Karen S. Lively, Pamela L. Maeger
Papers # 2014 Chicago
Medium Density Polyethylene (PE80/PE2708 type) pipelines have been used globally in natural gas service applications for over 50 years. The condition of existing pipelines is critical to assessing existing infrastructures for utility operators and various regulatory bodies. This paper includes a review of the development of a well-known MDPE polyethylene pressure pipe grade along with an evaluation of pipes that were in pressure service for over 30 years. Data will be presented that show basically few or minor changes in most of the physical properties for these orange and yellow pipes. Overall, it was observed that the test data of all the exhumed, aged pipes compared favorably to the recently extruded yellow pipe control when modifications in manufacturing control limits were accounted for. There were no unexplained differences in the physical properties of the service pipes and no indications of ageing after thirty years of field service, when compared to the 2011 control pipe samples. These results thus suggest very clearly that these MDPE pipes have exhibited not only extremely robust performance in service, but can also be expected to continue to perform well for years to come.