Final answer:
Relief valves should be inspected regularly to ensure proper functioning and pressure relief.
Step-by-step explanation:
The statement 'Relief valves should only be inspected every six to twelve years' is False.
Relief valves are safety devices used in engineering systems to prevent excessive pressure buildup. These valves need to be regularly inspected to ensure they are functioning properly and can effectively relieve pressure when necessary. The frequency of inspection depends on several factors, such as the type of valve, its usage, and industry regulations. In general, relief valves should be inspected at least once a year or based on the manufacturer's recommendations.