Tosco Avon Oil Refinery Fire

On February 23, 1999, a flash fire occurred at the Tosco Avon, California refinery killing four workers and critically injuring one other. The accident occurred while a critical piping repair job was underway on the crude fractionation unit. A small naphtha leak had been reported on February 10, but almost two weeks had lapsed while workers attempted to isolate the circuit and physically remove a corroded section of line. The unit remained in production while this work was taking place. 

The Tosco incident illustrates the importance of safe work practices and, in particular, the need to provide strong principled leadership in the field. Over the past few years, the quality of raw feedstock had varied and problems had heen reflected in the operation of the chemical desalter. Consequently, a marked deterioration in quality was noted in the crude unit operation. Before 1999, a number of serious incidents had occurred at the rehnery, some of which involved fatalities. The refinery had also undergone several recent personnel changes. 

The initial incident involved a pinhole leak on a 6-in. line located 112 feet above grade. The unit might have been shut down at this point, but a decision was made to keep it on line. Efforts to isolate the circuit by closing four block valves failed. The line remained hot and the level in the downstream stripper vessel continued to rise. Several attempts were made to depressure the circuit and free drain all the residual naphtha. At least 15 work orders were issued over a 13-day period and most of these failed to meet the company s own work standards. 

Both the failure of the isolation valves to hold and the difficulty in draining the system were due to solid build up in the circuit. In the previous two-year period, the refinery had changed its crude feedstock resulting in operating difficulties on the unit desalter. Carryover of salts led to accelerated corrosion in the crude column and associated piping circuits. 

Corrosion products plugged the lines making it difficult to operate the stripper. Ultimately, the stripper operation was discontinued while the crude column remained in operation. This should have signaled the need for a major turnaround. Management did not have the perspective to analyze and prohe the reasons behind these operating problems. 

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