Double Containment Piping: A Growing Trend in Safety and Compliance

By Steven Dolejsi

Double containment piping systems for commercial and industrial applications continue to gain significant traction across multiple industries. Designed to prevent leaks and ensure the safe transport of hazardous materials, these systems have become a critical component for applications dealing with hazardous chemicals, industrial waste, wastewater treatment, and other potentially dangerous substances.

Among the key drivers are stricter safety mandates and regulations amid growing concerns about environmental protection. For example:

• Under 40 CFR Part 280, the United States Environmental Protection Agency (EPA) requires double containment for underground storage tanks and associated piping. Systems that store or convey hazardous substances below ground must have some form of leak containment or mitigation. Pressurized systems also require continuous monitoring. The piping could be contained within a concrete trench, but that is very expensive. Double-containment piping is a generally more effective and less costly solution.
• The Occupational Safety and Health Administration (OSHA) has guidelines emphasizing the need for secondary containment to prevent exposure to hazardous chemicals, further enforcing safety protocols in industrial settings.
• In commercial building environments, the National Fire Protection Association (NFPA) codes, particularly NFPA 30 and NFPA 1, stipulate double containment for specific piping systems carrying flammable or combustible liquids.

These codes and standards collectively endeavor to ensure that hazardous media are safely contained, preventing leaks that could lead to litigation, costly clean-ups, and fines.

But beyond compliance with mandates and codes, a focus on protecting people, sensitive information, and valuable property is also driving the demand for safer and more efficient containment solutions. Even systems conveying potable water can cause substantial loss of property or life in certain applications. 

Double containment solutions in non-mandated applications offer businesses an effective and reliable way to protect workers and other key assets, as well as the environment.

What is double containment?

Double containment involves a piping system (“primary”) inside a piping system (“secondary”), creating a fail-safe method for the conveyance of fluids. If the primary pipe leaks, the leakage remains within that secondary containment, so it cannot harm anyone or anything outside the system.

These systems can be as large as 18 inches in diameter for the primary pipe, also called the “carrier” line, and 24 inches for the containment. However, the most common sizes extend from half an inch to 12 inches for the primary and 2 inches to 18 inches for the containment pipe.

Equally important is the EPA requirement that any pressurized system incorporate continuous electronic monitoring to identify leaks quickly. This combination of the preventive pipe-in-a-pipe design and continuous system monitoring is essential for applications where leaks pose serious risks.

Historically, electronic leak detection methods involved a cable sitting at the bottom of the secondary pipe and running through the entire interstitial space between it and the primary line. Should the cable become wet from a leak, it immediately signals the leak’s location to a control panel, prompting a rapid response and minimizing potential damage.

The downside of this traditional approach is that the containment pipe needs to be upsized to accommodate the cable and the cable must be removed whenever a leak occurs. An alternative solution is low-point detection where sensors are located at low points in the system. When there is a leak, it accumulates in these low points and the sensors trigger an alert to a control panel. Low-point systems are more cost-effective and customizable, offering designers and end users more options to monitor leaks.

Material and application flexibility

Double containment piping systems can potentially involve a range of thermoplastic and metallic materials to accommodate specific operational needs such as temperature resistance and chemical compatibility. System designers can choose thermoplastics such as PVC, CPVC, PVDF, and polypropylene. Metal pipe options include carbon steel, stainless steel, and copper. Some manufacturers even offer customized combinations of metallic and thermoplastic systems to satisfy the most demanding industrial applications.

This material flexibility allows system designers and installers to adapt to a wide range of applications that mandate containment piping for the transport of hazardous, corrosive, or aggressive chemical fluids. Among the more common of these are:

• Chemical processing
• Water and wastewater treatment
• Pharmaceutical manufacturing
• Battery manufacturing and recycling
• Semiconductor manufacturing
• Generator backup systems

A recent successful example involved the Clarion Altela Environmental Services (CAES) facility in Clarion, Pennsylvania. Here, double containment was crucial for transporting untreated frac water. Due to the chemicals and saline present in the water, a double containment piping system was required to transport it from incoming tank trucks to holding ponds, and from there to the treatment-processing equipment at CAES.

“Frac water recycling is a fairly new process, and the project didn’t start out requiring a double containment system for the piping,” explains Walter Smith, former mechanical engineer with Mid Penn Engineering and the system designer.

“During approvals, the [state] Department of Environmental Protection decided to require double containment for any area where buried pipes would be transporting untreated frac water. This was to prevent any possibility of leakage into the surrounding soil. Once the piping went inside the facility, we were able to transition to a single wall system.”

Engineered double-containment systems are known for their relative ease of installation. Many manufacturers offer hands-on training to make installation even faster and more efficient.

Because double containment systems feature prefabricated, modular components that simplify the setup process and minimize the number of joints, labor and overall project costs are typically reduced. The risk of leaks and maintenance issues is also lessened, ensuring long-term reliability.

That was the case at the CAES facility, where fewer joints lowered installation costs while enhancing end-user safety. The double containment system has operated reliably without leaks, demonstrating its effectiveness in handling sensitive fluids under strict regulations. (See the complete case study here.)

Let’s also keep people safe

As noted, double containment piping systems are for more than mandated or code-compliant situations involving the safe conveyance of dangerous substances underground. It can be used in systems conveying any type of fluid above sensitive areas.  Some important examples of applications where double containment can be used to protect people and vital information are: 

• Healthcare facilities
• Data centers
• Libraries and museums

Hospitals are an especially critical application. A leak could create a substantial risk to health and even life in these facilities.  That is why many facilities are choosing to double-contained piping systems over all the important areas.

Would you really need to contain a sanitary line in a hospital? What about drip trays: Wouldn’t they be enough?

Even a drain, waste, and vent leak would be a massive problem for a facility on perpetual alert against pathogens, bacteria, and viruses. Shouldn’t that DWV pipe be locked up as tightly as possible for maximum protection?

What harm can a potable water leak create in a hospital? In applications where the potable water piping runs overhead, such as through the ceiling of an operating room, a leak could interrupt a surgery. Wouldn’t any sort of leak in the midst of a surgical procedure create serious, even life-threatening dangers?

Double containment is an excellent way to protect the environment, minimize liability, and meet EPA mandates and other legal requirements. But double containment is also the right thing to do to protect people, sensitive information, and valuable property.

It may be necessary to have double containment of underground pipelines full of corrosive chemicals. But what about those same pipelines running overhead inside a factory? Don’t we want to avoid leaks in that piping and the harm they could cause workers?

Or what about piping running through critical areas where a leak could down production, damage artifacts, cause a loss of critical information, or — even worse — cause harm or death?

So, let’s not just double-contain per mandates and codes. Let’s also double-contain because it’s the right thing to do.

To learn more about IPEX double containment systems, download the brochure at https://ipexna.com/en-us/resources/document-repository/double-containment-product-catalogue/  Or visit https://ipexna.com/.

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About the author: Steven Dolejsi received a B.S. in Mechanical Engineering from Ryerson University. He is the Applications Engineering Manager at IPEX, where he has worked for over 19 years. He can be reached at [email protected].

About IPEX
As the North American business of global leader Aliaxis, a leading manufacturer of thermoplastic piping systems, IPEX has more than 60 years of experience and is a leader recognized for designing and manufacturing innovative solutions to the world’s water challenges and a transition to clean energy. Our state-of-the-art manufacturing facilities, new R&D center, and distribution centers across Canada and the United States employ over 4,000+ people committed to a sustainable future and our approach to environmentally responsible manufacturing. Learn more about IPEX online at ipexna.com or on LinkedIn.

About Aliaxis
At Aliaxis, we design sustainable, easy-to-install, and innovative solutions to address the world’s water challenges and accelerate the transition to clean energy. Thanks to our 15,000+ employees, our pipes and fitting systems meet our customers’ most demanding needs for the building, infrastructure, industrial and agriculture sectors. Operating in over 40 countries, the company is active through leading local brands and generated €4.3 billion in revenue in 2022. More on www.aliaxis.com.

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