Setting up a vibration Condition Monitoring programme in the Offshore Oil & Gas industry is challenging. Platform staff is rarely trained in vibration and the data collection itself can turn out to be risky for the personnel. In this challenging environment, collecting reliable measurement data while minimizing the time spent on the task are practical requirements for modern maintenance programmes.
In the offshore industry, Condition Monitoring is now common practice. It is indeed essential to carry out vibration analysis on critical machines in order to control and minimize unplanned shutdowns due to unforeseen machinery failures.
However, operators are facing specific challenges due to the day-to-day management of offshore platforms. A typical working schedule for personnel is to be e.g. 4 weeks on the platform and 4 weeks off.
This limited time offshore makes it almost impossible to qualify the staff involved to perform efficient vibration data collection.
Subcontracting the entire process to a service company is also not a sustainable option, as transporting service engineers by helicopter to the platform and back is costly and time consuming, and it also requires a lot of planning.
Reliability, Time and Safety
Classical route-based data collection is often carried out with a handheld vibration analyzer and a sensor attached to a mounting magnet.
This method presents some limitations in terms of data reliability especially when the measurement locations are hard to reach. For the vibration analyst the collected data can turn out to be meaningless when the readings were not taken at the exact same position across the various periodic measurements.
In hazardous areas, the collection of vibration readings using handheld devices can also present safety risks for untrained staff since the assets to be monitored are remote (e.g. drilling platforms), machines are hard to reach and located in hazardous areas. For the operators of pumping stations, drilling platforms, refineries and comparable sites with intrinsically safe areas, the safety of the employees must be ensured at all times. Therefore operators are interested in keeping the vibration data collection process as short and easy as possible in order to decrease the exposure to risks.
Specifically in the offshore sector, the requirements for data integrity are very high because data analysis is carried out onshore by in-house analysts or external service providers. Their reports are used as a basis to extend the inspection interval of critical equipment by classification societies like DNV (Det Norske Veritas).
In other words, route-based vibration data collection should be quick, safe and reliable. Ideally, online monitoring systems automatically take care of the critical equipment’s health. When this is not possible, other solutions are available, which allow keeping the data collection process as easy as possible while ensuring that the high requirements for safety and data integrity are fulfilled.
One existing approach is to use so-called “switchboxes”; the concept is simple and shown in Figure 2.
Permanently installed vibration sensors are wired to a junction box with a multipoint connector inside. The operator carries out the measurement by connecting the vibration analyzer to the main connector of the switchbox. The readings are then taken one sensor at a time. In order to do so, the operator must manually turn the switch into the correct position for each measurement
location. This concept ensures that the readings are not carried out directly in front of the machine and that the values are reliable, since the sensors are permanently mounted on the machine. However, this solution is still prone to human error.
Who can guarantee that an untrained person assigns the right channel to the measurement that should be taken? In the worstcase scenario, false alarms may be triggered later on due to incorrect sensor assignment.