This paper describes the integrity management framework utilized within the Enbridge Liquids Pipelines Integrity Management Program. The role of the framework is to provide the high-level structure used by the company to prepare and demonstrate integrity safety decisions relative to mainline pipelines, and facility piping segments where applicable. The scope is directed to corrosion, cracking, and deformation threats and all variants within those broad categories. The basis for the framework centers on the use of a safety case to provide evidence that the risks affecting the system have been effectively mitigated. A ‘safety case’, for the purposes of this methodology is defined as a structured argument demonstrating that the evidence is sufficient to show that the system is safe.
The decision model brings together the aspects of data integration and determination of maintenance timing; execution of prevention, monitoring, and mitigation; confirmation that the execution has met reliability targets; application of additional steps if targets are not met; and then the collation of the results into an engineering assessment of the program effectiveness (safety case). Once the program is complete, continuous improvement is built into the next program through the incorporation of research and development solutions, lessons learned, and improvements to processes.
On the basis of a wide range of experiences, investigations and research, it was concluded that there are combinations of monitoring and mitigation methods required in an integrity program to effectively manage integrity threats. A safety case approach ultimately provides the structure for measuring the effectiveness of integrity monitoring and mitigation efforts, and the methodology to assess whether a pipeline is sufficiently safe with targets for continuous improvement. Hence, the need for the safety case is to provide transparent, quantitative integrity program performance results which are continually improved upon through ongoing revalidations and improvement to the methods utilized. This enables risk reduction, better stakeholder awareness, focused innovation, opportunities for industry information sharing along with other benefits.