Which of the following is the pipe used to connect two separate piping systems on a tank vessel?

The correct term for the pipe used to connect two separate piping systems on a tank vessel is "crossover." A crossover pipe facilitates the transfer of liquid between different compartments or systems without the need for a physical connection within the same piping system. This is particularly important in managing different types of cargo or in situations requiring transfer from one tank to another.

The crossover helps in maintaining operational flexibility and efficiency in handling various types of cargo, which can be crucial during loading and unloading procedures. It also plays a role in ensuring safety by allowing for controlled transfer processes.

While terms like "connection," "junction," and "transfer" may refer to related concepts in piping systems, they do not specifically denote the particular function or design of a crossover pipe. A connection may simply refer to a joining point, while a junction typically implies a point where more than two piping systems meet, and transfer usually describes the action of moving cargo rather than the component that facilitates that action.