Ordinary purlins are formed by hot-rolled steel strips by machine rolling, and then made into C or Z shapes. After forming, the surface is sprayed with gray anti-rust paint. Ordinary purlins are just painted with a layer of anti-rust paint on the outside. If they are transported, the paint film is easily scratched off during installation. The hdg purlin, which is short for hot-dip galvanized purlin, is not afraid of scratching, and its corrosion resistance is greatly improved compared with ordinary purlins.
Hot-dip galvanizing is also called hot-dip galvanizing. Hot-dip galvanizing is a surface treatment method to improve the anti-rust ability of steel parts. Hot-dip galvanizing is the degreasing of steel parts in lye, and then derusting in acid (a certain composition of hydrochloric acid or sulfuric acid), exposing the clean metal surface, and then immersing it in a molten galvanizing pot, thereby making The parts are covered with a uniform and complete zinc layer, which greatly improves the anti-corrosion ability of steel parts and prolongs their service life. For example, common highway guardrails, transmission towers, etc. are all hot-dip galvanized, and these equipment will not rust for ten years, even twenty or thirty years.
The coating of hot-dip galvanizing is thicker, generally 30-60 microns, and the coating has a higher anti-corrosion ability. It is suitable for long-term rust prevention of steel parts for outdoor work, such as highway fences, power towers, and large-size fasteners. Older iron water pipes were also hot-dip galvanized.