The shipping container stacking process is important as it has a significant impact on the operational efficiency of the port. This has succeeded in reducing congestion and costs, both for the port and shipping companies.
Shipping containers are designed to be stacked, often up to 7–9 units high when done properly. They’re built with corner castings and steel frame reinforcement to handle vertical loads.
Neat stacking also facilitates access to containers, speeds up the loading and unloading process, and maintains the stability of containers so that they do not fall and are damaged.
With more efficient operations, the flow of logistics becomes smoother, which in turn reduces transportation costs and speeds up the distribution of goods. To know how to do the shipping container stacking process, find out in this article!
Contents
Key Considerations for Stacking Containers
1. Use of Corner Castings
Stacking is only safe when the corners are aligned and locked together using corner castings or metal blocks. They are located at the top and bottom corners. Never stack by resting the upper container on the side rails or roof panels. That will cause bending and collapse risk.
2. Weight Distribution
Weight distribution matters when stacking shipping containers because it directly affects the stability, safety, and structural integrity of the entire stack. Incorrectly distributing weight can lead to structural failure, tipping, or container damage, especially in tall stacks or modified containers.
Heaviest containers go at the bottom. Each standard container can carry a vertical stacking load of up to 423,000 lbs on its corner posts. For modified or damaged containers, consult structural engineers or limit to 2-3 levels.
3. Foundation and Ground Conditions
Containers that you place below will bear the load. Therefore, you will need a flat, compacted, and level surface like a concrete pad, piers, or footings. Drainage planning to avoid water pooling under the base.
4. Container Condition
Make sure that you only stack containers in good condition, which are free of severe rust or corrosion on the corner posts and dented or warped structural frames. Important to note, modifications like large windows or doors weaken stacking strength unless reinforced.
5. Wind and Safety Anchoring
Wind loads can tip over stacked containers, especially if empty or in high-wind areas. Use tie-downs, bolts, or anchor plates to secure stacks to the ground or adjacent structures.
6. Local Regulations
In most places, zoning codes or building permits are required for stacked container structures (homes, offices, towers). Therefore, you may need engineering approval, especially if people will occupy the upper levels.
How to Stack Shipping Containers
Step 1: Prepare the Stacking Equipment
During the shipping container stacking process, you will need equipment, such as:
- Forklift: to move containers within the storage area.
- Crane: to lift containers from ships to land and vice versa.
- Twist locks or stacking cones: to ensure safety, alignment, and stability during both temporary storage and permanent installations.
- Lifting lugs: for ISO container crane lifting
- Shims or pads: to level containers
- Reach Stacker: to move and stack containers quickly and efficiently.
With those equipments, the stacking process is carried out more quickly and efficiently, so that storage space can be utilized optimally.
Step 2: Prepare the Ground
After you have all the equipment needed, prepare the ground by ensuring it is flat, compacted, and well-drained. Then, use concrete pads, piers, or steel plates if needed. After that, place shims or leveling pads under the base container’s corners to level it.
Step 3: Place the Bottom Container
Make sure the container has no warped corners, bent frames, or rusted posts. Then, use your crane or heavy-duty forklift to move the container into position. Check that all four corners sit evenly and are well-supported. If stacking more than one level, install twist locks into each top corner of the bottom container.
Crane and lifting lugs are best for higher stacking (2+ levels), tight access, and heavy containers. Meanwhile, a forklift is best for 1-2 high stacking in an open yard space.
Step 4: Lift the Top Container
Attach lifting lugs to the top corner castings of the upper container. Then, connect the lugs to the crane cables evenly, ensuring a balanced lift. After that, lift the container vertically to prevent swaying or misalignment.
Step 5: Align and Lower the Top Container
Slowly lower the top container straight down to ensure the corner castings align perfectly. Use stacking cones if available to guide the corners into place. If you used twist locks earlier, lower the top container until it rests fully on them, then twist to lock.
Step 6: Secure the Stack
Lock all four corners using twist locks to prevent shifting or sliding. If stacking outdoors or in windy areas, consider tie-downs or anchoring to prevent toppling.
Conclusion
Stacking shipping containers is a common practice in both shipping yards and container-based construction. However, it must be done correctly and safely to avoid structural failure or safety hazards.
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