NUSTAR PIPELINE OPERATING PARTNERSHIP L.P.

Incident Narrative

AT 2:28 AM ON 06-01-2015 THE SAN ANTONIO CONTROL CENTER RECEIVED AN AMMONIA DETECTION ALARM AND STATION LOCKOUT AT THE RAMAH PUMP STATION, IN IBERVILLE PARRISH, LA. A STATION LOCKOUT ISOLATES THE STATION PIPING FROM THE MAINLINE PIPING. THE CONTROL CENTER OPERATOR CONTACTED THE AREA NUSTAR EMPLOYEE. THE NUSTAR EMPLOYEE ARRIVED AT 4:09 AM AND CONFIRMED THE SMELL OF AMMONIA ORIGINATING FROM BURIED MAINLINE PIPE WITHIN THE PUMP STATION AND NOT THE STATION PIPING. EMERGENCY SHUTDOWN PROCEDURES FOR THE MAINLINE WERE STARTED AT 0412. THE PIPELINE WAS COMPLETELY SHUT DOWN AND BLOCKED AT 0421. NUSTAR'S MAINTENANCE CREW ARRIVED ON 06-02-2015, EXCAVATED AND INSTALLED A STOPPLE TEE DOWNSTREAM OF THE LEAK LOCATION. ON 06-03-2015 THEY EXCAVATED THE PIPELINE AND CONFIRMED THE STOPPLE TEE FITTING AS THE CAUSE. THEY COMPLETED REPAIRS ON 06-03-2015 AND THE LINE WAS RESTARTED AT 23:45. THE STOPPLE TEE FITTING WILL BE SENT FOR METALLURGICAL ANALYSIS IN ORDER TO DETERMINE THE CAUSE OF THE LEAK. RESULTS OF METALLURGICAL ANALYSIS: THE LEAK WAS CAUSED BY A NEARLY THROUGH WALL CRACK IN THE LONGITUDINAL SEAM WELD OF THE STOPPLE(R) FITTING. THE CRACK INITIATED IN AN AREA OF MISALIGNMENT OF THE CUFF EDGES AND INCOMPLETE PENETRATION (IP); THESE ARE FABRICATION DEFECTS CREATED DURING INSTALLATION OF THE FITTING. THE IP CREATED A NOTCH-LIKE STRESS CONCENTRATION WHICH ALLOWED FOR THE INITIATION OF A CRACK. THE CRACK PROPAGATED UNTIL IT WAS NEARLY THROUGH THE WELD. THE REMAINING INTACT LIGAMENT WAS UNABLE TO CONTAIN THE INTERNAL LINE PRESSURE.