Not every operation handles the same load on the same pallet. Some store multiple pallet and load sizes in the same industrial storage rack system. That’s why it’s important to share pallet details with the storage rack design engineer upfront. With that information, the engineer can incorporate proper spacing and support into the rack’s structural design. Therefore, by knowing the largest possible load weight and dimension, the engineer can incorporate an adequate space allowance and ensure that the structure can support the heaviest loads.
As explained in RMI’s Considerations for the Planning and Use of Industrial Steel Storage Racks:
Beyond the site-specific geographic and geotechnical requirements, the required design information required to develop and build a specific design for a specific application, will include the planning information relating to the scope of the rack project, the height, depth, and the length of each of the sections of the rack row arrays. This planning-scale information will depend on the kind, variety, and character of the goods to be stored and their unit loads. The unit loads or pallet loads, in turn, will depend on the size and weight of each piece, their packaging, and how each unit load or pallet load will be assembled on a pallet (where pallets are used), in order to know the physical load size and gravity loading appropriate to each pallet-or unit-load position within the storage rack system.
Pallet Clearance Recommendations
Further, regarding pallet depth, the typical industry standard is to use uprights either 44 inches or 42 inches deep. As a result, a 48-inch-deep pallet can rest on the beams with 2 to 3 inches of overhand front and back. Moreover, this equally distributes the load on both beams. To ensure adequate clearance around the largest load placed in a single-selective bay holding two loads is typically:
- 3 inches between the edge of the column and the edge of the widest part of the load envelope.
- 6 inches between the two load envelopes.
- 6 inches between the top of the load and the bottom of the beam above it. This ensures adequate lift-off space in placement or removal.
Guidelines for Handling Multiple Pallet Sizes in Same Rack
For operations that receive multiple sized pallet loads for storage in the same selective rack, there are a few options available for safe handling to ensure that the load remains stable and supported after placement.
- For pallet loads that will not rest on the beams (also called pallet load support members), it is possible to integrate additional pallet supports. Ultimately, these rails extend between the shelf beams at a given level underneath the stored load to help support its weight.
- Properly engineered and capacity rated decking products can rest on industrial steel storage rack beams. Decking spans the distance between the beams and supports the pallet load. Different decking types include welded wire, cold-formed light gauge steel, bar grating, and structural lumber.
- Loads received on pallets not sized to match the racking system and its capacity ratings can be repalletized. This process moves the load onto appropriately sized pallets that will rest safely on the beams.
Additionally, it’s important to note the requirements of the National Fire Protection Association (NFPA) 13 Standard for the Installation of Sprinkler Systems. NFPA 13 typically requires a minimum space in the down-aisle direction between loads of 6 inches. Specifically, this applies to rack installed in a building with overhead sprinklers. This spacing ensures that water will flow through the racking to more effectively suppress a facility fire.
Learn More About Rack Safety
Need more information on proper sizing of racks for safety? Purchase RMI’s Considerations for the Planning and Use of Industrial Steel Storage Racks here.
