What do visible valves and piping on a non-pressure tank car indicate?

Visible valves and piping on a non-pressure tank car indicate that the car is designed for general service. These features suggest that the tank is not intended to withstand high pressures, as is the case with pressure tank cars which are sealed and often do not have visible valves. Instead, non-pressure tank cars are used to transport liquids that can be loaded and unloaded through these openings, making them suitable for a variety of cargoes that do not require the high-pressure containment features.

This configuration allows for easier access during loading and unloading operations. Additionally, it reflects the versatility of these cars, as they can handle different types of liquids that may not be corrosive or hazardous to the extent requiring high-pressure containment.