PVC vs. FRP in Sewer Pipes: The Truth About Stiffness and Performance
In the 24- to 60-inch sewer pipe market, PVC and fiberglass-reinforced plastic (FRP) are direct competitors. But while both materials are used in underground systems, FRP has a significant weakness—it’s far more sensitive to deflection (ovalization) under soil pressure and traffic loads. However, you wouldn’t know it from FRP manufacturers’ literature. Take pipe stiffness, for example. The entire flexible pipe industry recognizes "PS" as the standard abbreviation for pipe stiffness. FRP, however, opts for "SN," calling it a "stiffness number." The implication? That somehow, changing the letters makes FRP pipes stiffer. But pipe stiffness is pipe stiffness—no matter what acronym is attached to it. The Reality of FRP Performance The PVC Pipe Association recently published a technical report pulling back the curtain on FRP’s real-world performance. The findings are clear: PS and SN are equivalent measurements, meaning there’s no advantage in FRP’s terminolog...