A Framework for Safety-Constrained Integrity Management for Gas Pipelines Using Defined Risk Acceptance Criteria

Risk assessment has been used historically in pipeline integrity to provide relative risk rankings based on a mixture of qualitative and quantitative inputs. With the improvement of assessment and data collection techniques and technologies, and the corresponding improvement in hazard and consequence modeling that these techniques have made possible, pipeline operators are now able to calculate risk on an entirely quantitative basis. This improvement allows operators to manage pipeline integrity-related risk within a framework that allows levels of risk reduction to be related to integrity costs using comparable terms and to measure the acceptability of residual levels of risk against responsible and defensible risk acceptance criteria. The framework outlined in this paper, coupled with quantified risk models, allows pipeline operators the ability to identify areas that may require risk reduction, identify preferred risk-reduction methods, provide justification for the project, and monitor residual levels of risk. The introduction of defined risk acceptance criteria also provides operators with a tool to move beyond relative risk prioritization towards the ability to discriminate between pipe operating at acceptable integrity levels and pipe requiring risk mitigation.