Which valve operates by screwing a disc against a seat?

• A. Globe Valve
• B. Ball Valve
• C. Gate Valve
• D. Check Valve

Answer: (A)

A globe valve is designed so the sealing disk (or plug) is attached to a threaded stem. When you turn the stem, the disk is driven straight toward the seat, screwing into place to form a tight seal. This arrangement also allows fine control of flow because the gap between disk and seat can be adjusted precisely.

This differs from a ball valve, which uses a rotating ball with a bore to stop or pass flow; a gate valve, where a wedge or gate slides up and down to seal; and a check valve, which uses a free-moving disc that only seals when backflow would push it against a seat.