CONOCOPHILLIPS

Incident Narrative

"THE MX20 PIPELINE RUPTURED RELEASING NATURAL GAS LIQUIDS (NGL) UNDER PRESSURE. THE NGL VAPORIZED UPON REACHING THE ATMOSPHERIC PRESSURE, BUT DID NOT IGNITE. THE CAUSE OF THE RUPTURE IS UNDER INVESTIGATION PENDING METALLURGICAL STUDY AND ANCILLARY PIPELINE ACTIVITY. CPPL RECIEVED THE FINAL REPORT ON JULY 9, 2010, PHMSA RECIEVED A COPY OF THE REPORT ON THE SAME DAY. CONCLUSION: THE FAILURE WAS CAUSED BY EXTERNAL MICROBIOLOGICALLY INFLUENCED CORROSION (MIC). THE WALL THICKNESS HAD BEEN REDUCED SUCH THAT THE REMAINING LIGAMENT FAILED IN A DUCTILE MANNER AT NORMAL OPERATING PRESSURES. OTHER ANOMALIES WERE FOUND IN THE VICINITY OF THE RUPTURE, HOWEVER, IT WAS DETERMINED THAT NONE OF THE OTHER FEATURES CONTRIBUTED TO THE ROOT CAUSE OF THE FAILURE WHICH WAS EXTERNAL CORROSION OF THE PIPE. THE FAILURE OCCURRED WHERE CPPL'S PIPELINE CROSSED A LARGER DIAMETER, CURRENTLY IDLES PIPELINE OPERATED BY ANOTHER COMPANY. AT SOME POINT AND TIME, CPPL'S PIPELINE WAS RECOATED WITH TAPE IN THE VICINITY OF THE FOREIGN PIPELINE. IT APPEARED THAT THE TAPE WAS APPLIED OVER THE ORIGINAL COATING - NOT DIRECLY TO THE PIPE SURFACE. THE TAPE WAS POORLY BONDED AND SHEILDED THE PIPE FROM CATHODIC PROTECTION. THE GROUND WAS REPORTABLY WE DURING EXCAVATION OF THE FAILURE DUE TO A LEAKING WATER PIPE IN THE AREA. THE SHEILDING FROM THE TAPE RECOAT IN COMBINATION WITH THE PRESENCE OF GROUNDWATER PROMOTED AN ENVIROMENT CONDUCTIVE TO MICROBIOLOGICAL ACTIVITY."