Rack storage
Rack storage is the support condition where a pallet sits on two (or three) rack beams with nothing underneath, so the pallet itself must span the gap. It usually gives a pallet's lowest load rating: in a PDS example, the same 48x40 rated 1,558 lb racked across its length versus 5,223 lb on the floor.
Also called racking, racked, beam rack, free-span racking
Reviewed
Racking direction
| Condition | What spans the beams | Example span on a 48x40 |
|---|---|---|
| Racked across length | the stringers | 44 in |
| Racked across width | the top deckboards, between outer stringers | 36 in |
Racks may use 2 or 3 beams; a third beam shortens the span. Shelf support (rigid decking) is far kinder than open beams.
How capacity is checked
The pallet acts as a beam: bending strength and deflection over the free span govern. Notched stringers are weakest at the notch. palletdesign.ai runs an indicative simple beam check (uniform load, 2 in bearing on each beam, allowable bending stress for the species) and labels the result as a screening number. A certified rack rating needs a PDS analysis or a test to ASTM D1185 or ISO 8611.
What to specify
State the rack type (selective, drive-in, push-back, flow), which way the pallet is racked, the beam span or clear opening, and any deflection limit. Costco, for example, asks for racking capacity with a user-set deflection limit in its PDS reports; confirm with the current vendor guide. See racking pallets.
Questions
- Why is a pallet's rack capacity lower than its floor capacity?
- On the floor the whole bottom is supported. In a rack the pallet must bridge the gap between beams, so bending and sag limit the load.
Related
- Racking pallets: rack capacity, orientation and spanHow pallets carry load in racks: across-length vs across-width racking, beam span, bearing, deflection limits, and how to size stringers for a racked load.
- Free spanFree span is the unsupported distance a pallet bridges between supports, such as rack beams. A 48 in pallet on beams typically has about a 44 in free span.
- DeflectionDeflection is how far a pallet sags under load. Typical limits are about 2% of span in racking (about 0.75 in on a 44 in span) and 0.5 in for automated systems.
- Floor stackingFloor stacking is the support condition where a pallet rests on the floor, often under other loads. It gives the highest ratings, falling as stacks grow.
- Pallet load capacity: safe load, support conditions and ratingsPallet load capacity depends on support: floor, stacked, forklift or racked. How safe load differs from breaking load, and how ratings are set.
- RFQA pallet RFQ (request for quote) asks suppliers to price a pallet. It should state size, load, handling, storage, quantity, annual volume and compliance needs.