Some minor defects such as pressure pit, crush, scratch and graphite mimeograph are allowed on the surface of aluminium tubular busbar and tubing bar. The defect depth shall not exceed the deviation of wall thickness to ensure the minimum wall thickness, but the dent shall not exceed the negative deviation of diameter.
The area of allowable defects on the surface of aluminium tubular busbar and tubing bar shall not be greater than 0.5% for pipe and rod, and 3% for structural pipe.Longitudinal and transverse scratches are permitted.
