GB/T 17791-2017Seamless copper and copper alloy tubes for air conditioning and refrigeration equipment (English PDF)

1 Scope

China's national product standard for the seamless copper tube that carries refrigerant. It specifies the requirements, the test methods, the inspection rules, the packaging, marking, transport, storage and quality certificate, and the content of the purchase order or contract for seamless copper and copper alloy tubes used in household air conditioners, refrigerators and freezers, small and medium central air conditioning, and refrigeration equipment. Refrigerant tube is a component with an unusual failure economics. It is cheap, it is used by the kilometre, and a single pinhole empties the charge, kills the appliance and cannot be repaired in the field. So the standard is written around the defects that produce pinholes rather than around bulk strength. Wall thickness and its uniformity come first - a tube thinned on one side by an eccentric mandrel fails there under pressure cycling and vibration. Then the inner surface: residual drawing lubricant, carbon film and oxide left inside the tube contaminate the refrigerant circuit, break down the compressor oil and block the capillary, so the standard sets the residual carbon and cleanliness limits and how they are measured. Then the mechanical condition, since the tube must be soft enough to bend and flare during assembly without cracking, which the drift-expanding and flattening tests demonstrate, while being strong enough for the working pressure - and the harder refrigerants raise that pressure considerably. Dimensional tolerance and straightness matter because the tube is fed into automatic bending and brazing machinery. The final chapter, on what a purchase order must state, is not filler: for a product supplied in dozens of alloy, temper, size and coil combinations it is what prevents the wrong tube arriving. Issued on 12 July 2017 and in force since 1 February 2018, it replaces GB/T 17791-2007.

This standard specifies the requirements, test methods, inspection rules, packaging, marking, transportation, storage, quality certificates and purchase orders (or contracts) of seamless copper and copper alloys tube for air conditioner and refrigeration equipment. This standard applies to seamless copper and copper alloys tube (hereinafter referred to as tubes) for household air conditioners, refrigerators (freezers), small and medium-sized central air conditioners, refrigeration equipment.

2 Normative references

The following documents are essential to the application of this document. For the dated documents, only the versions with the dates indicated are applicable to this document; for the undated documents, only the latest version (including all the amendments) are applicable to this standard.

GB/T 228.1-2010 Metallic materials - Tensile testing - Part

4 Test method

4.1 Chemical composition The analysis of the chemical composition of the tube shall be carried out in accordance with the provisions of GB/T 5121 (all parts) or YS/T482.The arbitration shall be carried out in accordance with the provisions of GB/T 5121 (all parts).

4.4 Flaring test The flaring test of the tube is carried out in accordance with the provisions of GB/T 242.

4.5 Flattening test The flattening test of the tube is carried out according to the requirements of GB/T 246.

4.6 Eddy current flaw testing The eddy current flaw testing of the tube shall be carried out in accordance with the provisions of GB/T 5248.

4.7 Grain size The grain size inspection of the tube shall be carried out according to the requirements of YS/T 347.

4.8 Hydrogen embrittlement test The hydrogen embrittlement test of the tube is carried out according to the closed bending method in GB/T 23606.The repeated bending method in GB/T 23606 is used for arbitration; the number of bending is at least 6 times.

4.9 Cleanliness The inspection of internal surface residues (total) of tubes with an outer diameter of <= 30 mm shall be carried out in accordance with Appendix A.

4.10 Surface quality Visually inspect the surface quality of the tube.