• Company: Tidewater
  • Industry: Array
  • Services: Vibration Analysis, Remote Data Analysis, Cloud-based Reporting
  • Location: United Kingdom
  • Cost-Saving: £50,000

The Overview

Utilising vibration and stresswave spectral data collected from a vessel’s engine, PCMS Engineering engineers were able to identify gear damage on a critical oil pump, preventing a pump failure worth £50,000. Furthermore, this could have avoided a catastrophic engine failure and replacement worth £1 million.

The Situation

PCMS Engineering provides an ongoing Condition Based Maintenance (CBM) programme to one of the world’s largest providers of offshore service vessels. Routine data is submitted on a monthly basis to establish and analyse the condition of critical assets throughout their fleet of vessels.

The Challenges

PCMS Engineering engineers utilise multiple CBM technologies to determine an asset’s condition and remaining life-span. A recent data submission from an auxiliary generator, which provides power to the vessel during port calls critical to the operation of the vessel, showed a noticeable change.

The Solution

Utilising vibration and stresswave spectral data, PCMS Engineering engineers were able to identify non-synchronous frequencies at the NDE of the engine.

These are commonly associated with rolling element bearings however, as none were located close to the measurement point, PCMS Engineering thaengineers requested information from the vessel operator in regards to other components.

The Results

The non-synchronous activity was identified as being 1.160 orders (2075rpm) of engine shaft running speed. Utilising the information provided by the operator, PCMS Engineering engineers were able to identify (Item 10 - Oil pump 69 teeth so at 1800 rpm gear is doing 80 / 69 = 1.15942 x 1800 = 2087 rpm) as being the closest frequency.

Figure 1: Data from the engine NDE

As the engine was running at 1789.8 rpm, and using the information provided that 80 teeth are driving 69 teeth, PCMS Engineering analysts calculated that the oil pump would be operating at 2075 rpm. This matched the stresswave frequencies present.

As stresswaves are generated when metal is bent, impacted, scuffed and/or under increased friction, it was recommended that an inspection was performance on the component while rotating at this speed.

The inspection of the oil pump gear found significant damage – see figure 1 & 2. The unit was replaced and all levels returned back to normal for long term continued operation with a reduction in catastrophic failure risk to both the gear, pump and risk of damaging particulate entering the engine.

Figure 2: Oil pump gear damage