And How to Prevent It
What is a racking system collapse?
An ideal racking system consists of many factors including robust construction with solid materials engineered to RMI industry standards. These systems are loaded and unloaded by operators who never impact the system. But in the real world, a perfect system doesn’t exist.
The collapse of a racking system is an unusual happening, but unfortunately it’s not as rare as it once used to be. Racking systems are advanced engineered systems that are designed to specific requirements to meet exacting needs. Modern systems tend to make even better use of the vertical storage space by increasing the design load the racks can support. Forklift equipment design has also changed, resulting in higher speeds over time to increase operator efficiency and product moving capabilities.
If you would like to see videos of what a warehouse racking system collapse looks like, click here. CAUTION: these videos can be very graphic!
The causes of a collapse
Every racking system collapse is somewhat different from the others. A single factor usually doesn’t end up causing a collapse, but various factors, when combined, can ultimately end up causing a rack collapse.
Many different factors contribute differently to the collapse based on several variables involved in the system. For example, the type of products stored in the racks, the weight of these products, the height of racks, the protective equipment installed, changing the original engineered design and configuration, aisle width and lift truck or lift equipment impacts / collisions to the system and so much more.
The most commonly used type of racking system is Roll Form Pallet Racks (RFPRs) but C-channel structural or tubular uprights have become increasingly popular due to their durability and impact resistance. A pallet rack system consists typically of two main components: the upright frame and the load support beams. The upright frame consists of two vertical posts with horizontal and diagonal supports unitizing the front and rear post. The pallet beams engage into and are supported by the frame itself typically by pins, hooks, or bolts.
The pallet rack uprights are slender members which are strong in compression but are prone to buckling even under relatively minor frontal or side impacts to the front or rear frame post. The weight of the products stored on the pallets is transferred to the ground through the uprights. Damage due to various contributing factors can end up causing the buckling, which could result in a failure.
A warehouse racking system doesn’t collapse out of nowhere. Various factors contribute to the damage that ultimately results in the collapse. Here are a few common reasons and what to look for when identifying potential problems:
1. Forklift damage
A forklift is arguably your best friend for moving products in a warehouse. It lifts and carries weights that can’t be managed efficiently by a human being. However, this type of machinery sometimes doesn't work as planned. Due to unexpected behavior by the forklift itself, or operator error, the forklift might impact the rack. Some typical impacts are caused when narrow aisle forklifts become disconnected to the way your guidance system, rear end collisions caused by backing out of the rack on the opposite side of the aisle, forks slicing frames while pivoting, outrigger impacts on the bases of columns, side impacts to the frames, and pallet impact with struts and uprights while loading and turning into or out of the bay. Depending on the magnitude of the force exerted by the forklift or the pallets during the impact — the system might collapse immediately or could cause structural damage that can result in a collapse later on. Multiple minor or major impacts to the system in different locations in the same row of racking can cause a critical reduction in system capacity resulting in a catastrophic collapse.
2. Overloading or uneven distribution of the load
The system is designed to bear weights up to a safely-defined limit. A weight density exceeding that limit can cause integral damage over time to all components.
Loading the pallet support beams with uneven loads can also be a cause of structural damage. Beams are fabricated and welded at the ends. If weight is distributed unevenly, it can cause structural damage to the load support beams and welded connections over time.
3. Non-engineered or relocated rack system
The majority of warehouse racks are highly engineered systems and are meant for use in a specific location for a specified application. A rack that ideally works for storing a specific product may not work for the storage of another product in a different warehouse. Several variables are included in the calculations performed during the design of a rack tailored for a specific warehouse. Some of these are operational loading stress, rack sustainability, forklift travel distance, and speed calculations just to name a few. If the rack system is moved to a different location engineering calculations need to start from scratch to make sure the system is compliant with the new location and use.
If the engineering calculations are overlooked or ignored during the design or relocation of the racks, the system might not be able to properly hold the load — and could collapse.
Many companies chose to purchase used racks as they are cheaper. Some even tend to reuse racks from a previous project in a new application while doing so, the factors involved in the equation of safely reusing the racks are typically overlooked, which could result in a catastrophic system failure.
Slow and over-time damage is also a possibility that could contribute to the overall collapse probability. Specifically corrosion of anchor plates, struts, frames, and connection fasteners. Corrosion happens when the steel of racking parts is directly exposed to the environment, due to lack of protective coatings like galvanizing, paint or powder coating. Corrosion rates can depend on the amount of ambient standing water, humidity, caustic environment and temperatures. It can cause part failure in just a few years if not dealt with expeditiously.
5. Incorrect reuse of racks
Every rack is built differently and is engineered to support different levels of loads under various circumstances. Consulting with a reputed OEM rack company or experienced engineering firm familiar with the design and testing of storage racks can help you understand that capability and the different variables involved, i.e., beam capacity, upright capacity, and the alterations in these capacities due to different factors related to spacing or loading.
6. Setup errors
A pallet racking system might just look like a lot of shelves just stacked up — but it’s not that simple. There’s a lot of planning and calculations that go into the setup process of a racking system. Many types of safety components are installed to maintain the stability and integrity of the system.
Low-cost, low-quality system installations could overlook the safety measures that keep the system intact. Cutting corners during the design and installation can cause short- and long-term damage that has a high possibility of ultimately resulting in a collapse.
How do you prevent a racking system collapse?
After a racking system collapses, it’s costly to deal with the damage done and the logistics of clean up not to mention the catastrophic human component if involved. Some precautionary measures can help you keep this disaster away. Here are a few of them:
Repair damaged components immediately
RMI (Rack Manufacturers Institute) ANSI MH 16.1-2012 requires that all damage components be immediately unloaded and removed from service until repaired or replaced. RMI supports engineered repair but there are only currently two qualified repair companies operating in the United States that meet the tough RMI’s industry engineering requirements. The two qualified companies are members of RMI’s pallet rack repair industry subgroup. The original OEM rack companies may also be sources for engineered repair and or replacement components. The critical issue is, insist on a repair company that has valid, current engineering for all its repair components. Insist that all components are made in North America and are not imported from countries that cannot guarantee or have a reputation for questionable or unverified certification standards for steel. American made with American steel is always your best investment and peace of mind for the safety of your workforce.
Invest in engineering and experts
Get in touch with experienced consultants to deal with problems like poor rack designs and incorrect reuse. A carefully engineered racking system will last you for longer periods, with minimum risks of sudden collapses or long-term damages.
Warehouse racking systems are the backbone of any commercial business. While racking failures aren’t very common, their rate has been increasing over time. Investing in precautionary measures can save you from the hassle of having to deal with the risks of racking system collapse.
Install solid steel rack guard devices to protect your pallet racks
Purchasing and installing safety equipment sounds expensive, but it’s not. It essentially saves you from the risk of having to deal with a potential warehouse collapse. Installation of protective gear, like rack guards, and end of aisle guards is very viable in preventing sudden collapses upon impacts. Remember the old saying, “pay a little more now, save a lot more later”.
Allow generous aisle space
Making the most out of your warehouse space is the end goal, of course — but safety comes first. Allowing generous operational space between aisles can provide the necessary room for machinery to operate safely, reducing the risks of accidental impacts.
Promote operational training
Inexperienced operators are more likely to panic and make mistakes while handling heavy loads. Try to hire experienced operators with clean safety records. This practice will help protect your investment in your warehouse. If you can’t afford them, promote in-house training programs to boost the abilities of your existing staff.