Rackable plastic pallets and the beam gap

The gap changes the rating

On a floor, a pallet is supported across its whole base. On a rack, it rests on two beams and the middle is air. The same deck that holds 10,000 lb on a floor is loaded in bending between the beams, and the number it can carry falls. Rehrig Pacific's 40 x 48 rackable lists 10,000 lb static, 4,000 lb dynamic and 2,000 lb edge rack, which makes the racking figure one-fifth of static.

That is why a standard-duty nestable, whose sheet lists no racking rating, is the wrong choice for a rack even when its static number looks generous. If you cannot find a racking load on the sheet, the pallet is not rated for beams.

The empty-trailer cost

Rackable pallets are stiff and heavy, and they do not nest. The same maker lists 540 of them on a 53 ft trailer, against 1,200 or 1,260 of its nestables. A plant that races its racks with 6,000 rackable pallets a month and returns them empty needs 12 trailers (6,000 ÷ 540 = 11.1, rounded up) where a heavy-duty nestable needs 5.

Where to read next

• Specs of a rackable pallet, line by line.
• Plastic pallet racking: beams, supports and what slides off.
• Beam span guide: how span changes the rating.
• Why standard-duty nestables are not rackable.

A beam load worked out

Take a pallet with a 2,700 lb racking load. A loaded pallet of 1,610 lb uses 59.6 percent of it and leaves 1,090 lb; one of 3,228 lb is 528 lb over. Rack engineers also apply their own safety margins, so treat the figure as a ceiling.

A stack worked out

Take a stackable rated 10,000 lb static. The bottom pallet carries the pallets above it, so with each loaded pallet weighing 2,206 lb it can hold 4 above, a stack of 5. With 6,248 lb per pallet it can hold 1 above. This is a ceiling on a flat floor for a still stack, not a promise for a stack that moves or waits.

Questions to put to the maker

• What beam span was the racking load measured across?
• Does the pallet have runners or a cruciform base, and which way do they lie against the beams?
• Is a standard-duty nestable of the same maker rated for racking, or only the heavy-duty one?
• Is the racking load for an evenly spread load, and what happens when the load is concentrated?
• Which rack type was it tested on: edge rack, or a different arrangement?
• Does the maker publish the test method, so a second pair of eyes can read it?
• Does the maker print a deflection limit, and is it met at the printed load?
• Is the racking load printed for this exact model, or only for a family of models?
• What is the lowest rating on the sheet, and is it the one that applies to your use?
• Does the racking figure hold at the top of the temperature range?

From the dock

• Pallets are put on rack by forklift; a rack with tight clearance punishes any sloppy placement.
• Rack inspectors look for bent uprights and overloaded bays; the pallet is a part of the load path they check.
• A pallet bridging two beams flexes at its centre; the more it flexes, the less margin it has left.
• Racks in cold storage are tightly spaced; confirm the pallet rating holds at that temperature.
• Runner pallets lie flat across beams, which spreads load but stops them nesting; cruciform bases do the reverse.
• A beam clip or wire deck under the pallet changes what the rating means; ask which support the test used.
• Do not guess the racking load from the static one; the two numbers can differ by a large factor.
• Overhanging a pallet past the beam is the quiet cause of dropped loads; check the overhang as well as the span.
• Record the pallet model against each rack position, and a failure can be traced to its source quickly.

Words on this page

4-way entry

A pallet that forks or a pallet jack can enter from all four sides.

Edge rack

A rack arrangement where the pallet rests on the edges of the beams. It is the common test case for a racking rating.

Cruciform base

A base shaped like a plus sign under the pallet, which gives a stable footprint and slides well on conveyors.

Closed deck

A solid deck that keeps small items and torn bags from falling through and wipes clean on top.

Dynamic load

The weight a pallet holds while it is moved by a forklift, pallet jack or conveyor. It is lower than static because motion adds shock.

Runner

A continuous rail under a pallet. Runners lie flat across rack beams but stop pallets from nesting.

Static load

The weight a pallet holds while standing still on a flat floor, spread evenly across the deck. It is the highest of the three ratings.

Pallet jack

A hand or powered truck with two forks, used to move a pallet short distances.