Marine Client

  • Industry: Array
  • Services: Vibration Analysis, Remote Data Analysis, Cloud-based Reporting
  • Location: United Kingdom
  • Cost-Saving: £3,000

The Overview

Vibration data from a vessel identified a bearing defect on an aux boiler feed pump. Upon investigation of the bearing, it was noticed that the bearing had significant oxidation across the surface of the bearing cage. The bearing was replaced, avoiding unexpected downtime and possible catastrophic pump damage.

The Situation

VCI Consultancy, part of the PCMS Eng Group, carry out routine periodic vibration analysis for a global shipping company. The vessel’s engineers collect vibration data on all of their equipment within the vibration programme on a three-month basis, and send the data to the Group’s dedicated remote analysis centre for detailed analysis.

The Challenges

Upon receipt of baseline vibration data from a vessel, it was noted that overall acceleration levels on an aux boiler feed pump were significantly elevated at the pump NDE. Associated spectral data showed a dominant frequency with harmonics relating to an outer race defect frequency of the bearing. Furthermore, the time waveform at this location was showing Pk-Pk values of greater than 80g.

Typically, this behaviour is indicative of a bearing fault likely caused by a lubrication deficiency over the bearing. Continuous operation of the pump in this condition would likely lead to bearing failure and/or damage to the wider steam condensate system.

The Results

Initially, VCI engineers recommended that the pump bearings should be lubricated at the earliest convenience and further data should be sent for analysis.

Feedback was received from the vessel where the onboard engineers advised that lubrication was carried out and data sent. Upon analysis of this data, it was evident that the bearing defect was still present and the bearing would likely need replacing at the earliest opportunity.

Feedback was received and the vessel’s maintenance personnel informed VCI engineers that the pump NDE bearing was replaced with a new spare.

Figure 1: New (left) vs old (right) bearing. Corrosion on bearing cage can clearly be seen with visible spalling on the raceways.

Upon inspection of the old bearing it was noticed that the bearing had significant oxidation across the surface of the bearing cage (figure 1), which contributed to the elevated bearing frequencies seen in the enveloped data (figure 2).

New data was received after the bearing replacement, showing a marked improvement in vibration levels at the pump NDE.

Figure 2: An outer race fault frequency (BPFO) with harmonics in the envelope spectrum of the pump NDE

As the vessel was within the warranty period, timely analysis and recommendations for rectification resulted in zero cost implications for the client.