1. The influence of the zinc liquid temperature. When the temperature of the zinc liquid is lower than 430℃, the diffusion rate of zinc and iron is low, and it is not easy to generate a sufficient iron-zinc alloy layer, so the entire coating is thin; when the temperature is 460℃, the zinc layer thickens, and when the temperature continues to rise, the zinc liquid becomes thinner and the zinc layer becomes thinner. Therefore, the temperature of the zinc liquid must be strictly controlled to ensure the stability of the quality of the steel grating.
2. The influence of the residence time of the steel grating in the zinc liquid. The residence time of the steel grating in the zinc liquid has a certain time range, which is determined according to the thickness of the steel grating. As the galvanizing time increases, the coating thickness will increase, but excessive extension of the galvanizing time will make the zinc layer brittle, which will affect the quality.
3. Influence of the extraction method of steel grating from zinc liquid. When the galvanized parts are drawn out of the zinc liquid, they should be drawn out vertically, and when the steel grating is drawn out at an angle, the zinc layer is thin. Therefore, the steel grating should be drawn out vertically when it is drawn out of the zinc pot.

1. Strictly control the quality of the raw materials of the corrugated culvert. The corrugated pipes entering the site should be stacked neatly, and workers are not allowed to step on the corrugated pipes.
2. The corrugated pipe culvert should be cut straight, and it is strictly forbidden to cut it into an oblique mouth.
3. The positioning of the corrugated pipe culvert should be accurate, especially near the joint. The spacing of the corrugated pipe culvert positioning steel bars is 0.5m, and none of them can be missing.
4. The method of connecting the corrugated pipe culvert: The corrugated pipe culvert joint is wrapped with a 0.3-meter-long large corrugated pipe, half-twisted at both ends, and there is no gap in the middle.
5. When the welded steel bar is close to the corrugated pipe culvert, measures should be taken to keep the corrugated pipe from being burned. If you are not careful, the burned area should be tightly wrapped with tape.
6. The corrugated pipe culvert should be covered and maintained to avoid premature aging due to wind and rain.
7. Considering the gradual decrease in the number of corrugated pipe culverts on the roof, all parts that conflict with the corrugated pipe culvert should avoid the corrugated pipe.

The steel pipe billet is severely corroded, and a thick iron oxide layer appears on the surface. Because the elements in the steel matrix are not necessarily uniform, some places are deeply corroded, and some places are shallowly corroded. After pickling, large uneven pits appear. Such a surface leaves pits after heat leveling.

The steel pipe billet is too corroded, and a thick iron oxide layer appears on the surface. Because the elements in the steel matrix are not necessarily uniform, some places are deeply corroded, and some places are shallowly corroded. After pickling, large uneven pits appear. Such a surface still leaves pits after hot-dip galvanizing.

When the steel pipe is pickled, many pits are caused by over-pickling, especially in the welds. The action of micro-batteries causes this. Too large pits cannot be filled during hot-dip galvanizing.

The carbon (C) content, iron carbide (Fe3C), silicon, aluminum, copper, phosphorus, sulfur, and nitrogen in the steel pipe matrix will cause different dissolution rates during pickling and cause pits. This situation is very easy to occur in basic converter steel, so it is also easy to cause over-pickling.

The pickling steam scars formed during pickling are ring-shaped or bird's nest-shaped, which are easy to cause pits.