Gas processing facilities and pipeline networks play a key role in energy distribution. There is an ever increasing need to extend the life of the aging networks beyond their original design life and operators are continually looking for requalification and extension of the service life aimed at ensuring the integrity, functionality and availability of the network for the extended operating life. In order to ensure technical and operational integrity of this ageing infrastructure, the fitness for service of these systems is required be maintained for the intended service life.

Maximising the availability and functionality of the network, whilst operating safely and with minimal impact on the environment, is a major concern for requalification and life extension. Gas processing asset integrity management (AIM) and pipeline integrity management (PIM) consist of inspection, testing, maintenance and repair programs are critical to ensure integrity and sustainability in gas production. The AIM program is to assess and report upon the risks imposed on the community by natural gas supply facilities, and based on the available information; identify opportunities for improvements to ensure the risks to the community are as low as reasonably as practicable (ALARP) (UPSTREAM NATURAL GAS SAFETY REPORT 2001). Detailed integrity assessments are needed to demonstrate that there is sufficient technical, operational and organisational integrity to continue safe operation throughout an extended service life. Information on characteristic data, condition data, historical performance, maintenance management and inspection and testing results are required to assess the current state and to predict the future state of the network subsystems and critical components and the possible extension of service life. Effective record keeping and ongoing analysis of data are key inputs to a successful life extension program (Nezamian and Altmann 2013).

This paper presents state of art practices in life extension of existing gas distribution and pipeline facilities and an overview of a customised life extension methodology to address risk factors to the integrity of a gas distributio and associated facilities. It covers the required procedures and re-assessment criteria for a life cycle cost effective approach to decide on life extension in particular the one with the importance such critical subsystems.

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