What maintenance task can help solve leaking in gate valves?

Tightening or replacing the stem stuffing box packing is an effective maintenance task for addressing leaks in gate valves. The stem of a valve is the part that moves to open or close the valve. The packing around the stem creates a seal that prevents fluid from leaking out. Over time, this packing can wear down or become loose, leading to leaks. By tightening the packing, you can improve the seal and potentially stop the leak. If the packing is severely worn or damaged, replacing it ensures that a proper seal is restored, thus effectively solving the leakage problem.

The other options, while they might have their own benefits for valve maintenance, do not directly address the mechanism through which leaks occur in the case of gate valves.