QC/T 669-2019Pipe fittings and pipes for automotive air conditioning (English PDF)

3.1 Connecting thread tightening torque

The recommended tightening torque of the connecting thread in the assembly is divided into the connector connecting thread tightening torque and the flange connecting thread tightening torque.

3.2 Type of O-ring

The recommended specifications of O-rings for sealing connectors are expressed by their inner diameter and cross-sectional diameter.

3.3 Radial anti-rotating torque

After the sealing connectors are welded or riveted with pipes, the minimum torque that makes the relevant rotation between connectors and pipes around the axis.

3.4 Axial tensile force

After the sealing connectors are welded or riveted with pipes, the minimum tensile force between the connectors and the pipes in the two directions along the axis. The tensile rate is 5 mm/min.

3.5 Combined sealing flange connector

The structural type of pipe-fittings that adopts two sealing methods of radial and axial at the same time.

3.6 Expansion valve inlet and outlet flange connector

The structural type of flange connector that is dedicated to the double pipe connection of the inlet and outlet of the expansion valve.

5.1 Appearance

The appearance of pipe-fittings and pipes shall be free of defects that affect strength and performance such as cracks, damage, deformation, oxide scale, etc. The sealing surface shall be free of scratches, dents, corrosion spots and damages that cause leakage; and the pipe end interface shall be free of sharp angles, flashes and burrs.

5.3 Requirements for corrosion resistance

Test according to GB/T 10125. After the aluminum alloy pipes satisfy the neutral salt spray test for at least 480 h, the high-pressure pipes shall be kept under pressure of 3.53 MPa for 3 min without leakage.

5.5 Connecting thread specifications and tightening torque requirements

The tightening torque corresponding to the connecting thread specification of the threaded connector shall comply with the provisions of Table 2.

6.1 Structure and size of the axial sealing threaded connector

6.1.1 The pipe end shall comply with the provisions of Figure 1 and Table 4.

6.1.2 The nut shall comply with the provisions of Figure 2 and Table 5.

6.1.3 Threaded female connector shall comply with the provisions of Figure 3 and Table 6.

6.2 Structure and size of single-groove radial sealing threaded connector

6.2.1 The pipe end shall comply with the provisions of Figure 4 and Table 7.

6.2.2 Nut shall comply with the provisions of Figure 5 and Table 8.

6.2.3 Threaded female connector shall comply with the provisions of Figure 6 and Table 9.

6.5 Structure and size of double-groove radial sealing flange connector

6.5.1 Flange male connector shall comply with the provisions of Figure 12 and Table 15.

6.8 Structure and size of external muffler of pipe

6.8.1 Type-A external muffler of pipe shall comply with the provisions of Figure 18 and Table 19.

6.8.2 Type-B external muffler of pipe shall comply with the provisions of Figure 19 and Table 20.