Aging wastewater infrastructure faces no shortage of challenges. From fat, oils, and grease (FOG) buildups to corrosion caused by hydrogen sulfide (H2S), to the damage evoked by inflow and infiltration (I/I) incidents and outsized flow rates, there’s continuous need for repair and rehabilitation. The rise of trenchless repair solutions has made it possible for repair professionals to lean on products like spray-in-place piping (SIPP), which cures atop damaged substrate to effectively form a new pipe-within-a-pipe.
Sanitary sewer rehabilitation isn’t as easy as simply spraying on a protective coating. Choosing the right polymeric coating material is crucial for not only repairing current damage, but also for protecting and reinforcing infrastructure for the foreseeable future.
Here’s a look at the three major polymeric SIPP coating material options and how they’re best-applied to solve a growing number of wastewater infrastructure challenges.
Polyurea coatings
Polyurea coatings are perhaps the most versatile types of polymeric coatings on the market today. They’re also among the oldest types of SIPP solutions, meaning they’re tried and true across a variety of applications. Because they set with no annular space (0.5mm to 25mm), they’re well-suited to rehabilitation where flow rate preservation is integral.
These coatings are prized for their fast reactivity, boasting three- to six-seconds gel time, and 100% solids formulation base. The customizable nature of polyurea formulations makes it easy for technicians to meet specific application requirements depending on the scope of work or the unique nature of a rehabilitation project. That said, most polyurea coatings rely on an amine ending blend as the resin.
Key takeaways
- Extremely fast setup and gel times makes polyurea coatings a quick SIPP solution.
- Great for rehabilitation projects that preserve flow rate, with almost no annular space.
- Customizable for different SIPP applications; usually based on an amine ending resin.
Polyurethane coatings
Polyurethane linings rely on a polyol ending blend and can support multiple applications where buildup is required. Like polyurea liners, they have a quick set and gel time, but also require substrate surfaces to be completely dry or the application risks failure. When applied correctly, it’s tough to beat the protection and longevity that polyurethane coatings offer.
Polyurethane coatings are often the perfect marriage of cost-efficiency and durability for broad-scope SIPP applications. They’re highly rated against chemical abrasion, corrosion, microbial buildups, and even seismic activity. As a result, many municipalities now turn to these coatings for both emergent and preventive water utility rehabilitation.
Key takeaways
- Can support buildup applications, but they require a dry environment to set.
- Extremely resistant to most detractors, including corrosion, abrasion, seismic activity.
- Tend to be ubiquitous in their application across all types of water utility rehabilitation.
Epoxy coatings
Unlike polyurea and polyurethane coatings, epoxy coatings are formulated using a thermosetting epoxide polymer, which uses amines to cure. Fortified with ceramics to improve cure strength and fluid dynamics, epoxy liners are the gold standard in SIPP. They’re so durable and resilient that they’re often used not only in rehabilitation projects, but in water utility improvement projects, as well. At an average 2mm thickness, these liners won’t impede flow capacity in any meaningful way.
Their all-around resistance to chemicals, corrosion, adhesion, and other detractors makes epoxy coatings well-suited for just about any environment. That said, they’re particularly useful in high-heat and moisture-rich environments, where other coatings may suffer during setup. As a result, these liners are commonplace across raw, potable, and wastewater applications. Their chief drawback? Setup times range into the hours, instead of minutes.
Key takeaways
- Resilient against all detractors and capable of performing in extreme environments.
- Use across the spectrum of water utilities, including potable and wastewater lines.
- Require a longer setup time than other SIPP coatings.
Application matters above all
The right polymeric coating, applied correctly, can solve significant challenges that would otherwise require a more invasive approach to repair below-ground infrastructure. And, its ability to withstand heavy duress for potential decades means it’s a premier solution in combatting the growing amount of stress placed on aging water utilities.