This paper presents a safety case program approach used by Enbridge to assess proposed operational changes. This approach identifies the impact to threats, barriers, and consequences associated with a proposed change, and ensure the safety of the system is not compromised by following a plan-do-check-act methodology.
Enbridge integrity management uses a plan-do-check-act system. A key aspect of this is the integrity plan which is developed for each asset to balance integrity requirements (fitness for service) with business drivers (risk and asset plan). Completion of a safety case provides an independent check for each pipeline segment within the system, ensuring identified risks are managed to as low as reasonably practicable (ALARP). Additional mitigation actions are identified and implemented in the event that ALARP is not met.
Operational parameters are a key consideration in the development of the integrity plan and include variables such as flow rate, injection and delivery locations, service, maximum allowable operating pressures, temperature and pressure cycling. The safety case program acts as a check by considering the threats associated with the proposed change to operational parameters, and then identifies whether or not the current pipeline integrity barriers for that asset are sufficient for the proposed operation, and if ALARP is still achieved based on the safety case program assessment. Where current barriers are not sufficient, actions are identified and put into place as required. The program also considers alignment to set demonstrated program performance targets, including reliability targets such as probability of failure, and deterministic targets which are used to confirm the safety case status.
This paper details the operational change assessment process within the safety case program, and discusses the benefits where the process was used.