ONEOK NGL PIPELINE, LLC

Incident Narrative

THE FILTER VESSEL HAD BEEN PLACED IN SERVICE ON JULY 11, 2018 AFTER A PREVIOUS REPORTABLE ACCIDENT INVOLVING THIS FILTER VESSEL (7/09/2018). THE SEALING ELEMENT HAD BEEN REPLACED ON THE OEM'S RECOMMENDATION AND FOLLOWING THE OEM'S INSTALLATION PROCEDURE. THIS INSTALLATION WAS WITNESSED BY A REPRESENTATIVE OF THE SEAL ELEMENT VENDOR. ON JULY 13, 2018 A 3RD PARTY OPERATOR NOTIFIED ONEOK THAT THE FILTER VESSEL DOOR LEAKING. ONEOK REPRESENTATIVES RESPONDED TO THE SCENE, ISOLATED THE FILTER VESSEL, AND BLEW DOWN THE VESSEL. NITROGEN WAS USED TO PURGE THE VESSEL OF COMBUSTIBLES, UNTIL THE FILTER CHANGE CREW COULD BEGIN THE PROCESS OF OPENING THE VESSEL. ALL OTHER VESSELS OPERATING ON THE SAME PIPELINE SYSTEM, UTILIZING THIS CLOSURE LID, WERE ISOLATED, BLOWN DOWN, AND PURGED WITH A NITROGEN BLANKET BY ONEOK, UNTIL THE CAUSE OF THE RELEASE COULD BE DETERMINED. ON JULY 14TH AN OEM FIELD TECHNICIAN WAS ON SITE TO DIAGNOSED THE PROBLEM. THE TECHNICIAN MADE A FIELD MODIFICATION TO THE DOOR, AND SUPERVISED THE INSTALLATION OF THE SEALING ELEMENT SO THE VESSEL COULD BE SAFETY SEALED. THE VESSEL REMAINED ISOLATED, WITH A NITROGEN BLANKET, UNTIL THE MANUFACTURER, THE VENDOR AND ONEOK, COULD DISCUSS THE CAUSE OF THE FAILURE AND DETERMINE A PATH FORWARD. THE OEM DETERMINED THE CLOSURE LIDS MANUFACTURED PRIOR TO 2009 WERE DESIGNED FOR A TWO PIECE SEALING ELEMENT WHICH HAS BEEN DISCONTINUED. IN SOME INSTANCES, THESE OLDER CLOSURES COULD NOT SUCCESSFULLY USE THE NEWER OEM RECOMMENDED ONE PIECE SEAL DESIGN, DUE TO THE TOLERANCE RANGE OF THE CLOSURE LID DURING THE INITIAL MILLING. THE OEM IS CURRENTLY IN THE PROCESS OF RE-ACTIVATING PRODUCTION OF THE ORIGINAL TWO PIECE SEALING ELEMENT DESIGN FOR OPERATORS TO USE WITH CLOSURE LIDS MADE PRIOR TO THE DESIGN CHANGE IN 2009. 18/08/08 - UPDATED PART C QUESTION 1 - PIPELINE IS INTERSTATE PER NPMS AND ANNUAL REPORT. NJONES