Anticorrosion of Steel Pipes for Water Delivery

PINDEE PIPE MANUFACTURE AND SELL ANTI CORROSION OF WATER DELIVERY STEEL PIPES,FOLLOWING YOU CAN FIND SOME KNOWLEDGE OF STEEL PIPE
1.1 External anticorrosion
The external anti corrosion of water delivery steel pipes mainly includes 3PE coating and hot-melt PE powder. 3PE coating is currently a relatively complete and good external anti-corrosion process, as shown in Figure 1. Combining the corrosion resistance of fusion bonded epoxy powder and the anti-collision properties of high-density polyethylene, the external anti-corrosion has good mechanical properties, good adhesion, good insulation, and low water absorption. Currently widely used as external anti-corrosion coatings for various pipelines.

Figure 1

Hot melt PE powder coating is similar to powder spraying technology. After hot melting, PE powder is 100% bonded to the pipe body to form a complete coating. It can achieve consistency between the anti-corrosion coating of elbows and fittings and the hot-melt PE structure of the main pipe. The process of hot-melt PE powder is simple, but the disadvantage is that the adhesion is average; The anti-corrosion layer is thin (1.5mm) and not resistant to damage.

1.2 Internal anticorrosion
With the development of anti-corrosion of the pipeline, There are various forms of pipeline anti-corrosion, mainly including lining cement mortar coating, polyurethane coating, solvent-free liquid epoxy coating, fusion bonded epoxy coating, and IPN8710 coating. FBE epoxy resin inner coating is based on epoxy resin, with modified quartz sand added as filler. The epoxy powder prepared by grinding is melted and solidified at high temperature, and then adhered to the inner wall of the steel pipe after heating. Its characteristics are low inner wall friction coefficient (0.0081 to 0.091), low energy consumption, smooth inner wall, not easy to scale, no pollution to water quality, 100% curing, no ester bonds after curing, no hydrolysis reverse reaction, no reduction in anti-corrosion effect, and long theoretical service life (50 years). The disadvantage is that steel pipes will be heated during the anti-corrosion process, so it is limited to large-diameter steel pipes.

The solvent-free liquid epoxy inner coating is a fully automatic high-pressure spray coating without gas at room temperature. The solvent-free two-component epoxy coating is sprayed on the inner wall of the steel pipe. The advantage of this internal coating is that it does not contain harmful substances, has the characteristics of no leakage, environmental protection, good adhesion, long service life, and one-time formation of thick film. IPN-8710 coating is a new generation of non-toxic two-component coating specifically designed for drinking water, developed in combination with epoxy coating for drinking water tanks. The first component of the coating consists of modified epoxy resin, polyurethane resin, non-toxic pigments, fillers, and additives. The inner wall of the steel pipe is coated with IPN-8710 using spraying equipment. The disadvantage is that the paint should be used up within 6 to 8 hours after curing. Otherwise, it is easy to stick cement and the construction time is relatively long.

According to application cases of water pipelines abroad, cement mortar and polyurethane coatings can also be used for internal anti-corrosion of water pipelines, but the engineering cost is relatively high. It is rarely used in China. According to foreign sources, polyurethane coating is a comprehensive thermosetting plastic coating. Used for internal and external spraying of pipelines and fittings, it has the advantages of moisture resistance, temperature resistance (up to 160 ° C), good glossiness and color retention, high coating glossiness and decorative properties, simple process, and fast drying speed. It can also cure normally at 0 ° C, and the film thickens in one go. It is currently very expensive, so it is rarely used in China.

In addition, the internal coating of cement mortar is uniformly applied to the inner wall of the steel pipe by factory centrifuges or on-site spraying machines. The characteristics of this anti-corrosion method are low raw material prices and low requirements for rust removal on the inner wall of steel pipes. Cement mortar is used for anti-corrosion of water supply steel pipes. When water penetrates into the cement mortar layer and reaches the steel surface, it becomes a high pH alkaline solution, passivating the steel surface and tightly bonding the cement mortar with the inner wall of the steel pipe. The disadvantage is that improper maintenance during the production process of cement mortar can easily lead to defects such as cracks and hollowing, which affect the anti-corrosion effect.

To sum up, in terms of the 3PE Anti corrosion steel pipe, Welded steel pipes are more flexible than PCCP pipes and ductile iron pipes with a single anti-corrosion coating. According to the actual situation in the region, flexibly select anti-corrosion coatings that meet the requirements, meet the different requirements of the conveying medium and environment, and ensure the long-term safe operation of the pipeline.

2. Practical application

What is 3PE anti-corrosion coated steel pipe? After nearly 60 years of development in China's welded pipe industry, the rapid advancement of pipe making technology and steel metallurgy technology has ensured that welded steel pipes have high welding quality and dimensional accuracy, good pressure bearing capacity, excellent deformation resistance, good reliability, and safety. In recent years, with the assistance of anti-corrosion technology for steel pipes, the application of welded steel pipes in the field of water transmission engineering has been increasing.

The rapid development of anti-corrosion technology and materials has greatly extended the safe service life of water transmission steel pipes compared to other pipelines. In recent years, anti-corrosion steel pipes have been widely used in the field of water transportation.