How often must the valves in a cargo tank motor vehicle's pipeline system be visually inspected?

The correct choice regarding the visual inspection of valves in a cargo tank motor vehicle's pipeline system is once every month. This regular inspection is crucial for ensuring the safety and integrity of the liquefied petroleum gas (LPG) system. Inspecting the valves monthly helps to identify any wear, damage, or leaks that may pose a risk, thereby allowing for timely maintenance or replacement.

Frequent inspections are essential because the pipeline system, including valves, is subject to various operational stresses and environmental conditions that can lead to potential failures. Monthly inspections serve as a proactive measure to prevent accidents and ensure compliance with safety regulations outlined in NFPA 58.

While daily inspections, quarterly inspections, and annual inspections could be useful in other contexts, they do not align with the recommended frequency for visual inspections of cargo tank motor vehicle valves, which is designed to strike a balance between safety and practicality.