What tank condition would necessitate removal from service?

The necessity for tank removal from service hinges on safety and operational integrity, particularly concerning pressure relief valves. A pressure relief valve is a critical safety component designed to prevent over-pressurization within a gas tank. If the valve shows visible damage, it could indicate that it may not function properly, which poses a significant risk of failure during operation, potentially leading to hazardous situations such as explosions or gas leaks.

Ensuring that such safety components are in good working condition is paramount for safe operation. Therefore, the visible damage to a pressure relief valve is a clear signal that the tank should be removed from service to mitigate the risk presented to personnel and the surrounding environment. This aligns with the stringent safety standards that a Certificate of Fitness holder must adhere to during their duties.

On the other hand, low gas levels, age of the tank, or mere dents do not necessarily compromise the safety mechanisms of a gas tank in the same way. While these conditions might indicate the need for maintenance or evaluation, they do not automatically call for immediate removal from service as damaged safety devices do.