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3 Basic Factors to Designing Secondary Containment Systems

An aromatic polyurethane is applied to a concrete clarifier

I frequently get to build forts in my basement with my three kids, and the designs of these epic creations can be daunting. Are the chairs tall enough? Will the clothespins be sufficient to hold the blankets? Do we have enough floor space for activities? All of these details are critical to the success, longevity and awesomeness of the fort.

In the industrial coatings world, there’s a similar type of environment where attention to detail very much affects its success, longevity and, yes, even awesomeness. Much like an epic fort, secondary containment systems can be daunting to design. There are many factors that come into play during the design process, such as:

  • To which chemical commodity is the containment system being exposed?
  • What physical stress will the system incur throughout its lifetime?
  • Are there pipe or other mechanical penetrations that could result in a possible leak of the containment?
  • Are there joints that could cause potential seepage into the ground?
  • Is reinforcement needed to help mitigate the stress of concrete flexing on the coating system?

These are just a few examples of the many considerations that exist when designing a secondary containment system. However, to simplify the design process, we can break the system’s design down into three basic components—chemical exposure, physical requirements, and joint and penetration details.

(Note: If you haven’t read Steve Harrison’s recent article on industrial coating systems for secondary containment, it is a fantastic starting place for any discussion relating to the “why” behind secondary containment systems.)

  • 1. Chemical Exposure

    In simple terms, a secondary containment area is defined as the containment of a leak or spill of a commodity that is being held in a primary containment unit, such as a tank or vessel. In order to properly specify a secondary containment lining, we must first know the commodity/chemical and storage temperature of what is being stored in the primary containment. Estimating either of these factors could result in a catastrophic failure of the secondary containment lining.

    Generically, there are a few different chemistries when it comes to linings that provide varying levels of protection to secondary containment areas. Amine epoxies, such as Carboline’s Semstone 140 lining system, provide basic-level chemical resistance to a wide variety of chemicals. Novolac epoxies, such as Semstone 145, offer increased chemical resistance to more highly concentrated chemicals and acids. Vinyl esters, like Carboline’s Semstone 870 lining system, also cover chemical attack from a broad range of aggressive chemicals, while utilizing a slightly different chemistry than a true epoxy lining.

  • 2. Physical Requirements

    Choosing the right lining chemistry to combat chemical attacks is certainly important. However, evaluating the physical stress to which the lining system will be subjected is of equal significance. In secondary containment environments, foot traffic can be very mild. An example of this is what one might find in a very small pit that is surrounding a primary containment tank. It may only see light foot traffic or, on the opposite end of the spectrum, it might be subjected to consistent semi-truck traffic where loading and unloading of chemicals constantly occurs.

    On the mild side of things, a secondary containment system often referred to as a “neat coat” might be all that is needed. Within the realm of Carboline’s secondary containment systems, this is referred to as Semstone NC. The low physical stress that is created on this basic system allows it to perform adequately in mild environments. In more moderate exposures that might see heavier foot traffic or wheeled carts, an aggregate filled system like Semstone AFC might be appropriate. The strength imparted to the system by the aggregate and two layers of coating make it more than suitable for this type of environment.

    Finally, in the most aggressive of environments where vehicular or fork lift traffic is a constant factor, an aggregate filled reinforced system, typically reinforced with an engineering fabric, will impart ultimate strength to the system and protect the substrate from both chemical attack and extreme physical stress. Semstone AFRC is a tried and true system that incorporates fabric reinforcement and broadcast aggregate to deliver ultimate protection to a secondary containment system.

    Carboline’s Semstone System Selector is a great interactive tool that helps to provide considerations for both chemical resistances and physical considerations all in one place.

  • 3. Joint & Penetration Details

    While protection against chemicals and physical stress is examining a secondary containment system on a macro level, considering the details of the environment is deep diving into the micro aspects of the system’s design—equally as important as these big-picture considerations.

    The most common details come from either joints, such as expansion joints, control joints or, in the case of refurbishments, stress cracks; transition areas, such as horizontal to vertical transitions; or penetrations into and through the concrete via pipes or other mechanical structures.

    When it comes to addressing these details, one size does not fit all. Each detail is important to consider, with a specific coating system needed to properly address it. Within Carboline’s secondary containment resources, a set of construction details exists to address many of these specific situations. Most commonly, a flexible coating like the Semstone 805 epoxy polymer is used to coat the substrate and provide flexibility to accommodate for the movement often found in these locations.

Although this blog post offers a basic overview of the design factors for a secondary containment system, there are often more details that emerge needing specific attention. In this case, a local sales representative from Carboline’s Technical Service team can provide an in-depth review of a secondary containment system’s design to make sure your system will hold down the fort.

Want to Explore Our Secondary Containment Systems?

Check out Carboline’s new interactive hub of secondary containment sales tools.

Explained: Role of Bond Breaker Tape

Our Jeff Schmucker created a visual to explain the importance of using bond breaker tape in secondary containment systems.

4 Basic Questions to Consider When Selecting the Right Coating

Oil rigs pump oil from the ground in the hot sun.

Coatings recommendations are one of the most highly debated—and even misunderstood—aspects of the industrial coatings industry. Many different factors go into making the right selection. For instance, have you ever called a coatings manufacturer for a recommendation, only to have your question answered with even more questions?

Although it can seem counterintuitive, this initial research is a critical first step to making a proper coatings recommendation. With hundreds of industrial coatings options out there, the list must be narrowed down to the “best fit” selection by first considering a variety of factors.

Typically, the most popular types of coatings offer versatility and can perform a variety of functions—take our Carboguard 890 epoxy mastic coating as an example. However, an all-in-one solution is rarely the best choice. Instead, it’s important to consider the specific performance requirements of the project at hand—whether it’s protecting an oil tank, a bridge or a railcar—as this will greatly influence your coatings recommendation.

Below are the four basic questions a specifier, engineer or owner should ask in order to select the best possible coating for the job:

  1. 1. What Specific Function Does the Coating Perform?

    No element is more crucial to a coating system selection than its function. Consider the intended use of the coating. Is it a tank lining? Secondary containment? A flooring system? A bridge or a stadium that needs to be protected from the elements?

    Tank linings, for example, have drastically different performance requirements compared to atmospheric coatings. This disparity will have a significant influence on not only the selection of a coating, but its surface preparation requirements as well.

    Chemical immersion is one of the harshest functions a coating can perform, as the lining is under constant performance stress from the stored commodity. Because of this, coating manufacturers invest heavily in testing to validate linings for chemical service. A common misunderstanding is that the pH level determines a lining selection. In reality, pH level is only one piece of the puzzle in lining compatibility.

    Instead, the chemical commodity should always be the determining factor due to the molecular size of the commodity and the cross-link density of the lining. In addition, the temperature of the storage commodity is almost as valuable as the commodity itself, as corrosion levels generally increase and decrease with temperature.

  2. 2. What is the Environment and Exposure?

    Although this question seems pretty basic on the surface, it can actually become quite complicated as you dig into the specifics of the environment and exposure of the coating. Coatings are used everywhere to prevent the corrosion of assets. Knowing exactly where the coating will be physically located, as well as the environment it will be exposed to, is key to providing the right coating recommendation and, ultimately, ensuring a successful project.

    When selecting a coating for atmospheric service, there are several factors to consider. For instance, will the coating be exposed to an exterior or interior environment? Are there elevated temperature conditions? Is this in a rural area, a chemical plant, in a desert or near the ocean? In addition, are aesthetics or corrosion protection more critical for the given environment?

    Chemical plants, for example, will require chemical-resistant coatings even in non-immersion situations, whereas coatings located near the ocean necessitate additional resistance to salt-laden air, which can accelerate corrosion. Likewise, a job in the desert will have different performance requirements than one in a coastal environment, as it necessitates a coating that is suitable for extreme UV radiation.

  3. 3. What is the Expected Service Life?

    Everyone wants the top-rated, longest-lasting coating for every possible scenario… right? Not necessarily. Limited budgets frequently come into the equation, as material and labor costs can vary widely. The expected service life of a coating, as well as the available budget, will greatly drive a coatings recommendation.

    For instance, if a temporary fix is needed, the item will be replaced in the short term or there is a limited budget, then a maintenance coating with a shorter lifespan and lower cost could be sufficient. On the other hand, an elevated water tank with a design life of 90 years would necessitate a more durable coating with a longer lifespan expectancy.

  4. 4. Are There Any Application Restrictions?

    Spray application is the preferred method for most industrial coatings, but it is not always realistic in real-life situations and environments. For example, the asset that needs to be coated might be in a hard-to-reach or remote area where a pump is not efficient nor ideal. Or there could be an entire parking lot of cars just downwind of the project. In each of these situations, it is recommended that the coatings product feature better brush-and-roll characteristics to ensure it is the best fit for the challenging task at hand.

In the end, the goal of the coatings selection process is to achieve a win-win solution for everyone involved—from the owner, to the coatings manufacturer and the installer. Though it can be tedious, the information-gathering stage is one of the most vital phases of a coatings project—ultimately building the foundation upon which the project's success can either start off on the right foot or take a drastically wrong turn.

Need Help Selecting the Right Coating for Your Project?

Contact a local sales representative from Carboline’s Technical Service team.

Industrial Coating Systems for Secondary Containment

This containment pit is protected by a Carboline secondary containment system.

Accidents happen! Who hasn’t dropped a container filled with liquid at some point? For most of these instances, the liquid is quite harmless—aside from a resulting stain in your floor, or the inconvenience of having to clean up the spill.

However, when spills happen in an industrial facility, it often involves dangerous chemicals that are harmful to humans and the environment. When these types of spills occur, the containment and cleanup response is critical to minimizing impact on the environment, business operations and a company’s reputation in the community.

Because of this, the U.S. Environmental Protection Agency (EPA) set forth guidelines that companies must follow to ensure proper storage, handling, containment and cleanup of hazardous waste. This blog post will explain what secondary containment is, the EPA’s guidelines surrounding it, and the impact that spills involving hazardous waste can have on companies and their communities.

The Importance of Containment with Hazardous Waste

In order to understand why containment is critical in an industrial environment, it’s important to first define hazardous waste. According to the EPA, a hazardous waste can be in a liquid, solid or gas form. It is defined by four main characteristics:

  • Ignitability, or flammability
  • Corrosivity, or susceptibility to rust/decompose
  • Reactivity, or explosivity
  • Toxicity, or quality of being poisonous

The biggest concern with hazardous waste is when that material is unintentionally released from its primary containment, as well as what it subsequently contaminates. When not properly contained, a liquid hazardous waste (aqueous or hydrocarbon based) poses the risk of contaminating both small and large bodies of water—from soil and groundwater, rivers and streams, to lakes and oceans.

Probably the largest, most expensive and widely recognized spill of a hazardous liquid material was BP’s Deepwater Horizon oil spill that occurred in the Gulf of Mexico in 2010. The most significant loss was the lives of 11 workers. In addition, the offshore facility itself was a total loss and the well leaked for 87 days, releasing more than 3 million barrels of crude oil into the surrounding Gulf of Mexico. The accident actually shaved off one-third of the market capitalization of the company—a financial loss that most companies wouldn’t survive.

The Impact of Hazardous Waste Spillage

The impact and costs involved with hazardous waste spillage can be enormous and far-reaching. Thousands of hazardous spills occur each year in the U.S., both on land and in water. All of these spills have the potential to contaminate the environment—from a single gallon of paint falling off the back of a pick-up truck, to millions of gallons of oil or other waste products spilling at a chemical plant or offshore facility.

For instance, BP’s 2010 Deepwater Horizon oil spill cost the company more than $61 billion—without even factoring in the cost to the environment, losses associated with local fishing and tourism, and other damages. Land-based spills are normally easier to contain compared to water-based spills, although costs of remediation can still be significant.

The potential costs of hazardous waste spillage range from internal to external, including:

Internal Costs External Costs
  • Damage to equipment
  • Containment to stop/reduce spillage
  • Cleanup costs
  • Lost commodity
  • Cost of litigation (including punitive damages or other penalties)
  • Loss of life and/or injury
  • Cleanup costs incurred by government agencies
  • Repairs for public infrastructure
  • Lost income by affected businesses
  • Lost consumer value from shifting purchasing decisions and/or behavior
  • Damage to natural resources
  • Cost of litigation (both to government and victims)

Although it is impossible to prevent all spills, the EPA’s 40 CFR Part 264 standards provide guidance for how owners and operators of hazardous waste treatment, storage and disposal facilities should respond to spills of a certain nature and size. In addition, it discusses the importance of secondary containment plans and procedures.

Secondary Containment for Hazardous Waste

In simple terms, a secondary containment is a back-up system that is in place to handle a spill in the event that the primary containment is compromised, such as with a leak or rupture of a storage tank. The system provides temporary containment of the hazardous waste until appropriate actions can be taken to abate its source and remove the material.

Specifically, the EPA’s 40 CFR Part 264.193(b) guidance requires that secondary containment systems must be:

  1. Designed, installed and operated to prevent any migration of wastes or accumulated liquid out of the (primary containment) system to the soil, groundwater or surface water at any time during the use of the (tank) system; and
  2. Capable of detecting and collecting releases and accumulating liquids until the collected material is removed.

The most commonly used option for secondary containment of large tank storage structures is concrete in the form of flooring and walls. This type of concrete containment must be constructed in a way that controls spills in accordance with the EPA’s guidelines—including protecting it from corrosive chemical spills, and engineering the concrete with control and expansion joints to prevent cracking as it ages. After all, what good is a secondary containment system if it leaks because of a poor joint detail or crack in the floor?

A properly engineered industrial coating system will address all of these issues to maximize the performance of a secondary containment. As part of this, it’s important for companies to assess their potential risks and work closely with an industrial coating supplier and applicator.

Although not all disasters can be predicted or prevented, thorough planning and proper procedures can help companies promptly respond to hazardous waste spillage, resume normal operations as quickly as possible and minimize impact on the community.

Want to Learn More About Secondary Containment Coating Systems?

Listen to Carboline’s recent podcast episode that discusses the design of industrial coating systems for the purpose of secondary containment.

Using Thermal Insulative Coatings for Condensation Control

Insulative coatings are prevalent in plants like this one.

What’s worse than a sweating beer (or soda) can in the middle of summer? Warm beer, of course! This is why beer cans are often wrapped in insulative “koozies.” Not only does the koozie keep your beverage colder for a longer period of time—it won’t leave that dreaded water ring on your wooden table.

How Temperature & Humidity Impact Condensation

Condensation occurs on surfaces when there is enough humidity in the atmosphere and a cold enough surface temperature. Under the right conditions, humidity in the atmosphere will condense on the cool surface. There are two primary factors that come into play to determine whether this condensation will occur and to what extent:

  • The temperature of the substrate relative to the atmospheric temperature
  • The amount of humidity in the atmosphere

The chart below demonstrates how the dew point changes based on relative humidity (RH) and air temperature. The dew point can vary from the morning to the evening, as well as from season to season, depending on the level of humidity that is present—which is often lower during the colder months.



Dew Point at Relative Humidity (%)

Air Temperature





















Considering the beer can as an example, let’s say the beer is at 38°F and the RH is 80% on a warm summer day at 90°F. Based on this information, the chart indicates that the dew point is 85°F. In other words, the beer is 47 degrees colder than the dew point—which is why a beer can sweats profusely, and warms up so quickly, in a humid environment.

The use of a koozie helps to insulate the beer can, creating a thermal gradient between the can and the outside surface of the koozie. If the koozie is thick enough, the surface temperature can be effectively raised above the dew point to prevent condensation—and keep the beer cold!

Condensation in Industrial Environments

When it comes to industrial environments, a variety of condensation issues can occur on process vessels, piping, gas lines, storage tanks or even the sides of metal buildings. In fact, it’s not uncommon to see “sweating” occur on the north sides of storage tanks or the bottom half of railcars during the morning hours, before the sun has warmed the steel substrate.

When wet pipes or vessels drip on floors, this can present significant workplace safety issues—particularly if microorganisms begin to thrive, making the floors extremely slippery. Cyclic wet/dry exposures or the constant presence of water can lead to corrosion of the steel substrate unless properly protected.

Thermal Insulative Coatings as a Solution

Though not all “sweating” surfaces pose problems, the prevention and/or remediation of condensation is required when active corrosion of the steel substrate takes place or when workplace safety becomes a concern.

A newer technology that is applied like paint, thin-film insulative coatings can be used to provide the necessary insulation, effectively raising the dew point through a thermal gradient between the substrate and the outside air. These thermal insulative coatings work by trapping air throughout their film—much like a koozie. Their unique formulations balance the use of specialized fillers and industrial-strength binders to make them suitable for a variety of applications. Although they are most often used for high-temperature surfaces to protect workers from burns, another important function is for condensation control.

Because every situation and industrial environment are unique, the proper thickness for a thin-film insulative coating will be different for each application. For instance, the thicknesses needed for condensation control will vary for sweating pipes in the dry Southwest desert, compared to those in a high-humidity Gulf Coast environment.

An industrial coatings manufacturer can help you calculate the correct thickness for a thermal insulative coating based on a variety of factors, including the surface temperature, relative humidity and ambient air temperature.

Want to Learn More About Our Thermal Insulative Coatings?

Contact a local sales representative from Carboline’s Technical Service team.