What should be inspected after welding copper and aluminum pipes with a butt welding machine?

Copper-aluminum pipes are also called sleeve joints and copper-aluminum connecting pipes. They are mainly welded with special butt welding machines, such as pneumatic copper-aluminum pipe welding machines,Automatic copper and aluminum pipe butt welding machineetc., mainly used in refrigeration industries such as refrigerators and air conditioners. Their requirements are relatively high and there are many inspection items.

1. Appearance quality
1. Conduct a visual inspection of the anti-corrosion layer of the product. The outer surface of the copper-end aluminum connecting pipe should be anti-corrosion treated with heat shrink tube, or surface treated with color paint or coating. Other methods can also be used for anti-corrosion treatment. The anti-corrosion area should cover the weld and the surface of the aluminum pipe, and there should be no appearance on the surface.
Damage or exposure.

2. The dimensions, specifications and deviations of copper-aluminum connecting pipes should comply with the requirements of the drawings. Those not indicated on the drawings should comply with the relevant requirements of GB/T17791-2007, GB/T 6893-2000 and GB/T20250-2006.

3. The diameter and size tolerance of the selected specifications for roundness of the copper pipe mouth, and the maximum burr height ≤ 0. 1mm.
4. The copper pipe openings at both ends are not allowed to crack.
5. The inner wall roughness of the copper tube Ry≤20μm.
6. Air tightness test, no leakage.
8. 1) Leakage and deformation shall not occur during the strength test. 2) The burst test pressure should meet user requirements. 3) Pipeline cleanliness testing must meet specified requirements.

2. Joint quality inspection items
1. Appearance inspection of copper and aluminum pipe casing joints: there should be no welding defects such as welding spatter, copper pipe bulges, copper pipe dents, etc. on the outer surface of the weld.
2. Inner diameter detection of copper and aluminum pipe casing joints: there is no spatter on the inner surface of the welding, and the minimum inner diameter of the joint: (φ1>φ2: -1.5×t1.
3. Testing of peeling resistance of copper and aluminum pipe casing joints: Copper and aluminum peeling test strength of welded joints Pw>T=-12.4 + 38.6vtN/mm.
4. Axial tensile test of copper-aluminum pipe casing joint: tensile strength Rm (MPa) should be ≥ 60. The broken part of the sample should be on one side of the aluminum pipe and more than 10mm away from the outer weld.
5. Bending performance test of copper-aluminum pipe casing joints: copper-aluminum joints and adjacent aluminum pipes must not crack.

3. Quality requirements for anti-corrosion layer of copper-end aluminum connecting pipes
1. Conduct high and low temperature impact tests on copper-end aluminum connecting pipes with thermoplastic pipes. The pipes must not deform or leak, and the heat shrinkable tubes must not cause wrinkles, aging, cracking, etc.
2. Conduct an anti-aging test on the copper-ended aluminum connecting pipe with a thermoplastic tube. The heat shrink tube must not have cracks, looseness or other aging defects.
3. Conduct a salt spray test on copper-ended aluminum connecting pipes that are anticorrosive with colored paint or coatings. The paint film must not have bubbles or rust.

Generally speaking, you can do a one-point table test according to the following items:

Copper pipe raw material quality sampling inspection
Sampling inspection of raw material quality of drawn (tie) aluminum pipes
Sampling inspection of raw material quality of continuous extruded aluminum tubes
Sampling inspection of raw material quality of thermoplastic pipes
Appearance of copper-end aluminum connecting pipe Full inspection
Dimensional specifications and deviations of copper-end aluminum connecting pipes Sampling inspection
Full inspection of copper pipe mouth roundness and burrs
Cracked copper pipe mouth Full inspection
Sampling inspection of inner wall roughness of copper pipe
Air tightness test
Strength test
Blasting test Type test
Cleanliness Type test
Appearance of casing joints Full inspection
Casing joint inner diameter φ 1                                               Full inspection
Casing joint peeling resistance ability Sampling inspection
Axial tensile test of casing joint Type test
Bending performance of copper-aluminum sleeve joints Type test
High and low temperature impact test Type test
Anti-aging test Type test
Salt spray test Type test

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