Ball Valves

A ball valve uses a spherical closure member with a bore through its centre. A quarter turn aligns the bore with the pipe for full flow or turns it across the flow for shut-off. The seats, usually a polymer such as PTFE, wrap around the ball to give low-torque operation and tight, repeatable sealing. Ball valves are primarily isolation devices: they open and close quickly, hold shut-off reliably and suit frequent operation, which makes them one of the most widely used valve types in industry.

Two constructions cover most needs. In a floating ball valve the ball is held by the seats and shifts slightly downstream under pressure to seal, which suits smaller bores and moderate pressure. In a trunnion-mounted design the ball is fixed by upper and lower bearings, reducing operating torque and seat load on larger bores and higher pressure. Bodies are made in one, two or three pieces, and full-bore or reduced-bore patterns are chosen to balance flow against size and cost.

Applications include oil and gas, chemical and petrochemical process, water and gas distribution, HVAC, marine and general plant service. Ball valves handle liquids, gases and steam, and specialist versions cover cryogenic, fire-safe, high-pressure and metal-seated abrasive duties. Their quick action also makes them a common choice for emergency and remotely actuated isolation.

Relevant standards include EN ISO 17292, API 6D, API 608 and API 607 or ISO 10497 for fire testing, with flanges to EN 1092 or ASME B16.5 and testing to EN 12266 or API 598. Bodies are commonly carbon, stainless or duplex steel, brass or bronze, with PTFE, reinforced PTFE or metal seats for higher temperature and abrasive service. Actuation ranges from lever and gearbox to electric and pneumatic.

When enquiring, state the bore and pattern (full or reduced), the pressure rating, medium and temperature, the body and seat materials, the end connection and any fire-safe or antistatic requirement. We can then match a configuration and provide the appropriate certification.