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 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.

1. Nominal diameter is 25mm, and the corresponding outer diameter is about 33.5mm.
2. Nominal diameter is 32mm, and the corresponding outer diameter is about 42.4mm.
3. Nominal diameter is 40mm, and the corresponding outer diameter is about 50.8mm.
4. Nominal diameter is 50mm, and the corresponding outer diameter is about 61.8mm.
5. Nominal diameter is 65mm, and the corresponding outer diameter is about 76.2mm.
6. Nominal diameter is 80mm, and the corresponding outer diameter is about 88.9mm.
7. Nominal diameter is 100mm, and the corresponding outer diameter is about 114.3mm.
8. Nominal diameter is 125mm, and the corresponding outer diameter is about 139.7mm.
9. Nominal diameter is 150mm, and the corresponding outer diameter is about 168.3mm.
10. Nominal diameter is 200mm, and the corresponding outer diameter is about 219.1mm.

The nominal diameter of hot-rolled seamless steel pipe can be up to 600mm, while the maximum nominal diameter of cold-rolled seamless steel pipe is 200mm.