The steel pipe is a kind of traditional pipe, which is welded after the steel plate is spirally wound into a cylindrical shape. From the standpoint of strength and rigidity, both sand-clad FRP Pipe and steel pipe have excellent characteristics. However, from the analysis of corrosion resistance and service life, hydraulic characteristics, energy consumption, water quality, transportation, installation, and price, the sand-containing FRP Pipe is superior and more competitive than steel pipe.
First, technical performance comparison
1 Design flexibility
FRP Pipe has the design flexibility, can be designed and manufactured for any combination of applicable technical parameters, can meet the needs and requirements of customers maximally; and the design of the steel pipe is less specific, only to a certain extent Features.
2 Strength properties
FRP Pipe has excellent strength properties, the maximum allowable working pressure can reach 6.4MPa, the design safety factor is more than 6 times.
1) Tensile strength:
According to the fiber laying and content, the apparent tensile strength of FRP Pipe can be between 140~520MPa, and the axial tensile strength can be between 70~320MPa.
2) Bending strength:
According to fiber laying and content conditions, the apparent circumferential bending strength of FRP Pipe can be between 154~340MPa. Not only is the mouthpiece flexible, but the tubing is also flexible.
3) Impact strength:
FRP Pipe has a good impact strength of 300kgf•cm/cm2 or more. Tests have shown that: Φ2600FRP Pipe is free to fall from a height of 1.8m without any damage;
3 Stiffness performance
In terms of stiffness performance, both can meet engineering needs. The FRP Pipe is designed to increase the stiffness of the middle layer of the pipe wall that is subjected to the bending stress in accordance with the needs of the project. It can meet any stiffness requirements of the user. The rigidity of the steel pipe itself is large enough to be taken into consideration.
In the case of short-term accidental overloading (such as trucks), the FRP Pipe can be borne by its own elastic deformation, and can be automatically restored to its original shape after the load is removed; however, the steel pipe is easily sheared and damaged under certain deformation. fracture.
4 service life
FRP Pipe's substrate is an extremely stable polymer material, and its breaking pressure is designed to be 6 times the working pressure, ensuring a 50-year service life (see AWWA, ASTM standards).
The service life of steel pipes is generally 20 years. Frequent maintenance during operation, difficult maintenance and high cost. When the steel pipe is buried underground, factors such as water quality in the pipe, surrounding soil and groundwater, and presence of electric field near the buried zone will cause corrosion on the inside and outside of the pipe. Therefore, the standard stipulates that the inside and outside surfaces of pipes should be coated with asphaltenes or other anti-corrosion materials. Due to the different material of the coating material and the steel pipe, in the long-term operation, the interface is stratified and detached due to the effects of hot and cold weather, hydraulic impact, etc., and the corrosion-resistant coating layer is gradually lost, thereby causing oxidation of the iron molecules on the inner surface of the pipe. The role of electrochemical corrosion, etc., will certainly reduce the service life.
