Pallet racking is a steel frame system that stores loaded pallets on horizontal beams in several levels. The main types are selective racking (every pallet directly accessible), drive-in racking (deep lanes, highest density, last-in first-out), push-back racking (pallets on inclined nested carts, last-in first-out) and pallet flow racking (gravity rollers, first-in first-out). Whichever system is used, the pallet must be suited to it: its bottom deck, stiffness and condition decide whether it can safely span the beams.
The main racking systems
| System | Access | Stock rotation | Storage density | Typical use |
|---|---|---|---|---|
| Selective | Every pallet directly accessible; single or double deep | FIFO or LIFO possible | Lower, needs many aisles | Wide product range, few pallets per product |
| Drive-in / drive-through | Forklift drives into the lanes; limited access | LIFO (drive-through can allow FIFO) | Highest, aisles eliminated | Large quantities of few products |
| Push-back | Pallets stored a few deep on inclined carts; access from one aisle | LIFO | Medium to high | Moderate numbers of pallets per product |
| Pallet flow (gravity) | Pallets roll on inclined rollers from loading to picking side | FIFO | High | Perishables, date-sensitive goods, order picking |
A comparison from a rack supplier summarizes the trade-off: selective systems prioritize flexibility and frequent access over density, push-back balances density with reasonable selectivity, and drive-in maximizes cubic storage but sacrifices accessibility and needs inventory compatible with last-in, first-out handling. Drive-through variants and other designs such as double-deep, shuttle and mobile racking extend these options. Highly automated systems are discussed in pallets in automated warehouses.
Standards that apply
In Europe, adjustable pallet racking is covered by a family of CEN standards:
- EN 15512: design of steel static storage systems (adjustable pallet racking), the structural design standard.
- EN 15620: tolerances, deformations and clearances.
- EN 15629: specification of storage equipment.
- EN 15635: application and maintenance of storage equipment, which requires ongoing visual checks and documented expert inspections at regular intervals.
In the United States, the main standard for design, testing and use of industrial steel storage racks is ANSI MH16.1. Local building and fire codes add requirements for seismic design, sprinkler clearances and load signage.
Racks must carry visible load signs showing the permitted loads per beam level and per bay. The rack owner is responsible for inspection and for repairing damage; a damaged upright or beam can fail without warning.
Beam and bay planning
Planning figures commonly used for pallet racking are the beam load (capacity for each beam level), the bay load (total for all levels in a bay), the beam pitch (vertical spacing between levels) and the aisle width. Beam pitch must equal the pallet height plus the load height plus the clearance needed to put pallets in and take them out. Upright depth must allow the pallet to rest securely on both beams, and aisle width should suit the type of forklift and its turning radius.
Typical decision points:
- Pallet size and orientation in the bay, with the number of pallets per level.
- Load per pallet and the beam rating for that load.
- Handling equipment: counterbalance, reach truck, very-narrow-aisle truck or automated crane; see forklifts, pallet jacks and pallet compatibility.
- Height of the building, sprinklers and lighting.
- Rack protection: guards and column protectors against forklift impact.
Pallet requirements in racks
A pallet in a rack is not supported over its whole area. It rests on two beams (or on supports) and is loaded in between, so it deflects. The deflection and the bearing area set the main pallet requirements:
- Racking rating: pallets used on beams must have a tested racking load, typically established with a test such as ISO 8611 (see pallet testing standards), and the rating depends on beam spacing. A pallet rated for racking on one beam span may not be safe on another.
- Orientation: pallets are rated for particular orientations. A pallet that is stable with boards or runners spanning the beams may not be suited to the other direction. Follow the pallet manufacturer's instructions and the rack supplier's design.
- Bottom deck: the bottom boards or stringers must reach the beams with adequate bearing. Open-bottom skids and pallets with missing bottom boards are not suitable.
- Condition: damaged, broken or twisted pallets are a common cause of rack accidents. Remove them and do not put damaged pallets into racks.
- Overhang: pallets must not overhang the beams so far that they lose support, and loads must not overhang the pallet in a way that conflicts with the rack.
- Flush, stiff decks: protruding nails, loose boards and soft plastic that sags can cause jams, particularly in push-back, flow and automated systems.
- Same pallet type: mixing pallet types in drive-in and flow lanes causes jams and unstable stacks.
The pallet types to consider are explained in nestable, rackable and stackable pallets, and a pallet's static, dynamic and racking loads in pallet load capacity.
System-specific notes
Drive-in and drive-through
Pallets rest on rails supported by uprights, so the pallets' outer boards or runners must bear on the rails. Forklifts enter the lanes, which makes the rack vulnerable to impact; guide rails and careful operation are needed. Pallet quality matters greatly because the stored pallet is supported only at its edges.
Push-back
Pallets sit on carts that roll on inclined rails. Smooth, flat pallet bottoms and a consistent size give reliable movement. Differences in pallet type, damaged boards or loose film can cause carts to jam.
Pallet flow
Pallets roll on rollers or wheels. The bottom deck must be flat and continuous enough to roll, and pallets with open bottoms or protruding nails can catch. Many installations specify a particular pallet type, such as a plastic or block pallet with solid runners, for this reason.
Inspection and maintenance
Rack safety rests on three habits: visible load signs, protection against impacts and regular inspection. EN 15635 requires both ongoing visual checks by trained staff and a documented expert inspection at regular intervals. A rack inspection typically looks for damaged or bent uprights, deformed or disconnected beams, missing beam locks, floor anchoring problems, and overloaded or misaligned pallets. Damaged components should be unloaded and repaired or replaced according to the supplier's guidance. Fire protection, such as in-rack sprinklers where required, must be considered in the design.
Frequently asked questions
Which racking system is best for high density?
Drive-in racking has the highest storage density because it removes aisles, but it works as last-in, first-out and limits access. Push-back and pallet flow are alternatives with better selectivity or FIFO rotation.
What standards govern pallet racking in Europe?
EN 15512 covers structural design, EN 15620 tolerances and clearances, EN 15629 specification, and EN 15635 the use, inspection and maintenance of racks.
Can any pallet be used in a rack?
No. The pallet needs a racking rating for the beam span, an intact bottom deck, and the correct orientation. Damaged pallets and pallets without a rated bottom deck should not be placed in racks.
How often must racks be inspected?
EN 15635 requires continuous visual checks and a documented expert inspection at regular intervals. The interval is defined by the operator's risk assessment and local rules, and many operators use annual inspections.
Sources
- Pallet racking planning — Boxic24
- How to choose between selective, pushback and drive-in racking — ECS Eco
- What does the rack inspection check? — SSI Schaefer
- Choosing the right storage rack system — Manufacturing.net
- How Much Load Can My Pallet Carry? — Virginia Tech Center for Packaging and Unit Load Design