Differences in service life between sanded fiberglass steel pipes and steel pipes

Differences in service life between sanded fiberglass steel pipes and steel pipes
service life
The matrix of fiberglass steel pipe is its stable polymer material, and its failure pressure is designed to be 6 times the working pressure, which can ensure a 50 year service life (see AWWA, ASTM standards).
The service life of steel pipes is generally 20 years. During operation, maintenance is frequent, difficult to maintain, and costly. When a steel pipe is buried underground for operation, factors such as the water quality inside the pipe, the surrounding soil, groundwater, and the presence of an electric field near the buried area can all cause corrosion on the inner and outer walls of the pipe. Therefore, the standard stipulates that the inner and outer surfaces of the pipe body should be coated with asphalt or other anti-corrosion materials. Due to the difference in material between the coating material and the steel pipe, during long-term operation, it is prone to interface delamination and detachment due to the effects of cold and hot weather, hydraulic impact, etc., gradually losing the anti-corrosion coating layer, resulting in oxidation and electrochemical corrosion of iron molecules on the inner surface of the pipe, which will inevitably reduce its service life.
Comparison of hydraulic characteristics
The inner wall of the fiberglass pipe is very smooth, and the Hazen-Wllliams roughness coefficient C value of the new fiberglass pipe is 160~165, with a conservative design value (based on 50 years) of 150. The C value of new steel pipes is all 120, and after use, it is C=65. The decrease in C value is caused by the oxidation of iron molecules on the inner surface of the tube and the reflection of electrochemical corrosion on the inner wall scaling.
Comparison of flow rates between steel pipes and fiberglass pipes. Because the roughness of the new steel pipe is 0.05mm, the roughness of the corroded steel pipe is 3mm, and the roughness of the corroded steel pipe is 60 times that of the uncorroded steel pipe;
If the Hazen Williams average roughness coefficient C value of the steel pipe is 100 and the C value of the fiberglass pipe is 150, then the flow rate of the 12 inch fiberglass pipe is the same as that of the 14 inch steel pipe. Alternatively, under the same pipe diameter conditions, the flow rate of fiberglass steel pipes is 36% higher than that of steel pipes.