• November 25, 2025

What are Shipping Containers Made of?

Shipping containers are engineered to withstand extreme conditions across oceans and land, but what makes them so resilient? From the Corten steel walls that resist corrosion to the reinforced corner castings that bear tens of thousands of pounds, every component serves a critical purpose. This guide explores the materials, structural elements, and manufacturing processes that give shipping containers their legendary durability
06 Nov

Components of a Shipping Container

A shipping container steel shell provides structural integrity, but a shipping container is made up of many components that work together to ensure functionality and performance. From the corner casting to the locking mechanisms and door seals, each part must be designed for maximum resilience and efficiency. The overall durability of a container depends on the quality of every material used in its construction.

Corner castings

Corner castings are reinforced steel blocks at each of the container’s eight corners. They bear the entire structural load, allowing containers to be lifted, stacked, and locked together across ships, trains, and trucks. Made from high-strength cast steel, they’re engineered to handle tens of thousands of pounds without failing.

Tip: When buying used shipping containers, inspect cornercastings for cracks or rust. Damage here compromises both safety and
stackability.

Corner castings are reinforced steel blocks at each of the container's eight corners. They bear the entire structural load, allowing containers to be lifted, stacked, and locked together across ships, trains, and trucks.

Twist locks

Twist locks are small forged-steel devices that secure containers to each other or to a ship's deck. Inserted into corner castings and rotated 90 degrees, they lock containers in place during transport. Built to ISO standards, they're what make stacking possible in high winds and rough seas.

Cross members

Cross members are steel beams running beneath the container floor that support and evenly distribute weight. Made from Corten or mild steel, they directly determine load-bearing capacity.

Forklift pockets

Forklift pockets are steel-reinforced slots spaced 6.5 feet apart along the base of smaller containers, allowing forklifts to lift and move them when empty. Most 40-foot containers lack these pockets due to weight distribution issues.

Safety tip: Never use forklift pockets on loaded containers. This can cause structural failure or accidents. Use cranes or container handlers instead.

Forklift pockets are steel-reinforced slots spaced 6.5 feet apart along the base of smaller containers, allowing forklifts to lift and move them when empty.

Cargo doors

Cargo doors are made of Corten steel with rubber gaskets that create a watertight seal. Locking bars, handles, and cameras ensure secure closure while allowing quick access during loading and unloading.

Cargo doors are made of Corten steel with rubber gaskets that create a watertight seal.

Tip: Inspect rubber seals on used containers. Cracked or dried seals let in moisture, causing rust and mold

CSC plate

Every legitimate shipping container has a CSC plate (Convention for Safe Containers), a metal certification proving it meets international safety standards for structural integrity and transport. The plate must be valid and current for global shipping.

circled are the CSC plate, a metal certification proving it meets international safety standards for structural integrity and transport.

Tip: Check the CSC plate on used containers intended for transport to ensure compliance.

Marine-grade plywood flooring

The container floor is 28mm marine-grade plywood made of hardwood layers bonded with waterproof glue and treated to resist rot, insects, and moisture. It's durable, affordable, and easy to replace when damaged.

Bamboo flooring

Bamboo flooring, found in newer containers, is a sustainable alternative offering high density, natural moisture resistance, and a smoother finish. It's ideal for greener logistics or eco-conscious conversions.

The steel framework forms the foundation, but a container's reliability depends equally on corner castings, door seals, and countless other components. True durability stems from quality materials in every part of the assembly, not just the exterior walls. Choosing the right container ensures all components work together effectively in the long term.

What Material Is a Shipping Container Made From?

While the flooring and hardware vary, the body of a shipping container is primarily made from Corten steel, also known as weathering steel.This durable material is what gives containers their longevity, ensuring a long shipping container lifespan even in harsh environments.

Corten steel is a high-strength alloy containing copper, chromium, and nickel. These elements form a protective oxide layer that shields the inner metal from further corrosion.

Benefits of Corten steel:

  • Naturally resists corrosion and rust
  • Low maintenance and cost-effective
  • High tensile strength for stacking and transport
  • Ideal for long-term outdoor exposure
  • Excellent for modification and construction projects

Even though Corten steel resists corrosion, containers can rust if damaged or poorly maintained. Scratches, standing water, or worn paint can allow moisture in, leading to rust over time. Regular inspections, touch-ups, and proper drainage are key to preventing shipping container rust and preserving its durability.

How Shipping Containers Are Made

Creating a shipping container involves precision engineering, strict quality control, and layers of protection to ensure they last for decades. Here’s a step-by-step overview of how they’re made:

  1. Steel preparation:Large Corten steel sheets are cut to size, sandblasted, and primed with anti-corrosion coatings.
  2. Corrugation:The sheets are pressed into the corrugated pattern that gives containers their signature strength and rigidity.
  3. Frame and panel welding:The steel base is constructed using I-beams, and panels are welded together to form the walls and roof.
  4. Doors and hardware installation:Corrugated doors, rubber seals, locking bars, and hinges are welded into place.
  5. Painting:The entire container is sandblasted and coated with multiple layers of marine-grade paint for additional corrosion resistance.
  6. Flooring installation: Marine-grade plywood (or bamboo) is bolted onto steel cross members, completing the structure.

Shipping containers are built for strength, durability, and long-term use, with materials like Corten steel providing natural corrosion resistance. Proper maintenance, including using the right shipping container paint, helps protect the steel, prevent rust, and extend the container’s lifespan.

Looking for a quality shipping container?

At Viva Containers, we supply high-quality shipping containers that meet global ISO standards for safety and performance. We offer both new shipping containers and used container units, including specialized options like high cubes, open-side, and double-door units to fit your specific needs.

Verified quality Every container we sell is thoroughly inspected, graded, and photographed. We verify that each unit meets structural integrity standards, from reinforced corner castings to intact door seals and certified CSC plates.

Transparent process Our team provides expert guidance on selecting the right container for your project, whether it's for shipping, storage, or conversion. We help plan transport and placement, verifying site access and equipment requirements in advance to ensure smooth delivery.

Viva Containers delivers consistent quality, verified condition reports, and reliable service making us a dependable supplier for first-time buyers and experienced operators alike.

FAQ : What Are Shipping Containers Made Of?

No, standard containers are not insulated, but refrigerated containers have built-in insulation. 

The steel thickness of a shipping container varies by part: side walls and roof panels are typically 1.6- 2mm thick (14-gauge), while corner posts measure about 6mm (0.24 in) and top or bottom rails are around 4mm (0.19 in).

Yes, shipping containers can be safe for living or storage, but only with proper modification and care

Yes, many original shipping container floors are treated with pesticides like basileum and radaleum to protect the wood from insects and decay

Yes, shipping containers are recyclable, but repurposing them for other uses like housing is considered more environmentally friendly because it avoids the high energy costs of the melting process

Yes, a home can be safely made from a used shipping container, but it requires careful planning and professional help to ensure it meets safety standards and local building codes.

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Viva Containers Team

A team with over 30 years of combined experience in shipping container industry and a passion to share what we know. We are ready to provide you with all the information you need to buy the right container, maintain it well to ensure longevity, or customize it into a creative project.
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