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Grain Elevator SafetyBrad Freeman, CIH, CSP
Gary Hulbert, CHMM, CSP
Grain Elevator Overview
• Types and components of grain elevators
• OSHA standards
• Hazards associated with grain handling facilities:• Engulfment
• Explosions/combustible dust
• Electrical hazards
• Entanglements
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Grain Elevator
• Grain elevators typically consist of:• Dump pit
• Leg
• Distributor
• Down spouts
• Bins
• Conveying system
Parts of a grain elevator
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Dumping grain into the dump pit
Grain Leg with Down Spouts
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Grain Leg-Bucket elevator
1964-2013 Statistics
• Purdue’s Agriculture Confined Space Incident Data Base
• Entrapment represents 80% of all cases
• 45% of entrapments had corn as the medium
• 20% are under the age of 21
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1964-2013 Statistics• 1,640 documented grain bin incidents
• 1,201 involved entrapment or engulfment with free flowing grain
• 1964-2008 – 73% of entrapment leads to death
• 2008-2012 – 46.2% entrapments lead to death
1964-2013 Statistics
• 300,000 exempt grain handling facilities
• 70% of incidents occur on exempt facilities
• Falls from heights are on the increase since the 1990s
• Equipment entanglements are third leading incident
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Agriculture Confined Space Injuries-2013
• Purdue annual summary of grain related entrapment and engulfments
• 33 grain entrapment cases, 14 falls, and 12 equipment entanglements (including augers)
• Entrapments account for 49% of documented cases
• 4 Asphyxiation/poisoning
OSHA Standard 1910.272
• OSHA issued grain handling standard in 1987
• Standard addresses walking on or underneath grain
• The hazards include: engulfment and entrapment
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OSHA Standards
• OSHA standards• 1910.22 Walking/working surfaces
• 1910.23 Guarding floor and wall openings and holes
• 1910.111 Storage of anhydrous ammonia
• 1910.272 Grain handling facilities
• 1910.301-399 Electrical
• 1910.1000 Air contaminants
OSHA Standard 1910.272
• Standard covers: • Hot work
• Entering bins
• Inside bucket elevator legs
• Preventative maintenance
• Housekeeping
• Emergencies and training
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Grain Handling Engulfment
• More than 600 people have been engulfed and suffocated over past 40 years
• Purdue research indicates that 80% of cases resulted in fatalities
Geographic Distribution of Grain Entrapments for 2013
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Engulfment in grain bin from:Standing on moving grain
Bridging conditionsLoosening grain on side of bins
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Worker Entry into Grain Storage Bins –Flowing Grain Buries Worker
2-3 seconds to react with auger running
4-5 seconds worker is trapped
22 seconds worker is covered
Worker Entry into Grain Storage Bins –Bridging Condition
Bridging from unloading – auger is off
Auger starts – grain falls
Worker completely covered
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Worker Entry into Grain Storage Bins –Accumulation on Side of Bin
Pile of grain on side Grain falls Worker suffocates
Worker Entry into Grain Storage Bins –Rescue During Bridging
Person outside secured to bin
Person on ground can go for help or assist in rescue
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Amount of time it takes to be engulfed in grain
Pressure at each stage of engulfment
Rescue Equipment Available
Grain rescue tube surrounds worker
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Case Study - Engulfment
• Facility manager and worker enter bin when grain stops flowing
• Auger is left on
• After 5 minutes, manager exits bin leaving worker alone
• Worker becomes completely engulfed
• No one is aware that worker is still in bin
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Hazard Prevention
When workers enter storage bins:
• Turn off and lock out all powered equipment
• Prohibit walking down grain
• Provide all employees a body harness with a lifeline or a boatswains chair
Hazard Prevention
• Provide an observer stationed outside the bin or issue entry permit
• Test the air within a bin or silo prior to entry
• If detected by testing, vent hazardous atmospheres
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Combustible Dust - Hazard Prevention
• Written housekeeping program
• Identify "priority" housekeeping areas in within 35 feet of inside bucket elevators
• Dust accumulations in these priority housekeeping areas shall not exceed 1/8th inch
Grain Dust Explosions
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Westwego Louisiana Grain Elevator
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Atchison Kansas-6 employees killed 2011
Combustible Dust
To prevent dust explosions:• Implement a PM program
• Minimize ignition sources through controlling hot work
• Install wiring and electrical equipment suitable for hazardous locations
• Design and properly locate dust collection systems to minimize explosion hazards
• Install an effective means of removing ferrous material from grain streams
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Combustible Dust
• OSHA's grain handling standard requires that belts for 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
Combustible Dust• 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
• 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
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Case Study – Combustible Dust Explosion
• Tail pulley may have come off shaft
• Pulley struck concrete wall, creating sparks
• Mineral oil used to wet grain was not in use on day of explosion
• No alignment monitor for belt
Insert photo
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Grain Explosion
Grain Explosion
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Grain Explosion
Electrical
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Insert photo
Floor Opening
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Machine Guarding
• Screw conveyors
• Sweep augers
• Rotating parts of motors
• Belts and pulleys
Screw Conveyor
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Case Study – Caught in Auger
• Top of auger approximately 3 feet above ground
• Cover had been removed from top of auger
• Worker attempted to step over auger
• Leg wrapped up in auger
• EMS can’t remove worker
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Sweep Auger
• A horizontal auger used to push grain remaining at the bottom of a storage bin
• Sweeps grain toward the bin's discharge sump opening
• The sweep rotates around the discharge opening to "sweep" the grain toward that opening
• The screw portion of an auger is often at least partially covered by some type of guard
• It is accurate to describe a sweep auger as an "unguarded ... Auger”
Sweep Auger
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Sweep Auger
Sweep Auger Policy
• Follow 1910.272 permit requirements
• De-energized & LO/TO sweep and sub-floor augers before setting-up/digging-out
• Install and secure grates over sub-floor auger
• Sweep auger must be guarded as designed by manufacturer
• No walking on grain at depths presenting an engulfment hazard
• Rescue trained
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Sweep Auger Policy
• Use engineering controls to prevent contact with auger (use of administrative controls alone is insufficient)
• Use speed control mechanism or bin stop device to prevent uncontrolled rotation of the sweep auger
• No hands, legs, or other similar means to manipulate an operating auger
• To adjust auger, it must be unplugged (w/ plug controlled by adjuster) or locked out
Grain Vacuum
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Grain Vacuum
Grain Vacuum Hazards
• Dropping or releasing the nozzle on the grain surface can quickly pull the nozzle down into the grain and become buried
• In response, the operator may try to locate and lift the nozzle while the vacuum is running causing the grain to be sucked out from under them, burying him or her in seconds resulting in a fatality
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Grain Vacuum Hazards
• Used on partially spoiled grain
• Vacuum operators are at risk of being engulfed due to bridging and grain collapse
• Grain vacuums should have emergency stopping device
• Operators need to follow manufacturer operating guidelines
Conclusion
• Grain Bin Overview
• Statistics
• Standards that apply to commercial operations
• Hazard prevention
• Combustible dust
• Machine guarding
• Resources
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Questions?
Gary Hulbert, CHMM, CSP
Phone number: 574-583-9216
Brad Freeman, CIH, CSP
812-876-4904
