What is a common indicator that a pressure relief valve may need maintenance?

A pressure relief valve is a critical safety component in pressure piping systems, and identifying when it requires maintenance is essential for safe operation. One of the most telling indicators that a valve needs attention is visible corrosion on the valve itself. Corrosion can compromise the structural integrity of the valve, potentially leading to failure during operation.

Frequent system pressure fluctuations are another significant indicator, as they may suggest that the valve is not functioning properly or is becoming stuck, causing it to either open too often or not at all. Such fluctuations can lead to unsafe conditions if the system pressure exceeds safe limits.

Unexpected spikes in temperature can also signal issues with the valve or the system it protects. High temperatures may indicate that the valve is not opening as intended, which could result in pressure build-up.

Since all the choices provided highlight different aspects of potential malfunction or wear in a pressure relief valve, recognizing these signs collectively suggests that maintenance is necessary to ensure continued safe service of the piping system. Therefore, the comprehensive understanding of these indicators aligns with the answer indicating all the options are valid signs of necessary maintenance.