On tankers with manually operated tank valves, which type of valve is most commonly used?

The most commonly used type of valve on tankers with manually operated tank valves is the gate valve. Gate valves are preferred in this application because they provide a reliable means of controlling the flow of liquids, especially in large pipelines. They are designed to allow for minimal pressure drop when fully opened, which is crucial in marine operations where efficiency and maximizing throughput are important.

Additionally, gate valves have a straightforward design, making them easier to operate manually, particularly in situations where quick and safe closure is necessary to prevent spills or leaks. Their ability to create a tight seal when closed ensures that the contents of the tanks remain secure, which is vital for the safety of the vessel and its cargo.

In contrast, while ball and butterfly valves are also used in the industry, they serve slightly different purposes and may not be as commonly utilized for large-scale manual operations. Check valves are primarily employed to prevent backflow and are not typically used for manual control of tanks.