Oilers/Plant Tenders (HHC) Civil Service Practice Exam

What usually causes packing failures in pumps?

1. Too much lubrication being applied

2. Loosening packing gland nuts after shutdown

3. Not loosening packing gland nuts after shutdown

4. Using low viscosity oil

The correct answer is: Not loosening packing gland nuts after shutdown

Packing failures in pumps are often caused by not loosening the packing gland nuts after a shutdown. When the pump is operating, the packing around the shaft is under compression, which helps to prevent leakage. Once the pump is turned off, if the gland nuts remain tight, the packing does not have the opportunity to relax. This continued compression can lead to excessive wear and eventual failure of the packing material, creating leaks when the pump is restarted. In contrast, loosening the packing gland nuts after shutdown allows the packing to decompress, reducing stress and extending its lifespan. Therefore, the proper maintenance routines include managing the packing gland pressure appropriately during both operation and after shutdown. The other options relate to lubrication and maintenance practices that do not directly address the fundamental issue of packing material wear and stress caused by improper handling after shutdown. While lubrication is important for overall pump operation, excessive lubrication itself is typically not a direct factor in packing failures, and low viscosity oils can also have their challenges in certain applications, but they do not specifically lead to packing failures as failing to manage the gland nuts does.