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1) Corrosion Resistance and Long Service Life

FRP pipes possess excellent corrosion resistance, resisting corrosion from acids, alkalis, salts, seawater, oily wastewater, corrosive soil, and groundwater—that is, numerous chemical substances. They also exhibit good resistance to strong oxides and halogens. Therefore, the lifespan of these pipes is significantly extended, generally exceeding 30 years. Laboratory simulations show that FRP pipes can have a service life of over 50 years. In contrast, metal pipes in low-lying, saline-alkali, or other highly corrosive areas require maintenance after only 3-5 years, with a service life of only about 15-20 years, and higher maintenance costs in the later stages of use. Domestic and international practical experience has proven that FRP pipes retain 85% of their strength after 15 years and 75% after 25 years, with low maintenance costs. Both of these values ​​exceed the minimum strength retention rate required for FRP products used in the chemical industry after one year of use. The service life of FRP pipes, a matter of great concern, has been proven by experimental data from actual applications. 1) Excellent Hydraulic Characteristics: The FRP (fiberglass reinforced plastic) pipelines installed in the US in the 1960s have been in use for over 40 years and are still operating normally.

2) Good Hydraulic Characteristics

Smooth inner walls, low hydraulic friction, energy savings, and resistance to scaling and rust. Metal pipes have relatively rough inner walls, resulting in a high coefficient of friction that increases rapidly with corrosion, leading to further resistance loss. The rough surface also provides conditions for scale deposition. FRP pipes, however, have a roughness of 0.0053, which is 2.65% of seamless steel pipes, and reinforced plastic composite pipes have a roughness of only 0.001, which is 0.5% of seamless steel pipes. Therefore, because the inner wall remains smooth throughout its lifespan, the low resistance coefficient significantly reduces pressure loss along the pipeline, saves energy, increases transport capacity, and brings considerable economic benefits. The smooth surface also inhibits the deposition of contaminants such as bacteria, scale, and wax, preventing contamination of the transported medium.

3) Good Anti-aging, Heat Resistance, and Freeze Resistance

Fiberglass pipes can be used for extended periods within a temperature range of -40 to 80℃. High-temperature resistant resins with special formulations can even operate normally at temperatures above 200℃. For pipes used outdoors for extended periods, ultraviolet absorbers are added to the outer surface to eliminate ultraviolet radiation and slow down aging.

4) Low thermal conductivity, good insulation and electrical insulation properties

The thermal conductivity of commonly used pipe materials is shown in Table 1. The thermal conductivity of fiberglass pipes is 0.4 W/m·K, about 8‰ that of steel, resulting in excellent insulation performance. Fiberglass and other non-metallic materials are non-conductive, with an insulation resistance of 10¹² to 10¹⁵ Ω·cm, providing excellent electrical insulation, making them ideal for use in areas with dense power transmission and telecommunications lines and areas prone to lightning strikes.

5) Lightweight, high specific strength, and good fatigue resistance

The density of fiberglass reinforced plastic (FRP) is between 1.6 and 2.0 g/cm³, which is only 1-2 times that of ordinary steel and about 1/3 of aluminum. Because the continuous fibers in FRP have high tensile strength and elastic modulus, its mechanical strength can reach or exceed that of ordinary carbon steel, and its specific strength is four times that of steel. Table 2 shows a comparison of the density, tensile strength, and specific strength of FRP with several metals. FRP materials have good fatigue resistance. Fatigue failure in metal materials develops abruptly from the inside out, often without prior warning; however, in fiber-reinforced composites, the interface between the fibers and the matrix can prevent crack propagation, and fatigue failure always starts from the weakest point in the material. FRP pipes can be configured to have different circumferential and axial strengths by changing the fiber layup to match the stress state, depending on the circumferential and axial forces.

6) Good wear resistance

According to relevant tests, under the same conditions and after 250,000 load cycles, the wear of steel pipes was approximately 8.4 mm, asbestos cement pipes approximately 5.5 mm, concrete pipes approximately 2.6 mm (with the same internal surface structure as PCCP), clay pipes approximately 2.2 mm, high-density polyethylene pipes approximately 0.9 mm, while fiberglass pipes only wore down to 0.3 mm. The surface wear of fiberglass pipes is extremely small, only 0.3 mm under heavy loads. Under normal pressure, the wear of the medium on the inner lining of the fiberglass pipe is negligible. This is because the inner lining of the fiberglass pipe is composed of high-content resin and chopped glass fiber mat, and the resin layer on the inner surface effectively shields against fiber exposure.

7) Good designability

Fiberglass is a composite material whose raw material types, proportions, and arrangements can be changed to adapt to various working conditions. Fiberglass pipes can be designed and manufactured to meet various specific user requirements, such as different temperatures, flow rates, pressures, burial depths, and load conditions, resulting in pipes with different temperature resistance, pressure ratings, and stiffness levels. Fiberglass pipes using specially formulated high-temperature resistant resins can also operate normally at temperatures above 200℃. Fiberglass pipe fittings are easy to manufacture. Flanges, elbows, tees, reducers, etc., can be made arbitrarily. For example, flanges can be connected to any steel flange of the same pressure and pipe diameter that conforms to national standards. Elbows can be made at any angle according to the needs of the construction site. For other pipe materials, elbows, tees, and other fittings are difficult to manufacture except for standard parts of specified specifications.

8) Low construction and maintenance costs

Fiberglass pipes are lightweight, high-strength, highly malleable, easy to transport, and simple to install, requiring no open flame, ensuring safe construction. The long single pipe length reduces the number of joints in the project and eliminates the need for rust prevention, anti-fouling, insulation, and heat preservation measures, resulting in low construction and maintenance costs. Cathodic protection is not required for buried pipes, which can save more than 70% of engineering maintenance costs.