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Introduction

A large energy producer (electricity + heats) faced frequently 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 Centrifugal Pump
Deep Groove Ball Bearings with DDU seals Deep Groove Ball Bearings with DDU seals

Background Information

  • Sector: Power Plant
  • Country: Romania
  • End-product: Energy Producer (Electricity and Heating)
  • Application: Centrifugal pump

  • Number of machines: 30
  • Approx. lifetime 3 months
  • Problem: Frequently failures on pump bearings

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

Reference: SS-E-5012

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