CTA Report, Draft 1, ISP Review - US Chemical Safety and Hazard ...

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Plant personnel reported that the February 20 explosions caused large amounts of dust that had collected on overhead surfaces (e.g., on top of blend rooms, beams, ledges) to descend upon them. CSB found accumulations of combustible dust burned onto flat surfaces in the CTA production area. However, because of the extensive fire and explosion damage, CSB could not determine the thickness of the dust layer on flat surfaces prior to the fire. Housekeeping involved cleaning floors and plant equipment on a daily basis. In the year prior to the incident, the facility’s housekeeping crew for this type of cleaning was reduced in size. The reduced crew was able to clean a limited area within the plant each day. Daily housekeeping on production lines became a job duty of line operators. The CTA cleaning program focused on production line, floor, and baghouse cleaning. It did not adequately address other flat surfaces such as I-beams, process ducts and pipes, roof trusses, and the top of the blend rooms. Semi-annual cleanings (Section 4.4) during plant shutdowns were supposed to be scheduled; however, CSB did not find evidence that these cleanings occurred. Housekeeping inspections did not detect accumulations of combustible dust that could not be seen at floor level. Good housekeeping is critical for combustible dust control. NFPA 654 (2000) states: “[R]egular cleaning frequencies shall be established for floors and horizontal surfaces, such as ducts, pipes, hoods, ledges, and beams, to minimize dust accumulations within operating areas of the facility.” It further recommends that spaces inaccessible for cleaning be sealed to prevent dust accumulation and that combustible dust inspection programs specifically address housekeeping. A more effective housekeeping program at CTA would have limited the buildup of combustible dust. 8.5.3 Nonroutine Operations The doors on the line 405 oven were left open because the oven was operating too hot. Personnel viewed the temperature control problem exclusively as a product quality concern, so the safety hazard of 74
operating the oven with the doors open was not evaluated. On the day of the incident, combustible material in the oven probably caught on fire, and flames likely ignited a dust cloud that was created by cleaning activity. NFPA 654 (2000) states: “[W]ritten procedures to manage change to process materials, technology, equipment, procedures, and facilities shall be established and implemented.” 8.6 Maintenance The production lines were shut down once every 6 to 9 weeks for maintenance and cleaning. Maintenance activity typically included removing accumulated combustible material in the bottom of the ovens, sandblasting oven interiors, and replacing the bags in the baghouses. The last maintenance shutdown of line 405 took place on December 19, 2002—9 weeks prior to the incident. The next shutdown was initially scheduled for February 13, 2003; postponed until February 20; and then rescheduled a second time for February 21. The incident occurred on February 20. Employees reported that the delay in replacing bags in the baghouse caused increasing amounts of dust to escape from the production line and into the work area. The differential pressure gauge on the baghouse showed that suction was outside of the manufacturer’s limits. NFPA 654 (2000) recommends pressure drops of 3 to 5 inches of water to maximize baghouse efficiency. According to CSB interviews with line crew employees, the baghouse differential pressure was running above 6 inches on February 19, the day before the incident. Interviews also revealed that line 405 was much dustier than normal. 8.6.1 Oven Operation and Safety Oven temperature control equipment on line 405 had not been working properly for a few weeks prior to the incident. CSB interviews with line 405 employees revealed that the oven was running too hot. Electricians were unable to fix the problem. Operators compensated by opening two of the oven doors to cool it down. Supervisors and workers did not view the temperature control problem as a safety concern. 75
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KEY ISSUES: U.S. CHEMICAL S AFETY A
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5.1.2 Line 405 Oven Temperature Con
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9.1 FM Global Guidelines...........
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Figures 1 Simplified Layout of CTA
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ACC American Chemistry Council Acro
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Executive Summary A February 20, 20
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1.0 Introduction At approximately 7
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2.0 Key Findings 1. Combustible phe
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3.0 Facility Description 3.1 CTA Ac
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eams. Nonload-bearing masonry block
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Thirteen-foot-high freestanding enc
Page 23 and 24: 4.0 Process Description The product
Page 25 and 26: 4.1.2 Mat-former and Baghouse In th
Page 27 and 28: Circulating fans and dampers direct
Page 29 and 30: • Manually striking baghouse bags
Page 31 and 32: 5.0 Incident Description 5.1 Pre-In
Page 33 and 34: • The line was one week past due
Page 35 and 36: forklift with a semi-enclosed cab d
Page 37 and 38: panels and lights down inside the b
Page 39 and 40: occurred in the southeast corner of
Page 41 and 42: 5.3.3 Firefighting Activities 5.3.3
Page 43 and 44: 5.4 Incident Aftermath The CTA inci
Page 45 and 46: 6.0 Understanding Combustible Dust
Page 47 and 48: As depicted in Figure 11 (Eckhoff,
Page 49 and 50: Figure 12. Mechanism for a dust fir
Page 51 and 52: 7.0 Reconstructive Analysis To dete
Page 53 and 54: urned clean but otherwise intact an
Page 55 and 56: 7.1.2 Other Possible Initiating Eve
Page 57 and 58: Table 3 Borden Chemical Black Pheno
Page 59 and 60: 7.3 Line 405 Equipment Testing CSB
Page 61 and 62: determine if those products are haz
Page 63 and 64: that the phenolic resin could explo
Page 65 and 66: A 1998 internal Borden Chemical mem
Page 67 and 68: • Characterize new and existing p
Page 69 and 70: CTA that phenolic resins, when susp
Page 71 and 72: CTA department supervisors were res
Page 73: 8.5 Work Practices 8.5.1 Production
Page 77 and 78: 8.7 Incident Investigations The inc
Page 79 and 80: • Excessive accumulations of comb
Page 81 and 82: Data Sheet 6-9 also states: Clean o
Page 83 and 84: Table 5 Insurance Company Dust Issu
Page 85 and 86: standards (Appendix D). Kentucky OS
Page 87 and 88: 10.2.2 Division of Building Codes E
Page 89 and 90: 11.0 Combustible Dust Hazard Study
Page 91 and 92: 4. The Borden Chemical product stew
Page 93 and 94: 13.0 Recommendations CSB developed
Page 95 and 96: Kentucky Office of Occupational Saf
Page 97 and 98: BY THE U.S. Chemical Safety and Haz
Page 99 and 100: Lawson, Robert G., 1984. Beverly Hi
Page 101 and 102: APPENDIX A: Fire and Explosion Dama
Page 103 and 104: APPENDIX B: Laboratory Testing of P
Page 105 and 106: B.2 Minimum Explosible Concentratio
Page 107 and 108: B.4 Propagating Brush Discharge Ign
Page 109 and 110: Material Corona Charge Voltage (kV)
Page 111 and 112: APPENDIX C: Equipment Testing Line
Page 113 and 114: II controllers, only manufactured a
Page 115 and 116: Therefore, at any given time, it wa
Page 117 and 118: APPENDIX D: NFPA Guidelines In prom
Page 119 and 120: D.2 Other Pertinent NFPA Codes D.2.
Page 121 and 122: APPENDIX E: HMIS Rating System The
Page 123 and 124: APPENDIX F: Simplified Organization
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Subtree A Second dust explosion abo
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Subtree C Most CTA personnel had a
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