Surface finish:
Hot Rolled: Hot rolled seamless pipes usually have a rougher and scaly surface. Due to the cooling process after hot rolling, the surface may exhibit a scaly texture.
Cold Drawn: Cold drawn seamless pipe typically has a smoother, more polished surface. The cold drawing process improves the surface finish for a cleaner, glossier appearance.
dyeing:
Hot Rolling: The color of hot rolled pipe may become darker due to surface oxidation and scaling during cooling.
Cold Drawn: Cold drawn tubing typically has a brighter and lighter color, reflecting the smoother and cleaner surface produced by the cold drawn process.
Surface defects:
Hot-rolled: Hot-rolled pipe may exhibit surface defects such as scale, oxidation, and rough texture.
Cold Drawn: Cold drawn tubing is less likely to exhibit surface imperfections and tends to exhibit a more consistent, defect-free surface.
In terms of length
The length of cold-drawn seamless steel pipes is generally shorter than that of hot-rolled seamless steel pipes. The longest length of cold-drawn seamless steel pipes can reach 9 meters, the longest length of hot-rolled seamless steel pipes can reach more than 12.5 meters, and the longest thermal expansion length can reach 14 meters.
wall thickness
Cold drawn seamless steel pipes have thicker walls than hot rolled seamless steel pipes. The local wall conditions of cold drawn seamless steel pipes are not non-existent but very small. For example, the maximum deviation wall condition for a wall thickness of 3mm is 0.3mm, while the minimum deviation wall condition for hot-rolled seamless steel pipes is 0.3mm. Generally, the local wall thickness condition of hot-rolled seamless steel pipe is 0.3mm. The wall thickness range is 10%, that is, the wall thickness of 10mm can be offset by plus or minus 1mm (9mm-11mm) to be qualified.
