We often hear about the strength of shipping containers in promotions on shipping container security. Strong, durable, and secure – they are the common buzzwords we hear and read on any shipping container product page.
However, do these words actually hold any weight? While we know that shipping containers are structurally strong, people unfamiliar with them don’t know the details.
Because of that, we’ll explain the details of shipping container security below to give you an image of how strong these steel boxes are!
Also Read: The Best Platforms to Move Tall Containers During Work
Shipping Container Construction Materials
Shipping containers owe their robustness to Corten steel (ASTM A588), a high-strength, low-alloy steel infused with copper, chromium, nickel, and phosphorus.
Corten steel forms a stable, self-repairing oxide layer called patina, which slows corrosion progression when exposed to moisture and oxygen.
Standard container walls are 1.5–2.0 mm thick. Meanwhile, critical structural components like corner posts, roof bows, and floor cross-members are reinforced with 6–8 mm steel to support stacking loads of up to nine containers (216,000 lbs).
On the contrary, modified shipping containers use aluminum (lighter but less impact-resistant) and fiberglass (superior insulation but pricier) as construction materials.
Refrigerated containers (reefers), for example, often use fiberglass sandwich panels with polyurethane foam cores to maintain temperatures as low as -30°C.
However, Corten steel remains the industry standard for its balance of strength (50,000–80,000 psi yield strength), cost-effectiveness, and adaptability to retrofitting.
Shipping Containers’ Protection Levels
Now that we know the common construction materials for shipping containers, the next step is assessing how shipping container security fares against damage types.
Against Gunfire
Before we start, we must underline something important – shipping containers are not bulletproof, but their Corten steel walls offer limited ballistic resistance.
So, how do shipping containers actually stand against gunfire? According to calculations, a 1.5 mm wall may stop handgun rounds like 9mm or .45 ACP, but rifles (e.g., 5.56mm or 7.62mm) can penetrate easily.
While shippers don’t deliberately transport containers over warzones rife with gunfire, it’s still important to consider adding anti-gunfire protections.
Although reinforcing containers into resistant to bullets doesn’t make them impervious battle tanks, these steps can still highly boost their safety:
- Ballistic Steel Plating
Adding 10–12 mm AR500 steel plates to exterior walls boosts resistance to Level III (7.62mm NATO) or Level IV (armor-piercing) threats. These changes can add 2–3 tons but are ideal for military or secure storage use.
- Kevlar/Composite Liners
Lightweight Kevlar layers (e.g., Dyneema) absorb bullet energy without adding excessive weight.
- Concrete-Filled Walls
Pouring 6–8 inches of reinforced concrete between steel skins creates a cost-effective bulletproof barrier.
To give you an idea of the kind of steel type you need to prevent certain bullet calibers, you can check the breakup below:
| Ammunition Stopped | Steel Thickness Required |
| .44 Magnum | 10 mm AR500 |
| .30-06 AP | 12 mm AR500 + spall liner |
Against Weather Patterns
Corten steel’s patina layer provides a robust defense against rain, snow, and UV exposure. Properly anchored containers withstand winds up to 120 mph, but unsecured units risk tipping in hurricanes (Category 3+).
Even so, shipping containers by themselves are still subject to exposure to any degrading effects of weather patterns.
With that in mind, some modifications are needed to improve shipping container security against many weather conditions:
- Elastomeric Roof Coatings: Products like Henry Tropicool reflect 90% of UV rays and prevent water pooling that can damage the container’s interior.
- Hurricane Straps: ASTM D3957-compliant straps anchor containers to concrete foundations and resist uplift forces up to 3,000 lbs.
- Insulated Panels: Closed-cell spray foam (R-6.5 per inch) prevents condensation, a leading cause of rust that happens inside the container.
Against Pests and Vermin
Steel construction naturally deters termites, but rodents exploit gaps in door seals, vents, or flooring.
Even worse, if the conditions are sufficient, mold and fungus can grow inside the container because of a lack of proper maintenance.
Because of that, the container’s inherent resistance to pests and vermins means nothing if it’s not properly maintained and upgraded through the following:
- EPDM Rubber Gaskets
Replace standard door seals with 1-inch EPDM gaskets to block mice and insects.
- Steel Mesh Vent Covers
Install 19-gauge stainless steel mesh (1/4″ holes) over vents to prevent entry.
- Floor Upgrades
Replace plywood with marine-grade boards or galvanized steel sheets to eliminate chew-through points.
By doing the recommendations above, you can significantly minimize the chance for pests and vermins to ever sneak into the container.
Against Rust
Corten steel’s patina slows rust but doesn’t outright eliminate it. Coastal salt spray or industrial pollutants can accelerate corrosion, particularly in door hinges and floor joints.
So, what can you do to prevent rust from emerging in your container?
- Sandblasting: Remove 100% of rust using aluminum oxide grit, then apply zinc-rich primers (e.g., Carboline CZ-11).
- Rust Converters: Phosphoric acid gels (e.g., Ospho) convert iron oxide into inert iron phosphate.
- Elevation: Place containers on gravel beds or helical piers to reduce ground moisture exposure.
The steps above are good and all, but you still need to inspect the container every 6 months to see how it holds up.
If you give the container fresh paint, touch up paint scratches within 48 hours to assess its damages.
Lastly, you should reapply the container’s sealants annually if you use them in places with humid climates to prevent rust.
Against Blunt Force
Shipping container security can moderate impacts from forklifts or debris. However, the container can still dent under high-force collisions (e.g., falling trees).
As a result, adding the following can help secure the container from dents:
- Steel Plate Patches
Weld 3–5 mm corten steel patches over dented areas to restore structural integrity.
- Cross-Bracing
Install diagonal steel beams (50x50x5 mm) to distribute impact forces.
- Foundation Stabilization
Use geogrid-reinforced gravel or concrete piers to prevent shifting during collisions.
Against Fire
One thing that makes shipping container security notable among industrial actors is its fireproof nature against fires.
Even so, fires can still damage the container if it burns at particularly high temperatures over an extended amount of time.
Standard containers melt at 1,370°C (Corten’s melting point), but A60 fire-rated units with ceramic fiber insulation withstand 1,000°C for 60 minutes.
To counter that, use the following upgrades to make the container more fire-resistant:
- Intumescent Paint: Swells when heated, forming a char layer that delays heat transfer.
- Fire-Resistant Drywall: Type X drywall (5/8″ thick) adds 1-hour fire resistance to habitable units.
- Smoke Seals: Install intumescent strips around doors to block smoke and flames.
Also Read: 20 Common Issues in Steel Cargo Containers for Sale and Fixes
Conclusion
Shipping container security makes these steel boxes stay relevant after decades of use and potentially for so many decades in the future. To benefit from such security in transporting your cargo during freight, trust Tradecorp’s shipping containers for the job. Built with high-grade Corten steel and designed with exacting specifications, Tradecorp’s various products are the containers you need in any situation. Contact us now!
