4.1. Specifications: The outer diameter of the hot-rolled tube is 32-630mm. Wall thickness 2.5 ~ 75mm. The outer diameter of the cold-rolled (cold-drawn) pipe is 5 to 200 mm. Wall thickness 2.5 ~ 12mm.
4.2. Appearance quality: The inner and outer surfaces of the steel pipe shall not have cracks, folds, folds, delaminations, hair lines and scarring defects. These defects should be completely removed, and the wall thickness and outer diameter should not exceed negative deviations after removal.
4.3. Both ends of the steel pipe should be cut at right angles and burrs should be removed. Steel pipes with a wall thickness greater than 20mm are allowed to be cut by gas cutting and thermal sawing. After the agreement between the supply and demand sides, the head may not be cut.
4.4. "Surface Quality" of cold-drawn or cold-rolled precision seamless steel pipe refers to GB3639-83.
