NUSTAR PIPELINE OPERATING PARTNERSHIP L.P.

Incident Narrative

AT 1120 AM ON 6-21-2021, NUSTAR PERSONNEL CONFIRMED THE DISCOVERY OF AN ANHYDROUS AMMONIA LEAK NEAR VALVE 3-22 IN ARKANSAS, WHERE A SMALL MIST OF VAPOR WAS EMANATING FROM THE SOIL. THE LINE WAS SHUT DOWN IMMEDIATELY AND BLOCKED IN AT PINE BLUFF STATION AND HERMANN STATION. RESPONSE RESOURCES WERE DISPATCHED TO THE SITE TO EXPOSE THE PIPELINE. ON 6-22-2021, THE LINE WAS EXCAVATED, AND IT WAS DETERMINED THAT THERE WAS A FAILURE IN THE SIDE SEAM OF A STOPPLE TEE FITTING ON THE PIPELINE. THE STOPPLE TEE WAS REMOVED AND REPLACED WITH NEW PIPE, AND THE LINE WAS RESTARTED ON 6-24-2021. CONTAMINATED SOIL WILL BE REMOVED FOR LANDFARMING AT FLORAL STATION. PROPER INTERNAL AND EXTERNAL NOTIFICATIONS WERE MADE. THE STOPPLE TEE WAS SENT FOR METALLURGICAL ANALYSIS. THE LEAK/RELEASE OCCURRED AT THE WELD SEAM OF THE STOPPLE. CRACKING WAS OBSERVED TO BE INITIATING FROM THE WELD ROOT AT A LACK OF PENETRATION OF THE WELD SEAM AT THE INNER DIAMETER(ID). TWO DISTINCT AND DISCERNABLE SURFACE CRACKS WERE OBSERVED AT THE OUTER DIAMETER (OD) SURFACE, WHICH FORMED THE LEAK PATHS FROM THE ID CRACK TO THE OD. THERE WAS NO EVIDENCE OF WIDESPREAD OR EXTENSIVE GENERAL CORROSION. WE ARE ACTIVELY REMOVING OLD STOPPLE TEES FROM THE SYSTEM DURING HYDRO TESTS, LINE REPLACEMENTS, AND AS OTHER PROJECTS PROVIDE THE OPPORTUNITY TO DO SO.