In what situation should you replace packing material in a boiler feed pump?

Replacing packing material in a boiler feed pump is essential to ensure proper operation and prevent inefficiencies. One of the key indicators for replacing packing is when it starts to drip continuously. This dripping signifies that the packing is worn out and is no longer effectively sealing the pump shaft, which can lead to further leakage of water or steam. Over time, this can not only waste water but also create safety hazards due to the increased risk of leaks and pressure loss in the system.

In contrast, the presence of visible leaks in scenarios where there is no continuous dripping may not necessarily indicate immediate failure of packing material, as some pumps can operate with minor, non-continuous leaks. Noise from the pump can arise from various issues, not just packing wear, and it doesn't directly indicate that packing needs replacement. Lastly, operating a pump under overpressurized conditions may lead to other failures but does not directly correlate with the need for packing replacement unless it results in continuous leaking. Therefore, monitoring for continuous dripping is the most valid criterion for making the decision to replace the packing material in the pump.