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Incident Narrative

INCIDENT SUMMARY: AT 01:34 OPERATIONS CONTROL CENTER (OCC) RECEIVED A HIGH-LEVEL ALARM ON THE SUMP TANK H2S DETECTOR AT MIDLAND STATION, 20 SECONDS LATER THE ALARM DROPPED BACK DOWN TO A NORMAL STATE. THEN AT 01:37 THE H2S ALARM JUMPED BACK TO A HIGH STATE AND INCREASED TO A HIGH-HIGH STATE AT 1:38. AT THIS TIME (1:38) OCC PROMPTLY NOTIFIED THE LOCAL FIRST LINE SUPERVISOR (FLS) WHO MOBILIZED A TECHNICIAN TO SITE TO INVESTIGATE THE ALARM. THE TECHNICIAN ARRIVED ONSITE AT APPROX. 02:05 AND IDENTIFIED A RELEASE OF PRODUCT (CRUDE OIL) ORIGINATING FROM THE THERMAL RELIEF LINE ON THE OUTLET VALVE (MOV 1814) OF METER RUN 2 ON SKID 4800. THE TECHNICIAN IMMEDIATELY NOTIFIED OCC WHO WORKED TO SHUT DOWN THE DELIVERY AND ISOLATE THE LEAK POINT. AT 02:10 THE INLET VALVE TO METER RUN 2 (MOV 4810) WAS EFFECTIVELY CLOSED STOPPING FLOW TO THE LEAK POINT. MIDLAND OPERATIONS PERSONNEL DETERMINED THE RELEASE POINT TO BE A 1/2"" SWAGELOK NEEDLE VALVE THAT HAD VIBRATED LOOSE OF THE THREADED CONNECTION POINT ON THE THERMAL RELIEF LINE, WHICH RESULTED IN A PRODUCT RELEASE OF APPROX. 31.23 BBL. INVESTIGATION FINDINGS: THE RELEASE OCCURRED WHEN THE 1/2"" NEEDLE VALVE BECAME DISCONNECTED FROM THE PREMANUFACTURED SWAGELOK PORT CONNECTOR NUT/FERRULE. AFTER A ROUNDTABLE REVIEW OF THE EXXON MATERIALS LAB FAILURE ANALYSIS WITH SWAGELOK SMES (FITTING MANUFACTURER) AND EXXONMOBIL ENGINEERING SMES, IT WAS DETERMINED THAT IN VIBRATION SERVICE, THE MACHINED PORT CONNECTION ACTS LIKE A BALL JOINT AND ALLOWS MOVEMENT AT THE CONNECTION POINT. DUE TO VIBRATION, THIS MOVEMENT LED TO FRETTING/WEAR ON THE THREAD FACES AND ULTIMATELY PROPAGATED TO LOOSING OF THE NUT, ALLOWING THE 1/2"" VALVE & NUT TO DISCONNECT. BACK-UP DETAILS: THE REMOVAL OF FACTORY FINISH & PRESENCE OF THREAD POLISH ON THE PORT CONNECTOR NUT THREADS DETAILED IN THE LAB ANALYSIS INDICATES THE CONNECTION WAS TIGHTENED ON FINAL INSTALL (SWAGELOK & EXXONMOBIL ENGINEERING SME REVIEWED). THE MIDLAND TECHNICIAN WHO PERFORMED THE TUBING INSTALL WAS CERTIFIED BY SWAGELOK TRAINING IN MAY 2022. PREVENTING RE-OCCURRENCE: REPLACE 1/2"" FITTINGS ON THERMAL RELIEF LINE WHERE THE RELEASE OCCURRED AND INSTALL SUPPORT BRACING (COMPLETE) PERFORM DETAILED VISUAL AND PHYSICAL INSPECTION OF SKID 4800 TO VALIDATE TIGHTNESS FITTINGS, FLANGES, BOLTING, ETC. (COMPLETE) REVALIDATED VIBRATION LEVELS ACROSS SKID 4800 TO CAPTURE START-UP, STEADY-STATE AND SHUTDOWN CONDITIONS TO BETTER UNDERSTAND VIBRATION LEVELS EXPERIENCED ACROSS THE SKID (IN PROGRESS - NO CONCERNS WITH VIBRATION LEVELS BASED ON PRELIMINARY DATA REVIEW WITH SMES) ADD SUPPORT BRACING TO SMALL-BORE TUBING/PIPING/VALVES ON THE METER SKIDS TO PROTECT AGAINST ABNORMAL OPERATING CONDITIONS (IN PROGRESS) FINALIZE TECHNICAL RECOMMENDATION FOR APPLICATION OF SWAGELOK MACHINED PORT CONNECTOR FITTINGS AND IMPLEMENT PROGRAM OF WORK TO IDENTIFY WHERE PORT CONNECTORS ARE CURRENTLY UTILIZED ACROSS OPERATIONS (IN PROGRESS)