Copper Tubes are manufactured as per EN 1057 meeting the following requirements
Copper Tubes ore designated under alloy C 106 also called DHP (Deoxidised High Residual Phosphorized Grade).
The requirement is as follows :
Min. Copper including Silver % - 99.9%
Dimensional tolerance to confirm to the EN 1057. It must be noted that the dimensional tolerance on copper tubes as specified for the outside diameter is very important so that the annual gap between the tube & the fitting is within a designated dimensional tolerance to ensure correct & proper capillary action during the process of soldering or brazing. Please refer to Table 1,2 & 3 for dimensional tolerance on outside diameter, dimensional tolerance for wall thickness is given below:
Tolerances on wall thickness
|Nominal Outside ||Tolerance on wall thickness e" |
|diameter (mm) ||e < 1 mm(%) ||e > 1 mm(%) |
|< 18 ||10 ||13 |
|> 18 ||10 ||15 |
3) MECHANICAL (PHYSICAL) PROPERTIES ARE DESIGNED IN EN 1057 TO BE AS FOLLOWS :
|Material Temper ||Outside Diameter in mm ||Tensile Strength Mpa ||Elogation % ||Hardness (only indicative) Hv |
|Designated in Accordance with EN 1173 ||Common Term used ||Min. ||Max. ||Min. ||Max. || |
|R220 ||Annealed ||6 ||54 ||220 ||40 ||(40 to 70) |
|R250 ||Half-hard ||6 ||67 ||250 ||30 ||(75 to 100) |
| ||6 ||159 || ||20 || |
|R290 ||Hard ||6 ||267 ||290 ||3 ||(min. 100) |
4) FREEDOM FROM DEFECTS: Surface Quality
The outer diameter & inner surface of the tube shall be clean & smooth. An attack on copper tube can occur causing pitting corrosion when a thin film of carbon is formed within the bore of the tube during the manufacturing process. Concern over deleterious film in the bore has prompted the newly adopted EN 1057 to call for a carbon film & carbon content test, concerning the measurement of the residual & potential carbon in a copper tube bore. MEXFLOW Copper Tubes meet this criteria.
5) FREEDOM FROM DEFECTS TESTS :
Each lube shall be subjected to one of the following test: Eddy current test for detection of local defects, in accordance with pr EN1971. Or Hydrostatic test or Pneumatic test. The choice of the method selected from the above, is at the discretion of the manufacturer.
Hall hard copper tubes and soft annealed copper tubes must undergo a bending test without formation of wrinkles on the inner bend. Bending is an expansion of the outside surface of the bent tube & a contraction of the inner surface of the tube. The formation of wrinkles on the inner surface shows either the fact that the physical properties of the tube are not in order or the bending mechanism i.e. the bending tool has got a gap more than the diameter of the tube, which allows the tube to get raised while conducting the bending operation from the former, allowing wrinkle formation to take place on the inner surface.