Ball valves and plug valves differ significantly in several aspects, including structure, operating principle, mode of operation, flow control capability, sealing performance, and application scenarios. These differences enable the two types of valves to perform distinct roles in their respective fields.

Structural Differences

The ball valve, a design evolved from the plug valve, utilizes a spherical element as its core component. By rotating the ball 90° around the stem axis, the valve can be opened or closed. Its structure is straightforward, consisting primarily of a spherical closure element with a through-bore housed within the valve body.

In contrast, the structure of a plug valve is more complex. It comprises multiple components such as the valve body, bonnet, plug, seat, and stem. The closure element is a cylindrical or tapered plug that controls flow by rotating 90°, aligning or misaligning the port in the plug with the flow passage in the valve body to achieve opening or shutoff.

Operating Principle

The operating principle of a ball valve relies on the rotation of the ball to control the on-off flow of fluid. When the ball is in tight contact with the valve seat, the clearance between them is completely sealed, thereby preventing fluid leakage. When the ball rotates to a position disengaged from the seat, the fluid is allowed to flow freely through the passage inside the valve body.

The operating principle of a plug valve differs in that it primarily controls the flow passage by rotating the plug element to open or close the valve. In a plug valve, the plug is connected to the stem and rotates together with it to achieve flow control. The closure element is a tapered plug with a port, and the flow passage is designed to be perpendicular to the axis of the plug. This configuration enables the plug valve to operate more efficiently and reliably during opening and closing.

The operation of a ball valve is notably simple, requiring only a 90-degree rotation to achieve opening or closing. This design allows the flow passage to be opened or shut off quickly and smoothly when the ball is rotated by 90 degrees, providing both convenience and efficiency. In addition, ball valves offer relatively low flow resistance in the fully open or fully closed position, making them particularly suitable for applications that require rapid on-off operation.

By contrast, the operation of a plug valve is comparatively more complex, as several turns are typically required to complete the opening or closing action. The valve plug is designed in a cylindrical or tapered form and regulates fluid flow through rotation. Nevertheless, plug valves demonstrate excellent performance in flow regulation, enabling precise adjustment of the flow passage diameter and accurate control of flow rate. However, due to the relatively complicated operating process, plug valves are not well suited for frequent operation.

Differences in Flow Control

In terms of flow control, plug valves demonstrate superior performance. Thanks to their distinctive plug design, they are capable of precisely adjusting the diameter of the flow passage, enabling accurate regulation of flow rate. Although ball valves can also regulate flow by adjusting the opening position through rotation, their flexibility in flow control is generally inferior to that of plug valves.

Differences in Sealing Performance

With regard to sealing performance, plug valves typically provide excellent results due to their multi-sealing design, making them highly suitable for applications with stringent sealing requirements. However, with the continuous advancement of ball valve technology, the sealing performance of ball valves has been steadily improving, and their range of applications is expanding accordingly. In comparison, ball valves offer significant advantages in terms of simple structure, light weight, and compact size, providing greater convenience for users. Although the structure of plug valves is relatively more complex, their features of rapid operation and low flow resistance remain notable advantages.

Differences in Application Scenarios

Owing to their quick on-off operation and low flow resistance, ball valves are widely used in industries such as petroleum, chemical processing, papermaking, and pharmaceuticals, particularly in applications that require fast opening or closing. Plug valves, on the other hand, benefit from excellent sealing performance and strong flow control capability, and are therefore extensively applied in oilfield production, transportation, and refining equipment. They are especially suitable for applications with strict requirements for sealing integrity and precise flow control.