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Angle of Repose Dangers



Every Monday by
Grain Journal
Editor Kendall Trump

The angle of repose of a granular material, such as grain, is the steepest angle of descent or dip relative to the horizontal plane to which a material can be piled without slumping.

At this angle, the material on the slope face is on the verge of sliding. The angle of repose can range from zero to 90 degrees depending on the material.

When bulk materials are poured onto a horizontal surface, such as within grain storage structures, grain pods, bunkers, or exterior ground piles, a conical pile will form. 

The angle of repose is related to the density, surface area, shapes of the particles, and the coefficient of friction of the material?

A material with a low angle of repose forms flatter files than a material with a high angle of repose.

In other words, the angle of repose is the maximum angle at which an object can rest on an inclined plane without sliding down.

The angle of repose will vary based on the commodity handled:

  • Corn - Approximately 21.5 - 23 degrees.
  • Soybeans - Approximately 25 degrees.
  • Wheat - Approximately 25 degrees.
  • Oats - Approximately 28 degrees.

Grain that forms an angle steeper than its angle of repose may indicate a potential problem with grain condition and poses entrapment and engulfment hazards.

Workers should evaluate the grain's angle of repose prior to entering grain storage structures and when working with grain storage piles, pods, and bunkers.

The requirements outlined in OSHA's Grain Handling Standard 1910.272 must be implement when applicable.


Live and Learn (PowerPoint Slides). Retrieved from

Best Management Practices For Stored Grains in South Dakota (PowerPoint Slides). Retrieved from:

By: Joe Mlynek is president of Progressive Safety Services LLC, Gates Mills, OH;; and content creation expert for Safety Made Simple Inc., Olathe, KS;

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