Anti-corrosion of galvanized steel pipe welding: After surface treatment, hot spray zinc.
If galvanizing is not possible on-site, you can follow the on-site anti-corrosion method: brush epoxy zinc-rich primer, epoxy micaceous iron intermediate paint, and polyurethane topcoat. The thickness refers to relevant standards.
Features of galvanized steel pipe process
1. Optimization of sulfate galvanizing: The advantage of sulfate galvanizing is that the current efficiency is as high as 100% and the deposition rate is fast, which is unmatched by other galvanizing processes. Because the coating crystallization is not fine enough, the dispersion ability and deep plating ability are poor, so it is only suitable for electroplating pipes and wires with simple geometric shapes. The sulfate electroplating zinc-iron alloy process optimizes the traditional sulfate galvanizing process, retaining only the main salt zinc sulfate, and discarding the other components. In the new process formula, an appropriate amount of iron salt is added to form a zinc-iron alloy coating from the original single metal coating. The reorganization of the process not only promotes the advantages of the original process of high current efficiency and fast deposition rate but also greatly improves the dispersion ability and deep plating ability. In the past, complex parts could not be plated, but now both simple and complex parts can be plated, and the protective performance is 3 to 5 times higher than that of a single metal. Production practice has proved that the continuous electroplating of wires and pipes has finer and brighter coating grains than the original ones, and the deposition rate is fast. The coating thickness reaches the requirement within 2 to 3 minutes.
2. Conversion of sulfate zinc plating: Sulfate electroplating of zinc-iron alloy only retains the main salt zinc sulfate of sulfate zinc plating, and the remaining components such as aluminum sulfate and alum (potassium aluminum sulfate) can be added with sodium hydroxide during the plating solution treatment to generate insoluble hydroxide precipitation for removal; for organic additives, powdered activated carbon is added for adsorption and removal. The test shows that aluminum sulfate and potassium aluminum sulfate are difficult to completely remove at one time, which has an impact on the brightness of the coating, but it is not serious and can be consumed as it is taken out. At this time, the brightness of the coating can be restored. The solution can be treated and supplemented according to the content of the components required by the new process, that is, the conversion is completed.
3. Fast deposition rate and excellent protective performance: The current efficiency of the sulfate electroplating zinc-iron alloy process is as high as 100%, and the fast deposition rate is unmatched by any galvanizing process. The running speed of the fine tube is 8-12 m/min, and the average coating thickness is 2m/min, which is difficult to achieve with continuous galvanizing. The coating is bright, delicate, and pleasing to the eye. According to the national standard GB/T10125 “Artificial Atmosphere Test-Salt Spray Test” method, the coating is intact and unchanged after 72 hours; a small amount of white rust appears on the surface of the coating after 96 hours.
4. Unique clean production: The galvanized steel pipe adopts the sulfate electroplating zinc-iron alloy process, which means that the production line slots are perforated directly without any solution carryover or overflow. Each process of the production process consists of a circulation system. The solutions in each tank, i.e., acid and alkali solution, electroplating solution, light emitting, and passivation solution, are only recycled and reused without leakage or discharge to the outside of the system. The production line has only 5 cleaning tanks, which are recycled and discharged regularly, especially the production process without wastewater generation after passivation without cleaning.
5. The particularity of electroplating equipment: The electroplating of galvanized steel pipes is the same as the electroplating of copper wires, which are all continuous electroplating, but the plating equipment is different. The plating tank designed for the slender strip of iron wire has a long and wide but shallow tank body. During electroplating, the iron wire passes through the hole and spreads out in a straight line on the liquid surface, maintaining a distance from each other. However, galvanized steel pipes are different from iron wires, and have their unique features, and the tank equipment is more complicated. The tank body consists of two parts, the upper part is the plating tank, and the lower part is the solution circulation storage tank, forming a trapezoidal tank body that is narrow at the top and wide at the bottom. There is a channel for the electroplating of galvanized steel pipes in the plating tank. There are two through holes at the bottom of the tank that are connected to the storage tank at the bottom, and form a plating solution circulation reuse system with the submersible pump.
Therefore, the galvanized steel pipe is the same as the iron wire electroplating, and the plating parts are dynamic. Unlike the iron wire electroplating, the plating solution of the electroplated galvanized steel pipe is also dynamic.
Post time: Sep-27-2024