What are the composition and working principle of 3PE anti-corrosion coating?
3PE consists of epoxy powder (bottom layer), adhesive (middle layer) and polyethylene (surface layer). Epoxy powder provides cathodic protection, adhesive enhances interlayer bonding, and polyethylene resists mechanical damage. This structure can achieve an anti-corrosion life of more than 30 years, especially suitable for acidic soil environment.
What are the design points of spiral tube cathodic protection system?
The number of sacrificial anodes (such as magnesium alloy) or impressed current parameters needs to be calculated according to soil resistivity. The anode burial spacing is usually 200-300 meters, and the potential needs to be maintained at -0.85 to -1.2V (CSE standard). When designing, it is necessary to avoid stray current interference with other metal structures.
What are the advantages and disadvantages of FBE (fused bonded epoxy) coating?
The advantages include strong adhesion, high temperature resistance (up to 100°C), and environmental protection and solvent-free. The disadvantage is low mechanical strength, easy to be scratched during construction, and needs to be used with cathodic protection. It is suitable for pipelines within the station or directional drilling crossing sections, but not suitable for gravel geology.
How to choose the inner anti-corrosion coating of spiral pipe?
Water pipelines are often lined with cement mortar, which is low-cost and resistant to water erosion. Chemical pipelines use polyurethane or fiberglass linings to resist acid and alkali. When choosing, you need to consider the medium temperature (such as epoxy resin temperature resistance ≤80℃), friction coefficient (affecting transportation efficiency) and hygiene standards (drinking water requires FDA certification).
What are the on-site repair methods for damaged anti-corrosion layers?
Small area damage can be repaired with liquid epoxy resin + fiber tape, and large area needs to be stripped and re-coated. Before repair, sandblasting and rust removal to Sa2.5 level are required, and the compatibility of the repair material and the original coating needs to be tested. Submarine pipelines need to use underwater curing coatings and be operated by divers or ROVs.
