1. Follow the standard design and material selection, and choose different materials and steel grades for different service environments. High alloy pipes like stainless steel pipes are also used in corrosive environments (the cost is 4 times more than that of carbon steel), but stainless steel pipes also have the problem of pitting corrosion of Cl-.
2. Adopt appropriate and effective protective coatings such as anti-corrosion coatings and metal plating protection technology.
3. Adopt other auxiliary methods such as adding corrosion inhibitor and closed water injection system to reduce the dissolved amount of O2, CO2 and H2S and using sulfate reducing bacteria fungicide.
4. Use cathodic protection; establish a corrosion monitoring system; grasp the dynamics of corrosion and prevent problems before they occur.
OCTG pipes coatings performance requirements
The anti-corrosion of OCTG pipes is essentially shielding. It is to block the contact of H2S, CL-, CO2 and acidic compounds formed by dissolving in water with the pipe body. The specific requirements are that the coating has smooth coating surface, no defects and good adhesion, certain temperature resistance, good barrier to corrosive media in the environment, stable chemical properties of the coating material and reliable mechanical properties.
The roles of internal anti-corrosion coatings
The coating is corrosion resistant due to its electrical insulation. It can improve fluid efficiency due to the smooth surface. It can also reduce waxing due to its smooth surfaces and chemical properties. The scale can be reduced due to the chemical nature of the coating. The reuse rate of pipes can be improved. Avoid salvage and workover operations. The internal anti-corrosion coating is conducive to improving quality of water injection.