Which valve is suitable for large diameter applications and can have seat leakage?

• A. Globe valve
• B. Butterfly valve
• C. Ball valve
• D. Needle valve

Answer: (B)

For large-diameter pipelines, a valve that combines a compact, lightweight body with a straightforward sealing mechanism is ideal, and a butterfly valve fits that need. Its disk rotates to open or close against a seat, so it scales nicely to big sizes without the heavy bonnet and complex packing found in globe or gate valves. The sealing relies on the disk pressing into a seat, which gives good shutoff but isn’t always perfectly leak-tight—soft seats, wear over time, or high-pressure conditions can lead to some leakage around the seat. That potential for seat leakage is part of the reason this valve is described as suitable for large diameters while not guaranteeing absolute zero leakage. In contrast, globe valves become bulky and costly at large diameters, ball valves are less practical for very large sizes, and needle valves are intended for precise throttling in small ports.