Steel bin installation and maintenance
March 9, 2015
During the recent GEAPS Exchange in St. Louis, Missouri, U.S., Kirk Nelson, international sales manager, Behlen Manufacturing, addressed a number of key issues involving the installation and maintenance of steel grain bins as well as safety issues that affect grain elevator workers.
Steel bins have been utilized for grain storage for many decades and are popular in the grain industry because of their durability and longevity. But even sturdy steel structures will lose their strength and deteriorate if not properly maintained.
Nelson said before erecting a steel bin a company should test the soil at the site and take into consideration seismic and wind conditions in the area.
He said one grain company that failed to do proper soil testing ended up with a bin tilting at a 27-degree angle. “You must make sure to find a reputable company to do that,” he said. “If you only do a shallow test you can find that the deeper soil is worse than you think.”
If a grain company is located in an area that has frequent and sometimes severe earthquakes, it must choose a bin that is better able to endure the seismic tremors.
“If you happen to be in a high seismic area, you want to look at a bin that is short and wide as opposed to one that is tall and narrow,” said Nelson, who also noted that certain types of bins are better-suited to windy areas.
Another factor to consider prior to construction at a new site is the storage of the galvanized sidewall sheets. “You don’t want them sitting on site too long where they get rain damage, which can cause white rusting,” he said. “If water gets between the panels sitting close together, this sort of thing can happen. We recommend that you store those sidewall sheets in a dry warehouse if at all possible. White rust over time can turn into red rust, and obviously nobody wants that.”
Grain Bin Maintenance
Nelson said proper grain bin maintenance will ensure that a structure can provide many years of service.
He said a steel bin should be examined on a regular basis from top to bottom, beginning with the roof, roof vents, stairs and ladders. “You want to make sure you have grain cleaned off the roof, peaks, vents and stairs. There’s going to be a lot of dust in your facilities so you want to make sure it is cleaned off to keep rust from occurring as well as preventing slip and trip hazards.”
Any thorough inspection also includes looking for loose, broken or missing bolts, especially on roof stairs, roof ladders and outside ladders, he said. The ladders must be inspected for rusty rungs. Many times rungs rust from the inside out. If this occurs, the rungs will be significantly weakened and must be replaced.
The same goes for sidewall sheets and stiffeners. “Check to see if there are any missing bolts, broken bolts, buckled or torn sheets,” he said. “It’s a lot better to take care of that earlier rather than later.”
Closely examine any openings in the sidewalls. Most bins have some type of access door in the sidewall, but the opening must be properly supported to withstand the hoop stresses. Most doors use some type of tie-bar system. This may be an integral part of the door, such as special door boards, or tie bars that are removable. Other openings might be for flumes, or in larger bins, doors large enough for front end loaders to enter. If any bulging is noticed in these areas, it is essential that the pressures be reduced or corrective action taken. If the bin is empty, make sure all bolts, fasteners, etc., are properly installed before filling.
Be vigilant in looking for any signs of rust and when it is spotted it is important to promptly cover it with galvanized rich paint, Nelson said.
Since the loads on the sidewalls and floor can weigh thousands of pounds, a properly designed and maintained foundation is a must. When performing regular maintenance checks, the foundation is a critical place for inspection. It has to be strong enough to both support the grain and prevent an empty bin from overturning or being pulled off the foundation by high winds.
Nelson said foundations should be checked for uneven settlement and cracking. “You want to make sure the base of the bin is uniformly resting on the foundation, that the anchor bolts are in place and the nuts are tight.”
There should be a watertight seal between the base of the bin and the foundation.
Aeration systems must also be checked periodically, he said. “Remove the fans and check to see if there’s any trash or foreign materials building up in there. Look at the condition of the support brackets and check the transitions for corrosion and those sorts of things.”
Nelson said the price of not doing routine inspections and steel bin maintenance can be costly in the long run, leading to a shortened lifespan of the bin or, worse, a collapsed bin.
“An ounce of prevention is worth a pound of cure,” Nelson said. “Bad things can happen if you’re not keeping your eyes and ears open.”
Nelson also addressed the issue of safety, and offered a checklist for commercial grain facility personnel to follow prior to filling a bin. The checklist included:
Make sure the grain bin is completely cleaned out before refilling it;
Make sure the grain unloading equipment is functioning properly; it’s easier to do this before grain is inside the bin;
Make sure the intermediate gates are closed; and
Make sure no one is inside when you close the door.
Steel grain bins are thin-shell structures, and to maintain their shape and structural integrity, uniform loading of the sidewalls is required.
When filling the bin, to prevent catastrophic bin failure, make sure it is loading in the center. “You could have a lot of issues if you’re putting all the weight on one side of the bin,” he said. “You really need to be right in the center when loading so you’re not putting extra grain on one side of the bin versus the other.”
When initially dumping grain into a newly installed grain bin, Nelson suggests filling it by one-third and letting it settle for 7 to 10 days, and then filling the second third of the bin and letting it settle for another 7 to 10 days before completely filling it. When filling the bin, make sure that you’re stopping at the eaves so grain is not blocking the roof vents.
When unloading a steel bin, Nelson said make sure to unload from the center sump first. “You need to be getting all the grain out of there that you can before moving to the intermediate sumps, otherwise you get a lot of side loading on the bin wall, which can cause some problems.”
One of the most dangerous aspects of grain handling has to do with sweep augers that clean bins after unloading. “Never, under any circumstance, enter the grain bin while equipment is operating,” Nelson said.
He said there are single sweep augers and multiple pass sweeps. If installing a single pass sweep auger, it can put a lot of stress on sidewalls so grain bin operators should check with the bin manufacturer to make sure the bin is designed to handle that stress load.
When sweeping out a bin, an operative wants to make sure there is no bridged grain or vertical crusting occurring, he said.
“You want to run the sweep only after all grain is flowed out from the center sump and the intermediate sumps,” Nelson said. “If the sweep is designed for a multiple pass operation, make sure you lock out the inner sweep before adding outer sweeps.”