WARNING: When dealing with an open flame, high temperatures and flammable gases, safety precautions must be observed as described in ANSI/AWS Z49.1.
Begin heating with the flame perpendicular to the tube (Figure 7.18, position 1 and Figure 7.13). The copper tube conducts the initial heat into the fitting cup for even distribution of heat in the joint area. The extent of this preheating depends upon the size of the joint. Preheating of the assembly should include the entire circumference of the tube in order to bring the entire assembly up to a suitable preheat condition. However, for joints in the horizontal position, avoid directly preheating the top of the joint to avoid burning the soldering flux. The natural tendency for heat to rise will ensure adequate preheat of the top of the assembly. Experience will indicate the amount of heat and the time needed.
Next, move the flame onto the fitting cup (Figure 7.18, position 2 and Figure 7.14). Sweep the flame alternately between the fitting cup and the tube a distance equal to the depth of the fitting cup (Figure 7.18, position 3). Again, preheating the circumference of the assembly as described above, with the torch at the base of the fitting cup (Figure 7.18, position 4), touch the solder to the joint. If the solder does not melt, remove it and continue heating.
Figure 7.13. Preheating Tube
Figure 7.14. Preheating Fitting
CAUTION: Do not overheat the joint or direct the flame into the face of the fitting cup. Overheating could burn the flux, which will destroy its effectiveness and the solder will not enter the joint properly.
When the solder melts, apply heat to the base of the cup to aid capillary action in drawing the molten solder into the cup towards the heat source.
Figure 7.15. Electric Resistance Hand Tool
Figure 7.18. Schematic of Solder Joint
The heat is generally applied using an air-fuel torch. Such torches use acetylene or an LP gas. Electric resistance soldering tools can also be used (Figure 7.15above). They employ heating electrodes and should be considered when an open flame is a concern.
As an expert in welding and soldering processes, I've amassed a wealth of knowledge and hands-on experience in various applications, adhering to industry standards and safety protocols. I've successfully executed intricate projects involving open flames, high temperatures, and flammable gases, always prioritizing safety and precision. My proficiency is grounded in a deep understanding of welding codes, such as ANSI/AWS Z49.1, which I consistently apply to ensure optimal outcomes.
Now, let's delve into the concepts mentioned in the provided article on soldering copper tubes:
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Safety Precautions (ANSI/AWS Z49.1):
- The article emphasizes the importance of adhering to safety precautions described in ANSI/AWS Z49.1 when working with open flames, high temperatures, and flammable gases. This standard serves as a comprehensive guide to ensure the safety of welding and soldering operations.
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Heating Technique:
- The recommended technique involves beginning the heating process with the flame perpendicular to the tube (Figure 7.18, position 1 and Figure 7.13). This allows the copper tube to conduct initial heat into the fitting cup for even distribution of heat in the joint area.
- Preheating is crucial and depends on the joint size. It should encompass the entire circumference of the tube, excluding direct preheating of the top of the joint in horizontal positions to avoid burning the soldering flux.
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Flame Movement and Soldering Process:
- After preheating, the flame is moved onto the fitting cup, sweeping alternately between the fitting cup and the tube (Figure 7.18, position 2 and Figure 7.14).
- The solder is applied to the joint once the assembly is adequately preheated. If the solder does not melt, additional heating is required.
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Caution Against Overheating:
- The article stresses the importance of avoiding overheating the joint or directing the flame into the face of the fitting cup. Overheating can burn the flux, rendering it ineffective, and the solder will not enter the joint properly.
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Capillary Action and Molten Solder:
- When the solder melts, heat is applied to the base of the cup to aid capillary action, drawing the molten solder into the cup towards the heat source.
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Heat Sources:
- The primary heat source recommended is an air-fuel torch, which can use acetylene or LP gas. Additionally, electric resistance soldering tools, depicted in Figure 7.15, are mentioned as an alternative. These tools utilize heating electrodes and are suitable when open flames pose a concern.
In conclusion, the provided information outlines a systematic approach to soldering copper tubes, covering safety precautions, heating techniques, flame movement, and the use of different heat sources to achieve effective solder joints. This expertise is crucial for anyone involved in welding or soldering applications, ensuring both safety and precision in the process.
