Grain Storage Bins and Confined Spaces – Special Hazards

Entering grain storage bins can be a very dangerous activity and requires following safety procedures to prevent potentially fatal hazards. The atmosphere inside the bins can sometimes be toxic and lack adequate oxygen. There is also a danger that workers can be engulfed by grain and suffocate as a result. In many cases, the grain storage bin dust can combine with available oxygen or other material to cause intense flash fires.

Grain storage bins are configured in such a way that they fall under OSHA’s Confined Space Entry standards in 29 CFR 1910.146 and the new 1910.146 Subpart AA for Construction worksites. Companies that store, install or maintain these bins should undergo General Industry confined space training or, if applicable, Construction Industry training  as a cornerstone to an overall, compliant safety program.

Safety Precautions for Grain Storage Bins

The following safety procedures should be followed when entering grain storage bins:

• Turn off, disconnect, lock-out and tag, or block off all equipment, particularly grain-moving equipment.
• Test the air in the bin for oxygen content and the possible presence of hazardous gases before workers enter. Ventilation should be provided, if necessary, to eliminate unsafe atmospheric conditions. If the unsafe conditions cannot be eliminated, respirators should be provided to workers.
• Prohibit “walking down” grain to make it flow.
• Prohibit entry where grain is built up on the sides of  grain storage bins.
• Provide each worker with a body harness that has a lifeline, or with a boatswain’s chair. Ensure that the lifeline is long enough and positioned in a way that will prevent the worker from sinking more than waist-deep in the grain.
• Provide workers with rescue equipment, such as winch systems.
• Have an observer outside the grain storage bin who is equipped to provide assistance or perform rescue operations.
• Ensure that the observer and the workers inside grain storage bins maintain visual, voice or signal line communications at all times.
• Unless the employer is present during the entire operation, a permit should be issued each time a worker enters a bin certifying that all of the above precautions have been implemented.

The hazard of engulfment within grain storage bins can be caused by several different situations. “Walking down” grain can result in the grain acting like quicksand and a worker can become buried within a few seconds. Another cause of engulfment is known as bridging. This occurs when a worker stands on or below “bridged” grain, which is grain that has clumped together due to moisture or mold. There can be empty spaces below the clumps that can cause the bridged grain to suddenly collapse under the weight of a worker, causing the worker to become buried in the grain storage bins. Grain which has accumulated on the sides of a bin can suddenly collapse onto a worker. Sometimes workers are instructed to dislodge the grain from the bin’s sides and it will collapse during this procedure. Often when other workers attempt to rescue a coworker who is buried in grain, they also become victims.

By following these procedures which are required by OSHA’s Inspection of Grain

Handling Facilities standard, 29 CFR 1910.272, injuries and fatalities of workers entering grain bins can be prevented.