LOUISVILLE GAS & ELECTRIC CO

Incident Narrative

A FAILURE ON A PIPE SEGMENT IN DOE RUN STORAGE FIELD, LOCATED DOWNSTREAM OF AN UNATTENDED FIELD COMPRESSOR, OCCURRED ON OCTOBER 22, 2015. REVIEW OF PRESSURE DATA RECORDED FOUND THE FIELD COMPRESSOR DISCHARGE PRESSURE DROPPED SUDDENLY AT APPROXIMATELY 12:50 PM RESULTING IN THE AUTOMATIC SHUTDOWN OF THE FIELD COMPRESSOR. AT APPROXIMATELY 2:15 PM A STORAGE FIELD MECHANIC WAS NOTIFIED BY A LOCAL RESIDENT OF A POTENTIAL ISSUE IN THE STORAGE FIELD. UPON INVESTIGATION THE FIELD MECHANIC FOUND GAS ESCAPING FROM A PIPE SEGMENT LOCATED DOWNSTREAM OF THE FIELD COMPRESSOR. THE FIELD MECHANIC ISOLATED THE PIPELINE SEGMENT AT APPROXIMATELY 3:23 PM STOPPING THE GAS RELEASE. NOTIFICATION WAS MADE TO THE INDIANA UTILITY REGULATORY COMMISSION AND PHMSA AFTER ENVIRONMENTAL CLEANUP OF THE SITE WAS COMPLETED AND EXCAVATION OF THE PIPE ENABLED DEFECT MEASUREMENTS PROVIDING THE BASIS FOR AN ENGINEERING ESTIMATE OF NATURAL GAS VOLUME RELEASED. THE FAILED PIPE SEGMENT WAS SENT TO A METALLURGICAL LAB FOR FAILURE ANALYSIS. THE RESULTS OF THE METALLURGICAL ANALYSIS INDICATE THAT THE FAILURE OCCURRED AT AN AREA OF WALL THINNING DUE TO INTERNAL CORROSION THAT FAILED BY DUCTILE OVERLOAD UNDER THE IMPOSED OPERATING PRESSURE. SIGNIFICANT WALL THINNING AT THE LOCATION OF THE RUPTURE LIKELY CORRESPONDED TO HISTORIC FLUID LINES. ADDITIONAL ANALYSIS PERFORMED ON LIQUID SAMPLES AND DEPOSITS FROM INSIDE OF THE PIPELINE, ALONG WITH A REVIEW OF THE GAS COMPOSITION DATA, POINT TOWARD THE INTERNAL CORROSION BEING CAUSED BY THE PRESENCE OF WATER, OXYGEN, CARBON DIOXIDE, AND HYDROGEN SULFIDE. THE OXYGEN IS SUSPECTED TO HAVE BEEN THE KEY DRIVER OF THE CORROSION.