CHS MCPHERSON REFINERY INC.

Incident Narrative

OPERATORS RESPONDING TO LEL ALARMS IN WELL #9 VICINITY OBSERVED LIQUID PRODUCT AT THE GROUND SURFACE ABOVE KNOWN NGL PIPING. OPERATORS ISOLATED THE PIPING SEGMENT BY CLOSING NEARBY VALVES, WHICH STOPPED THE RELEASE. VACUUM TRUCKS WERE UTILIZED TO DE-INVENTORY ALL AFFECTED PIPING. THE SOIL NEAR THE RELEASE LOCATION WAS EXCAVATED AND AFFECTED PIPING WAS EXPOSED TO DETERMINE THE LEAK LOCATION. A PIN HOLE WAS IDENTIFIED BY VISUAL INSPECTION. THE PINHOLE IS LOCATED IN A SEGMENT OF PIPING THAT IS NOT AT A LOW POINT. THE AFFECTED DEADLEG WAS ELIMINATED BY CUTTING OUT THE TEE AT THE BRANCH CONNECTION AND THE FAILED PIPE WAS SENT FOR THIRD PARTY METALLURGICAL ANALYSIS. THE ANALYSIS DETERMINED THAT AQUEOUS CORROSION WAS THE LIKELY CAUSE OF FAILURE. CHSMRI PLANS TO TAKE THE FOLLOWING STEPS TO IDENTIFY FURTHER CORROSION IMPACTS TO THE EFFECTED PIPING CIRCUITS: 1. PERFORM INSPECTION OF DEAD LEG PIPING AND DEVELOP PLAN TO REMOVE PIPING. 2. EVALUATE PRODUCTS FOR ACTIVE CORROSION CONTRIBUTIONS. 3. PERFORM ADDITIONAL INSPECTIONS ON NON-DEAD LEG PIPING. 4. WHERE POSSIBLE, FLUSH DEAD LEGS ON A QUARTERLY BASIS. 5. PERFORM HYDROTEST AFTER DEAD LEG REMOVAL.