OSHA has developed this webpage to provide workers, employers, and safety and health professionals useful, up-to-date safety and health information on grain handling facilities.
What are grain handling facilities?
Grain handling facilities are facilities that may receive, handle, store, process and ship bulk raw agricultural commodities such as (but not limited to) corn, wheat, oats, barley, sunflower seeds, and soybeans. Grain handling facilities include grain elevators, feed mills, flour mills, rice mills, dust pelletizing plants, dry corn mills, facilities with soybean flaking operations, and facilities with dry grinding operations of soycake.
What are the hazards in grain handling facilities?
The grain handling industry is a high hazard industry where workers can be exposed to numerous serious and life threatening hazards. These hazards include: fires and explosions from grain dust accumulation, suffocation from engulfment and entrapment in grain bins, falls from heights and crushing injuries and amputations from grain handling equipment.
Suffocation is a leading cause of death in grain storage bins. Suffocation can occur when a worker becomes buried (engulfed) by grain as they walk on moving grain or attempt to clear grain built up on the inside of a bin. Moving grain acts like "quicksand" and can bury a worker in seconds. "Bridged" grain and vertical piles of stored grain can also collapse unexpectedly if a worker stands on or near it. The behavior and weight of the grain make it extremely difficult for a worker to get out of it without assistance.
Grain dust explosions are often severe, involving loss of life and substantial property damage. Grain dust is the main source of fuel for explosions in grain handling. Grain dust is highly combustible and can burn or explode if enough becomes airborne or accumulates on a surface and finds an ignition source (such as hot bearing, overheated motor, misaligned conveyor belt, welding, cutting, and brazing). OSHA standards require that both grain dust and ignition sources must be controlled in grain elevators to prevent these often deadly explosions.
Falls from height can occur from many walking/working surfaces throughout a grain handling facility. Examples of such surfaces include (but are not limited to) floors, machinery, structures, roofs, skylights, unguarded holes, wall and floor openings, ladders, unguarded catwalks, platforms and manlifts. Falls can also occur as workers move from the vertical exterior ladders on grain bins to the bin roof or through a bin entrance.
Mechanical equipment within grain storage structures, such as augers and conveyors, present serious entanglement and amputation hazards. Workers can easily get their limbs caught in improperly guarded moving parts of such mechanical equipment.
Storage structures can also develop hazardous atmospheres due to gases given off from spoiling grain or fumigation. Workers may be exposed to unhealthy levels of airborne contaminants, including molds, chemical fumigants (toxic chemicals), and gases associated with decaying and fermenting silage. Fumigants are commonly used for insect control on stored grain and many have inadequate warning properties. Exposure to fumigants may cause permanent central nervous system damage, heart and vascular disease, and lung edema as well as cancer. These gases may result in a worker passing out and falling into the grain, thus becoming engulfed and suffocating or otherwise injuring themselves.
What can be done to reduce the hazards in grain handling facilities?
When workers enter storage bins, employers must (among other things):
- Turn off and lock out all powered equipment associated with the bin, including augers used to help move the grain, so that the grain is not being emptied or moving out or into the bin. Standing on moving grain is deadly; the grain can act like "quicksand" and bury a worker in seconds. Moving grain out of a bin while a worker is in the bin creates a suction that can pull the workers into the grain in seconds.
- Prohibit walking down grain and similar practices where an employee walks on grain to make it flow.
- Provide all employees a body harness with a lifeline, or a boatswains chair, and ensure that it is secured prior to the employee entering the bin.
- Provide an observer stationed outside the bin or silo being entered by an employee. Ensure the observer is equipped to provide assistance and that their only task is to continuously track the employee in the bin. Prohibit workers from entry into bins or silos underneath a bridging condition, or where a build-up of grain products on the sides could fall and bury them.
- Train all workers for the specific hazardous work operations they are to perform when entering and working inside of grain bins.
- Test the air within a bin or silo prior to entry for the presence of combustible and toxic gases, and to determine if there is sufficient oxygen.
- If detected by testing, vent hazardous atmospheres to ensure that combustible and toxic gas levels are reduced to non hazardous levels, and that sufficient oxygen levels are maintained.
- Ensure a permit is issued for each instance a worker enters a bin or silo, certifying that the precautions listed above have been implemented.
To prevent dust explosions and fires, employers must (among other things):
- Develop and implement a written housekeeping program with instructions to reduce dust accumulations on ledges, floors, equipment and other exposed surfaces.
- Identify "priority" housekeeping areas in grain elevators. The "priority" housekeeping areas include floor areas within 35 feet of inside bucket elevators, floors of enclosed areas containing grinding equipment and floors of enclosed areas containing grain dryers located inside the facility. Dust accumulations in these priority housekeeping areas shall not exceed 1/8th inch. Employers should make every effort to minimize dust accumulations on exposed surfaces since dust is the fuel for a fire or explosion, and it is recognized that a 1/8 inch dust accumulation is more than enough to fuel such occurrences.
- Inside bucket elevators can undergo primary explosions. OSHA's grain handling standard requires that belts for these bucket elevators purchased after March 30, 1988 are conductive and have a surface electrical resistance not exceeding 300 megohms. Bucket elevators must have an opening to the head pulley section and boot section to allow for inspection, maintenance, and cleaning. Bearings must be mounted externally to the leg casing or the employer must provide vibration, temperature, or other monitoring of the conditions of the bearings if the bearings are mounted inside or partially inside the leg casing. These bucket elevators must be equipped with a motion detection device which will shut-down the elevator when the belt speed is reduced by no more than 20% of the normal operating speed.
- Implement a preventative maintenance program with regularly scheduled inspections for mechanical and safety control equipment, which may include heat producing equipment such as motors, bearings, belts etc. Preventive maintenance is critical to controlling ignition sources. The use of vibration detection methods, heat sensitive tape or other heat detection methods can help in the implementation of the program.
- Minimize ignition sources through controlling hot work (electric or gas welding, cutting, brazing or similar flame producing operations).
- Install wiring and electrical equipment suitable for hazardous locations.
- Design and properly locate dust collection systems to minimize explosion hazards. All filter collectors installed after March 1988 shall be located outside the facility or located in an area inside the facility protected by an explosion suppression system or located in an area that is separated from other areas by construction having at least a one hour fire resistance rating and which is located next to an exterior wall vented to the outside.
- Install an effective means of removing ferrous material from grain streams so that such material does not enter equipment such as hammer mills, grinders and pulverizers.
For more information, see OSHA standard (29 CFR 1910.272).