With new exploration technologies enabling natural gas extraction from shale formations, transmission requirements to serve the expanding production sources are more dynamic now than the past 50 years. Pipeline system managers must not only be proactive in capacity planning, but must ensure system sustainability for both short and long term value creation. Reliability modeling of repairable systems provides benchmarks for gap analysis quantification. Once the level of risk exposure is determined, options for mitigation and/or reducing the impact of an unscheduled failure event can be explored with economic balance. This presentation details a process methodology utilized to ensure that contract requirements of natural gas transmission are managed in a quantitative manner. Assessment of critical locations, critical assets, system capacity constraints and system capability by operational context are considered foundational to the analytic philosophy described in the details forward. Multiple reliability engineering tools are utilized to ensure the transmission system is sustained as a function of managed risk to the overall enterprise. Large transmission networks are often challenged with an expansive mix of technology applications from the mid-twentieth century to many of the most recent advances in compression, metering, real time gas quality analysis and regulation. Always dependent upon the age and modernization strategy applied to repairable assets, managing system sustainability has been and continues to be a significant challenge. Execution of progressive strategies to manage this critical function of the energy supply industry is not only prudent, but necessary as energy management continues to evolve.