High precision ,excellent brightness, no oxidization scale, high cleanness inner surface, flushing the inner diameter, antirust oil painted, total impurity<1.5mg/m. Maximun granule 8 degree (≤0.2mm), withdraw high pressure, no deformation after cold bending, the complicated geometrical forming and machining can be realized, color of the tube : gray with white. The tolerance for OD and ID : ±0.05, quality inner surface : Q, work pressure 2000 kilos, max testing pressure: 6000 kilos without deformation. 180 bending degress without cracks.