Just days into his post as the Imperial Sugar Co.'s chief executive, John Sheptor was touring the company's Port Wentworth, Ga., refinery when a blast knocked him back about 100 feet to the floor. Sheptor walked away unscathed, but the explosion on Feb. 7, 2008, killed 14 workers and left 38 people injured.

More than one year after the incident, Sheptor says the refinery located near Savannah is on the road to recovery with newly implemented safety features and standards aimed at minimizing the presence of sugar dust, which two federal agencies concluded was a primary contributor to the explosion. The plant is expected to be fully operational by the fall. Among new features in the rebuilt facility is the implementation of dense-phase conveying systems rather than bucket elevators or screw conveyors to transfer product to storage.

The dense-phase systems will move sugar through a transfer pipe as a "solid bullet," leaving no room for a combustible dust cloud to form, whereas other systems have an open space that can create a combustible dust environment, Sheptor says. The U.S. Chemical Safety Board (CSB) noted in its investigation of the explosion that at least one blast occurred near a bucket elevator that lifted sugar from the refinery and carried it to storage silos. The previous five-story packaging area is being rebuilt as a two-floor structure with all the equipment on the ground floor and electrical wiring on the second-level floor to close any space above the packaging machines where dust can accumulate.

Technology Isn't Foolproof

The new systems should lessen the likelihood of a repeat incident, but technology alone isn't a panacea to process manufacturers' safety issues. In April, CSB determined that an explosion that killed two workers at a Bayer CropScience plant in August 2008 resulted from safety management lapses, possibly related in part to a lack of worker training on control systems after a maintenance shutdown.

Workers begin rebuilding silos at the Imperial Sugar Co.'s Port Wentworth, Ga., refinery where 14 workers were killed and 38 injured in a Feb. 7, 2008, explosion. After the blast, the tops of two silos storing sugar were missing, suggesting that at some point explosions occurred within the structures, according to a federal investigation.

"Prior to starting up, Bayer had recently upgraded the computer control system for the unit, replacing a Honeywell system with one purchased from Siemens," said CSB lead investigator John Vorderbrueggen in an agency statement. "The control screens were completely different -- and Methomyl production equipment control was changed from a keyboard to a computer mouse -- yet operators had not been fully trained and prepared to operate the complex process equipment on the new system."

Any time a process facility adopts new technology, plant operators should be consulted first, says Joe Scalia, a controls system architect for Invensys Process Systems. "If you're going to bring a new system into an existing manufacturing operation, the people who are the current operators and the current production people should be involved in helping define the requirements for what the new system is going to do."

Frequently, that doesn't happen, says Scalia. "So now you have a new system in and the guys who know it are your skilled tradesman and/or whatever instrumentation control techs you have and they often, as the people who should be experts, don't get nearly enough training when the system comes in the door," Scalia explains.

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