How can you be sure the pallet rack you ordered is up to the challenge?
These pictures are real, sent to us by a customer. We are not naming names, but the pallet rack was made by a well-known rack manufacturer here in the U.S. and sold by a well-known nationwide material handling dealer. The rack is in a big heap now because it did not hold up to the challenge. The system was “under designed,” meaning the design of the rack did meet the use. The pallet rack did not ultimately carry the load it was supposedly designed for — and the the entire system had to be removed. Both the material handling dealer and the manufacturer in this case were responsible for the error.
What does it take to properly design a pallet racking system?
There are a number of factors that come into play when designing a pallet racking system. The distributor/dealer (or the manufacturer, if dealing directly) is responsible for asking the customer all the right questions, collecting the layout drawings, along with all pertinent data.
Here’s a look at the information that should be gathered to make sure your rack system is designed to perform as it should.
Soil Bearing Capacity
In a storage facility or warehouse environment, as weight is distributed down through the pallet rack storage system, it is ultimately distributed into the soil beneath your building. It is important to determine the soil bearing capacity to confirm that it will meet the load requirements of your racking system.
The actual flooring in the facility plays a role too. Floor slab thickness and concrete strength in pounds per square inch (PSI) are factors that will help decide the pallet racking system that will safely hold your materials.
Know the dimensions of the pallets (including product overhang and product height) being stored; and know the minimum, maximum, and average weights of the pallets.
Vertical Beam Spacing
Vertical Beam Spacing (VBS) is the maximum distance between levels, or the distance from the floor to the first beam level, whichever is greater. An upright frame’s stated capacity is affected by this measurement.
It’s important to understand how the loads will be distributed because stated beam capacities are based on uniformly distributed loads, meaning loads that are evenly spread across the beam pairs.
Any pallet rack system that is in seismic zones 2A, 2B, 3, or 4 with loads above 8’ must be designed to resist seismic activity. To achieve compliance in your local municipality, special requirements will have to be met. When designing a seismic zone pallet rack system, an analysis must be performed by a seismic engineer.
How steel performance characteristics affect your racking system.
Once all of the project data is gathered, the rack system can be designed for your specific project. The type of steel used and the steel quality will factor in to how your rack system will perform.
Your rack capacity is dependent on the type of steel used in the manufacture of the rack. While roll formed rack (cold roll-formed steel) can have high capacities, structural steel rack (hot-rolled) has even higher load capacities. Learn about the differences in roll formed and structural steel here.
The thickness (gauge) of the steel of both beams and upright frames affects the capacity. The thicker the steel (the lower the number), the more weight it will hold, but note that a stated steel gauge is actually a range of steel thickness, not a fixed number because gauges can vary by up to 18%. This variance doesn’t invalidate the gauge as an indicator of capacity, but it’s important to understand that gauge is not the only factor.
Tensile & Yield Strength
Tensile strength and yield strength are important measures of a steel’s ability to perform in an application. Different grades of steel will have different tensile and yield strengths, and this will affect pallet rack capacity. It’s generally accepted and recommended by engineers that steel used for pallet rack have a minimum yield strength of 50,000 psi. How can you know what you are getting? Ask for a mill certificate. (Learn more about tensile and yield strength here.)
We take the design of your pallet rack system seriously. Our engineering department is here to ensure that your rack will stand up to the challenge it was designed for. Next Level uses a high yield strength carbon steel. Our frames start at 55,000 PSI, and our beams start at a minimum 60,000 Kpsi yield steel. We can produce mill certificates for every piece of coil that we purchase.
This article was originally published on teh Next Level Material Handling Blog, August 21, 2017.