fluids to pass with minimal resistance. It is ideal for on-off control but not as suitable for throttling or flow regulation, as partial opening can cause vibration and damage to the sealing surfaces.

Ball Valve: While it offers full flow similar to a gate valve when open, it is not generally used for precise flow control either. However, it closes and opens faster than a gate valve, which may not always be ideal for systems that require gradual control of flow.

2. Size Availability

Gate Valve: Typically better for larger diameter applications, as they are available in larger sizes, making them suitable for large pipelines in industries like water treatment, oil, and gas.

Ball Valve: More commonly used in smaller pipe sizes but can also be found in larger sizes. However, large ball valves can become bulky and expensive compared to gate valves.

3. Pressure Drop

Gate Valve: When fully open, the gate valve provides a straight flow path with minimal pressure drop, which is beneficial in applications where maintaining fluid pressure is critical.

Ball Valve: Even though a ball valve offers low resistance to flow when fully open, the pressure drop might be slightly higher due to the internal mechanism of the ball and seat, especially in smaller sizes.

4. Cost Efficiency in Larger Systems

Gate Valve: More economical for large-diameter and high-pressure systems, making it a preferred choice in large-scale applications like water supply systems or oil pipelines.

Ball Valve: Generally more expensive for large diameters, as the ball itself and its seat must be designed to handle high pressures without deforming.

5. Operational Effort

Gate Valve: Requires more time and effort to open and close fully, as the gate needs to travel vertically through the fluid. This can be a disadvantage in situations where fast operation is needed but may be an advantage in preventing water hammer.

Ball Valve: Opens and closes quickly with a 90-degree turn, which is more convenient for applications requiring rapid shutoff. However, this quick action may cause issues like water hammer in some fluid systems.

6. Maintenance and Wear

Gate Valve: Due to its simple design, gate valves are easier to maintain and have a longer lifespan in systems where they are rarely operated. The seating surfaces experience less wear when the valve is either fully open or fully closed.

Ball Valve: The sealing surfaces in ball valves are more prone to wear, especially in high-pressure or abrasive flow conditions. Maintenance can be more complex, particularly with large valves.

7. Suitability for Dirty Fluids

Gate Valve: More suitable for handling fluids containing solids or slurries, as the gate can cut through debris or sediments. It is less prone to clogging in such environments.

Ball Valve: Not ideal for dirty or viscous fluids, as the tight tolerances between the ball and seat can trap particles, leading to damage or failure of the valve over time.

The maintenance of valves is an important measure to ensure their long-term stable operation and extend their service life. Here are some key steps to note for valve maintenance:

1.Preservation and maintenance

a.Orderly storage: Valves should be stored in categories, with small valves placed on shelves and large valves neatly arranged on the ground to avoid disorderly stacking and damage caused by flange connection surfaces coming into contact with the ground.

b.Cleaning and Protection：

(1)Seal the inlet and outlet of the valve with wax paper or plastic sheets to prevent dirt from entering.

(2)Apply anti rust oil to the machined surface that can rust in the atmosphere for protection.

(3)Valves placed outdoors should be covered with oil felt or cloth to prevent dust and rain.

c.Regular inspection:

(1)For valves that are not used for a long time, asbestos packing should be removed to avoid chemical corrosion.

(2)The valves newly added to the warehouse should be checked for rainwater or dirt and wiped clean in a timely manner.

2.Usage and maintenance.

a.Keep clean: Regularly keep the valve clean and lubricate the transmission threads regularly.

b.Correct operation:

(1)The valve stem thread needs to be coated with lubricant (such as yellow dry oil, molybdenum disulfide, or graphite powder) to reduce wear.

(2)Valves that are not frequently opened or closed should also have their handwheel turned regularly to prevent the valve stem threads from biting.

(3)Outdoor valves require protective sleeves for the valve stem to prevent rain, snow, dust, and rust.

c.Inspection and maintenance

(1).Regularly check the sealing performance and operational flexibility of the valve to ensure no leakage or blockage.

(2).Check whether the connecting components (such as bolts and nuts) are loose or damaged, and tighten or replace them in a timely manner.

d.Packing maintenance

(1).Packing is the key to valve sealing and requires regular inspection and timely replacement of failed packing.

(2).After the valve is installed in the pipeline, if there is leakage, the packing gland nut should be tightened, but it should not be tightened all at once to avoid losing elasticity.

3.Lubrication and grease injection

a.grease injection volume and pressure:

(1)When injecting grease, the amount should be accurately calculated based on the sealing capacity of the valve type to avoid excessive or insufficient grease.

(2)The grease injection pressure needs to be lost. If it is too high, it may block the grease injection port, and if it is too low, the sealing effect will be poor.

b.Injection timing:

(1)During the use of valves, due to the loss and drying of lubricating grease, regular replenishment is required.

(2)Especially during the process of valve opening and closing, the lubrication condition of the transmission parts should be checked in a timely manner.

4.Special maintenance for different valves

a.Gate valve

(1)When fully open, the operating pressure loss of the medium is minimized, making it suitable for situations that do not require frequent opening and closing.

(2)Not suitable for use as a regulator or throttle to avoid damaging the sealing surface.

b.Globe valve

(1)After opening, there is no contact between the valve seat and the sealing surface of the valve disc, and the wear of the sealing surface is small.

(2)Attention should be paid to the flow direction of the medium during installation, generally from bottom to top.

c.ball valve

(1)The structure is simple, the operation is convenient, and it is suitable for situations with fast opening and closing.

(2)When in use, only fully open or fully closed, not used to regulate flow.