Rust is the natural enemy of shipping containers. It can damage and degrade containers, shortening their lifespan. Luckily, there are ways to prevent, remove, and protect against rust on shipping containers. 

In this article, I will provide an overview of common causes of rust, methods for rust removal and prevention, and tips for maintaining rust-free shipping containers.

What are the signs of rust on shipping containers?

Here are some common signs of rust on shipping containers:

What are the signs of rust on shipping containers
Sign of RustIndication
Brown or reddish staining on exterior metal surfacesEarly rust formation.
Pitting, flaking, or bubbling of the metal surfaceMore advanced rusting that is damaging the metal.
Visible metal loss, corrosion, or holes in wallsSevere rust causing significant metal deterioration.
Rust staining dripping from seams, joints, or rivetsAreas collecting moisture, accelerating rust formation.
Rust dust or particles inside the containerExterior rust spreading internally.
Sagging, bending, or distortion of panels or doorsRust weakening the metal and compromising structural integrity.
Squeaking or resistance when opening doors/hingesRust buildup causing friction.
Mold growth inside the containerExcess moisture promoting rusting.
Peeling or bubbling paintReveals unprotected metal underneath, often a sign of underlying rust.

What Causes Rust in Shipping Containers?

What Causes Rust in Shipping Containers

Rust leads to several issues for shipping containers. It causes structural weakness as the rust damage leads to metal loss, compromising the container’s strength over time. Several factors can lead to rust formation on shipping containers, including:

  • Exposure to moisture – Rain, ocean spray, humidity, and condensation inside the container—can cause rust. Even small amounts of trapped moisture speed up rusting.
  • Salt air and water – Ocean salt accelerates the rusting process as the salt interacts with water and oxygen on the steel’s surface. Coastal areas see higher rates of rust.
  • Damage to the paint coating – Scratches, dents, and unsealed joints expose the bare metal and allow rust to take hold.
  • Road chemicals like calcium chloride – chemical deicers used on roads can cling to containers and promote corrosion.

Preventing Rust on Shipping Containers

An ounce of prevention is worth a pound of cure when it comes to shipping container rust. Here are some key prevention methods:

  • Use rust-resistant steel – Many shipping containers are made from weathering steel, which develops an outer rust layer that slows down further corrosion.
  • Apply protective coatings – Paint, galvanization, zinc plating, powder coating, and other treatments form a barrier against moisture and oxygen.
  • Seal joints – Caulk and seal all joints, seams, rivets, and places where water can enter.
  • Ventilate interiors – Prevent condensation buildup inside containers with vents or desiccant packets.
  • Wash regularly – Clean off road salts, chemical residues, ocean spray, and other contaminants before they can cause damage.

Treating Existing Rust

There are several effective methods for treating and removing rust that has already formed on shipping containers. First, loose rust should be removed from the bare metal using abrasive techniques like wire brushing, sanding, or grit blasting. 

These methods remove the flaky rust and get down to a sound surface. Next, a rust converter can be applied to chemically convert any remaining rust into a protective layer. Any bare metal or lightly rusted areas can then be spot primed to seal them. 

Finally, the entire container should be repainted with a complete coating system, including primer, intermediate, and finish coats, to protect the steel. There may be a need to cut out sections of steel and weld in new steel panels for containers with severe rust damage. Even badly rusted shipping containers can be restored with the right combination of abrasive removal, rust conversion, and fresh paint.

Maintaining a Rust-Free Container

To keep containers rust-free for the long run:

  • Inspect regularly – Check for new rust spots or coating damage. Address issues immediately.
  • Wash and clean – Use fresh water, not saltwater. Remove dirt, salt spray, and bird droppings.
  • Reapply coatings – Refresh paints and sealants per manufacturer specifications.
  • Touch up damaged areas – Spot paint any scratches, dents, or uncoated areas.
  • Keep records – Note dates of inspections, washes, and repairs to stay on top of maintenance.

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