This process standard is applicable to the anti-corrosion construction operations of equipment and pipelines in civil and general industrial buildings. metal is a kind of damage phenomenon caused by the chemical and electrochemical action of the surrounding medium. According to the corrosion part of the pipeline, it can be divided into inner wall corrosion and outer wall corrosion; according to the pipeline corrosion form, it can be divided into general corrosion and local corrosion; according to the pipeline corrosion mechanism, it can be divided into chemical corrosion and electrochemical corrosion.
Pipeline anticorrosion process
base surface treatment → Distributing paint → Brushing intermediate paint → Brushing or spraying construction → Maintenance
Pipeline anti-corrosion is divided into main anti-corrosion and repair weld anti-corrosion
The choice of materials for pipeline anti-corrosion depends on the material of the main pipeline anti-corrosion layer. Commonly used mending methods include petroleum asphalt mending, epoxy coal tar mending, adhesive tape mending, powder epoxy mending, and PE heat shrinkable material mending.
If the main body of the pipeline is a three-layer PE composite structure, the patch material is preferably a three-layer PE heat shrink patch material, and the patch of a single-layer epoxy powder coating can use epoxy powder, adhesive tape + primer and three-layer PE There are three ways to shrink the mouth.
In addition: the most commonly used steel pipeline anticorrosive coatings in China include petroleum asphalt, PE jacket and PE foam jacket, epoxy coal tar pitch, coal tar enamel paint, epoxy powder and three-layer composite structure, epoxy coal tar pitch cold wrapping tape (PF Type), rubber-plastic epoxy coal tar pitch cold-wrapped tape (RPC type), etc. At present, the most widely used pipeline anti-corrosion methods are three-layer PE composite structure, single-layer powder epoxy, PF type cold-wrapped tape, RPC Type cold-wrapped belt.
Petroleum asphalt has a wide range of raw materials and low prices. However, the working conditions are poor, the quality is difficult to guarantee, and the environmental pollution is serious.
Epoxy coal tar pitch is easy to operate, but the covering layer has a long curing time and is greatly affected by the environment. It is not suitable for field operations and is difficult to construct below 10°C.
Epoxy powder anti-corrosion, using electrostatic spraying method, good fusion with the same material anti-corrosion pipe body, strong adhesion, but epoxy powder has poor water resistance (high water absorption rate, up to 0.83%), designed for cathodic protection Bring certain difficulties. On-site equipment requires high requirements, difficult to operate, and difficult to control quality.
3PE heat-shrinkable material, strong pipeline anti-corrosion and sealing, high mechanical strength, strong water resistance, stable quality, convenient construction, good applicability, and no pollution to the environment. PE has low water absorption rate (less than 0.01%), high epoxy strength, low PE water absorption and good hot melt adhesive flexibility, etc. It has high anti-corrosion reliability. The disadvantage is: compared with the cost of other splicing materials ,costly.
The construction of the PF type and RPC type cold-wrapped tapes is simple and easy. The matching three types of sizing adhesives make the PF-type epoxy coal tar pitch cold-wrapped tapes can be constructed in any environment, any season, and any temperature conditions.
The characteristics of cold-wrapped tape and 3PE heat-shrinkable tape are: it is suitable for the main anti-corrosion layer pipes of various materials, while other methods are suitable for the main anti-corrosion layer pipes of the same or close to the material.
Secondly, along with the development, some pipelines also need insulation during anti-corrosion. Petroleum is a very complex mixture, and it is easy to corrode pipelines. Anti-corrosion is necessary. However, product oil pipelines also need to be insulated in the case of anti-corrosion. In the northeast and winter, Thermal expansion and contraction will freeze and crack the pipeline, affecting stable supply.