ONEOK NGL PIPELINE, LLC

Incident Narrative

ON 7/14/2020, A THIRD-PARTY CONTRACT CREW PERFORMING PIPELINE INSPECTIONS DISCOVERED A VAPOR RELEASE COMING FROM A CASING VENT RISER ON THE 11107 PIPELINE AT THE ROUTE 30 CROSSING IN JOLIET, IL (41.58275 -88.16556). AT THE TIME THE LEAK WAS DISCOVERED, THE PIPELINE CONTAINED PROPANE BUT WAS NOT FLOWING. POST DISCOVERY, BLOCK VALVES WERE MANUALLY SHUT AND THE PIPELINE WAS NITROGEN PURGED AND DEPRESSURED TO FACILITATE THE REPAIR. ONCE THE LOCATION WAS EXCAVATED, A PINHOLE WAS CONFIRMED JUST INSIDE THE END OF THE CASING. A 10 FOOT SECTION OF PIPELINE, WHICH INCLUDED THE PINHOLE, WAS CUT-OUT AND REPLACED, AND THE PIPELINE WAS PLACED BACK IN SERVICE ON 7/18/20. THE PIPELINE SECTION CONTAINING THE PINHOLE HAS BEEN SENT FOR METALLURGICAL LAB ANALYSIS TO DETERMINE CAUSE OF THE FAILURE. AN NRC REPORT (#281895) WAS SUBMITTED ON 7/14/20 DUE TO REPAIRS ESTIMATED OVER $50,000. UPDATED 11/5/2020 - BRENT THEEDE THE RESULTS OF THE METALLURGICAL ANALYSIS INDICATE THAT THE METALLURGICAL CAUSE OF THE LEAK WAS AC STRAY CURRENT CORROSION. THIS CONCLUSION IS BASED ON A NUMBER OF OBSERVATIONS, INCLUDING: THE ASSOCIATION OF THE FAILURE WITH A WELL-COATED PIPE SEGMENT, THE MORPHOLOGY OF THE PIT, THE COMPOSITION OF THE CORROSION PRODUCTS, AND THE PH OF THE DEPOSITS AT THE LEAK.