Which valve type is used for high-pressure shutoff in pump discharge and is commonly called Large plug valves?

• A. Gate valve
• B. Ball valve
• C. Large plug
• D. Check valve

Answer: (C)

High-pressure shutoff in pump discharge lines requires a valve that can seal tightly and handle large bore sizes. A plug valve achieves this because its cylindrical plug rotates to block flow and presses against seating surfaces inside the body, creating a very tight seal that stands up to high pressures. This design is particularly well-suited for large-diameter piping found in pump discharge service, which is why such valves are commonly referred to as large plug valves.

Gate valves are often used for isolation but can be less practical for very large sizes or tight shutoff under high pressure. Ball valves offer strong shutoff and quick operation but become bulky and expensive in large diameters. Check valves are intended to prevent backflow and are not used for isolating a line. Therefore, for high-pressure shutoff in pump discharge, large plug valves are the best fit.