The requirement to establish, implement and maintain an Integrity Management System (IMS) is crucial for safe guarding the pipeline assets of any Operator. Risk assessment represents a key element of such a system and requires evaluating the risk for all potential threats jeopardizing the integrity of the pipeline system. A key challenge which typically faces the Operator is how to combine the risk assessment of different threats in order to quantify the overall risk level for the entire pipeline system.
This paper presents a new approach that was developed for risk assessment and risk ranking of subsea pipeline systems. It describes the methodology used to evaluate the risk for each threat quantitatively and to integrate the individual risk assessments to arrive at an overall risk level for the entire pipeline system.
The new approach is used to carry out an integrated risk assessment for all threats jeopardizing the integrity of a pipeline system. The approach is valid for subsea pipeline systems and the calculations were calibrated based on in-house experience from historical inspection data. However, the approach can also be applied to other assets with due consideration of the nature of the relevant threats and re-calibration of the calculations based on the in-house experience of the Operator.
The standardization of the risk assessment methodology for the different threats allows for seamless integration of the individual risk assessments into an overall risk level for the entire pipeline system. The approach is therefore capable of risk ranking a fleet of subsea pipeline assets based on the calculated overall risk level for each pipeline. It also offsets the inherent uncertainty in the quantitative risk assessment to a large extent since the calculated overall risk level for a pipeline is relative to other lines in the network.
The presented approach represents a novel method for quantitative risk assessment of all threats jeopardizing the integrity of a pipeline system in a standardized way. The risk ranking of the Operator's pipeline network based on this approach provides a consistent and technically sound basis for prioritizing the pipelines inspection and mitigation plans.
