Which component of a gate valve provides the housing for the stem and the packing?

• A. Body
• B. Bonnet
• C. Gate
• D. Seat

Answer: (B)

The part that provides the housing for the stem and the packing is the bonnet. The stem passes through the bonnet, and the packing sits in a stuffing box formed by the bonnet and a gland. When the gland is tightened, the packing is compressed to seal around the stem and prevent leakage along it. The bonnet is bolted to the body to create a pressure-tight chamber that supports the stem, guides its movement, and allows removal or replacement of the stem and packing for maintenance. By contrast, the body is the main pressure boundary, the gate is the moving barrier, and the seats are the sealing surfaces for the gate.