Question 34Safety & Environmental - 1st Asst/Chief

The correct answer is C) damage to tank boundaries. Pressure-vacuum relief valves on tank vessel cargo tanks are critical safety devices that prevent excessive pressure or vacuum from building up in the tanks. If these valves are not kept in good working order, the tanks could become overpressurized or undergo excessive vacuum, which could lead to damage to the tank boundaries. This could result in a breach or failure of the tank structure, which would be a serious safety hazard. The other answer choices are incorrect because they do not directly address the primary purpose of the pressure-vacuum relief valves, which is to protect the structural integrity of the cargo tanks. Options A and B relate to the prevention of fire and explosive vapors, but these are secondary considerations compared to the valves' role in maintaining the tank boundaries. Option D about oil spillage is also not the main function of the pressure-vacuum relief valves.