A large energy producer (electricity + heats) faced frequent failures on their water recirculation centrifugal pumps. NSK jointly with the local distributor performed a bearing failure investigation on site. The result showed that the lubrication of the pump bearings as the source of repeated failures. NSK proposed to change the bearing type over to a sealed for life greased bearing featuring DDU seals and high temperature grease. This gave significant improvement in performance reducing maintenance costs.


Key Facts

  • Energy producer – water recirculation centrifugal pumps
  • Frequently failures due to poor lubrication
  • NSK Solution: DDU Sealed Deep Groove Ball Bearings
  • A trial was performed on 3 out of 20 pumps without any failures for more than 6 months
  • After changing to the NSK solution on all pumps no failure occurred witin a period 12 months
  • Significant cost savings due to failure-free running but also due to reduced material and maintenance cost
  • Centrifugal Pump
  • Deep Groove Ball Bearings with DDU seals

Value Proposals

  • Repeated failures on the pumps were recognised. The customer requested the local distributor to check the possibility to improve the lifetime of the bearings.
  • NSK and the local distributor performed a bearing analysis on site and concluded that the failure occured due to lack of lubrication. Considering the age of the equipment and the poor condition of the seals, a design modification to avoid the oil leaks was not considered.
  • Instead NSK proposed to use Deep Groove Ball Bearings with DDU seals and a high temperature grease.
  • A trial was performed on 3 pumps and the bearings have been monitored for 6 months without any failures.
  • After changing to NSK Deep Groove Ball Bearings with DDU seals and a high temperature grease on all pumps no failure occurred within a period of 12 months period.

Product Features

  • High Quality Steel - Ultra clean steel to extend bearing life by up to 80%
  • Super Finished Raceways – Specially honed to minimise noise, improves lubricant distribution and life
  • Patented Seals – Provide resistance to contamination in the toughest environments, standard seal material is nitrile rubber
  • Pressed Steel Cage - close coined cage pockets and tightly controlled clearances reduce friction and ensure even distribution of lubricant. The pressed steel cages also have the advantage of high temperature resistance.
  • Grease Technology - High temperature resistance and speed capability with good resistance to water and contamination

Cost Saving Breakdown

Before Cost p.a. NSK Solution Cost p.a.
Cost of bearings used before € 1,550 DGBB bearings with DDU seals € 480
Oil replenishment costs € 1,700 Oil replenishment costs € 0
Maintenance costs € 7,200 Maintenance costs € 0
Downtime costs € 19,000 No downtime costs € 0
Total Costs € 29,450 € 480



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