Offshore Rig Structural Health Vibration Monitoring CSR Project

Development of health monitoring system for remotely located structures : Vibration analysis of the rig platforms at ONGC

Objective

• Monitoring of structural integrity of an unmanned offshore rig platform., Vibration sensors are used to capture the vibration and determine the natural frequency of the structure., Comparative study between the natural frequency and the theoretical frequency from the model analysis is done to draw out observations related to fatigue failure.

Description

• Mounting vibration sensors at critical locations and connecting the sensors to a Data Acquisition System (DAS) that allows for remote monitoring., The vibration sensors are mounted to the rig structure such that they are shielded from the saline environment and seawater splashes., At least three vibration sensors must be installed on the deck structure in the principal wave directions., The data from the vibration sensor is in the form of time series which is then analyzed at the monitoring station. The data analysis provides the natural frequency of the structure., The jacket rig is modelled using SACS offshore structural analysis software and analyzed for the frequency of the structure which can be considered as theoretical frequency using design drawings of the rig structure.

Impact

• The remote data transfer would enable to access the real time data., It is initially proposed for one-year observation by IIT Madras for data analysis., Numerical modelling would be performed during the first 3 months., The SACS fatigue software for the model analysis would be adopted.