What are the differences between a full bore ball valve and a reduced bore ball valve?

Ball valves come in a wide variety of types, and they can be combined to create products with different functions based on differences in structural forms, connection methods, pressure ratings, and actuation types. However, at the most fundamental level, ball valves can be categorized into two main types: full bore ball valves and reduced bore ball valves.

In general, ball valves come in various types based on their structural forms, connection methods, pressure ratings, and actuation types, allowing for the creation of different functional products. However, at the most basic level, ball valves can be categorized into two main types: full bore ball valves and reduced bore ball valves.

(Definition) What are full bore ball valves and reduced bore ball valves:

1. Full bore ball valves have a flow passage with a consistent width throughout, meaning that the size of the hole from the inlet to the outlet remains the same. The internal diameter of a full bore ball valve cannot be smaller than the specified standard value and is typically equivalent to the nominal diameter, such as DN50 full bore ball valve with a flow passage diameter of approximately 50.

2. Reduced bore ball valves have an inlet wider than the flow passage diameter. The actual flow passage diameter is usually one size smaller than the specified standard. For example, a DN50 reduced bore ball valve would have a flow passage diameter of around 38, roughly equivalent to the DN40 standard. The reduction in size is typically one size for DN250 and below, two sizes for 250-600, and depends on the specific circumstances for sizes above 600.

(Suitable media) What media are full diameter ball valves and reduced diameter ball valves suitable for:

1. Full bore ball valves are generally used for pipelines that transport viscous or easily fouling media. Due to their low fluid resistance, they have minimal flow resistance and are convenient for periodic wax scraping and blow-through operations.

2. Reduced bore ball valves are suitable for pipelines that transport gas or media with physical properties similar to water. They are approximately 30% lighter than full bore ball valves, resulting in about 1/7 of the flow resistance of a globe valve of the same size. This is advantageous for reducing pipeline loads and lowering costs.

(Suitable applications) What applications are full diameter ball valves and reduced diameter ball valves suitable for:

1. Full bore ball valves are necessary for pipelines that require periodic cleaning, regardless of the transported media. Full bore ball valves do not reduce the flow rate and offer low flow resistance, making them ideal for pipeline control, especially in demanding conditions. They are particularly suitable for buried main pipelines in oil and gas transmission lines, where full bore welded ball valves must be used.

2. Reduced bore ball valves are suitable for applications with less demanding conditions and lower flow resistance requirements. When the valve's internal diameter is more than 80% of the pipe end diameter, it has little impact on the fluid flow capacity. Many valves have a reduced bore, typically controlled within 0.8. Reducing the bore diameter decreases the valve's flow capacity (Kv value) and increases the pressure drop at both ends, resulting in energy loss. However, this has little impact on the pipeline and may increase pipe scouring.

Comparison of advantages and disadvantages between full bore ball valves and reduced bore ball valve:

1. Installation space: Reduced bore ball valves have smaller dimensions, requiring less installation space. They are approximately 30% lighter than full bore ball valves, which helps reduce pipeline loads, transportation burdens, and costs.

2. Cost: Reduced bore ball valves are priced lower than full bore ball valves. Considering cost-effectiveness, it is generally accepted internationally that adjacent pipe sizes should use the same ball valve diameter. For example, DN32 and DN40, DN50 and DN63, DN90 and DN110, DN160 and DN200, DN250 and DN315 would use the same ball size.

Note: Due to the smaller internal diameter of reduced bore ball valves, the torque applied to the valve stem is reduced, making them more suitable for extending the valve's operational lifespan. This is especially beneficial for low torque design in large-diameter valves. However, the bore reduction should not be excessive, as it would increase the system resistance. If the bore is not reduced, it would increase the procurement cost and generally degrade the valve's control characteristics, resulting in poorer regulation performance. For instance, if a control valve is frequently operated at low opening degrees, it would reduce the valve's lifespan.