Risk based inspection and maintenance strategy for subsea pipelines using Bayesian influence diagram

Subsea pipelines are exposed to various threats that may affect their integrity and serviceability. To maintain their integrity, pipeline maintenance should be well planned to avoid excessive repairs and inspections. The uncertainties associated with the deterioration of the subsea pipeline require a comprehensive decision making methodology for maintenance prioritisation. This study proposes a risk based framework for the prioritisation of subsea pipeline segment maintenance schemes subjected to various threats. Bayesian Network and its extension, Influence Diagram are developed to rank the pipeline segments based on the utility value utilising their expected total cost incurred due to risk factors. A case study of a subsea pipeline from the North Sea is used to demonstrate the methodology. Results from the proposed influence diagram are also employed to model preventive maintenance using cost-benefit analysis. It is found that the proposed model can support the decision making of the pipeline's operators in the process of prioritising subsea pipelines for integrity maintenance and optimising the maintenance interval.