Which type of valve is commonly found on the discharge side of a cargo pump on a tank vessel?

The commonly used valve on the discharge side of a cargo pump on a tank vessel is a check valve. This type of valve is designed to allow fluid to flow in one direction while preventing backflow. It is crucial for maintaining the integrity and efficiency of the cargo system, especially in scenarios where the discharge might be interrupted or where there is a risk of reverse flow once the pump is turned off.

Check valves help to protect the pump and associated equipment from damage that can occur if the liquid flows backward. This function is particularly important on tank vessels where the cargo being transported may be hazardous, and any leakage or contamination can have serious consequences.

As for the other types of valves mentioned, they serve different purposes. Spectacle valves, for example, are typically used for isolation and maintenance purposes, but they lack the automatic one-way flow feature of check valves. Butterfly valves are efficient for flow regulation but can leak if not fully sealed, making them less effective in preventing backflow. Globe valves are primarily used for regulating flow and can create significant pressure drops, so they are not the first choice for discharge applications where maintaining back pressure is essential.