Pipeline corrosion protection materials are divided into main pipeline corrosion protection materials and their corresponding jointing materials. Main corrosion protection materials mainly include petroleum asphalt, epoxy coal tar pitch, adhesive tape, epoxy powder coating, PE coating, and PP coating.
Common jointing methods include petroleum asphalt jointing, epoxy coal tar pitch jointing, adhesive tape jointing, epoxy powder jointing, and PE heat-shrinkable material jointing.
If the pipeline body is a three-layer PE composite structure, three-layer PE heat-shrinkable jointing material is the preferred jointing material.
For single-layer epoxy powder coating jointing, epoxy powder, adhesive tape + primer, and three-layer PE heat-shrinkable jointing can be used.
Additionally, commonly used steel pipeline corrosion protection layers in China include petroleum asphalt, PE jacket and PE foam jacket, epoxy coal tar pitch, coal tar enamel, epoxy powder, and three-layer composite structures. The two most widely used pipeline corrosion protection methods are three-layer PE composite structures and single-layer epoxy powder.
Petroleum asphalt is widely available and inexpensive. However, poor working conditions, difficulty in guaranteeing quality, and serious environmental pollution are all problems.
Epoxy coal tar pitch is easy to apply, but the curing time of the coating is long, it is greatly affected by the environment, unsuitable for field operations, and difficult to apply below 10℃.
Cold-applied tape for corrosion protection is easy to apply, but its adhesion is slightly weaker, its waterproof performance is low, its strength is low, and it is greatly affected by the environment.
Epoxy powder coating, using electrostatic spraying, has good fusion with the pipe body coated with the same material and strong adhesion, but epoxy powder has poor waterproof performance (high water absorption rate, reaching 0.83%), which brings certain difficulties to cathodic protection design. High requirements for on-site equipment, difficult operation, and difficult quality control are also present.
3PE heat-shrinkable material provides strong pipe corrosion protection and sealing, high mechanical strength, strong waterproof performance, stable quality, convenient construction, good applicability, and does not pollute the environment. PE has a low water absorption rate (below 0.01%) and combines the high strength of epoxy with the low water absorption of PE and the good flexibility of hot melt adhesive, resulting in high corrosion resistance reliability. Its disadvantage is its higher cost compared to other jointing materials.
Cold-applied tape and 3PE heat-shrinkable tape are suitable for pipelines with various main anti-corrosion layers, while other methods are suitable for pipelines with main anti-corrosion layers of the same or similar materials.
Secondly, with development, some pipelines require insulation in addition to corrosion protection. Petroleum is a complex mixture that easily corrodes pipelines, making corrosion protection necessary. However, refined oil pipelines also require insulation in addition to corrosion protection. In Northeast China and during winter, thermal expansion and contraction can cause pipelines to freeze and crack, affecting stable supply.
