Papers # 2014 Chicago
Aldyl A piping systems are closing in on fifty years of service in North America. Several North American gas utilities are assessing the remaining lifetime expectancy of their Aldyl A piping systems and preparing replacement programs. GTI has been actively involved in multiple research efforts related to Aldyl A remaining lifetime and has also conducted many evaluations of field failures over the past years. This experience has culminated in a comprehensive causal risk model for vintage plastic piping systems, including Aldyl A, being developed. The model is being used to help utilities assess their vintage PE piping systems for risk hot spots and provide guidance on the sequencing of replacement programs. The principles on which the causal model has been built will be discussed together with the key risk factors in vintage PE piping systems. These factors include the condition of the inner wall of the pipe, material properties, installation quality, damage introduced during routine repairs and environmental factors such as ambient temperature, soil subsidence and impingement. How to properly identify, quantify and combine these multiple effects into a risk score that can guide replacement policy will be discussed.