Copper Pipe Fittings Brazing

Q1: What Does It Mean To Braze Copper Pipes?

Figure 1: Brazing Copper Pipes

Brazing copper pipes is a process of heat bonding two joints together with the help of filler metal. Brazing is a kind of welding that is done by flame heat. Brazing copper pipes give strong joints.

Filler metal is a term for an alloy that is used in brazing that has a liquidus greater than (842°F). During the copper pipes brazing the filler metal is placed between joints. When the filler metal meets its liquidus with the heat of the flame, the filler metal melts and forms soldering between copper pipes.

Our industrial brazing machines offer automatic brazing for copper pipes, ensuring that the copper pipe fittings are properly brazed.

Q2: Why Are Copper Pipe Fittings Cleaned Before Brazing?

Figure 2: Cleaning Copper Pipe Fittings

The filler metal requires a clean surface to work properly. If the copper pipe fittings are not cleaned the filler metal won’t adhere to the copper pipes. It is highly important to clean copper pipe fittings before brazing.

A dirty pipe is basically covered with lots of contaminants such as oil, dirt, oxidation layer, etc. due to these contaminants and oxidation layer the filler metal won’t work properly, and result in a weak joint after brazing. Cleaning copper pipe fittings is simple and easy. Steel wool or metal brush is used to clean copper pipes before proceeding with the brazing process. When the cleaning is done, there’s no need to apply flux. This process of copper pipes brazing uses alloys like BCuP series which contains phosphorus. Phosphorus containment prevents oxidation during the brazing process.

Q3: How Does An Automatic Brazing Machine Improve Copper Pipe Brazing Efficiency?

Figure 3: Automatic Brazing Machine

A highly advanced automatic brazing machine improves the quality of copper pipe brazed joints and also improves efficiency up to 10 to 20x.

Automatic brazing machines are pre-programmed to deliver certain power to the joints, ensuring repeatable and high-quality copper pipe brazing. The copper pipe fittings brazing is done faster by the machine as compared to manually brazing. With the automatic brazing machine, you can braze multiple copper pipe fittings at the same time. The automatic brazing machine does all the jobs from preheating, and brazing to water cooling copper pipes, everything is done by the machine.

This also improves the brazing efficiency and the brazed joints’ quality stays the same for each cycle. You can reprogram the automatic brazing machine for different types of brazing. With the help of a multi-language control panel, you can easily access and program the machine to your requirement.

Q4: Is Brazing Copper Pipe Fittings Better Than Soldering?

Figure 4: Braze

As compared to soldering the brazing provides more strength to the joints. Brazed joints are durable and they can also handle more pressure than soldered joints.

Brazing is generally done to achieve more strength joints and as compared to soldering it’s more reliable. Some Copper pipe fittings require extra strength like in the refrigerator copper fittings are supposed to handle more pressure and high temperature. Therefore a true braze joint is highly necessary and that’s the reason why Brazing is better than soldering in such conditions.

Figure 5: Brazed Joint

Q5: Which Gas Is Used For Brazing Of Copper Pipe Fittings?

Figure 6: Brazing Gas

Generally, when brazing the copper pipe fittings acetylene is the best choice. This gas consists of oxygen and acetylene and combined together it produces a higher temperature flame that is about 3 500°C.

However, the automatic brazing machine can use different glasses for copper pipe brazing. The lower temperature gasses such as propane, natural, and MAPP gas can also be used for brazing copper pipe fittings in automatic brazing machines. With the help of an automatic adjustable heating feature, you can set it to warm for a while to reach the desired temperature.

Q6: What Temperature Should You Braze At?

Brazing temperature varies from metal to metal and alloy to alloy. Mostly the brazing is done at a higher temperature of 850°F and it can go up to 2,000°F.

The filler metals which are used in brazing have a liquidus greater than 850°F.  For the strong joint the brazing is usually done at 850°F to 2,000°F which ensures that both pieces form a strong joint. A slow heat cycle is recommended for a better result because faster heat cycles are less effective in reaching the desired temperature. When the filler metal reaches its desired temperature it will melt down and fill the joint area gap.

Q7: What Is The Difference Between Soldering And Brazing Copper Pipes?

Temperature is the only difference for each process. Below 842°F or (450°C) is where soldering takes place while the brazing is done above 842°F or (450°c). Another major difference between soldering and brazing copper pipes is good joint strength which can only be achieved by the brazing process.

Brazing copper pipes or the process of brazing in general takes place above 842°F – 450°c. Due to the specific filler metals which are required for brazing liquidus at this temperature. Soldering copper pipes or soldering, in general, is done by filler metals which liquidus at below 842°F – 450°C. Therefore the temperature is different for both processes.

Another great difference between soldering and brazing copper pipes is the strength and quality of the joint. Because the brazing is done at higher temps the joint that is formed by the brazing process is a lot better in quality and potentially stronger. Brazing uses Capillary Action and because of that the molten filler metal distributes between surface joints and forms a strong joint after the process is completed.  Soldering specifically for copper pipes is not a recommended way of achieving a good quality joint.

Different industries prefer brazing over soldering copper pipes due to its benefits and long-term quality assurance. Industries like HVAC, plumbing, and refrigeration also use brazed copper pipes.

Q7: What Are The 4 Stages Of Brazing Copper Pipe Fittings?

4 stages of brazing copper pipe fitting include Good fitting, proper cleaning, Assemble for brazing, and last but not least Brazing process.

Stage 1: Insuring Good Fitting

Figure 7: Copper pipe cutting

Make sure that the pipe fittings have good clearance because when capillary action happens the molten filler metal will fill the gap between surfaces. If the joint surface has more or too less clearance then the filler metal will not work properly. The typical clearance range for filler metals is usually 0.001 to 0.005 inches.

Stage 2: Cleaning Contaminants

Figure 8: Cleaning the copper pipe

For a successful and optimal brazing process, this stage is very important. If the copper pipe fittings have contaminants such as oil, dirt, grease, or oxidation, it will prevent filler metals from joining pipe fittings together. To clean the contaminants, first, you have to start with removing oil and grease. You can use a degreasing solvent to remove the oil and grease. Then move on to the next step which is removing rust or oxidation from the metal.

Once you are done cleaning the metal, use a dry piece of cloth to wipe off any remaining chemicals or contaminants.

Stage 3: Assemble For Brazing

When the copper pipes are cleaned you can move on to the next stage of assembling for brazing. Hold the copper pipes in a correct position because during the brazing process the filler metal will melt down. If the pipes are not aligned correctly the filler metal will not work and the brazing process will fail.

Stage 4: Brazing Process and Cleaning

Figure 9: Brazing process

The brazing is about heating the metals with a gas flame till you reach the desired temperature. The important thing which you have to keep in mind is that during the heating cycle make sure that both surfaces are heated equally. If there’s any temperature difference between both surfaces then the brazing will likely fail. Once the heating cycle is done you can place filler metal between the joint and continue the brazing process till the capillary action takes place and the filler metal will be drowned inside the joint.

When the brazing process is completed, clean the assembly and remove any oxide scale formed during the brazing process.