How frequently must overflow line valves that are accessible without entering the tank be inspected and cleaned?

The correct answer is that overflow line valves that are accessible without entering the tank must be inspected and cleaned annually. This regular inspection schedule is essential for ensuring the proper functioning of the valves, which are critical in preventing overflow and maintaining safety standards. Annual inspections help in identifying any blockages, wear, or potential failure points that could lead to operational issues or hazards.

The requirement for annual inspections is typically set to ensure that maintenance is performed before any buildup of debris or corrosion could impair the functionality of the valves. Given that these valves are a key component in maintaining the integrity of the tank systems, keeping them in optimal condition is a vital safety measure.

While other frequencies like monthly or quarterly may seem appropriate, they may not be necessarily practical for the specific conditions required to monitor overflow line valves. Annual cleaning aligns with industry standards for maintenance schedules, balancing safety and operational efficiency.