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

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There were indications that the oven 405 burner was operating at a natural gas pressure below the manufacturer’s minimum recommended level. The CTA plant was running the burner (Eclipse) at a maximum natural gas pressure of 11 inches of water column—which is below the minimum rate of 14 for this burner model. In addition, the burner’s fixed gas butterfly valve was set at 80 to 90 percent closed to reduce gas input. Recorded flow rates indicate that the burner, with a maximum output rating of 5.5 million Btu/hr (at a maximum gas pressure of 2 psi at the proportionator inlet), was being operated at only 210,000 Btu/hr. All timers on the burner control panel were found at their minimum settings—contradictory to the National Fuel Code, which requires a timed purge cycle prior to burner ignition. The audible alarm mounted on the cabinet door of the burner control box (presumably for alerting operating personnel of conditions such as flameouts) was not electrically connected. Particulate matter was observed on the electronic components and the cabinet lip, where the door engages the cabinet. The amount of particulate matter indicated that the cabinet was open frequently during operation. The high gas pressure cutoff switch was set too high to control an over-gas pressure situation. This setting allowed the feeding of excessive amounts of gas into the burner if a high-pressure situation occurred, such as failure of the pressure regulator. The main gas line primary or safety valve (2-inch flanged, North American) was found with a loose actuator cover and showed debris accumulation on the upper mechanical parts (see Figure C-1). This dust, fiberglass, and oil contributed to the valve’s failure to adequately close, thereby creating an internal leak in the gas line. During down time or “burner-off” conditions, the safety valve may have been leaking natural gas through to the gas vent line at the rate of 7.5 L/min. In the “burner-on” condition with the gas control valves open and the normally open solenoid gas bleed valve closed, there was still a 0.7 L/min leak-through to the vent system from the bleed valve itself. 114
Therefore, at any given time, it was possible that there was continuous gas leakage through the gas vent lines. The electronics for the oil pump control box were mounted on a plywood base plate. Several feed- throughs were inadequately sealed. Under observed conditions, the burner control boxes would not meet the intended dust-proof NEMA ratings. Failure to comply with these standards exposes the internal electronics to potentially damaging environmental conditions. The burner 405 oil pump was found to have no abnormalities beyond the damage attributed to excessive external heat. There is no indication of failure or that the oil pump acted as an ignition or initiation source. If the pump had been operating at the time of the incident, the oil may have acted as an additional fuel source. No significant external gas leaks into the building were found. All internal gas leaks (i.e., gas control valve, gas bleed valve) would have been directed to the externally piped gas vent line. CSB reviewed these findings and conclusions and determined that equipment testing results identified no single component failure as the cause of the incident. 115
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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
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4.0 Process Description The product
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4.1.2 Mat-former and Baghouse In th
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Circulating fans and dampers direct
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• Manually striking baghouse bags
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5.0 Incident Description 5.1 Pre-In
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• The line was one week past due
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forklift with a semi-enclosed cab d
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panels and lights down inside the b
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occurred in the southeast corner of
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5.3.3 Firefighting Activities 5.3.3
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5.4 Incident Aftermath The CTA inci
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6.0 Understanding Combustible Dust
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As depicted in Figure 11 (Eckhoff,
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Figure 12. Mechanism for a dust fir
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7.0 Reconstructive Analysis To dete
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urned clean but otherwise intact an
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7.1.2 Other Possible Initiating Eve
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Table 3 Borden Chemical Black Pheno
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7.3 Line 405 Equipment Testing CSB
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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 and 74: 8.5 Work Practices 8.5.1 Production
Page 75 and 76: operating the oven with the doors o
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: II controllers, only manufactured a
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
Page 125 and 126: Subtree A Second dust explosion abo
Page 127: Subtree C Most CTA personnel had a
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