Let's first look at the core structural differences.

The key lies in the "sand inclusion layer." Ordinary FRP pipes (fiber-reinforced plastic pipes) are made of a pure resin and glass fiber composite, lacking a sand inclusion layer. The fibers provide strength, resulting in a relatively uniform structure but relatively low hoop stiffness. RPMP pipes (glass fiber-reinforced resin sand inclusion pipes) are essentially an upgraded FRP pipe, incorporating an additional core layer of quartz sand and resin, creating a three-layer structure: an inner resin-rich anti-corrosion and anti-seepage layer, and a glass fiber reinforcement layer in the middle. The added sand inclusion layer is crucial, significantly improving the pipe's hoop stiffness and providing the most significant difference between RPMP and FRP pipes.

Looking at performance

there are significant differences in stiffness and pressure-bearing capacity. FRP pipes' hoop stiffness depends primarily on fiber density, resulting in relatively low pressures, typically below 1.6 MPa, making them suitable for medium- and low-pressure applications. However, they are lightweight and offer good impact resistance. RPMP pipe is different. Its sand inclusions give it exceptionally high hoop stiffness, reaching over 10,000 Pa. This provides strong resistance to soil pressure, even up to 2.5 MPa, making it suitable for high-pressure projects. However, due to the additional sand layer, it weighs slightly more than FRP pipe, but only about one-quarter the weight of steel pipe. Both have smooth inner surfaces and excellent hydraulic performance, but RPMP pipe's superior stiffness allows it to be one or two diameters smaller than other pipes for the same flow rate. In terms of lifespan, FRP pipe has a lifespan of approximately 30 years, while RPMP pipe can reach over 50 years, with superior corrosion resistance and anti-scaling properties.

In terms of application scenarios

each has its own strengths. FRP pipe is more suitable for protecting power or telecommunication cables because it is insulated and non-magnetic, preventing eddy current heating in cables. It is also well-suited for low-pressure corrosive media transport in chemical plants, especially for small-diameter pipelines (DN ≤ 200). RPMP pipe is more common in municipal engineering projects, such as large-diameter (DN100 to 4000) water supply and drainage pipes buried underground and subject to high external pressure. It is a reliable alternative to ductile iron or PCCP pipe in high-pressure water transmission projects, offering a cost advantage. In trenchless construction projects, such as pipe jacking, its smooth outer wall reduces resistance during jacking and facilitates correction. Its acid- and alkali-resistant properties and resistance to microbial growth also come in handy in corrosive environments like sewage and seawater.

There are also differences in production processes and economic efficiency.

FRP pipe is generally made by winding or rolling pure fibers, with single pipe lengths typically ranging from 4 to 6 meters and a relatively low unit price. RPMP pipe requires a more complex process, including winding and sand inclusions, and computer-controlled quartz sand distribution. Single pipes can be 6 to 12 meters long and have fewer joints. While the unit price may be slightly higher, it's more cost-effective in the long run: transportation costs are only one-tenth of cement pipe, installation is quick, joints are minimal, and sealing is excellent. Furthermore, the smooth interior reduces resistance, reducing pumping energy consumption by approximately 10%.

In general

the choice of pipe depends primarily on project requirements: FRP pipe is more suitable for cable protection, lightweight construction, or conveying low-pressure corrosive media. For municipal water supply and drainage, high-pressure buried pipelines, and especially large-diameter or trenchless construction, RPMP pipe is more suitable. Simply put, RPMP pipe is an "enhanced" version of FRP pipe. Its sand inclusion layer overcomes the lack of hoop stiffness of pure FRP pipe, allowing it to function in heavier-load infrastructure. While the two are essentially subdivided options within the same material system for different scenarios, it's not a matter of one replacing the other.