Press Release from CSB About Root Cause Analysis/Investigation of Imperial Sugar Company Explosion and Fire
The following press release is from the U.S. Chemical Safety Board, Washington DC.
Statement of CSB Investigations Manager Stephen Selk, P.E., Updating the Public on the Investigation of the Imperial Sugar Company Explosion and Fire, Savannah, Georgia — February 17, 2008, 1 p.m.
Good afternoon and welcome to this first U.S. Chemical Safety Board briefing on the Imperial Sugar Company explosion and fire.
I will begin this afternoon by explaining the Chemical Safety Board’s role. Following that I will present a primer on dust explosions. And then I will show you a pair of large photographs and describe some of the devastation to the Imperial sugar refinery. Finally, I will try and answer any questions you may have.
The state fire marshal, firefighters, the police, and agents of the Bureau of Alcohol, Tobacco, Firearms, and Explosives departed the site on Friday evening after ruling out any intentional setting of a fire or explosion. They have left because this tragic event was an accident.
Two federal entities remain onsite at Imperial Sugar, the Occupational Safety & Health Administration (otherwise known as OSHA) and the Chemical Safety Board. We are working with each other both logistically and technically. However, we will conduct independent investigations. The reasoning for that is OSHA is a regulatory arm of the government and the Chemical Safety Board is not. The Safety Board is an independent scientific and technical agency. Our mission is prevention. We are here to identify how to keep this from happening again at Imperial Sugar and across the country at other industrial establishments. We will do that by making public our findings and issuing safety recommendations. The Board may make recommendations to trade associations, professional organizations, code making bodies, companies, and even to the government itself through recommendations to OSHA if appropriate.
We recognize Senators Isakson, Chambliss, Kennedy, Enzi, and Murray for their attention to this tragic event and their joint request that both the Chemical Safety Board and OSHA conduct thorough investigations. We also thank Representative Barrow and House Labor Chairman Miller for their concern and support during the investigations.
The Board will conduct a thorough investigation to understand why this tragedy occurred. The product of the investigation will be a detailed written report that we will release to the public. We may also conduct public briefings and hearings here in the community over the coming months, as appropriate.
The Chemical Safety Board has been concerned about dust explosions for at least four years. In 2003 the Board investigated three catastrophic dust explosions. One at West Pharmaceutical Services in Kinston, North Carolina, where plastic powder that had accumulated above a suspended ceiling exploded, killed six and gravely injured many others. At CTA Acoustics in Corbin, Kentucky, phenolic resin – another plastic powder – exploded killing 7 and again injuring many others. And at the Hayes-Lemmerz automobile wheel plant in Indiana, aluminum powder exploded killing another worker. That plant has since closed. Both the other plants had to be demolished and rebuilt.
After investigating these three explosions in just one year the Chemical Safety Board undertook a larger study of the extent of the industrial dust explosion problem. The Board identified 281 fires and explosions over a 25-year period that took 119 lives and caused 718 injuries. Some 24% of these incidents took place in the food industry. Pursuant to its findings the Board made several recommendations – including recommendations to OSHA – which OSHA has so far partly acted on. But the tragic event that occurred here in Savannah demonstrates that the problem of dust explosions in industry has yet to be solved. It is a problem that requires further attention.
Chemical Safety Board investigators arrived at the Imperial Sugar Company refinery approximately 18 hours after the explosion and we have been here since. Additional Safety Board investigators will arrive on Monday. The full resources of the Board are at the disposal of the investigation team and they will be brought to bear accordingly.
The team has been conducting interviews and examining damage. There is much more work to be done and we will keep you apprised of our progress in future briefings.
Let me now provide a primer on dust explosions:
It is necessary for five elements to be in place for a dust explosion to occur.
First is the presence of a combustible dust itself. That can be almost any organic material – grain flour, plastic, corn starch, pharmaceuticals, and even powdered metals such as aluminum. And as was the case here in Savannah sugar particles are a combustible dust.
An important parameter is the particle size. Finer particles are more likely to be both ignitable and dispersible. Additional parameters are particle shape and the molecular composition of the substance itself.
A second needed element is a source of oxygen. Because air contains appreciable amounts of oxygen, air is all that is necessary to support an explosion.
Thirdly, the dust needs to be dispersed into the air.
Finally, some energy source is required to ignite the mixture. That may be something with as little energy as static electricity or a stronger energy source such as an open flame or an electrical fault.
A final element is confinement. And because buildings have walls, ceilings, floors and roofs, they create confinement. However, another form of confinement may be process equipment and even ducting. It can be ironic that ducting used for dust extraction and other equipment such as dust collectors can themselves be conducive for the initiation of dust explosions.
An important attribute of dust explosions is that they may propagate. In such instances some primary event occurs that kicks up larger amounts of dust that may have accumulated and disperses the dust into the air. When this happens the stage can be set for catastrophe. A very large flammable dust cloud ignites with devastating consequences. In other instances an initial explosion may simply propagate as the blast wave ahead of a rapidly advancing flame front – the fireball – which disperses more dust and ignites as the fireball expands.
When a dust explosion occurs in a building, walls may blow out, floors may heave, and ceilings may collapse. This can all occur in a few seconds. It is therefore not unusual for local fire protection and electrical systems to be almost instantly crippled. Occupants may at first find themselves burned, or blown about, or struck, or among rubble. At worst they may experience all of that. At first they may find themselves in darkness or the obscurity of smoke. But fires initiated by the thermal energy of the explosion may follow and grow. The scene is set for tragedy.
Let me now turn to the circumstances of the Imperial Sugar Company refinery explosion here in Savannah. There are two photographs that I will show you that depict the physical devastation to the facility.
In the first photograph three large storage silos are visible. The granular table sugar produced in the refinery passed through and was stored in these silos. The tops of two of the silos are missing or largely missing suggesting that at some time in the sequence of events, explosions occurred within them. In the foreground there is a building in which there has obviously been an explosion. The brick walls are largely blown out. Sugar was packaged in this building. Additionally, granular sugar was pulverized into powdered sugar. There were other operations in the building as well. This building will figure prominently in the ensuing investigation. To the left or southwest is an area where cartons of the packaged sugar were palletized and then transferred to the storage warehouse. This area displays fire damage as opposed to explosion damage. There has been a fire which has caused the steel structure of the building to soften from heat and to collapse.
Let me turn now to the second photograph. This photo was taken by CSB investigators from an elevated platform suspended by a large crane. To the left side of the picture there are the remains of a burned out building. It is my understanding that this interior building dates back to a very early time in the refinery’s evolution. It was constructed many decades ago and while it had brick walls and a steel truss much of the construction was timber. A maintenance shop and the refinery laboratory were in this building. The building is almost completely consumed by fire. To the east adjacent to the silo, known as the number one silo, there was a bucket elevator that lifted the sugar from the refinery and carried it to the silos. Explosion and fire damage appear in this area and further eastward.
As you can see the damage to the facility is widespread and extensive. In the ensuing weeks, investigators will enter these areas as part of their effort to reconstruct the explosions and fires.
It is also apparent in the photographs that many structures within the refinery have been compromised. It will be necessary to perform a strategic disassembly of these areas while, simultaneously allowing for investigative access. The Imperial Sugar Company has engaged structural engineers to assist them and we will also do so if necessary. This afternoon I will meet with the company and their engineers to begin this planning process.
This is a most difficult time for the people of the Imperial Sugar Company and for the community here as a whole. Imperial Sugar employees have cooperated with the Chemical Safety Board. We appreciate their cooperation and look forward to working with them further to help prevent something like this from happening again here and elsewhere.
I will now take your questions.
[For more information contact CSB Public Affairs Specialist Hillary Cohen at (202) 446-8094 cell or Daniel Horowitz at (202) 441-6074]