Air Backup Is Disconnected

A maintenance supervisor decided to temporarily use instrument air as a source of breathing air. For the safety of the workers, he disconnected the automatic nitrogen backup system as a well-intended one-minute modification.  

The nitrogen backup system was not reconnected. Later, when the instrument air compressor tripped, the auxiliary pneumatic power (nitrogen) was unavailable. Without the 

An Operator Modifies tt InstrumMatfon to Handle an Aggravating Alarm 

A chemical process operator taped down the acknowledge button on the instrument cabinet to slop an incessant alarm after a level alarm switch had slipped. The alarm switch slipped down its support into a sump and alarmed every few minutes as the sump pump cycled on and off, The acknowledge button, common to a number of alarms, deactivated the whole system. A critical high-temperatme alarm was not. sounded because of this modification. The operator failed to see the alarm light, and the situation eventually led to a hirge toxic vapor release. [1] 

A major fire empted 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 L) 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, die 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. 12] 

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