Requirements for surface quality of copper tube
- There should be no crack, peeling, air hole, looseness, folding, corrosion and inclusion on the surface of copper pipe.
- The outer surface of copper tube can be allowed to have slight, local scratch, spot, dent, indentation and other defects within the allowable deviation
- There shall be no pinholes on the inner surface of copper tube within the range of 50 mm-300 mm from the upper end face. The diameter of pinholes in other parts shall not be greater than 0.4 mm, and the depth shall be less than the thickness of the coating. The number of pinholes shall not exceed 2 for every 300 mm2 w area.
- The coating shall have fine grain, uniform color, no pitting, crack, bubble, peeling and other defects
- Routine inspection items of each mould copper tube: surface quality; Dimensions, tolerances and roughness; Taper of copper tube; Coating thickness; Hardness of copper tube and coating; Conductivity.
- Sampling inspection items of each batch of crystallizer copper tubes: chemical composition (except oxygen and impurity content; Room temperature mechanical properties: hydrostatic test; Nondestructive testing; Bonding strength between copper tube and coating
- The optional inspection items shall be determined by the supplier and the demander: chemical composition: oxygen and impurity content; High temperature mechanical properties (200 ° c)； Physical properties: other items except conductivity; Softening temperature.