Assessing FRP composites in water system infrastructure

June 26, 2024

water system infrastructure

Regular inspection critical for water infrastructure assets

The recent failure of a water main feeder line in Calgary, Alberta, Canada, is a stark reminder of the need for cities to pay closer attention to inspection and ongoing maintenance and replacement planning. 

In cities and towns across Canada, water distribution and sewage pipes are typically several decades old. Some are nearing the end of their service life — if they’re not leaking already.

In 2019, the Canadian Infrastructure Report Card stated that a third of Canada’s roads, bridges, water, wastewater and stormwater systems are in “fair” or “very poor” condition. Climate change will add further strain on infrastructure that’s already struggling to provide essential water and wastewater services for a growing population. 

Calgary water main hadn’t been evaluated in 10 years

According to media reports, the water main in Calgary was expected to have another 50 years of service life — but it hadn’t been evaluated in 10 years. The pre-stressed concrete cylinder pipe (PCCP) is a type used across North America for decades and now known to be vulnerable to major failures. According to the Globe and Mail, Calgary has 187 kilometres of PCCP in service similar to the one that failed. 

Clearly, new long-term strategies are needed to replace or rehabilitate water pipes and other municipal infrastructure.

More and more city engineers and managers are looking to fiber-reinforced polymer (FRP) equipment as part of the solution.

The $600-billion infrastructure investment gap

In 2021, the Financial Accountability Office of Ontario estimated that $12.6 billion is needed in that province alone to bring drinking water and wastewater infrastructure to a state of good repair. In 2023, a study by the Federation of Canadian Municipalities suggested that in order to meet federal and provincial housing targets to approve 5.8 million homes by 2030, the investment gap could reach $600 billion. Globally, the World Bank estimates urban infrastructure investment requirements will reach US$4.5 trillion to US$5.4 trillion in the same period.

Bridging the gap: the role of FRP composite materials

Faced with chronic gaps in funding and resources, municipal engineers and planners must balance planning for future growth with the need to keep infrastructure functioning and maximize its lifespan. They must also plan for minimal service interruptions due to inspections, maintenance, or equipment replacement.

FRP composites are already widely used in potable water and wastewater systems for pipes, storage tanks, scrubbers, ducting and other equipment.

While best practices are continually evolving to meet those challenges, it’s clear that FRP technology has a larger role to play in bridging the infrastructure gap. This is now possible due to advances in the design, construction and Fitness For Service assessment of these materials.

Advantages of FRP in water infrastructure

FRP has many advantages over the iron and concrete used to make most water and wastewater piping:

  • FRP is lightweight and easier to install. FRP pipes are ¼ the weight of ductile iron and 1/10 of concrete.
  • FRP has superior corrosion resistance. 
  • The smooth surface minimizes friction and resists sludge and mineral build-up in the piping system
  • FRP can be used to line concrete pipes by pushing FRP pipe through existing pipe (called “jacking”), extending its lifespan while minimizing disruption caused by excavation.
  • FRP is mechanically strong and can be used to make large storage tanks and pipes designed to withstand harsh environments and ground conditions. (Polyethylene is commonly used for water pipes under 400 mm in diameter but is not suitable for larger pipes needed for water mains.)
  • FRP can be bonded/joined to existing concrete or steel pipes
  • FRP is a cost-effective and sustainable choice with a much lower carbon footprint than concrete

Wastewater applications for FRP

Tanks, scrubbers, piping and ducting

FRP is often the material of choice for equipment used in wastewater treatment for storing and transporting solutions that are acidic or have free chlorides including brine, chlorine dioxide, chlorine, sodium hypochlorite, sodium bisulphite and numerous acids. FRP materials often provide better corrosion resistance at lower cost than stainless steel. 

For some applications, regulators require structural evaluation of containers or piping for public health and safety purposes.

Most asset management programs require periodic inspection and evaluation of the equipment’s remaining service life (RSL). However, while there are established objective methods for determining RSL of equipment made from conventional steel, there are no consensus standards that apply to inspecting steel-reinforced concrete like the failed pipe in Calgary. Conventional methods also don’t work for stainless steel because the damage mechanisms affecting it are profoundly different. Finally, with respect to ducting and piping, traditional techniques that rely on visual inspection are impractical in many situations and provide limited insight, so often no inspection occurs and a failure happens without warning.

UTComp’s UltraAnalytix® NDT system is a proven, non-intrusive and non-destructive evaluation method that provides objective data to evaluate the current condition and RSL of FRP equipment, from small- and large-diameter piping to ducting up to the largest storage tanks.

See an overview of UltraAnalytix technology and its applications in assessing FRP storage tanks at wastewater treatment facilities.

Repairing steel pipes with FRP wrap

Adding layers of FRP to reinforce damaged steel piping and pressure vessels is an approved, fast, inexpensive and safe alternative to traditional repair methods that require removing and replacing damaged sections of pipe, encasing it with a steel sleeve, or welding a patch onto the pipe.

The process of dismantling defective sections of pipe can cause even more damage and typically requires a partial or temporary shutdown of operations. For example, wastewater from residences and businesses is collected into wet wells within pumping stations through gravity-fed pipelines. Pumps in these stations are used to transfer the wastewater to a treatment facility.

UTComp was asked by a large Canadian municipality to repair a pumping station’s two force mains. The team was able to quickly repair and reinforce the pipes using an FRP wrap as the force mains were too vital to be shut down for complete replacement.

Read the FRP wrap case study to learn more.

Inspecting and assessing FRP wrap

While it’s impossible to predict the remaining lifespan of FRP overwrap until the material encased by the FRP begins to fail, UltraAnalytix inspection quickly and reliably evaluates the condition of the repair by: 

  • accurately measuring the thickness of the FRP wrap, and 
  • assessing the quality of the bond between the FRP and the pipe and between layers of the wrap (the contact factor)

Drinking water applications for FRP

Reverse Osmosis (RO) pressure vessels

In addition to pipelines and storage tanks, FRP composites are used to make reverse osmosis (RO) pressure vessels used in desalination facilities that supply potable water in arid regions such as the Middle East, Africa, Australia and some cities in California.

This filtration technology has been around for decades, so there are potentially tens of thousands of these units worldwide that may be nearing the end of their service life. However, while design and construction codes cover how RO vessels must be manufactured, they provide no guidance for determining Fitness For Service.

Collaborative research with UTComp licensee RPC Technologies Pty demonstrated the value of UltraAnalytix NDT in providing a fast, reliable, and cost-effective method for determining the Fitness For Service of RO pressure vessels.

Regular inspections using the UltraAnalytix system could save the global desalination industry billions of dollars by reducing losses of a valuable resource (water) through leaks and other failures, improving reliability, increasing operational uptime and lowering capital replacement costs.

Read the RO vessel case study for more.

Chemical storage vessels for water treatment

FRP is widely used for storage vessels needed to contain the various chemicals used in the water treatment process. For example, FRP vessels are used to store acidic solutions used in water treatment and disinfection, as well as NaOH (sodium hydroxide, or caustic soda), a highly corrosive substance used in the desalination process. 

NaOH is used to change the pH of seawater to make it less corrosive and prevent fouling of the water treatment equipment. However, it can also damage FRP resins. Using UltraAnalytix, trained inspectors can accurately measure the condition and assess the mechanical integrity of chemical storage vessels.

To learn more, see the sodium hydroxide storage vessel case study.

A wake-up call for asset management and inspection

UltraAnalytix non-destructive testing (NDT) is a fast, accurate, safe and cost-effective way for municipalities to assess their FRP assets while avoiding unnecessary downtime and replacement costs.

Meanwhile, Calgary’s water crisis is an alert for all cities to make asset management planning a priority by:

  • Determining the Fitness For Service of all their potable water and wastewater infrastructure
  • Putting engineers to work on remediation strategies and long-term solutions
  • Taking a hard look at asset replacement plans, what they are and what they should be
  • Including regular inspections as part any long-term strategy 

Questions about your FRP composite equipment?