Poe Container Loading Calculation Bags Per 20 Vs 40 Fcl
POE Container Loading Calculation: Bags per 20′ vs 40′FCL
Polyolefin elastomer (POE) shipments are commonly packed in 25 kg polyethylene-lined paper or laminated woven sacks with external dimensions near 750 mm × 450 mm × 140 mm. The pellets exhibit an apparent bulk density of approximately 0.48–0.56 g/cm³ when measured by ASTM D1895 Method A or ISO 60, which places a 25 kg bag near 1.8–2.1 m³/t stowage factor. Because POE pellet bulk density is far lower than the density of the solid copolymer, container loading cannot be derived from net weight alone. The floor-loaded bag count in a 20′ FCL is almost always cube-restricted, whereas the 40′ FCL is often rated-payload-restricted when pallet-free bags are used. The following treatment uses representative dimensions and nominal internal ratings from ISO 668:2020; actual container capacities must be taken from the CSC plate and the operator technical cutsheet.
Can Simple Volumetric Division Predict the 20 ft POE Bag Count?
For the representative 25 kg bag, external volume is:
0.750 m × 0.450 m × 0.140 m = 0.04725 m³
A nominal 20′ GP container with internal dimensions 5,898 mm × 2,352 mm × 2,393 mm has a cargo volume of approximately 33.2 m³. The raw volumetric quotient is 33.2 ÷ 0.04725 = 702 bags, equivalent to 17,550 kg. This is below the nominal 28,200 kg payload rating. However, the volumetric quotient is not achievable because the bag footprint cannot fill the container cross-section without void space. Two stable horizontal-plane orientations are available. With the bag length oriented along the container length, the floor layer is 7 bags long by 5 bags wide. With the bag width oriented along the container length, the floor layer is 13 bags long by 3 bags wide. The second orientation is superior because it consumes 5,850 mm of the 5,898 mm internal length and 2,250 mm of the 2,352 mm internal width, leaving only 48 mm longitudinal void and 102 mm crosswise void.
The vertical stacking count is limited by the door opening, not only the internal ceiling. A standard 20′ GP door opening height is approximately 2,280 mm. With an uncompressed bag height of 140 mm, a 16-layer stack reaches 2,240 mm and leaves a 40 mm clearance; a 17-layer stack would require 2,380 mm and cannot pass through the door unless the supplier verifies an average stacked bag height at or below 134 mm. Therefore the pallet-free 20 ft floor-loaded count is 13 × 3 × 16 = 624 bags for uncompressed height, and up to 13 × 3 × 17 = 663 bags when a compression credit is certified. Both values are cube-limited; the corresponding net weights are 15,600 kg and 16,575 kg, only 55–59% of the nominal payload rating. This reveals that the 20′ FCL has unused payload capacity but exhausted geometric capacity.
In a 40′ GP container with internal dimensions 12,032 mm × 2,352 mm × 2,393 mm and door opening near 2,280 mm, the same bag dimensions permit a geometric floor layer of 16 bags along the length and 5 bags across the width when the bag length is aligned with the container length. At 16 vertical layers, the door-limited geometric load is 16 × 5 × 16 = 1,280 bags. If a 17-layer compression credit is accepted, the geometric count becomes 16 × 5 × 17 = 1,360 bags. The raw cube quotient is 67.7 m³ ÷ 0.04725 m³ ≈ 1,432 bags. These geometric and volumetric figures exceed the rated payload. Using a nominal 40 ft payload of 26,500 kg, the payload-limited count is 26,500 ÷ 25 = 1,060 bags. The resulting net weight is 26,500 kg, and the occupied volume is only 1,060 × 0.04725 = 50.1 m³, approximately 74% of the 67.7 m³ internal cube. A 40′ HC container with an internal height of 2,698 mm and a door opening near 2,585 mm can accept 18 uncompressed layers, yielding a geometric count near 16 × 5 × 18 = 1,440 bags, but the same 26,500 kg payload limit still restricts the full unit load to 1,060 bags. Therefore high-cube equipment does not increase the pallet-free bag count for this bag mass unless the destination allows a higher verified payload rating.
Stowage Factor and Bag Compression Effects on Floor-Loaded POE Shipments
Published bulk density and stowage factor data can differ from external bag volume calculations because of bag crown, seal folds, pellet compaction under stack height, and void formation between filled sacks. In floor-loaded operations, the external dimensions are reliably measured before loading, but the effective block volume consumed by a bag can increase by 3–8% after repeated container head movements if the stack settles and the bag crown expands. The calculation above uses a packing efficiency of 1.0 against the rectangular envelope of the bag. On actual loading docks, a 50 mm door-header clearance is conventionally maintained, and the top layer is often omitted when bag fill is inconsistent. When supplier vacuum-packed or compressed bag dimensions are not available, published data for this specific configuration is limited; operators therefore use the CSC plate payload and the internal length, width, and door opening height as the controlling dimensional constraints.
Bag orientation affects both count and floor pressure. In the 20′ GP 624-bag configuration, each stack has a footprint of 0.450 m × 0.750 m = 0.3375 m² and a mass of 16 × 25 = 400 kg, producing a nominal static floor pressure near 11.6 kPa. The 40′ GP payload-limited configuration of 1,060 bags cannot be uniformly distributed as a full cube because the load occupies only 50.1 m³; in practice the bags are distributed over the floor to avoid concentrated floor loading and to meet intermodal loading regulations. Dunnage, air bags, or load-stabilizing sheets should be included as deductions from the rated payload, not as afterthoughts. A shipper who calculates 1,060 bags without deducting 250–400 kg of dunnage and packaging tolerance may exceed the statutory payload if individual bag masses drift above 25 kg.
| Container type | Internal length × width × height | Door opening height | Door-limited geometric count | Volume-equivalent count | Payload-equivalent count | Binding constraint | Load count range |
|---|---|---|---|---|---|---|---|
| 20′ GP | 5,898 mm × 2,352 mm × 2,393 mm | 2,280 mm | 624 bags at 16 layers; 663 bags at 17 layers if compressed to ≤134 mm/bag | 702 bags | 1,128 bags at 28,200 kg | Cube/door | 624–663 bags |
| 40′ GP | 12,032 mm × 2,352 mm × 2,393 mm | 2,280 mm | 1,280 bags at 16 layers; 1,360 bags at 17 layers if compressed | 1,432 bags | 1,060 bags at 26,500 kg | Payload | 1,060 bags |
| 40′ HC | 12,032 mm × 2,352 mm × 2,698 mm | 2,585 mm | 1,440 bags at 18 layers | 1,616 bags | 1,060 bags at 26,500 kg | Payload | 1,060 bags |
When Palletized Loading Becomes the Operational Constraint
Palletized POE shipments require a separate calculation because the ISO 6780:2003 pallet footprint and door clearance override the floor-layer orientation of pallet-free sacks. A 1,200 mm × 1,000 mm pallet can hold the representative 750 mm × 450 mm bag in an interlocked layer of 3 bags without overhang. A 15-layer stack at 140 mm per layer gives a 2,100 mm stack height; with a 150 mm pallet, the total is 2,250 mm, leaving 30 mm under the nominal 2,280 mm door opening. This configuration yields 45 bags per pallet and 1,125 kg net. A 20′ GP deck can accept 8 such pallets, yielding 360 bags (9,000 kg). A 40′ GP deck can accept 20 pallets, yielding 900 bags (22,500 kg). Both values are below the respective payload ratings and below the pallet-free floor-loaded counts. The 40 ft palletized unit does not become payload-limited until the bags per pallet exceed 53; with the stated stack height that would require 18 layers plus pallet height, exceeding the standard door opening. Published data for this specific interlocking configuration is limited; exporters should obtain a pallet loading drawing and a compression-height certificate from the bag supplier before ordering an FCL palletized shipment.
