MCAC-VTSM-2011-09
Installation
92
Refrigerant Piping Installation
Outer
Diameter
Material
Minimum
Thickness
Outer
Diameter
Material
Minimum
Thickness
Outer
Diameter
Material
Minimum
Thickness
Ф6. 35
O
0. 8
Ф19. 0
O
1. 0
Ф38. 0
1/2H
1. 5
Ф9. 52
O
0. 8
Ф22. 0
1/2H
1. 2
Ф45. 0
1/2H
1. 5
Ф12. 7
O
0. 8
Ф25. 0
1/2H
1. 2
Ф54. 0
1/2H
1. 8
Ф15. 9
O
1. 0
Ф28. 6
1/2H
1. 3
Ф67. 0
1/2H
1. 8
3.1.4.2. Nitrogen filling for protecting copper pipe during brazing welding
1. Purpose: Avoid oxide scale from appearing on the inner wall of the copper pipe in the high temp.
2. Risks of non-protective welding:
If no sufficient nitrogen is charged into the refrigerant pipe being welded, oxides will be generated on the
inner wall of the copper pipe. These oxides will block the refrigerant system, which will lead to all kinds of
malfunctions such as burn-out the compressor, poor cooling efficiency.
To avoid these problems, charge nitrogen continuously into the refrigerant pipe during the brazing
welding, and ensure that the nitrogen passes through the operating point until the welding is completed
and the copper pipe cools down completely. The schematic diagram for nitrogen charging is shown
below.
3. Making Nitrogen-Charging Pipe Joint
When welding the pipe joint, connect the nitrogen-charging joint to the pipe fittings to be welded.
The nitrogen-charging joint is shown below:
4. Cautions for Welding Pipe Fittings
1) Adopt transition pipe.
2) Charge nitrogen from the side of the short pipe, because short distance may result in perfectible
nitrogen replacement effect.
nitrogen
brazing welding part
assistant pipe assembly
copper pipe direct connection
