Compared with ordinary steel pipes, seamless pipes can withstand higher pressures. Therefore, in industrial production, seamless steel pipes are used when pipes that need to withstand greater pressure. Some people call it “the tiny blood vessel in industry”, whether it is manufacturing airplanes, ships, trains, or transporting oil, gas, and water, it is inseparable from him. Naturally, how to prevent corrosion of seamless steel pipes? What are the technical requirements? This is a question that many people are concerned about.
Anti-corrosion technical requirements for seamless steel pipes
Pipeline anticorrosion: The anticorrosion of steel pipes needs to be in accordance with the requirements of the drawings, using epoxy coal tar pitch to outsource glass cloth, and coating the topcoat for anticorrosion;
External wall construction process: rust removal of pipes – primer – first top coat – second top coat – third top coat
1. Pipeline derusting
Before the primer is applied, the surface of the pipe is cleaned of grease, ash, rust, and iron oxide scale; the quality standard of rust removal by sandblasting reaches Sa2.5 level.
2. Derusting the surface of the pipeline
After the surface of the pipe is derusted, the primer should be applied, and the time interval between them should not exceed 8 hours. When applying the primer, the base surface should be dry. The primer should be applied evenly and fullly without clots or foaming, and it should not be painted within the range of 150-250mm at both ends of the pipe.
3. Primer
After the surface of the primer is dry, apply the topcoat and wrap the glass cloth, and the time interval between the primer and the first coat of topcoat should not exceed 24 hours.
4. Various material specifications
Epoxy coal tar pitch paint is a two-component, room temperature curing paint. The glass silk cloth is dry, dewaxed, untwisted, edge-sealed, medium-alkali, and the warp and weft density is 10*12 threads/cm~12*12 threads/cm. Immediately after the topcoat is painted, glass cloth should be wrapped. The width of the glass cloth is 30~40mm, and the lap length of the joint should not be less than 100mm. At the same time, the overlapping streets of each layer are staggered from each other. The oil penetration rate of the glass silk cloth should reach more than 95%, and there should be no gaps larger than 50mm*50mm, and a stepped stubble of 150~250mm should be left at the pipe end
5. Pipeline interface
The construction of the joint of the pipeline shall be carried out after the welding and pressure test is qualified. The old and new anti-corrosion flanges shall not be less than 50mm, the lap length of the joint shall not be less than 100mm, and the stubble joint shall be firmly and tightly bonded;
6. Outer wall of steel pipe
Coating requirements for the outer wall of the steel pipe: one bottom and two sides, one cloth and two sides, the total dry film thickness is 400 μm (microns);
7. Inner wall of steel pipe
Steel pipe inner wall coating mechanism: one bottom and three sides. The total dry film thickness is 300 μm.
8. Quality inspection
After the external anti-corrosion construction is completed, the quality inspection shall be carried out according to the design requirements or the corresponding requirements in the “Water Supply and Drainage Pipeline Engineering and Acceptance Specifications”.
Seamless steel pipe is a steel pipe without weld seam manufactured by hot processing methods such as piercing and hot rolling. If necessary, the hot-processed pipe can be further cold-processed to the required shape, size and performance; at present, seamless steel pipe is the most widely used pipe in petrochemical production equipment. It is also an inevitable requirement to do a good job in steel pipe anti-corrosion. Only by understanding the anti-corrosion requirements and technologies of pipelines can the continuous use of steel pipes be guaranteed.
