1. Before pipe installation, each pipe must be inspected for quality, impurities and oxides must be removed, and the inside of the pipe must be very clean. Cleaned pipes must be plugged with wooden stoppers at both ends and should not be stored outdoors.

 

2. In the project installation, the welding of steel pipes is done using argon arc welding for the root pass, followed by manual electric welding. For pipes that need to be cut on-site, the cut pipes must ensure that the internal cleanliness meets the standards of the first item.

 

3. During transportation and storage, all pipes, components, and parts must be protected against rust to ensure that equipment, pipes, and components are not directly exposed to the air.

 

4. The welding of copper pipes to copper pipes or copper pipes to steel pipes can be done using silver brazing or copper brazing. The brazing rods should be silver-based filler metal (material 303) or silver-phosphorus brazing material (material 303). Fluxes 101, 102, 103 or borax can be used as flux for material 303, while material 204 does not require a flux. Welding should be conducted at temperatures above 5°C. If the temperature is below 5°C, moisture and frost on the pipes should be removed before welding, and preheating may be necessary.

 

5. Connections between pipes and equipment, valves, and other fittings should be made with detachable connections using flanges, threaded joints, or flare fittings. Flange connections should use oil-resistant and fluorine-resistant asbestos rubber sheets with a thickness of 1-2mm as gaskets. Before installation, the gaskets should be soaked in refrigeration oil. For copper pipes with a diameter less than D22, the pipe ends should be flared and connected using fittings and union nuts, with the interfaces cleaned and without additional padding.

 

6. Refrigeration system pipes should have a slope, with the return gas pipes installed to slope towards the compressor with a gradient of no less than 0.2%, and the liquid pipes should slope towards the object they supply.

 

7. The selection of materials, specifications, models, and welding materials for refrigeration system pipelines and pipeline components should be determined based on the requirements of working pressure and temperature.

 

8. Civil engineering related to the installation of refrigeration system pipelines should be inspected and qualified to meet the installation requirements.

 

9. The processing method for pipe beveling is preferably mechanical processing, but it can also be done using oxy-acetylene flame or similar methods. However, it is necessary to thoroughly remove scale and other contaminants within a 10mm range from the surface and grind smooth any unevenness that affects welding quality.

 

10. Branch pipe connections should be located away from the welding points of the main pipe. If a pipeline is welded more than twice, the welded section should be cut off and rewelded.

 

11. The anti-corrosion paint used for pipelines should be non-toxic and environmentally friendly paint.

 

12. Inert gas protection welding must be used when welding pipelines, and the inert gas should continue to flow until the weld has cooled to room temperature.

 

13. Install oil return bends according to specifications and drawings.

 

14. All lifting materials used should be standard products and must ensure their solidity and safety.

 

15. The distance between supports and hangers for uninsulated refrigeration pipes and brackets should comply with the regulations in Table 1. When insulated, the distance between supports and hangers should be 0.7 times the maximum spacing in Table 1.

Table 1 Refrigeration pipe support and hanger spacing
Pipe diameter (mm)	10	16	25	40	50
Maximum spacing (m)	1.3	1.6	2.1	2.7	3.0