CARREEN GIBBONS, Communications Specialist, RedGuard
In an industry as young as blast-resistant buildings (BRBs), the terminology is still very new. This industry only came to be in 2005, after an explosion at a Texas City refinery killed 15 people and injured nearly 200.
I am often asked about "blast-proof buildings," and I typically don't correct the people saying it, because I know what they mean. But I prefer the term "blast-resistant."
The word "proof " implies something is impervious. However, there is really no such thing as a blast-proof building. If you exceed the load that a building is designed to resist, there's a strong possibility it could fail.
The word "resistant" means the object can resist some type of hazardous penetration -- in our case, blasts or explosions, but you may also think of objects that are water-resistant, slip-resistant, heat-resistant or puncture-resistant.
Blast-resistance has a lot of nuance to its meaning because, during an explosion, there are many factors at play that determine the amount of damage, such as the structure of the building, the building material, proximity to the blast wave and the duration of the blast.
We'll start with structure because the structural engineering of a BRB is probably the most critical factor in protection. When talking about a blast or explosion, there are a few ways you might see the details expressed. One of those is the building's response.
Engineers use mathematical models to predict how objects will respond to a blast to design safer buildings. This is where the term "blast response" comes from, in relation to a BRB.
The American Society of Civil Engineers defines criteria for blast-resistant structures: They are rated high, medium or low response. A high response means a high level of damage may occur in response to an explosion. A low response means very little damage or response to a blast. All structures classified as high, medium or low response are considered blast-resistant, though not all are equal. And none of them would be considered "blast-proof."
Manufacturers of BRBs will have different explanations for their design methodology, or why they design to a specific blast response level, but it's important to look at whether they regard structural integrity as a priority or simply meet the minimum requirements to get their building rated.
Hand-in-hand with the structural engineering of a building is the building material itself. Going back to the example of the Texas City refinery, experts observed the on-site offices, which were temporary trailers, were completely destroyed, while metal shipping containers inside the blast zone were still standing, their contents intact. The shipping containers became the basis for an idea to create BRBs, and extensive engineering helped create a final design that has led the industry in blast resistance.
BRBs employ many different structural designs and materials. There are blast-resistant structures that are permanent brick-and-mortar buildings, temporary blast structures made of fabric, and modular buildings made of hardened metals that are either portable for temporary use or anchored for permanent use. Though many materials can be used, none of them are blast-proof, and their levels of blast-resistance vary.
If you are far away enough from an explosion, I suppose you could say anything was blast-proof. Like structure, proximity to the blast makes a difference. A high-response BRB placed in a hazardous process area would be very dangerous in the event of an explosion, even though it is technically blast-resistant. However, if located far enough away from a hazardous area, it does provide sufficient protection. In this way, you could say a structure's proximity to hazards can determine how blast-resistant it is.
Manufacturers of BRBs usually employ a combination of psi and a duration of time expressed in milliseconds (msec). Seeing that a building can withstand 8 psi for 200 msec is good, but what if you saw "8 psi/500 psi-msec"? Would you know the difference?
One description communicates the duration and the other the "impulse," or measure of energy of the blast event (psi-msec). Unfortunately, that difference is lost on many seasoned professionals in the oil and gas industry. Be cautious of manufacturers that fail to give you clear information when you ask about the duration of time a building can withstand its psi rating. It's possible that they don't understand this nuance themselves.
Put this all together, and you can see why the terms "blast-resistant" or "explosion- resistant" are the preferred terminologies. Simply put, we don't say "blast-proof " or "explosion-proof " because we know that explosions are powerful forces. If you exceed the load a building is designed to resist, it might fail.
For more information, visit www.redguard.com or call (855) 733-4827. For more content like this, visit https://inbound.redguard.com/blog.
