①Raw material inspection: The raw material inbound screening standard is wall thickness controlled within ±8% and outer diameter controlled within ±0.75%.
② Post-annealing inspection: Some pipes need to be annealed before drawing.Inspection of the annealing effect after annealing.
③Inspection after chemical treatment: Test the effects of pickling, bonderizing, and saponification.
④Check after drawing: check the deviation accuracy of outer diameter, inner diameter, wall thickness, and so on, as required.
⑤Mechanical properties inspection: Do tensile, yield, elongation, hardness, and other tests to check whether the mechanical properties required by clients are satisfied.
⑥Straightness inspection: Ensure the straightening reaches the straightness required by clients.
⑦Polishing and inspection: Polishing the outer surface according to the client’s needs so that the appearance is more beautiful and more convenient for painting.After completion of the inspection, ensure the appearance is qualified.
⑧Second drawing: according to the client's requirements, we can make the second drawing to achieve the required size and deviation accuracy.

Notes on the accuracy of the outer diameter, inner diameter, wall thickness, straightness, and other aspects of the pipe:
1. The deviation range of the outer diameter and the allowance left for the inner diameter are per client requirements.
2. Inner diameter roundness is controlled: within 15 Si.
3. Wall thickness deviation is controlled: ≦±5%.
4. Straightness is controlled: ≤0.5mm.