This article is based on information from a presentation by Tom Nealey, PE, engineer, Ag Facility Engineers, Bloomington, IL, with assistance from Warren Odekirk, Growmark, Bloomington, given July 13 at the CONVEY ‘21 conference in Omaha, NE. To view a recording of the presentation at no cost, go to convey21.com.
Things were quite a bit different when I got my start in the grain industry back in the 1970s, and there were a lot of bin collapses. I actually know that, for some manufacturers, bin gauging was determined by the marketing departments, and they didn’t employ product engineers.
The engineering of grain structures has improved substantially over the years, but collapses still occur, so it’s important for grain elevator operators to know what to do operationally to minimize the likelihood of bin collapse.
According to data from one of the largest grain facility insurers, the top three causes of bin collapse are:
2. Improper unloading and loading.
3. Age of the structure.
We can’t prevent wind, but we can focus on the other two major causes of bin collapse.
Unloading and Loading
Think of a grain bin like it’s a balloon. The structure will move and reshape, oftentimes irregularly, based on its contents. Off-center loading and unloading can cause the bin to move irregularly, and once that has happened, you can’t move it back to a normal shape with center unloading or loading.
To unload properly with a sidedraw spout, you need to have a flume (see graphic below), which allows grain to fill the bin from the top to minimize the wall pressure and maintain its vertical strength.
Due to safety concerns, many facilities prefer single-pass bin sweeps to double-pass sweeps, so employees won’t have to enter bins. The problem is that many bins older than 10 years are not designed for single-pass sweeps.
With a single-pass sweep, you do not have the ability of a double-pass sweep to reduce the height and even out the remaining grain. Furthermore, using a single-pass sweep in a bin c not designed for it can lead to bin failure over time.
One of the biggest issues we see right now are facility designs that exceed the peak loads of grain bins. Just about every grain elevator is looking to increase material handling capacity, many times by upgrading to a higher-capacity conveyor. However, you need to be aware of the peak load of your grain bins. Exceeding the peak load leads to failure. Be careful when doing new construction atop old bins.
It’s important to inspect older bins visually for signs of wear. Wear will occur naturally over time, but improper engineering or operation will exacerbate it. Some areas to check are:
• Steel thickness.
• Door frames and other openings.
• Crumbling or cracking concrete.
Tucker Scharfenberg, managing editor