The main construction contractor had not resolved and closed out some defects, as they needed research as well as coordination with vendors. One of the pending items (in the punch list of pending items) related to frequent failures of the mechanical seals of ten boiler feed-water (BFW) pumps used in the waste heat recovery systems in different units. We had two of these pumps P1409A and P1409B in our area.

Maintainers who have worked with boiler feed pumps will be aware that seals in this service worked in a harsh environment. Hence, they tended to fail more frequently than seals in other services. When the pump was running, there was a tiny flow of feed water through the neck bush to the stuffing box of the pump. This flow made up for the controlled leakage through the seal. Normally, the stuffing box contents will cool down due to heat loss by radiation. However, the flow through the neck bush provided heat continuously, so the stuffing box fluid remained hot.