Plastic Pallet for Racking Systems: Racking Load, Steel Cores and How to Choose

Many warehouses buy plastic pallets rated at 3,000-4,000 kg static load, place them on rack beams, and end up with sagging or cracked pallets. The reason: racking load - the capacity when only the two ends rest on beams - is completely different from static load on a flat floor. This article explains all three load types, why pallets fail on racking, when steel cores are required, and ICD’s measured racking load table so you can choose correctly.

Three pallet load types: do not mix them up

Every pallet has three separate load ratings. Choosing a racking pallet based only on static load is the most common mistake.

Racking load is always the lowest of the three, typically only 20-30% of static load. A pallet rated 4,000 kg static may carry only 1,000 kg on a rack because the centre has no floor support.

Why plastic pallets fail on racking

Loss of centre support

On a floor the entire underside of the pallet is supported evenly. On a rack the pallet rests only on the two beams and the centre hangs free. The weight of the load is concentrated at the centre, bending the pallet like a loaded bridge. Unreinforced plastic will sag progressively and eventually crack along the middle.

Creep: deflection that grows over time

Plastics exhibit creep, meaning they deform slowly under sustained load. A pallet left on a rack for several weeks under heavy goods will deflect more than when it was first placed there, even though the load has not changed. This is why a pallet looks fine when stacked but fails weeks later.

Warehouse temperature makes it worse

Heat accelerates creep; cold makes plastic brittle. The safe racking load of the same pallet is lower in a warm, unconditioned warehouse than in a cool one. A derating allowance must be applied when the warehouse is not temperature-controlled.

When steel-core pallets are required

A steel core is a steel bar moulded inside the plastic pallet body that absorbs the bending stress at the centre when the pallet spans two beams. Use steel-core pallets when:

Load on the rack exceeds 700-1,000 kg

Standard plastic pallets handle racking loads of 700-1,000 kg. Heavier goods require steel cores to raise the racking capacity to 5,000-6,000 kg without deflection.

Wide beam spacing

The further apart the two beams, the longer the unsupported span and the greater the bending moment. Wide beam spacing always calls for steel cores, even when the load is not exceptionally heavy.

Long-term storage with low turnover

Goods stored on a rack for a long time accumulate creep. Steel cores prevent progressive deformation over months, making them the right choice for long-term storage warehouses.

ICD racking load table for plastic pallets

Measured values. Use this table to select the correct pallet for your racking load, not the static load column.

Pallets without steel cores should only be used on racking for loads below the racking load threshold shown above. Loads exceeding that threshold must use the steel-core series.

Rack accessories that compensate for low racking capacity

If your existing pallets have a low racking load and replacing them entirely is not immediately practical, racking accessories can help support them safely.

Support bars

A support bar is a steel bar placed horizontally across the two beams, sitting under the pallet to share the load and reduce the unsupported span. Pallets with a low racking rating become safer when used with support bars.

Galvanised wire mesh decking

Wire mesh decking - welded mesh panels approximately 50 x 50 mm with 5-6 mm wire - is laid flat across the full beam opening to support the entire pallet base, eliminating the unsupported centre. This is cheaper than replacing all pallets with steel-core units and suits warehouses that already have standard pallets.

How rack type affects pallet requirements

The fewer support points a rack provides, the stronger the pallet or the more necessary the steel core.

Beam span and deflection rules

Acceptable deflection is typically 1/100 to 1/150 of the span length. For a 1,000 mm beam span, maximum deflection should stay below 7-10 mm. The wider the beam spacing, the longer the centre of the pallet hangs unsupported and the greater the deflection, so wide spans require steel-core pallets. When goods will be stored for more than six months, apply an additional derating to account for accumulated creep.

Rules for selecting pallets for racking safely

Use the racking load, not the static load

When describing your requirements to a supplier, state the weight of goods per pallet and confirm that the pallet will be used on racking. Compare your load against the racking load column, not the static load column. Apply an additional 20-30% safety margin for warm warehouses or long-term storage.

Measure beam spacing before ordering

Measure the clear distance between the two beams in your rack. The pallet must sit firmly on both beams without falling through any gap. Wide beam spacing requires a stiffer pallet or a steel-core unit.

Do not use used pallets on racking

Used pallets have degraded over time and their racking load is significantly lower than when new. Racking systems that bear load must always use new pallets with the correct racking rating.

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Frequently asked questions about pallets on racking

1. What is racking load and how does it differ from static load?

Racking load is the capacity of a pallet when only its two ends rest on rack beams with the centre unsupported. Static load is the capacity when the pallet sits on a flat floor with full support underneath. Racking load is always much lower, typically only 20-30% of the static load.

2. Can a pallet with a 4-tonne static load be placed on a rack?

Only for goods below its racking load, which is approximately 1,000 kg. A 4,000 kg static load rating does not mean the pallet can carry 4,000 kg on a rack. Heavier loads require a steel-core pallet.

3. When is a steel-core pallet required?

When goods on the rack exceed 700-1,000 kg, when beam spacing is wide, or when goods will be stored for a long time. Steel cores raise racking capacity to 5,000-6,000 kg and prevent deflection over time.

4. Why does a pallet left on a rack sag over time?

Because of creep, the slow deformation of plastic under sustained load. A pallet may look fine when first placed but deflect progressively over several weeks. Using the correct racking load rating or choosing a steel-core pallet prevents this.

5. Which performs better on racking - open deck or closed deck?

Closed deck pallets generally have a higher racking load (1,000 kg versus 800 kg for the same-size open deck) because of their continuous structure. Both types still need to be verified against their actual racking load rating, and steel cores must be used when the load exceeds that threshold.

6. Can I use standard pallets on racking without upgrading to steel-core?

Yes, by reinforcing the rack: placing support bars or galvanised wire mesh decking across the beams to support the full pallet base. This is cheaper than replacing all pallets and suits warehouses that already have standard pallets with a lower racking rating.

7. Which plastic pallet is suitable for drive-in racking?

Drive-in racking supports the pallet along two longitudinal side rails, which creates high stress at the pallet edges. Rigid pallets or steel-core pallets are required. Standard pallets with a low racking load are prone to sagging and cracking on drive-in systems.

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