Eliminating unplanned outages on North Sea main oil line (MOL) pumps caused by poor John Crane seal performance, extending MTBF, stopping output losses and cutting maintenance costs
Main oil line (MOL) pumps and their mechanical seals are critical to offshore oil production.
When one platform operator reported an epidemic of MOL pump seal failures, NASH helped to quickly pinpoint the causes, provide solutions and improve future seal performance associated with John Crane Flexibox DRSP-1000 units.
The NASH team reviewed the service history and assessed the condition of failed seal units.
We also visited the platform to inspect both the pumps and seal support system at first hand. We found three primary problems:
- Blocked filters reducing seal oil pressure
- Contaminated seal oil leading to abrasive wear of seal parts
- Excessive operating temperatures blistering and cracking seal faces
As a result of our work:
- Upgraded seal oil filters were fitted
- The seal oil pressure gauge and switch were moved from in front of the filters to the return line immediately after the seal
- An oil polisher was fitted to maintain seal oil quality
- MOL pump seal meantime between failures (MTBF) increased from four weeks to three years
- We introduced subtle upgrades making seals more robust and less sensitive to upset
- Platform production was quickly returned to normal