A Furnace Temperature Safeguard Is Altered

A major fire erupted in a nonflammable solvents manufacturing unit in a U.S. Gulf Coast chemical complex. A furnace tube in a natural-gas-fired heater ruptured due to overheating. At least 1,800 gallons (6,800 liters) of a combustible heat transfer fluid spilled and burned intensely. Within about 25 minutes, the intense hot fire damaged four levels of structure and associated process equipment. The plant on-site emergency squad quickly and properly responded. However, the price tag for short-lived incident was over 1.5 million in direct property damage and over 4 million in business interruption (U.S. 1979). Fortunately, there were no injuries. [2] 

Operators use the heater to heat each reactor to startup conditions, one at a time. The reaction is exothermic, and once the reactor is up to full production the heater is shutdown and the operator isolates the reactor from that heater circulation loop. When another reactor is scheduled for startup, the operator aligns the valving, starts the circulation pump, ignites the heater burner, and brings the reactor up to temperature. 

Investigators determined that during a hectic day of operations, the chemical process operator erred. On this afternoon, he inadvertently tried to startup the heater with the burner firing and the heater tubes isolated from the circulating pump by closed blocked valves. Shortly after firing the heater, the lead operator checked the flame pattern but observed nothing out of the ordinary. 

Within 20 to 35 minutes after the heater was fired, a fire-water sprinkler system tripped. A heater flame failure alarm occurred a short time later. Witnesses stated flames were over 50 ft. (15 m) high in approximately five seconds after the tube ruptured. The fire damages 

This was a complex case, requiring a full and detailed investigation by members of technical, engineering, operations, and process safety groups. Investigators made numerous interviews and detailed observations. Inspectors found a 6-inch (150 mm) long and 4-inch (100 mm) wide hole on a ballooned section of a heater tube. Normally the tube had a 6.6 inch (168 mm) outside diameter, but it had swollen to about 8.0 inches (200 mm) in diameter at a point about 2.5 ft. (0.75 m) above the heater floor. 

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Let s apply the concept of shared responsibility to an incident found earlier in Chapter 6. See A Furnace Temperature Safeguard Is Altered, in Chapter 6, to see the entire incident and the six supporting photos. 

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