Ball Valves

Ball Valve Classifications

Ball valves can be classified in many ways. One typical way to classify valves is according to its operation method. If the movement of the closure member is driven by the fluid flowing through the valve or its internal mechanism, such as in check valve and safety relief valve, the valve is called an automated valve or automatic valve. If the movement of the closure member is driven by an external actuator, such as handle lever, wheel, worm gear, or pneumatic/ hydraulic/ electric actuator, the valve is called an actuated valve.

Ball valves can also be classified according tonominal size: small-size valve (≤ DN 40); medium-size valve (DN 50 ~ DN 300); large-size valve (DN 350 ~ DN 1200); super large-size valve (≥ DN 1400). Ball valve classification according to nominal pressure: vacuum valve (< 1 standard atmosphere); low-pressure valve (≤ PN 1.6 MPa); medium-pressure valve (PN 2.5 MPa ~ PN 6.4 MPa); high-pressure valve (PN 10.0 MPa ~ PN 80.0 MPa); ultra-high-pressure valve (> 100 MPa). Ball valve classification according to working temperatures: high-temperature valves (T > 450°C); medium-temperature valves (120°C ≤ T ≤ 450°C); room-temperature valves (-29°C ≤ T < 120°C); low-temperature valves (-100°C ≤ T < -29°C); ultra-cryogenic valves (T < -100°C).

Ball valves classification according to the material they are made from: non-metallic valves such as PVC valve, ceramic valve; metal valves: cast iron valve, ductile cast iron valve, cast steel valve, copper alloy valve, nickel alloy valve, titanium alloy valve, stainless steel valve, alloy steel valve, forged steel valve; lined valves: lead-lined valve, PTFE-lined valve, ceramic-lined valve. Valve classification according to end connection types: flanged valves (RF or RTJ flanged); threaded valves (NPT or BSPT end); butt welding or socket welding valves; ferrule or grooved valves.

Ball valve can also be classified according to structure of the ball: The ball that floats is a floating ball valve, under the action of the medium pressure, the ball can produce a certain displacement and press on the sealing surface at the outlet end to ensure the outlet end seal; The ball that elastic is flexible ball valve, ball and seat sealing ring are made of metal materials, sealing pressure is very high, depending on the pressure of the medium itself has reached the requirements of sealing, must apply external force, this ball valve is suitable for high temperature and high pressure media; The ball  that trunnion mounted is trunnion mounted ball valve, after compression does not produce movement, this valve has been widespread in severe service applications where pipeline flow may contain solids and harsh corrosives, operating at elevated temperatures and high pressures.

GA Drawings of Trunnion Mounted Ball Valve

Ball valves classification according to the assembly structure, it can be divided in three commonly used designs: one-piece, two-piece and three-piece housings. The difference is how the ball valve is assembled:

• One-piece —The valve parts are pressed or welded. The diameter of the ball is slightly smaller than that of the pipe. The valves can not be opened for cleaning or maintenance.

• Two-piece — Two-piece ball valve is composed of two parts, the sealing effect is better than one-piece ball valve, the diameter of the ball and pipe diameter of the same, than one-piece ball valve easy to remove. Usually, the parts are connected via a threaded connection. The valve must be completely removed from the pipe in order to separate the two parts.

• Three-piece — Three-piece ball valve is composed of three parts, valve cover and intermediate valve body, the parts are generally clamped together by bolt connections, it is easy to remove and maintain.