Classification section: 2160
Amended order of 29 March 2004 relative to the prevention of risks generated by silos containing cereals, grains, food or any other organic product emitting flammable dust and its implementing Circular of 20 February 2004 (with a list of 264 sensitive silos)
Ministerial order of 29 December 1998 applicable to silos subject to a declaration obligation under section 2160.
Silos and generally storage installations for cereals, grains, food or any other organic product emitting flammable dust, are classified installations under section 2160 of the nomenclature of classified installations. This section includes approximately one thousand permit holding facilities and several thousand facilities with a declaration obligation, complying with the following thresholds:
1. for silos or storage installations:
1a. if the total storage volume is greater than 15,000 m3: the installation requires a permit.
1b. for storage capacity ranging from 5,000 m3 to 15,000 m3, the installation has a declaration obligation.
2. In the case of inflatable structures or tents:
2a. if the total volume of the structure is greater than 100,000 m3, the installation requires a permit.
2b. if the total volume ranges from 10,000 to 100,000 m3, the installation has a declaration obligation.
These installations can generate three main types of hazards: self-heating phenomenon, fire and explosion.
The last two are considered major and very often underestimated hazards.
The main reason is that the nature of the product stored (straw or stemmed cereals, oil and protein crops, sugar, wood, flour, dust particles etc.) seems less hazardous to local residents and even to certain operators than the chemicals used in other industrial sectors.
Self-heating is caused by the aerobic or anaerobic fermentation of the grains, or storage conditions with excessively high temperatures.
If self-heating is not controlled, it can lead to a fire. This type of phenomenon generally occurs following the combination of three factors:
The most dramatic accidents are often caused by explosions, which occur when suspended dust or flammable gases (produced by the self-heating phenomena) are ignited by a sufficient source of energy.
Finally, the three abovementioned events (self-heating, fire and explosion) can sometimes be present in combined form in accident scenarios. In addition, there is also a risk of the structure failing (collapsing) if it is not properly maintained.
2Main accidents: 2 Several accidents with dramatic consequences have led to the creation, then update of the legislation applicable to installations specialising in the storage of cereals, grains, food and any other organic product emitting flammable dust:
From 1997 to 2005, 95 silo accidents were registered in France: approximately 86% resulted in a fire and 7% in an explosion. Furthermore, 6 accidents relate to grain spills due to collapsed or ruptured cells (excluding explosion). Since 1980, 264 French silo accidents have been registered in the ARIA database of the BARPI (BARPI - Office of Risk and Industrial Pollution Analysis). Silo accident rates therefore remain significant, even though it does not always affect the same type of installation. In terms of accident seriousness, 12 fatal accidents have occurred in these installations since 1980, resulting in 33 fatalities. These accidents illustrate the difficulty for emergency and fire services to intervene, the importance of complying with the legislation on silos (notably the necessity of having burning permits in case of maintenance or repair works and systematically controlling the cleanliness of the installation), as well as the fact that accidents are always a possibility, which is why protection measures limiting the effects of explosions are sometimes necessary (blowable areas, discharge vents, isolation)
Example of accidents:
State of the art guide on silos for the application of the ministerial order relative to the risks inherent in silos and storage installations for cereals, grains, food or any other organic product emitting flammable dust.