The base material of anti-corrosion steel pipe mainly includes straight seam steel pipe, spiral steel pipe and seamless steel pipe, and has a wide range of applications. 3PE anti-corrosion steel pipe is suitable for high-rise building water supply, heating network heating, water supply engineering, gas transportation, buried water delivery and other pipelines.
Process pipelines for transporting corrosive media in petroleum pipelines, printing and dyeing industries. Sewage treatment discharge pipe, sewage pipe and biological pool anti-corrosion project. For agricultural irrigation pipes, deep well pipes, drainage pipes and other networks, it can be said that 3PE anti-corrosion steel pipes are indispensable in the current construction.
It is believed that through the extension of technology, there will be even more brilliant achievements in the future. In the use of electric resistance welded pipes, the protection technology of the pipeline from soil, air and transportation medium (oil, natural gas, etc.) should be avoided.
Most of the pipelines for transporting oil and gas are in a complex soil environment, and the medium to be transported is also corrosive, so that both the inner and outer walls of the pipeline may be corroded. Once the pipeline is corroded and perforated, it will cause oil and gas loss, which will not only interrupt the transportation, but also pollute the environment, and may even cause fire and damage.
It is necessary to remove grease, burrs, dirt and welding slag from the surface of the steel pipe. The pipe insulation layer can separate the pipe and the soil, increase the resistance between the two, and thus achieve the anti-corrosion purpose of reducing the corrosion current. The main anti-corrosion insulation materials for buried gas steel pipes include: coal tar pitch, petroleum asphalt, and epoxy coal tar pitch, plastic film and polyvinyl chloride wrapping tape. In China, the anti-corrosion layer of buried steel pipe is mainly made of epoxy coal tar pitch. It has strict requirements in pipeline construction.
Secondly, the rust is removed to the standard level. The rust removal method may be selected by spray rust removal or mechanical rust removal. Then, it is necessary to deal with the defects on the surface of the steel pipe, remove the surface abrasives and dust, and keep the surface of the steel pipe clean and dry.
If surface contamination and rust are present, the surface should be reprocessed. The primer should be applied evenly and without defects such as clots, leaks or sag. After the primer has dried, the tape is wound, requiring tight winding and smooth surface without empty drum or wrinkle problems.
In the actual pipeline engineering and the pipeline of the use environment, although the construction is carried out cautiously, it is impossible to ensure that the corrosion-resistant layer has no defects. If there is a defect in the anti-corrosion steel pipe layer, the pipe is placed at the anode potential, and the corrosion current is concentrated to the defect portion. From the theoretical or practical experience, it causes perforation faster than the steel pipe.
Actually judge the advantages and disadvantages of the underground pipeline coating; this is to determine the total leakage resistance of the pipeline to the earth, according to its size. In addition, when measuring the ground potential of the underground pipeline with the protection of the discharge iso-electric method, generally press It is determined along the attenuation state of the pipe.
At present, the application effect of the anti-corrosion layer is well evaluated, and there are few reports on the defects generated in its use. The main disadvantages reported are dew point, peeling, cathodic dis-bonding, cathodic protection shielding, and peeling of the coating under the film.
Moreover, most of the reports on defects still remain in the theoretical speculation stage. For example, the problem of cathodic protection shielding is mentioned in the data. There is no report on the cathodic protection shielding in the actual operation of the anti-corrosion layer. After many years of practice, the coating system with fewer defects has been a FBE/extruded polyethylene 3-layer structural anti-corrosion system with increasing use years.