This article was adapted to be printed in the November/December 2021 issue of BIC Magazine, where it was edited for length and relevance. You can read the original comparison of blast resistant buildings and shipping containers on our blog, or proceed with the BIC article below.
For many years, RedGuard claimed to be the only manufacturer of blast-resistant buildings to test and make the data in its blast tests readily available. Since then, some companies have followed suit, even publishing videos showing their buildings’ response.
One competitor shows its design’s performance, but also illustrates a high-level blast impacting what appears to be a steel shipping container. What is the implication of that comparison?
It is important to point out, in no uncertain terms, that a steel shipping container is not a blast-resistant building. While the appearance may be similar, the differences between a shipping container and a blast-resistant building are significant.
RedGuard has been developing blast-resistant buildings since 2005, when an oil refinery accident killed 15 people and injured nearly 200 more. At the time, RedGuard (then known as ABox4U) leased and sold shipping containers for use as storage boxes on refineries, construction sites and other hazardous worksites.
Engineers who investigated that accident observed that portable trailers used as offices and break rooms were decimated during the blast, while steel shipping containers that stored tools and equipment mainly appeared unharmed. Conversations started behind the scenes, and RedGuard’s founder saw an industry need to fill.
Because of this history, many people assume that a steel blast-resistant building is nothing more than a shipping container. That is far from the reality. Let’s take a look at the similarities and differences.
Shipping container similarities
Shipping containers are made to haul goods across the ocean and, once they reach port, by railcar or semi-truck. They are designed to be used for around 15 years. However, some last as many as 30 years, with people finding alternative uses for them after their use for shipping goods worldwide ends.
Shipping containers are built ruggedly. To survive many years of salty ocean spray, heavy rain, wind, hurricanes and a lot of rough handling, most are made with steel walls welded to a steel frame. They have a closed top and doors that swing open on either end. For some of these same reasons, RedGuard’s designers began with steel when designing its first blast-resistant buildings.
Because of their use across ships, trains and trucks, shipping containers must conform to ISO standards. They come in standard shapes and sizes, and can be moved using the same equipment. Blast-resistant buildings also make use of these same standards to ease their transport.
So, yes, it’s fair to point out that there are a few similarities, but the differences are key.
Blast-resistant building differences
In designing RedGuard’s blast-resistant buildings, its engineers began with a steel frame, but unlike a standard container, they added closely spaced vertical and horizontal stiffeners. The frame acts as a “rib cage” of sorts. The ribs of the human body, closely spaced in the same way, protect the body’s internal organs. The ribs compress to protect the body, the same way the steel frame of a blast-resistant building will. In industry, this is called “dynamic load transfer” or “flex.”
Talking about flex can be controversial in the blast-resistant building industry. Too much flex could be bad. That’s why RedGuard buildings are designed to minimally flex, allowing for much less deformation when compared to shipping containers or other steel blast-resistant buildings on the market. And it’s no theory: RedGuard has tested its designs to demonstrate that they provide a safe environment for occupants.
Next, RedGuard uses steel sheeting, either corrugated steel walls or flat plate, welded to the frame. Shipping containers may have steel walls, and they may be rugged, but they aren’t tested for their ability to withstand a blast.
Blast-resistant buildings also have engineered steel blast-resistant doors — and possibly windows, depending on how the building will be used. In contrast, shipping containers do not use blast-resistant doors or windows.
Individually, the doors and windows of a blast-resistant building must be as strong as the structure itself to protect the integrity of the building’s blast-resistant envelope.
RedGuard’s building design uses structural redundancy to ensure protection so the failure of one element will not cause the failure of the whole structure. The same is not true of a shipping container.
Another big difference from a shipping container is the blast-resistant structure’s interior. Everything placed inside the building, like floor and ceiling tiles, electrical or plumbing components, furniture, wall coverings, etc. has to be scrutinized for its performance. This isn’t necessary in a standard shipping container.
When you think of shipping containers, remember that while the humble beginnings of steel blast-resistant buildings may have started there, today they are but distant cousins.
For more information about blast resistant buildings, visit us online or call (316) 554-9000.