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Messages for Manufacturing Personnel
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Dust Explosions - Clean up this Hazard! 1
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October 2014 3
In August 2014 the United States Chemical Safety Board (CSB) reported the results of an investigation of a December 2010 explosion in a titanium and zirconium 4 scrap metal processing facility in West Virginia. The explosion resulted in three fatalities and one injury. Here is a brief summary of what is believed to have happened: 1. A blender was being used to process zirconium powder. Employees had observed mechanical problems before the explosion. Blender paddles were striking the sidewall of the blender causing damage. Adjustments and repairs were made but problems continued. Note: All pictures are screen captures 2. It is believed that sparks or heat from metal-to-metal contact between the blender from the US Chemical Safety Board video describing the incident blades and the blender side ignited the zirconium powder. (http://www.csb.gov/al-solutions-fatal-dust3. The burning zirconium dust resulted in a deflagration - hot gases expanded, explosion/) producing a “wind” observed by two witnesses. The burning zirconium dust ignited open drums of titanium and zirconium stored nearby, propagating the fire. 4. The initial explosion lofted other dust in the plant into the air causing a secondary dust explosion and fire.
Did you know?
What can you do?
The CSB has investigated 9 serious combustible dust incidents in the USA since 2003. These explosions and fires caused a total of 36 fatalities and 128 injuries. Five of these explosions involved metal dusts, and three occurred in the same plant. On August 2, 2014 an explosion in a plant in Kunshan, China that manufactures aluminum automobile wheels caused at least 75 fatalities and 180 injuries. Initial reports indicate that the incident was an aluminum dust explosion. Most solid organic materials, as well as plastic powders and many metals, can create an explosive cloud if the particles are small enough and dispersed in the air at a sufficiently high concentration. More information about dust explosions can be found in the following Beacons: 9/2003, 5/2006, and 5/2008. You can view these at www.sache.org.
The CSB report identified many contributing causes for this incident. Most were related to facility design, failure to comply with dust explosion protection standards, and management systems. But there are things that you can do as a plant worker to prevent dust explosions. Know whether or not you have any dust explosion hazards in your plant, and what you must do to ensure proper operation of your plant’s protective systems. US OSHA has a useful poster with guidance on what kinds of materials might be dust explosion hazards: https://www.osha.gov/Publications/combustibledustposter.pdf
Recognize that good housekeeping is critically important for dust explosion safety. Accumulated dust on equipment, floors, and elevated surfaces such as lighting fixtures and ceiling support beams can contribute to secondary dust explosions. Report any maintenance issues which could result in sparking or overheating in any dust handling equipment, and do not operate the equipment until it is repaired.
Do you have dust explosion hazards in your plant? ©AIChE
2014. All rights reserved. Reproduction for non-commercial, educational purposes is encouraged. However, reproduction for any commercial purpose without express written consent of AIChE is strictly prohibited. Contact us at
[email protected] or 646-495-1371. The Beacon is usually available in Arabic, Afrikaans, Chinese, Czech, Danish, Dutch, English, French, German, Greek, Gujarati, Hebrew, Hindi, Italian, Japanese, Korean, Malay, Marathi, Farsi (Persian), Polish, Portuguese, Romanian, Russian, Spanish, Swedish, Tamil, Telugu, Thai, Turkish, and Vietnamese.
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Messages for Manufacturing Personnel
Is sugar an explosion hazard?
Sponsored by CCPS Supporters May 2008
YES, if it is a fine powder or dust! Any material which can burn is capable of causing a catastrophic dust explosion if it is suspended as a fine dust or powder in air or other oxidizing atmosphere. On February 7, 2008 there was a severe explosion in a sugar refinery near Savannah, Georgia, USA. The explosion injured more than 30 people, and the death toll had reached 13 as of the end of March 2008. The explosion is still being investigated, and the detailed causes are not yet known. However, the initial investigation indicates that this was a dust explosion. Many people are not aware of the explosion hazard of many dusts and fine powders. Some examples of materials which may be a dust explosion hazard if present as a fine powder include almost any organic material grain flour, sugar, plastic, corn starch, pharmaceuticals. Powdered metals such as aluminum and magnesium also present a dust explosion hazard.
CCPS PSID Members search Dust Explosion
Do you know what conditions are necessary for a dust explosion? The conditions needed for a dust explosion can be represented as a pentagon (see figure at left above): • FUEL – The presence of a combustible dust. Particle size is important – smaller particles are more likely to be both ignitable and dispersible. • OXIDANT – usually oxygen in the air, which is generally enough to support an explosion. • SUSPENSION – The dust needs to be dispersed into the air. The dust may normally be dispersed in air in the process equipment. In a building, this could be done by a large leak or spill, a small initial dust explosion, or any other disturbance which could shake dust layers off of equipment or lift dust off of the floor. • IGNITION SOURCE – Energy is required to ignite the mixture. This may be something with as little energy as static electricity or a stronger energy source such as an open flame or an electrical fault. • CONFINEMENT – For example, the walls, ceilings, floors and roof of a building create confinement. Plant equipment including process equipment, storage silos, dust collectors, and ducting also creates confinement.. Sometimes an initial explosion occurs and lifts larger amounts of dust that may have accumulated in the plant and disperses this dust into the air. This creates the conditions for a second, much larger explosion, which can be catastrophic. A small amount of dust – a layer as small as 1/32 inch (less than 1 mm) thick on exposed surfaces – can create an explosive dust cloud once suspended. A dust layer can be considered to create a hazardous condition if it covers an area, on all surfaces, greater than 5 % of the floor area of a room. How can you tell if there is too much dust? Two guidelines which people have used are that there is too much dust accumulation (1) when you cannot tell the color of the equipment or floor beneath the layer of dust, or (2) when you write your name in the dust and very slight ridges form at the edge of the letters. Good housekeeping is a necessary safe work practice when dust hazards are concern. Other safe work practices for dust include reducing static discharge potential through the use of grounding and bonding, proper electrical area classification and equipment selection. If your plant handles potentially explosive dusts, make sure that you understand the hazards, and all of the safe work practices and safety equipment needed for safe operations.
Know the hazards of the materials in your plant! AIChE © 2008. All rights reserved. Reproduction for non-commercial, educational purposes is encouraged. However, reproduction for the purpose of resale by anyone other than CCPS is strictly prohibited. Contact us at
[email protected] or 212-591-7319 The Beacon is usually available in Afrikaans, Arabic, Chinese, Danish, Dutch, English, French, German, Gujarati, Hebrew, Hindi, Hungarian, Indonesian, Italian, Japanese, Korean, Malay, Marathi, Persian, Polish, Portuguese, Russian, Spanish, Swedish, Tamil, Thai, Turkish, and Vietnamese.