The Top-entry Ball Valve is a type of ball valve that allows for inspection and maintenance through the bonnet assembly from the top. Unlike side-entry ball valves, the design of the top-entry ball valve enables technicians to perform maintenance without removing the entire valve body, thus enhancing operational convenience, especially in situations where the pipeline is fixed.

Structure and Working Principle

The core components of top-entry ball valves are similar to those of traditional ball valves, including the valve body, bonnet, ball, seat, sealing elements, and actuator. However, its distinctive structural feature lies in its bonnet design. The bonnet is located at the top of the valve body and is connected by bolts or flanges, allowing users to open the bonnet without disassembling the pipeline, providing direct access to internal components such as the ball and seat.

The ball is connected to the actuator via a valve stem. When the valve stem rotates, the ball also rotates, thereby opening or closing the valve. In the closed position, the hole of the ball is perpendicular to the fluid passage, preventing fluid flow; in the open position, the hole of the ball is parallel to the pipeline direction, allowing fluid to flow freely.

Feature

(1) Easy maintenance: 

The most significant advantage of top-entry ball valves is their ease of maintenance. Since they can be disassembled from the top of the valve, technicians can quickly replace or repair critical components without removing the valve from the pipeline, saving a considerable amount of time and cost. This feature is particularly beneficial in pipeline systems with limited installation space or where disassembly is difficult.

(2) High reliability: 

Top-entry ball valves typically feature fully welded or flanged connections, offering excellent sealing performance and structural strength, allowing them to withstand high pressure and harsh conditions. In industries such as oil and gas, and chemicals, top-entry ball valves are often used for critical process control due to their strong reliability, enabling long-term operation without the need for frequent replacement.

(3) Suitable for large-diameter and high-pressure conditions: 

Top-entry ball valves are commonly used in large-diameter and high-pressure applications. Their robust design and top-entry maintenance approach enable them to maintain stable performance under high-temperature and high-pressure conditions. As a result, they are widely used in industries such as natural gas, oil, and offshore platforms.

(4) Emergency shut-off function: 

Top-entry ball valves are frequently used in emergency shut-off systems. Due to their compact structure, rapid and reliable opening and closing, they play a crucial role in conditions where quick shut-off of the media flow is required.

Application area

Top-entry ball valves are widely used in industries such as oil, gas, chemical, and power, particularly in pipeline systems that require high sealing performance, high pressure, and frequent maintenance. They are commonly applied in:

(1) Refineries and chemical plants 

When handling flammable and explosive media, top-entry ball valves provide safe fluid control and an emergency shut-off function.

(2) Natural gas transmission systems 

In high-pressure and large-diameter pipelines, top-entry ball valves offer excellent durability and sealing performance, ensuring the stable operation of the transmission system.

(3) Power plants and steam systems 

In these high-temperature and high-pressure environments, top-entry ball valves, with their structural advantages and stability, can withstand demanding operating conditions.

Comparison with side entry ball valves

Compared to side-entry ball valves, the main advantage of top-entry ball valves lies in maintenance. The maintenance of side-entry ball valves requires the entire valve to be removed from the pipeline, which may result in higher downtime costs and longer timeframes in large pipeline systems. In contrast, top-entry ball valves offer a significant advantage in such applications as they allow for disassembly and maintenance from the top.

However, the manufacturing process of top-entry ball valves is more complex, leading to relatively higher costs. Therefore, while they offer advantages in maintenance, side-entry ball valves still hold a certain market share in cost-sensitive projects.