Optimal use of the internal volume of a 20-foot marine tank requires accurate calculation of the usable area, since the standard height of 2591 mm and width of 2352 mm dictate strict limitations for the placement of home-made structures.
When planning racking system It is necessary to take into account not only the dimensions of the stored items, but also the load-bearing capacity of the corrugated floor, which can withstand a distributed load of up to 7300 kg, but is afraid of the point pressure of narrow supports.
Independent production of the frame allows you to adapt each tier to specific needs, avoiding voids that are inevitable when using ready-made store solutions, and turning the transport module into a full-fledged warehouse complex.
Dimensional analysis and interior space planning
Before purchasing metal, you should take accurate measurements of the inside, keeping in mind that the usable width between wall corrugations may vary depending on the container manufacturer.
The standard length of 5900 mm allows you to organize several storage areas, dividing the space into compartments for large cargo and small parts, using vertical space as efficiently as possible.
It is important to leave technological passages at least 700 mm wide to provide access to the far corners and the possibility of loading equipment if the container is used as a mobile garage.
- 📏 Measure the exact height from floor to ceiling at three points, as the floor may have unevenness.
- 📐 Determine the location of the stiffeners on the walls for attaching additional elements.
- 🚪 Consider the dimensions of the end doors and the possibility of their full opening to 270 degrees.
The layout should be built around a central axis or along one of the long walls, leaving free access to the end for possible unloading of heavy equipment.
Selection of materials and calculation of load-bearing capacity
To create a reliable frame, it is most often used profile pipe square or rectangular cross-section, which provides better torsional rigidity compared to angle.
The optimal choice for vertical racks would be a pipe with a cross-section of 60x60 mm or 80x80 mm with a wall thickness of at least 3 mm, which guarantees the stability of the structure when fully loaded.
For horizontal beams (crossbars), a profile of 40x60 mm or 50x50 mm is suitable, which allows you to lay heavy sheets of plywood or OSB boards on them without deflections.
⚠️ Attention: Using round pipe for shelving is not recommended, as it is more difficult to attach shelves to it and is less resistant to lateral loads.
The load is calculated based on the weight of the items planned for storage, with a mandatory safety margin of at least 30% in case of dynamic impact during loading.
For shelves for heavy tools, use plywood with a thickness of at least 21 mm or sheet steel 2-3 mm.
Required tools and supplies
The quality of the welds and the accuracy of the cut directly affect the geometry of the entire product, so having a working welding machine and an angle grinder is a must.
To work, you will need a set of measuring tools, including a tape measure 5-10 meters long, a building level and a magnetic square to control right angles during assembly.
Protecting the metal from corrosion inside the container is critical due to the possible formation of condensation, so there should be an adequate supply of rust-resistant primer and paint.
- 🛡️ Primer-enamel “3 in 1” for protection against rust and decorative coating.
- 🔩 Fastening elements: bolts, nuts, metal screws for assembling dismountable units.
- 🧱 Sheet materials: plywood, OSB or metal sheet for laying shelves.
Do not forget to prepare personal protective equipment: a welding mask, leggings and a respirator, since the work will take place in a confined space with limited ventilation.
☑️ Checking readiness for welding
Step-by-step instructions for assembling the frame
Assembly begins with the manufacture of side frames, which are easier to weld on a flat surface outside, and then brought inside for final installation and connection with jumpers.
First, the rectangular contour of each section is welded, after which the vertical posts are welded in increments corresponding to the planned span width, usually 1000-1200 mm.
Horizontal shelf lintels are welded to the inside of the studs, allowing the decking sheets to be subsequently installed flush with the edge of the frame.
| Item type | Profile section (mm) | Installation pitch (mm) | Span Load (kg) |
|---|---|---|---|
| Vertical stand | 80x80x3 | 1500-2000 | up to 2000 |
| Horizontal beam | 60x40x2 | 500-600 (tier height) | up to 500 |
| Diagonal (brace) | 40x20x2 | As needed | Gain |
To increase the rigidity of the structure, it is recommended to use diagonal braces or gussets at the junction of racks and beams, especially if you plan to store heavy automobile units.
The secret to sustainability
Additional fastening of the tops of the racks to the ceiling beams of the container will prevent the rack from tipping over during an earthquake or a strong roll of the vehicle.
Specifics of installation inside the container
The finished sections are inserted through the end doors, so the maximum size of the assembled frame should not exceed the width of the doorway with a margin of 2-3 cm.
Attaching the rack to the container floor must be careful: you cannot drill through the corrugated floor, breaking the tightness; it is better to use the existing holes for the rigging brackets or attach it to the lower strapping beams.
If the floor is wooden (plywood brand is often used Brown Bamboo or tropical rocks), you can use powerful screws, but only to fix the support heels, without creating through holes.
⚠️ Attention: It is strictly forbidden to weld structures directly to the walls or floor of the container, as this damages the anti-corrosion coating and leads to rapid corrosion of the metal.
To secure it from shifting during transportation, you can use rubber anti-slip mats under the supports or temporary wooden wedges spread between the wall and the stand.
Corrosion protection and finishing
The microclimate inside a metal volume promotes condensation, especially during temperature changes, so high-quality painting is not just decoration, but a necessity.
All welds must be cleaned of slag and coated with primer, after which at least two layers of weather-resistant enamel, preferably hammer type, are applied to hide minor defects.
Wooden shelf elements also require treatment with an antiseptic or varnish to prevent rotting and mold in conditions of high humidity.
- 🎨 Use light paint colors for shelves to visually expand the space and improve lighting.
- 💡 Provide places for attaching LED strips under each tier for local lighting.
- 🌬️ Leave gaps between the ends of the shelves and the walls for air circulation.
Regular maintenance includes checking mounting points and refinishing paintwork where chips or scratches have occurred.
The main secret to the durability of a rack in a container is high-quality ventilation of the container itself and the absence of contact between the metal of the shelves and the wet floor.
Do I need to cook the rack inside the container?
Welding inside is highly undesirable due to the risk of fire and smoke. It is better to assemble them in sections from the outside and bring them in ready-made, connecting them with bolts.
What is the maximum load the floor can withstand?
A standard floor can withstand up to 7300 kg of distributed load, but the point pressure from the legs of the rack should be minimized by supporting platforms.
What is the best way to paint metal inside?
Alkyd enamels or primer enamels for rust are optimal, which can be applied even to corrosion residues, after first cleaning the loose layer.