The Difference Between Full Bore and Reduced Bore Ball Valves

Ball valves are prominent mechanical components in the valve market, consisting of the valve body, seat, ball, stem, and transmission device. Their functionality, whether switching or regulating flow, is achieved by actuating the rotation of the ball core. Widely utilized across various industries like chemicals, environmental protection, water treatment, urban construction, machinery, and food, ball valves are highly versatile and popular.

There's a diverse range of ball valves available, categorized based on structure, connection, pressure rating, and driving mechanism. Essentially, they fall into two main categories: full bore ball valves and reduced bore ball valves. A reduced bore ball valve is identified when the ball's inner diameter is less than or equal to 85% of the inner diameter of the ball port. Conversely, a full bore ball valve is recognized when the ball's inner diameter exceeds 95% of the inner diameter of the ball port. So, what sets them apart, and how do we choose the right one for our application? Let's explore.

Definition:

A full bore ball valve features a flow channel width equal to the nominal diameter, ensuring the hole size remains consistent from inlet to outlet. Its size must meet standard specifications, typically corresponding to the nominal diameter. For instance, a DN50 full bore ball valve would have a flow channel diameter of approximately 50.

In contrast, a reduced bore ball valve has a flow channel entrance wider than the actual flow channel diameter. The effective flow channel diameter is approximately one size smaller than the nominal specification. For example, DN50 reduced bore ball valves have a flow diameter of around 38, roughly equivalent to DN40 specifications.

Applicable Media:

Full bore ball valves are commonly employed in pipelines conveying viscous or abrasive media. Due to minimal fluid resistance, they offer virtually no flow obstruction, facilitating the passage of substances like waxy materials and debris.

Reduced bore ball valves are suitable for transporting gases or water-like fluids in pipelines. Their lighter weight, about 30% less than full bore ball valves, and significantly lower flow resistance, approximately 1/7th that of globe valves of the same caliber, make them ideal for such applications.

Applicable Process:

Full bore ball valves are essential for regular pigging of pipelines, regardless of the medium being conveyed. Using a full bore ball valve ensures that the flow remains unaffected and that there is minimal flow resistance. This makes it an ideal choice for pipeline control, especially under stringent conditions. In particular, for oil and gas pipelines buried underground, full bore welded ball valves are indispensable.

Reduced bore ball valves are suitable for certain applications with lower requirements and minimal resistance considerations. When the inner diameter of the valve is more than 80% of the pipe end's inner diameter, it has little impact on the pipeline's flow capacity. Many valves feature a reduced bore, typically controlled within 0.8. While the reduced bore diminishes the valve's flow capacity, resulting in increased pressure drop at both ends and energy loss, its impact on the pipeline itself is minimal. However, it may potentially increase pipeline erosion.

Comparison of Advantages and Disadvantages:

Installation Space: Reduced bore ball valves have a smaller volume, requiring less installation space. Their lighter weight, about 30% less than full bore ball valves, is advantageous for reducing pipeline and transportation loads, as well as overall costs.

Cost: Reduced bore ball valves are priced lower than full bore ball valves, offering better cost performance. To optimize cost-effectiveness, adjacent pipe diameters can utilize the same ball diameter body. For example, DN32 and DN40, DN50 and DN63, DN90 and DN110, DN160 and DN200, DN250 and DN315 employ the same sphere.

While the smaller inner diameter of the ball valve results in lower torque on the stem, enhancing the valve's switch lifespan, especially with low torque designs for large-diameter valves, reducing the diameter too much can lead to increased system resistance. This could raise procurement costs and negatively impact valve control characteristics, potentially diminishing adjustment effectiveness. For instance, constant use of a regulator in a small opening may shorten the valve's service life.