The Ultimate Guide for
What You Should Know Before You Buy
You Have Questions
Maybe you've been through a facility siting study, or maybe you know you need to add occupied space at your refinery. Or, it could be time for a planned shutdown, and you're going to be bringing in a lot more contractors. For those reasons or many more, you need to invest in a blast-resistant structure. But, before you pick up the phone to start making calls or send that email, let's look at all of the considerations you'll need to make.
We Have Answers
As the industry leader in blast-resistant modular buildings, RedGuard takes pride in sharing the wealth of information we've gained since becoming one of the industry's first manufacturers of blast-resistant buildings. We’ve put together The Ultimate Buyer's Guide for Blast Resistant Buildings, but you can also check out individual topics in our Learning Center.
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What is a blast-resistant building?
THE BASICS ABOUT BLAST-RESISTANT BUILDINGS
A blast-resistant building is a structure that has been designed to withstand significant blast events. These buildings are often constructed with thick steel walls and interior features and fixtures designed to withstand the heightened psi levels associated with small to large blast events. Sometimes they are referred to as blast-resistant modules, blast-resistant units, or simply as a BRB or BRM. They are often found in oil refineries, chemical processing plants, or similar operations.
WHAT ARE THE REGULATIONS COVERING BLAST RESISTANT BUILDINGS?
There are no official regulations that cover blast-resistant modular buildings. There are some recommended practices laid out by the American Petroleum Institute that cover permanent and portable structures that are located within blast zones. These are known as API RP 752 and 753. They ensure that occupied buildings protect against potential hazards by recommending specific blast response ratings to protect occupants from potential hazards in hazard zones.
As a safety authority in blast resistance, RedGuard recommends using only blast-resistant buildings with a low or medium response rating (meaning low- to medium- damage after a blast event). While still considered “blast resistant,” a building with a high response rating could sustain structural damage during a blast event and may even collapse due to environmental conditions. We’ll talk more about what “high response” means in Chapter 3.
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What dangers are there to people during a blast event?
Why blast resistant buildings?
Those who work for oil and gas companies take on a certain amount of risk. Because of this, companies should take the steps needed to protect them from as much risk as possible. This chapter will examine how a refinery explosion affects the human body and how a blast-resistant building can prevent injuries and mitigate the risk.
HOW DOES A BLAST AFFECT THE HUMAN BODY?
The effects of a blast event on the human body will depend on several factors, a person’s proximity to the center of the explosion, the terrain and surroundings within the area of the blast, the cause of the explosion (i.e., the type of gas or other material that caused the event), and the intensity and frequency of displacement waves.
With these factors in mind, it is important to note that the human body can typically survive high blast overpressure. For example, a 5 psi blast overpressure can rupture eardrums, while lung damage can occur at an approximately 15 psi blast.
One significant factor that must be considered when taking precautions to protect personnel during a blast event is the impact of blunt force trauma to the human body. Injuries like these can occur with overpressure as low at 1-2 psi, when windows may shatter, and debris is thrown. Crush injuries may occur at slightly higher response levels when the building’s structural integrity begins to fail.
In a blast event, or explosion, the human body might be thrown, large objects might be propelled at a person, and light objects can quickly become speeding projectiles. Fortunately, a blast-resistant building is designed to protect people from the aforementioned injuries.
A blast resistant building that has the right psi ratings for its intended use and location within your facility can not only protect personnel during blast events; it can also save lives and reduce the risk of nonstructural items causing bodily harm in the aftermath of a blast event.
Because there are so many people involved in oil and gas processing, the financial risk of NOT protecting them as they do their work is huge. Understanding the financial impact of a blast with real-world examples is essential. To do this, let’s take a look at the trickle-down continuous financial costs of a blast event.
UNDERSTANDING THE FINANCIAL IMPACT OF A BLAST EVENT
One of the easiest ways to understand the long-term financial impact of a blast event within the oil and gas industries is to explore historical incidents.
- On May 5, 1988, in Norco, Louisiana, a refinery experienced a blast event that caused 42 injuries and seven fatalities. The major blast event hurled debris as far as five miles away. The incident itself was heard nearly 25 miles away in New Orleans. The total estimated cost of the event was $706 million. The latter funds were used to pay for property damages, injuries, rebuilding, an investigation, and other components directly related to the event.
- On March 23, 2005, in Texas City, Texas, one of the world’s largest refineries experienced a blast event that caused 180 injuries and 15 fatalities. The cost of this blast event included an Occupational Health And Safety Association (OHSA) imposed $87 million fine (due to 700 safety violations found during the investigation into the incident) and an estimated $2 billion for repairs and compensation.
THE REAL IMPACT OF BLAST EVENTS
As seen in the proceeding two events, the far-reaching impact of oil and gas blast events extends beyond structural costs. In fact, the effects of a blast event on the human body can result in expensive medical bills, workers compensation, paid time off, and (if warranted) legal compensation. Additionally, as seen in the Texas City refinery blast event, a failure to meet specific safety standards can result in hefty fines. In this vein, oil and gas companies should take the necessary safety precautions to a) protect against blast events and b) protect their structures and workers from the negative physical and financial impacts of blast events.
One way companies and facilities can protect their structures and personnel is to use blast-resistant buildings. This will protect personnel from bodily harm, save lives, reduce the risk of nonstructural items causing physical injury or property damage, and reduce the financial impact of a blast event.
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What is response level?
Is high response acceptable?
When it comes to blast-resistant buildings, the industry’s manufacturers will often use the term response level to predict the extent of repair needed on a building after an explosion. This section defines what each response level is, and what to look for in a blast-resistant building.
WHAT IS RESPONSE LEVEL?
Blast response levels are ratings established by the American Society of Civil Engineers (ASCE) to predict the extent of repair resources that would need to be devoted to a building after an explosion. Their descriptions include:
Low response — Localized building and component damage; the building can be used, however, repairs are required to restore the integrity of the structural envelope; and the total cost of repairs is moderate.
Medium response — Widespread building/component damage; the building cannot be used until repaired; and the total cost of repairs is significant.
High response — Building/component has lost structural integrity; a building may collapse due to the environmental conditions, and the total cost of repairs approaches replacement cost of the building.
Substitute the term "damage level" for "response level," and you have an instant picture of what these ratings mean. Given the options of low damage, medium damage, and high damage, you obviously don't want to be working in an area that is highly damaged during a blast event.
WHAT TO LOOK FOR IN A BLAST-RESISTANT BUILDING
Anything worse than medium response is virtually synonymous with injuries and fatalities. And suppose you plan on using the building to house critical control systems in a petrochemical facility. In that case, casualties are only one of many problems you'll face in a high response situation.
WHAT ABOUT BLAST TESTING?
The final proof is in the testing of the blast-resistant design. RedGuard was one of the first companies to do a field test of our design. In our original blast test, we detonated 1,250 pounds of high explosive ammonium nitrate/fuel oil charge at a standoff distance of 110 feet from our building. This explosive amount created a blast strength far above the ratings required to meet ASCE low to medium response standards.
The building suffered no structural damage, and neither did the furnishings, office equipment, or the crash test dummy we placed inside. The building is still in use today at the RedGuard headquarters.
This outlines the importance of taking a closer look at both response level ratings and test results before buying a blast-resistant building. In response to the question, "Is high response acceptable?" - the answer at RedGuard will always be a resounding no.
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What is blast proof?
At RedGuard, we use the term “blast-resistant” rather than “,” and this chapter delves into why. We’ll define those terms and talk about the factors at play in blast-resistance, such as the structure of the building, the building’s material, the building’s proximity to the blast wave, and the duration of the blast.
WHAT DOES BLAST-PROOF MEAN?
The word “proof” implies that something is impervious. However, there really is 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 that it could fail.
The word “resistant” means that the object can resist some type of hazardous penetration. In our case, the hazard is 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 there are many factors at play that determine the amount of damage during an explosion. Let’s look at the factors in play when it comes to how blast-resistant a building is.
STRUCTURE OF THE BUILDING
We’ll start with structure because the structural engineering of a blast-resistant building is probably the most critical factor in protection. This goes back to those response levels, mentioned earlier in Chapter 3.
Remember High, Medium, or Low Response? All of them are considered blast-resistant, though not all are equal. And none of them would be regarded as “blast-proof.”
Manufacturers of blast-resistant buildings will have different explanations for their design methodology, or why they design to a specific blast response level. Still, it’s important to look at whether they regard structural integrity as a priority, or if they 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. Today’s manufacturers of blast-resistant buildings are wise to take lessons from the past. In some of the early blast events that shaped the industry, onsite offices in temporary trailers were completely destroyed, while metal shipping containers inside the blast zone were still standing, their contents intact. Though today’s designs are far more complex and protective, shipping containers became the basis for an idea to create blast-resistant buildings. Extensive engineering helped create a final design that has led the industry in blast resistance.
Blast-resistant builders employ many different structural designs and materials. There are blast-resistant structures that are permanent brick and mortar buildings; there are temporary blast structures, there are even tents, sometimes called air shields; and there are modular buildings made of hardened metals that are either portable for temporary use or anchored for permanent use.
Though many materials can be used in the design, none of them are blast-proof, and their levels of blast-resistance vary.
PROXIMITY TO THE BLAST WAVE
The further you are from an explosion, the less of an impact you will feel. Like structure, proximity to the blast also makes a difference in the damage a building will sustain after a blast. The closer to the blast wave, the stronger the building’s blast resistance should be.
A high response blast-resistant building placed in a hazardous process area would be very dangerous in the event of an explosion, even though it is technically blast-resistant. A low response building in the same area may sustain little to no damage.
Both buildings may be resistant to damage in an explosion, but are either really blast-proof? Not really. The most we can do is prepare for the dangers that we know are present.
DURATION OF THE BLAST
If how close a building is to a hazard and the ruggedness of the building’s structure are vital components to blast resistance, it makes sense that the blast’s duration, or how long it lasts, is also a significant factor. There are some details you can consider when planning for safety.
Manufacturers of blast-resistant buildings usually employ a combination of pounds per square inch (psi) and a duration of time, expressed in milliseconds (msec) that the pressure of a blast is applied. Unfortunately, the terminology is often inconsistent from one manufacturer to the next.
As an example:
- A blast resistant building can be engineered to withstand an explosion of 5 psi for 200 msec.
- That same building could also be advertised to withstand a blast of 5 psi at 500 psi-msec, which would also be a correct calculation.
One description communicates the duration and the other the impulse, or measure of the energy of the blast event (psi-msec). Unfortunately, that difference is lost on many seasoned professionals in the oil and gas industry. The 500 psi-msec impulse appears to signify a more substantial building than the 200 msec duration rating, even though both ratings apply to the same building, with the only difference being what is calculated.
This simple nuance can lead to confusion and possibly cause someone to accept an inferior level of blast protection. It’s essential to understand these calculations and to ask whether the description you see communicates a duration or a measure of energy. Understanding the level of threat that a building can withstand, within a set time, is critical. 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.
THE VERDICT ON THE TERM “BLAST-PROOF”
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 that a building is designed to resist, it might fail.
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A breakdown of the benefits of blast resistant buildings
In the previous chapters, we talked about the lifesaving benefits to people and the financial benefit to the bottom line. Now, let’s delve into seven benefits of blast-resistant buildings that will help you make an informed decision mitigation options for your facility.
1. STAFF, EQUIPMENT, AND ASSETS ARE PROTECTED DURING A CATASTROPHIC EVENT
Blast-resistant modules, or BRMs, are built to withstand the devastating damage resulting from an explosion. The people, equipment, and assets inside of the buildings will be protected.
The level of damage is all dependent on the blast rating and the building’s proximity to the hazard. If you work in a classified area, in a building with a low to medium response (which, as mentioned earlier, means it would sustain low to medium damage), your chances of survival are much higher than in a soft-sided trailer, which is still used on some worksites.
2. REDUCE LIABILITY, INCREASE PEACE OF MIND
When the risks to human life are decreased, the amount of liability is also reduced. For every significant blast event that has occurred, when there were numerous fatalities or injuries, the investigation to determine cause and fault begins almost immediately.
Including blast-resistant buildings as safe havens or shelters-in-place can give those who work in hazardous areas peace of mind. Should a catastrophic event happen, it can reduce the company’s liability since it took measures to keep its workforce safe.
3. REDUCE TIME LOST TO RETRIEVE TOOLS OR OTHER EQUIPMENT
One benefit of blast-resistant buildings that's often overlooked is the amount of time, and therefore money, that you will save by storing equipment and tools in blast-resistant tool cribs inside the hazardous area.
Some refinery sites are huge. Often, the time required to get into and out of the classified area involves checking in and out and even arranged transportation.
When you store tools and equipment outside of the blast zone in order to keep them safe, employees must make a trip each time a specific piece of equipment must be used or checked out. When you begin to calculate the amount of time spent going back and forth to retrieve tools, you realize the benefit of just keeping those tools closer. Depending on the size of the workforce, the lost time savings could be huge. The amount of time saved over time might even pay for the cost of the blast-resistant building.
4. REDUCE THE AMOUNT OF TIME EXPOSED TO HAZARDS
It goes hand-in-hand with reducing time and money, that each time a worker must travel across a worksite to retrieve a tool, they are spending time exposed to hazards.
Reducing the amount of travel time reduces the time that the workforce is exposed to risks.
5. FLEXIBILITY AND MODIFICATIONS
Modular buildings are easy to modify. If the process area changes after five years, and your facility siting study now shows that the blast zone has changed, you may need to modify existing buildings in order to provide protection.
If your building is a multi-section, this might be a matter of adding additional sections. Alternatively, you may choose to use the existing building and add more buildings to accommodate your need. Modular buildings can even be stacked to save space.
Traditional buildings are permanent structures. Modular buildings, on the other hand, and specifically blast-resistant modular buildings, are built with the knowledge that the ability to move it after it’s been placed on a worksite is of great benefit.
A building may need to be moved to accommodate a facility’s turnaround schedule. A blast-resistant module can be placed on a site to provide shelter for more people during a turnaround, and then removed once the turnaround is complete and the plant returns to its regular operating schedule.
Most oil and gas facilities go through turnarounds every three to five years. Having a permanent structure that is only at peak usage during a turnaround is not economically feasible. Blast-resistant modules can be moved to a different part of a plant to be used elsewhere, or to a completely different location altogether, perhaps for a different turnaround.
The relocation of buildings is also desirable when an area becomes more densely populated. A population swell makes the environment for oil production less safe, both due to natural disasters and the possibility of chemicals in highly populated areas. Many refineries choose to move when the population grows. The ability to transfer the buildings during the move can save millions of dollars in buildings that would otherwise have to be purchased again.
7. BUILT OFFSITE
When a structure is mobile, in addition to the benefits listed above, that also means it can be manufactured off-site and then transferred to the worksite and assembled.
Compared to an on-site, traditional build, where the location will be out of commission for weeks at a time, there will be fewer restrictions on the area’s use since it won’t be tied up in construction for as long. In a traditional build, you may go through a multitude of steps, like:
- Site preparation/grading
- Construction, including windows, doors, masonry, etc
- Roughing the electrical, plumbing, and HVAC
- Finishing the interior walls
- Trimming/painting the exterior
- Installation of interior elements like cabinets or workspaces
- Installation of flooring
- Finishing electrical, plumbing, and HVAC
- Connection to water, sewer, or other services
In comparison, the vast majority of the work on a blast-resistant modular building is done before the building leaves the production center. When it arrives on site, the "to-do" list will look more like this:
- Site prep (done before the building arrives)
- Foundation (done before the building arrives)
- External finish of the structure (including welds, if the building is multi-section)
- Finishing electrical, plumbing, and HVAC
- Connection to water, sewer, or other services.
In addition, the process itself is safer, since the skilled labor constructing the building will need to be in a hazardous area for only the amount of time it takes to install it.
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How much does a blast-resistant building cost?
If you’ve done your research online, you know that information about the real cost of a blast-resistant building is nearly impossible to find. Let’s examine the factors that affect a blast-resistant buildings’ cost.