May 1, 2014
Working in or around a grain bin exposes farmers and storage workers to serious and life threatening hazards, including fires and explosions caused by grain bin dust accumulation, suffocation from engulfment and entrapment, and crushing injuries and even amputations from grain handling equipment.
Accidents associated with grain bins are nothing new. According to researchers at Purdue University, more than 900 cases of grain engulfment have been reported with a fatality rate of 62 percent over the past 50 years. In 2014, as of mid-March, two fatalities and at least two serious injuries have resulted across the nation from grain bin mishaps.
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In addition to engulfment, grain bin mishaps also include the risks of exposure to toxic fumigants, potential for unexpected fires and the threat of explosions caused by the build-up of combustible grain dust.
Grain bin safety and the dangers associated with engulfment and entrapment were the central theme of a special Coastal Bend Grain Storage and Handlers Safety Conference at the San Patricio County Fairgrounds Civic Center in Sinton April 23.
Texas AgriLife Extension specialist David Smith, one of the conference presenters, told producers that a growing percentage of engulfment cases come from facilities that are exempt from Occupational Safety and Health Administration (OSHA) regulations.
"One thing we need to be aware of is just how quickly a man can be trapped in flowing grain. As one example, if the auger is moving grain at 68 bushels per minute, with a six foot tall man weighing 165 pounds standing inside the bin, it only takes about five seconds before he gets trapped. After about 25 seconds, he would be completely engulfed," Smith warned.
He said most incidents occur when grain is being moved or transported and someone enters a bin to walk down the moving grain or is buried by falling grain that was bridged to the walls and suddenly collapsed. Smith said moving grain acts like quicksand and can bury a worker in seconds. In addition, grain that is too wet or in poor condition can cause pockets to form and these can collapse beneath a worker as he walks across the grain.
"Once they are stuck, the behavior and weight of the grain make it extremely difficult for a worker to get out of it without assistance. Even with assistance, it can be a monumental undertaking," Smith explained.
Pressure: The heavyweight of grain bins
Safety officials say one foot of grain over an individual provides about 300 pounds of pressure. With two feet or more around the body, it would be extremely difficult to pull yourself out without assistance, and even with assistance there is high probability that it could take a considerable amount of time to free someone engulfed by grain.
Smith says if a 165-pound individual is fully emerged in grain, it would require 900 pounds of lift pressure to pull him out of the grain, and lifting a submerged person can cause additional injuries.
The frequency of grain bin incidents and the growing number of fatalities in recent years, many of them children, fueled industry concerns and garnered the attention of OSHA safety officials. The federal agency sent notification letters to approximately 13,000 grain elevator operators last year warning employers not to allow workers to enter commercial or co-op grain storage facilities without proper equipment, precautions and safety procedures, such as turning off and locking/tagging out all equipment used so that the grain is not being emptied or moving into the bin, and training.
"Another risk is that grain bins are confined spaces and there is often organic material stored inside that can produce dangerous gases including carbon dioxide, nitric oxide in high concentrations and other toxic gases caused by rotting or infected grains. Also, fumigants used to treat grain bin pests can be the source of dangerous toxins in a bin," Smith adds.
Exposure to fumigants can cause permanent central nervous system damage, heart and vascular disease, and lung edema as well as cancer. These gases can also result in a worker passing out and falling into the grain and becoming engulfed, often resulting in death by suffocation.
Another cause of injury can be the mechanical equipment within grain storage structures, such as augers and conveyors that present serious entanglement and amputation hazards. Workers can easily get their limbs caught in improperly guarded moving parts that can result in mangling, accidental amputation and in some cases death.
"OSHA issued warning letters to the grain handling industry following a series of incidents including the suffocation of two teenagers in an Illinois grain elevator in 2010, and since then commercial grain storage operations have been targeted for inspections and a number of hefty fines have been issued. So understanding the law, safety education and training, and having the right equipment and procedures in place are critically important if you want to maximize safety and avoid stiff fines," Smith said.
Following a tragic year of fatalities, in 2010 OSHA established rules and procedures for workers entering grain bins and safety procedures that all workers must rigidly follow. According to a U.S. Department of Labor website, a fact sheet entitled Worker Entry Into Grain Storage Bins is available for grain storage operators.
Also, a health information bulletin entitled Combustible Dust in Industry: Preventing and Mitigating the Effects of Fire and Explosions, and a Hazard Alert: Combustible Dust Explosions fact sheet are available.
Know the rules, follow the rules
According to Smith, OSHA requires that for all workers entering storage bins, employers must:
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 boatswain’s 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 his 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.
OSHA also says to prevent dust explosions and fires, employers must:
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 1/8 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 percent of the normal operating speed.
Implement a preventive 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—such as hammer mills, grinders and pulverizers—from grain streams so that such material does not enter equipment.
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