Construction of the ball valve

The shut-off element in ball valves is a ball with a hole fixed in a housing on a stem perpendicular to the axis of the pipeline. Rotating the stem by 90 degrees moves the ball from the open position, where the hole axis coincides with the axis of the pipeline, to the closed position, moving the hole axis to a plane perpendicular to the flow direction.

Brass ball valve with a split body is the most popular design. It is characterized by low price and small size. Brass ball valves are installed in internal heating systems, cold and hot water supply systems. The price of brass valves is so low that no one bothers with their repair, and a non-working valve is replaced with a new one.

The only drawback of brass valves is selective leaching of zinc from brass, leaving copper. Manufacturers of quality valves have solved this problem and use brass resistant to leaching.

In ball valves designed for installation on pipelines that transport drinking water, the inner surface is not nickel-plated in accordance with European standards.

Steel ball valve with a welded body is a very reliable and relatively inexpensive shut-off valve. They are designed for use in boiler rooms, heating networks, thermal stations, and industrial facilities. They are installed in critical areas of the pipeline, where a long service life and high sealing of the closure are important.

Ball valves of a welded design cannot be repaired and must be replaced if they fail. The sealing of the closure is ensured by pressing a fluoroplastic gasket to the ball valve with a disk spring.

Steel ball valve with a disassembled body - is typically used in industrial applications with high requirements for reliability, tightness, and repairability. They are installed on pipelines that transport water, steam, and compressed air.

The main feature of the three-component construction of a ball valve is the possibility of replacing the end seals of the ball after dismantling the middle part of the valve without unscrewing the threaded connection to the pipeline.

The tightness of the valve is achieved by pressing the fluoroplastic ring seals against the ball using tightening bolts.

Based on the design of the valve element, ball valves are divided into valves with a movable and fixed ball.

In valves with a fixed ball, the valve element is rigidly fixed on a vertical axis of the stem, and the seals that provide it with a tight shut-off of the flow are pressed against the ball by a plate spring or tightening bolts.

In valves with a movable (floating) ball, the valve is not connected to the spindle and can move slightly in the body under the pressure of the working medium, providing additional sealing. On pipelines with a large diameter and high pressure of the working medium, significant effort may be required to open a valve with a floating ball, so valves of this design are usually made with a diameter of not more than DN200.

In all threaded ball valves, the valve element design is made with a movable closure (ball).

Based on the diameter of the opening in the valve element, ball valves are divided into full-bore valves, in which the diameter of the opening is equal to the inner diameter of the connected pipeline, and reduced-bore valves - in which the diameter of the opening is slightly smaller than the diameter of the pipeline.