GB/T 4437.2-2017Aluminium and aluminium alloy extruded tubes—Part 2: Seam tubes (English PDF)

3.1 Product classification

3.1.1 Grade, supply state

The grade, supply state of tube shall conform to the provisions of Table 1. When other grades or supply states are required, they shall be negotiated between the supplier and the purchaser, and be specified in the ordering list (or contract).

3.9.4 Appearance quality of surface treatment tube

The appearance quality of the surface treatment tube shall conform to the relevant provisions of GB/T 8013.1~GB/T 8013.3.

4.1 Chemical compositions

4.1.1 The analysis method of chemical compositions shall conform to the provisions of GB/T 20975 or GB/T 7999; the arbitration analysis shall adopt the method stipulated in GB/T 20975. The "AI" mass fraction is calculated as per the method stipulated in GB/T 3190; when calculating the "AI" mass fraction, take the analysis values sum between conventional analysis element and suspiciously excessive unconventional analysis elements as the "sum of the element mass fraction".

4.1.2 The judgment of analysis values shall adopt the rounding comparison method; the numerical rounding rules shall be carried out as per the relevant provisions of GB/T 8170; while the number of rounding digits shall be consistent with the limit digits specified in GB/T 3190.

4.2 Dimension deviation

The measurement method for dimension deviation of the tube shall conform to the provisions of GB/T 4436-2012.

4.3 Mechanical properties of tensile at room temperature

The test for mechanical properties of tensile at room temperature shall be performed as per the method specified in GB/T 16865.

4.4 Conductivity

The test method for conductivity of tube shall be performed as per the method specified in GB/T 12966.

4.5 Macrostructure

The test for macrostructure of tube shall be performed as per the method specified in GB/T 3246.2.

4.6 Microstructure

The test for microstructure of tube shall be performed as per the method specified in GB/T 3246.1.

4.7 Film performance

5.5.1 When the chemical compositions of any specimen is unqualified, if the product can be distinguished the melting times, then such melting times represented by the specimen shall be judged as unqualified; other melting times shall be inspected one by one; only the qualified one can be delivered. If the melting times can't be distinguished, then such batch shall be judged unqualified.

5.5.2 When the dimension deviation of any specimen is unqualified, the such piece of specimen shall be judged unqualified.

5.5.3 When the mechanical properties of tensile at room temperature of any specimen is unqualified, take double number of the specimens from such batch (or heat treatment furnace) products to re-test. If the re-test results are all qualified, then such batch (or heat treatment furnace) products are qualified. If there is still specimen that is unqualified in the re-test results, then such batch (or heat treatment furnace) products shall be judged unqualified. The supplier is allowed to inspect the product piece by piece through the negotiation between the supplier and the purchaser; only the qualified ones can be delivered.

5.5.4 When the macrostructure of any specimen is unqualified, the judgment shall be as follows.

a) If the specimen is unqualified due to cracks, non-metallic inclusions, then such batch of products are rejected. However, the supplier is allowed to inspect the product piece by piece, only the qualified ones can be delivered;

b) If the specimen is unqualified due to layer, coarse-grained ring, the tube is allowed to extrude the tail end and cut a section to re-test till it is qualified; other tubes in such batch shall accept the cutting tail on the maximum length where the defects distribute on the tube or inspection of piece by piece; only the qualified ones can be delivered.

c) If the specimen is unqualified due to weld seam, the tube is allowed to extrude the head end and cut a section to re-test till it is qualified; other tubes in such batch shall accept the cutting head on the maximum length where the defects distribute on the tube or inspection of piece by piece; only the qualified ones can be delivered.

5.5.5 If the microstructure of the specimen is unqualified, the product can distinguish the heat treatment furnace times, then such furnace times represented by the specimen shall be judged as unqualified; other furnace times shall be inspected one by one; only the qualified ones can be delivered. The product that can't distinguish the furnace times, then such batch of products shall be judged unqualified.

5.5.6 If the film performance of any tube is unqualified, then it shall be judged as specified in GB/T 8013.1~GB/T 8013.3.

a) Supplier name;

b) Product name or surface treatment tube categories;

c) Grade, supply state, dimension and specification;

d) Color (or color number), film code of surface treatment tubes;

e) Product batch number or production date;

f) Net weight or the number of pieces;

g) Results of various analytical tests;

h) Inspection seal of the supplier's quality supervision department;

i) This Part number;

j) Package date (exit-factory date).