Copper is one of the widely used materials in the piping industry due to its durability, heat resistance, and ability to withstand high pressure. It is used in plumbing, heating, ventilation, air conditioning (HVAC), and refrigeration systems. Apart from copper, the second common thing in all these applications is brazing.
Copper pipe brazing is a critical process in HVAC systems, as it creates a strong, leak-proof joint between two copper pipes. Brazing involves heating the pipes and the brazing material to a temperature above 840°F (450°C), causing the material to melt and flow into the joint, bonding the pipes together.
There are several ways, which can be employed to braze copper pipes. In this article, we will be exploring the four main methods.
Method 1: Torch Brazing
Torch brazing is the conventional brazing method, which is also referred to as simple brazing. In this technique, a flame torch heats the filler metal and the copper pipes until they reach the required temperature. Once the filler metal melts it fuses into the joint between two copper pipes due to capillary action.
Torch brazing is the conventional brazing method that has been used for centuries to join metals. Being versatile in nature, it can be used in a variety of applications, including small and large-scale projects.
The common use case is creating copper pipe joints in plumbing, refrigeration, and automotive applications. It is best suited for small to medium-sized pipe joints that require precision and accuracy.
Pros:
- It is a versatile method that can be used in a variety of applications.
- Relatively inexpensive, as it only requires a simple torch and filler material.
- Offers precise control over heat, making it suitable for small to medium-sized joints.
- Ideal for repairing existing pipes or making small modifications to plumbing systems.
Cons:
- Requires a skilled technician to perform the process safely and effectively.
- The whole process can be time-consuming, as each joint needs to be brazed individually.
- Pre-heating is required for pipe diameters greater than 1-inches
Method 2: Induction Brazing
Induction brazing is the modern brazing method, which differs only in terms of heat source. Instead of flame, electricity is used as a heating element.
In induction brazing, the alternating current (AC) to heat the copper pipes and the filler metal is placed inside an AC inductor loop. As the circuit is turned on, the alternating current produces an electromagnetic field that heats the material from inside, causing it to melt and bond the pipes together.
In comparison to flame brazing, this method is quick, efficient, and doesn’t require pre-heating. So, it is often used for mass-production applications. However, it is ideal for creating and repairing copper pipe joints in the HVAC industry.
Almost all applications, that once used required flame brazing can be manufactured using induction brazing. However, in complex geometry where induction coil equipment is difficult to place, this process may not be feasible.
Pros:
- A fast and efficient method that can handle high-volume production.
- Provides consistent, repeatable results; best for mass production applications.
- Ideal for small to medium-sized joints, the ones used in the HVAC industry.
Cons:
- Expensive compared to torch brazing, as it requires specialized equipment.
- Specific induction loops may need to be to designed for large sizes.
- Limited control over the heat source, can be a challenge for joints that require precise heat input.
- Not suitable for large joints that require high strength and durability.
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Shop High-Quality Welding EquipmentMethod 3: Furnace Brazing
For a geometry that is quite large, for instance, copper piping of an industrial heat exchanger. Or applications, in which multiple brazed joints are needed within an assembly, a furnace is used for brazing.
In furnace brazing, the whole copper piping setup is sent in batches to a furnace where they are until they reach the required temperature. The brazing filler melts, creating a strong bond between the pipes.
Furnace brazing is ideal for large-scale production applications, as it can handle large volumes of parts at once. Moreover, this process is also popular for the brazing of dissimilar metals.
Pros:
- The process can handle large volumes of parts at once.
- Uniformly heats the pipe creating a high-strength joint.
- Ideal for large-scale production applications.
- Provides consistent results, making it ideal for mass production.
Cons:
- More expensive than other brazing methods, as it requires specialized equipment.
- It takes much time to set up a furnace and then reach the required temperature.
- Impractical solution for brazing small parts.
Method 4: Resistance Brazing
Resistance brazing, as the name suggests, uses the electrical resistance of pipes to generate heat. It seems similar to induction brazing but it is different. In this process, the pipes to be joined are a part of the electric circuit instead of being placed inside the loop.
The set includes a brazing machine with electrodes. The two metal parts to be joined are placed in between the electrodes along with the filler metal. As the circuit is turned, the electrical current generates heat in the workpieces and melts the filler metal, which then flows into the joint. The pressure applied by the electrodes helps to ensure a strong bond between the workpieces and the filler metal.
It is a quick process and generally completes in a few seconds. However, this process is generally not used for joining copper pipes since induction and torch brazing are relatively simpler and easy to perform. It can be used at a small scale for repair purposes of HVAC pipes, just like torch brazing.
Pros:
- Fast and efficient method.
- Provides consistent, repeatable results.
- Ideal for small to medium-sized joints that require high strength and durability.
- Offers precise control over heat, making it suitable for precision joints.
Cons:
- Equipment can be challenging to find.
- Limited to joints that can be accessed by the electrode, which can be a challenge in tight spaces or complex parts.
- Not suitable for large joints that require high strength and durability.
Conclusion
Torch brazing and resistance brazing are often used in small to medium-sized joints that require precision and accuracy. Induction brazing and furnace brazing are ideal for production applications that require consistent, repeatable results and high-strength joints.
It’s important to consider the pros and cons of each method when choosing the best brazing method for your specific project. The final call depends on factors such as joint size, production volume, precision requirements, and budget constraints.
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