Root Cause Analysis Report for the Tank 650 seal fire

Transcription

1 April 5, 2011 Mr. Randy Sawyer Director, Hazardous Materials Division Contra Costa Health Services 4585 Pacheco Blvd. Martinez, CA Via Fax: (925) Original will follow in the mail. Subject: Root Cause Analysis Report for the Tank 650 seal fire Dear Mr. Sawyer: The is submitting a Root Cause Analysis report for the October 10, 2010 Tank 650 seal fire. The investigation is complete and the Root Cause Analysis report is attached. This Root Cause Analysis report is submitted in satisfaction of the requirements set forth in County Ordinance 98-48, the Industrial Safety Ordinance for root cause analysis reports. If you have any questions regarding this report, please call me at (925) or Ms. Sabiha Gokcen at (925) Sincerely, Richard Leland Health and Safety Manager Cc: Ms. Cho Nai Cheung

2 Root Cause Analysis Report Summary of Event: At 12:20 PM, a seal fire was reported on Tank 650, which contains concentrated sour water with a 3 foot hydrocarbon top layer. Maintenance activities were being performed on the tank seals at the time of the incident. A CWS Level 1 was issued at 12:28 and later elevated to a CWS Level 2 at 12:50 once the smoke plume became visible from offsite. Emergency Response crews responded with firefighting equipment and the Emergency Operations Center (EOC) was also activated. Notifications were made to the requisite outside agencies and to Golden Eagle personnel. The Bay Area Air Quality Management District, Sheriff s Department, Tesoro Industrial Hygiene and Odor Science and Engineering conducted community monitoring. No odors or impact of smoke were reported. No reportable quantities of hazardous compounds were released. At 15:00 hours, the fire was extinguished and there were no reports of visible smoke offsite. The incident was declared localized at 15:23 and all clear at 16:10. A brief timeline follows: 12:20 hrs: Fire at TK650 seal 12:23 hrs: CWS level 1 notification sent over terminal 12:45 hrs: One contractor taken off site for smoke inhalation 12:51 hrs: CWS level 2 notification sent over terminal 13:38 hrs: Contra Costa Sheriff arrives at EOC 14:00 hrs: Secured tank area to set up fire fighting 15:00 hrs: Fire extinguished 15:20 hrs: Contractor released from offsite treatment 15:23 hrs: Incident declared localized by Tesoro IC 16:10 hrs: All Clear issued Agency Notification and Response: The following agencies were immediately notified: Contra Costa Health Services (CCHS) via the CWS, the Bay Area Air Quality Management District (BAAQMD) via the CWS and phone, Contra Costa Fire Protection District, and the Contra Costa County Office of Emergency Services. The following agencies responded with personnel to the scene: CCHS, BAAQMD, Contra Costa Fire and Contra Costa Sheriff. [Note: Notifications over the CWS terminal: CWS level 1 notifies CCHS, Contra Costa OES, and the Contra Costa Sheriff with a specific message. Additional notice informs BAAQMD, Contra Costa Fire Protection District, Martinez Police, Antioch Police, Pinole Police and Richmond Police. CWS level 2 notifies CCHS, Contra Costa OES, Contra Costa Sheriff and BAAQMD with a specific message. Additional notice informs Contra Costa Fire Protection District, California Highway Patrol, California Dept. of Page 2 of 6

3 Health, San Ramon Valley Fire, Martinez Police, Antioch Police, Pinole Police and Richmond Police.] Emergency Response Actions: Emergency response team members applied fire fighting foam to the tank seal on top of the tank. Material Released: The material that burned was mixed hydrocarbons; hydrocarbons are used as a cap on the sour water to suppress odors. A tank gauge the next day showed no level change in the tank. The final amount of hydrocarbon estimated to be combusted is 3 barrels. Note: this calculation was revised downward because the original estimate assumed the entire surface of the tank was involved. Only about one-third of the seal area was actually involved in the fire. Meteorological Conditions: The weather was clear with wind direction varying from the NW with a wind speed of 8-12 mph. The temperature was about 78 degrees F. Injuries: One contractor employee suffered hyperventilation due to the incident (this was initially reported as a smoke inhalation in earlier reports). The contractor was taken to an off-site medical facility for observation and was subsequently discharged. Community Impact: The smoke plume was visible from offsite, but air monitoring by Tesoro Industrial Hygiene yielded non-detect levels of hydrocarbons. Monitoring performed by Odor Science and Engineering and the Bay Area Air Quality Management District did not detect any off site odors. Incident Investigation of the event: A seal fire occurred on Tank 650 while contractors were working on the tank repairing the primary and secondary seals. Tank seals are part of the tank roof and are designed to prevent hydrocarbon emissions from the tank while still allowing the tank roof to move up and down as the tank level changes. Tank 650 holds concentrated sour water with a hydrocarbon layer on top which is used to suppress any potential odors from the sour water. Note: tank seal work is a specialty task performed by highly specialized contractor companies. Page 3 of 6

4 The fire began at the north side of the tank, at about the 1 o clock position using the ladder platform as reference at the 6 o clock position. There were four contractor employees on the tank roof, one on the platform serving as hole-watch and one on the platform serving as a spotter for the evacuation man-basket and crane. Two employees were working on either side of the location where the fire first ignited, one was on the east side, the other was on the west side near where a foam eductor was found. The investigation focused on the causes of the incident, with particular attention to the possible ignition source. A tank seal repair or replacement involves specific precautions to prevent ignition of the tank contents. The contractor s procedure for the seal replacement contained these precautions; specifically, the procedure required the application of a foam layer and performing an LEL check to verify the foam application was adequate to keep hydrocarbon vapors suppressed. As part of the investigation, it was found that while the seal replacement was in progress, no foam had been applied per procedure. The tank seal replacement project had been assigned to a Tesoro maintenance supervisor whose specialty was process unit maintenance rather than tank maintenance. However, Tank 650 was within his area and the current maintenance practice is to assign supervision of maintenance work based on area. The investigation team evaluated 7 different potential ignition sources. Based on the evidence gathered, it was concluded the ignition source was likely pyrophoric iron. Pyrophoric iron readily reacts with air and that reaction generates a fair amount of heat, which is sufficient to ignite any hydrocarbons present. Pyrophoric iron must be kept wet with water or foam to prevent reaction with air. Pyrophoric iron occurs in equipment where H 2 S vapor reacts with the iron in the equipment walls and forms Iron Sulfide (pyrophoric iron). Tank 650 contains sour water, which contains H 2 S. Even though Tank 650 is labeled as possibly containing pyrophoric material, the presence of pyrophoric iron in the tank and the tank seals was not recognized during preparation for the repair of the tank seals. The Hazardous Materials Warning Sheet (HMWS), which is the primary equipment-specific reference of hazards, did not contain information regarding the hazard of the pyrophoric iron nor the hydrocarbon layer. The Rules and Standing Instructions (R&SIs) pertinent to tank maintenance also did not contain information about pyrophoric iron or specify any special requirements for tanks that may contain pyrophoric material. In addition, R&SI 8-7 Pyrophoric Vessels is specific for process vessels and does not address tank precautions, nor does it list tanks or tank seals as potential locations for pyrophoric iron. Each of these documents affects the planning of maintenance tasks to ensure they are executed safely. Root Causes: Root Cause # 1: The Contractor s procedure Working on External Floating Roofs with Tank in Service was not followed. The procedure requires application of a foam layer. Page 4 of 6

5 The foam layer was not applied to prevent the ignition of the hydrocarbon layer. The procedure also required an LEL check after foam application to verify there is an adequate layer of foam to prevent ignition. Root Cause # 2: There was a lack of Tesoro supervisory oversight to verify the contractor s compliance with the site s procedures and the approved contractor procedure. Root Cause # 3: The Tesoro Rule and Standing Instruction (R&SI) 8-6 Tank Requirements was not followed regarding the application and maintenance of the foam blanket during tank seal replacement. Root Cause #4: The hazard was not recognized. Tesoro R&SI 8-6 Tank Requirements, R&SI Tank Seal Replacement, and R&SI 8-7 Pyrophoric Vessels do not address potential pyrophoric hazards in storage tanks. This was one factor in why the hazards of the job were not recognized. Root Cause #5: The hazard was not recognized. The Tank 650 Hazardous Materials Warning Sheet (HMWS) did not include precautions for potential for pyrophoric material. This was one factor in why the hazards of the job were not recognized. Root Cause #6: The hazard was not recognized. The Tank 650 HMWS did not include precautions for the hydrocarbon layer. This was one factor in why the hazards of the job were not recognized. Root Cause #7: The hazard of pyrophoric material on Tank 650 was not recognized by the Operations Supervisor, the Maintenance Supervisor, and the Operations Shift Supervisor that signed the HERA for Tank 650, nor by the responsible operator that issued the entry permit for Tank 650 despite the label on the tank noting it as containing pyrophoric material. Corrective Actions: Corrective Actions Anticipated Date Root Cause of Completion 1 Follow up with HMT on why they failed to follow their procedure and reset the expectations that they do so 6/1/ Modify the Tesoro Execution oversight philosophy for high risk work. Modify the MWP work process binder and train maintenance supervision on changes. Modify R&SIs 8-6 Tank Requirements and Tank Seal Replacement to include consideration 3 of possible pyrophoric iron presence in tanks and add a requirement for a pyrophoric material 9/1/2011 2, 3 4, 7 Page 5 of 6

6 management plan before beginning work that could potentially involve pyrophoric material. Modify R&SI 8-7 Pyrophoric Vessels to include tanks and tank seals in its scope. Require job specific work execution plans for repairs of in-service tanks or other high risk work reviewed and approved by the Tesoro representative for the job. As part of the job specific work execution plan, add a section for Health & Safety to review emergency response aspects of the job Correct the HMWS for Tank 650 to include pyrophoric considerations and the hydrocarbon layer. Review the HMWS for other tanks and vessels in similar service to ensure that pyrophoric considerations are noted. Review of R&SI for modification as follows: 1) inclusion of limits for LEL and toxics and 2) consideration of the following concepts when replacing tank seals (these should be included in the contractor s procedure to replace the seal): a) Continuous atmospheric monitoring of the tank annular space wherever the seal has been removed. b) Adequate application of Firefighting Foam, including specifying amount and frequency of application, c) Approval of the firefighting foam being used and documentation of approval in the job specific work execution plan Complete Root Cause Analysis Report 4, ,6 7 3 Page 6 of 6