3 min read

A fix to bulging containers

A fix to bulging containers

Maybe you have noticed containers whose sides are bulging. Some look more round than rectangular. They are a shipping line's worst nightmare waiting to happen.

Bulging containers really irk me. As a stevedore and someone who wants to eventually own and run a maritime operation, they are a pain in the ass - and dangerous. Containers with sides bowing out are usually filled with a bulk commodity. Like grain or peas. Way too much grain or peas.

Containerization was based on the concept of taking the box of a truck off and lifting it directly to a ship or train. Cargo no longer needed to be handled by hand. This sped up the process of operations as well and decreased pilferage (theft). The container works exceedingly well for cubed commodities like boxes of medical supplies or a pop-up tent. The container fell short when people tried to stuff grain in them.

To clearly understand why containers of grain won't work, you need to understand how the container was created and designed. There is very little difference between a flat rack and a standard dry container (in theory). Both are designed to lift cargo with a piece of equipment from the top of the container. Cargo is supported by the structure on the bottom. The roof and sides of a standard container are provided for protection from the elements and, to maximize cargo space (stowage) without much rigging. The sidewalls can withhold a load but not a whole lot.

The walls are designed to hold 60% of the carrying capacity uniformly across the surface. That sounds like a lot - it's not. With some very rough math, for example, the container can hold 10,000lbs, the walls can hold 6,000 lbs evenly. 10,000 pounds of grain will fill the container approximately halfway. Because the container is only half-filled, the load is concentrated on the bottom half of the wall, which can hold, 3,000 lbs. Assuming the grain sifts and lays against the wall, you have somewhere between 3,000 & 5,000lbs of force against the wall. Typically, the first time this happens, the walls will not bend much. The second and third time, that’s another story.

By now, you’re wondering why it matters if the container bends or not. It’s difficult to load. Ships are designed to hold containers up tight to each other on board. The gap between containers is usually a few inches. Bulging walls require aggressive handling by crane operators to make them fit on board. If the container is already compromised, then the walls may fail. When loading below the deck, the bulge may catch on the guides for containers and cut the side open. There is a high potential for cargo loss and damage as well as damaged equipment.

Years ago someone designed a bulk commodity container. It had reinforced sides, a hopper, everything to make a successful operation. It has two major downfalls. The hopper container is a highly specific type. It cannot be loaded both ways since build commodities (grain, barley, peas) are typically shipped one way. This means the container will not be loaded both ways, and lines burn money on empty returns. Second, because of the extra structure, these containers have a diminished cargo carrying capacity. The extra structure increases the container's base weight (tare weight) reducing the carrying capacity. Meaning it took more containers to ship the same volume of wheat. It has since been almost completely discounted.

My proposed solution, carbon fiber reinforced dry containers. Adding weight won't work. Creating a one-way container won't work. My proposed solution is to add structure to a dry container without adding significant weight. Theoretically, it is easy to add several carbon fiber posts strategically placed outside of the container, between the corrugation, to increase sidewall capacity. This would decrease damage to the container, protect shippers loads, and help stevedores productivity.

It's time for me to get to designing.