Copper tubes are widely used in refrigeration systems, such as connecting tubes, heat exchangers and capillaries. However, the materials of copper tubes are also different, other brands are also used. 1. The brand, condition and specification of the product shall conform to the requirements of Table 1:

EXAMPLE: a round tube made from TP2, in soft state, with a diameter of 4.76 mm and a wall thickness of 0.5 mm, is marked as TP2M Φ4.76 × 0.5 Gb/t 527 -- 19972. The chemical composition of the tubing for material analysis shall meet the requirements of the corresponding grade in Gb/t 5231. T2 is pure copper, TP1 and TP2 are phosphorus deoxidized copper. The chemical composition of T2 is specified as follows: Cu + Ag ≥99.90% . Other ingredients as specified in GB 5231. The chemical constituents of TP1 are specified as follows: Cu + Ag ≥99.90% , p = 0.004% ー0.012% . Other ingredients as specified in GB 5231. The chemical composition of TP2 has been specified as follows: Cu + Ag ≥99.9% , p = 0.015% ー0.040% . Other ingredients as specified in GB/t 5231. 

3. Dimensions and permissible deviations of dimensions

4. Mechanical Properties of pipes at room temperature shall be in accordance with Table 3.

5. Mick weight calculation method 1: If the sample is less than 1000mm, take 200mm ± 10mm copper pipe to grind the two ends flat, the end should be perpendicular to the axis and no necking phenomenon. Measure the length with a Vernier scale, weigh it with a balance of 1 mg, and calculate the weight per unit length, which is called the Mick weight. CALCULATION FORMULA: Mick weight = length/weight * 1000 method 2: If weight is required on the drawing, the scale with accuracy of 0.1 g is used to weigh it. 

Source: Refrigeration breakout