05.PR041 DNV Equipment Baseline and Alarm Level Setup
3.3 Identify and record reference settings Once baseline readings have been acquired, these should be reviewed against historical data, typical values for the specific type of machine and OEM values to create initial alarm thresholds and expected trend development for remaining useful life calculations - specific bearing life calculations and OREDA reliability data can also be used for this.
These should be updated in the configuration register and reflected in the monitoring report.
Note: These are not the same as client alarm levels and are used to aid on-site analysis and data verification.
Thruster Senior CM Engineer
05.PR042 DNV Thruster Data collection & Analysis
2.1 Consider data quality throughout analysis Data quality shall be reviewed.
Process conditions shall be reviewed. Note varying and unavoidable operating conditions that may have been prevalent at the time of collection e.g. sea state, vessel loading etc
Syntactic data quality Syntactic quality is the degree to which data conforms to its specified syntax. For example vibration data is collected from a point in mm/s but is returned in g, data is out of range, or to a different level of accuracy.
Semantic data quality Semantic quality is the degree to which the data corresponds to what it represents i.e. it must represent something meaningful and real about the thruster application. Issues may include missing data, duplicated data etc.
Pragmatic data quality Pragmatic quality is the relevancy of the data being collected. It must be timely and useful to the end user. Data must be collected and reported in an appropriate time for an operating response to be implemented and effective. A schedule for routine monitoring is in place, with ad hoc samples made in response to developing faults. This is instigated by the CM Engineer and validated by the Responsible Engineer.
Thruster CM Engineer
05.PR042 DNV Thruster Data collection & Analysis
2.2 Perform detailed analysis of data acquired offshore Vibration shall be assessed using three factors: vibration magnitude; any significant change in vibration, and; the rate of change of vibration. Reference shall be made to Metron baseline and historical values (which reference historical data, ISO 10816 etc as appropriate). This shall include specific fault frequencies and time waveform data, not simply overall levels. Any unexpected frequencies or other issues shall be reviewed and discussed with the OEM if required.
Oil shall be reviewed for typical causes of contamination and general degradation due to age and use. Particular attention should be paid to the use of ‘clean’ oil without proper pre-treatment / polishing to meet OEM specification.
Any notes from the engineer acquiring the data shall also be considered (anecdotal or otherwise) with suitable weighting.
The analysis of all data collectively will support an indication of confidence in diagnosis. This shall be based on the robustness of analysis and number of indicators.
Remaining useful life shall be estimated based on historical trend development. Review of bearing component life and consultation with the OEM may also benefit.