When are MFW pump lube oil strainers typically bypassed?

Bypassing the lube oil strainers on Main Feedwater (MFW) pumps typically occurs when the differential pressure (dp) across the strainers exceeds a certain threshold, which is often set at 15 psi. This bypassing is necessary because excessive pressure buildup can indicate that the strainers are clogged or insufficiently allowing flow, thus potentially leading to inadequate lubrication for the pump.

When this threshold is surpassed, continuing to operate the strainers without bypassing could risk overheating or damaging the pump due to insufficient lubrication. Bypassing the strainers allows the lubrication system to maintain an adequate flow of oil, ensuring that the pump functions properly without the risk of damage from dirty or insufficient lubrication.

In these situations, it's critical to ensure that the strainers are cleaned or replaced during maintenance to restore normal operation and prevent future clogging. This practice is essential for maintaining the health and reliability of the pump's operation.