How do you know that your pallet racking is not being overloaded?
Load capacities per beam level might be indicated on labels affixed to beams. Fair enough, but how do you know whether or not the load capacities are correct, and whether or not the total weight of pallet loads placed per beam level is less than the load capacity indicated?
Truth is, it is not too difficult to overload pallet racking, and this article highlights some of the reasons why.
New, or fairly new, pallet racking is generally not a major concern. For recent installations of new racking, where load capacities were provided, along with a Pre-Start Health and Safety Review (PSR) exemption certificate from the manufacturer, chances are that the load capacities shown on labels affixed to beam levels, or in documentation provided by the manufacturer, should be reliable. In this scenario, one cautionary note is to ensure that the total weight of pallet loads placed per beam level is less than the rated load capacity.
More problematic than recently installed new racking is existing racking which, in many cases, might have been in use for a long time. Over time, changes could have been made to the configuration of the racking and also, some components might have been replaced with new or used racking components. This scenario generally describes the reality in many warehouses and manufacturing facilities. And, to add to the problem, there could be a variety of sizes and types of upright frames and beams in the racking system.
As such, whenever a racking inspection or PSR (Pre-Start Health and Safety Review) is done, great care needs to be taken in order to ensure that the existing components in the racking system are accurately identified. Yes, it does take extra time and effort; but, considering the likely consequences, in event that some of the rated load capacities are incorrect and, as a result, the racking is overloaded, the extra time and effort is well worth it.
It is fair to ask, what are the likely consequences of overloading pallet racking? For one thing, a number of load beams might display a permanent ‘smile’, i.e. deflection; these beams should be replaced. Another consequence could be partial or complete collapse of the overloaded racking.
In the above discussion, a couple of things are important. One is getting the rated load capacities right. And, the other is ensuring that the actual total weight of pallet loads placed per beam level is less than the rated load capacity.
One of the challenges of rating an existing pallet racking system is the variance in specifications of racking components. Let’s say, for instance, that there is racking consisting of upright frames and beams. There might be a variety of upright frames and, even if most of the load beams are 4”D, roll-formed, box beams, there could be 3-1/2”D or 3”D beams in the mix as well. Neglect this ‘minor point’, and the rated load capacities, based on 4”D beams, would be incorrect for some of the beam levels.
This example points to one of the reasons why it is important to be extra careful in accurately identifying components in the racking system.
Another factor that sometimes contributes to uncertainty of the rated capacity of pallet racking is a change in configuration. For example, let’s say that there are 5 beam levels, spaced at 60”H and then, at some point, one of the beam levels, typically the bottom beam level is removed, in order to accommodate taller pallet loads, or in order to have pallet loads double-stacked on the floor. This change in configuration could result in a reduction of the rated capacities of the remaining beam levels above.
Note that a PSR is required any time a change in racking configuration occurs.
There are other factors as well that contribute to the rated load capacity of pallet racking. For example, there are a number of situations where beam levels of pallet racking are completed with wire decks, shelf panels or plywood. The rated load capacity could be incorrect, depending on what the rated capacity was based on, and how the racking is actually used.
Consider a situation where beam levels are completed with plywood decks. If the racking is used in a way that pallet loads are directly supported by both beams (front and back), the rated capacity might be higher than if they are not. However, in actual practice, there is really no way of guaranteeing that the racking, completed with plywood decks, will always be loaded in this way. And, for this reason, the rated capacity of the racking might be reduced based on the size of plywood decks, how they are supported and the direction in which they are installed on beam levels.
In the case of wire decks, somewhat similar reasoning applies, i.e. the rated load capacity per beam level is generally based on pallet loads being supported by both front and back beams. Variations in the way loads are placed on the racking can alter the rated capacity, and result in overloading of the wire decks.
In regards to overloaded pallet racking, there are a number of contributing factors, such as the age of racking components, whether or not changes were made to the racking configuration, and how the racking is actually loaded.
For the reasons mentioned above, and other considerations, it is best to keep on top of things by always having updated documentation for racking. Knowing the rated load capacities of your pallet racking, and ensuring that loads placed on beam levels are less than the rated capacities, can help avoid overloading, which could result in partial or complete collapse of the overloaded pallet racking.
Jack Jagernauth, P.Eng. is a project engineer with Rack Inspections Ontario, an engineering company providing services related to racking safety, racking inspections and PSRs. He may be reached at 905-847-3640 or jack@rackinspectionsontario.ca, or through the company website: www.rackinspectionsontario.ca.