When repacking a stuffing box fitted with a lantern ring, which of the following precautions should be observed?

Correct Answer: Option B — Replace all of the packing rings.

When repacking a stuffing box, it is standard maintenance practice to replace the entire set of packing rings. Mixing old and new packing results in uneven pressure distribution, poor sealing, and accelerated wear on the shaft or sleeve. Replacing the full set ensures uniform compression and optimal performance of the seal.