구리 파이프를 납땜하는 방법은 많은 브레이저들이 고민해 온 문제입니다. 물 공급을 위한 구리 파이프의 사용은 기원전 2150년으로 거슬러 올라갑니다. 오늘날 이러한 파이프는 모든 HVAC 및 온수 난방 시스템에서 볼 수 있습니다. 그 이유는 무엇일까요? 구리는 무독성, 불침투성, 내구성, 유연성 등 수도 배관에 필요한 이상적인 조합을 갖추고 있기 때문입니다.
구리 파이프는 유체를 운반하기 때문에 기계적으로 고정할 수 없습니다. 구리 파이프를 브레이징하는 것은 누수 방지 조인트를 얻는 가장 좋은 솔루션입니다. 브레이징에서는 파이프를 결합하고 고온에서 가열하여 필러 금속을 녹인 다음 내부를 융합하여 영구적인 조인트를 만듭니다.
용융 공정은 직접 불을 사용하는 방법이나 유도 납땜과 같은 불을 사용하지 않는 방법 등 다양한 방식으로 이루어질 수 있습니다. 이 문서에서는 구리 파이프를 납땜하는 세 가지 주요 방법을 살펴보고 각 방법에 대한 장비와 세부 단계를 설명합니다.
Method 1: Brazing Copper with a Torch
This is the traditional way of brazing copper, common for small-scale HVAC jobs. In this method, a direct flame (typically from an oxy-acetylene or propane torch) heats the joint area. The higher temperature (around 1300 to 1500°F ) melts the filler metal, which is then drawn into the joint by capillary action.
Remember, the temperature is high but not enough to melt the base metal (copper); instead, it liquefies only the filler to form a strong, leak-proof bond. A flux may also be applied before heating to prevent oxidation of the metals.
Tools Needed
The torch brazing process requires these supplies and tools:
- Flame Torch – Acetylene or propane
- Filler Rod – Phosphorus copper (BCuP) for copper-to-copper pipes and silver-based (BAg) for mixed metals.
- Flux (Optional): Borax-based
- Cleaning Brush/Emery Cloth, Sandpaper
- Pipe Cutter, Deburring Tool
- Igniter or Lighter
How to Braze Copper Pipes with a Torch
To braze copper pipe with a flame torch, here’s a more structured approach, with all detailed insights gathered from expert technicians:
Step 1: Cut and Clean
First, use a pipe cutter to cut the copper pipe to the desired length. Use a deburring tool to get rid of any cutting burs on the edges.
Clean the mating surfaces with a wire brush or emery cloth until they shine. Any dirt, grease, or oxidation will hinder the bond.
Step 2: Apply Flux (Optional)
Apply flux to both the pipe and fitting using a brush (optional for copper-to-copper brazing, but required for other metal combinations). Then, join the loose ends of the pipe and fitting.
3단계: 토치를 사용하여 가열하기
토치에 불을 붙이고 중성 불꽃(너무 산화되거나 환원되지 않는 불꽃)으로 조절합니다. 구리를 균일하게 가열하기 위해 불꽃을 접합부 주위로 고르게 움직입니다. 바닥을 먼저 가열한 다음 천천히 전체 면을 덮습니다.
4단계: 필러 추가
파이프가 충분히 뜨거워지면(빨간색이 되면) 필러 막대를 조인트에 접촉합니다. 필러 막대를 불꽃으로 직접 녹이지 마세요. 대신 파이프에서 나오는 열이 필러를 녹여 모세관 작용을 통해 이음새로 흘러 들어가게 하세요. 조인트 주위로 막대를 돌려서 균일하게 녹이도록 합니다.
Step 5: Cool and Clean
Allow the joint to cool naturally; using a wet rag too soon can cause cracks. After it’s cooled, inspect the joint for gaps or weak spots. Wipe off excess flux (if used) to prevent corrosion over time.
Method 2: Induction Brazing
Induction brazing is a modern, flame-free method that uses electromagnetic induction to heat the joint. An alternating magnetic field, generated by an induction coil, induces eddy currents in the copper pipe, heating it to the required temperature. The filler metal, pre-placed as a ring or wire, melts and flows into the joint without direct contact with a flame.
Tools Needed
- Cleaning Brush/Sandpaper
- Induction Heater
- Filler Rings/Rod
How to Induction Braze Copper Pipes
Step 1: Cut and Clean
The induction brazing process for copper pipes requires similar cleaning steps as torch brazing. You’ll first need to clean the joint with a wire brush or sandpaper. The next steps are:
Step 2: Prepare an Overlap Joint
Apply flux, if mating copper pipe with another joint. For copper-to-copper pipe joints, you can skip the fluxing. Create a lap joint between the two pipes. The American Welding Society recommends that the overlapping must be 3x the pipe thickness for an optimal joint. If you’re going to use filler rings, they have to be applied in this step.
Step 3: Assemble and Clamp
Since the joints are loose before brazing, a clamp setup is required to temporarily hold them in place for the induction brazing operation.
4단계: 인덕터 히터로 가열하고 필러 도포하기
Place the clamped joint inside the induction coil setup such that the joint is fully surrounded. If a portable coil is being used, hold it near the joint. Turn it on for 5 to 10 seconds, until the pipes get red hot.
If filler rings are in place, they’ll melt and infuse the gaps. If using filler rod, rotate the rod around the join slowly so that it melts and moves inside.
Step 5: Cool and Clean
Allow the joint to cool and clean it before usage.
Method 3: Controlled Atmosphere Brazing/Furnace Brazing
Controlled atmosphere brazing (CAB) is a process where brazing is performed in a sealed furnace filled with an inert or reducing gas (e.g., nitrogen or hydrogen). The atmosphere prevents oxidation and contamination, which produces stronger and cleaner joints.
This process is common for batch-brazing aluminum heat exchangers in the auto industry. It’s also suitable for critical copper applications, for instance, x-ray tubes, wave tubes, and linear accelerators.
Tools Needed:
- Cleaning Tools
- Furnace
- Filler Rings
- Inert Gas
How to Perform Furnace Brazing
CAB requires a closed furnace to take place, limiting its use to industries. Here’s an overview of the process.
Step 1: Cleaning
The parts need thorough cleaning. That can be done via simple brushing, or they may undergo solvent baths.
Step 2: Filler Application
The filler metal is applied in the form of pre-shaped rings or washers. It is positioned such that when the pipes get heated, the filler melts and infuses inside of the joint.
Step 3: Transport to Furnace
The prepared parts are loaded onto conveyor belts for transport into the furnace. Fixtures may be used to hold the components in precise alignment during the brazing process.
Step 4: Heating
The furnace is purged with an inert or reducing gas to remove oxygen and create a controlled atmosphere. The temperature is ramped up to a point (about 1300°F ) where filler starts to melt and flow into the joint.
Step 5: Cooling
The parts are slowly cooled down to avoid cracking and the development of stresses.
How to Choose the Right Method for Brazing Copper Pipes
We’ve listed three methods, but you can only go with one. So, to choose, we want you to keep in mind a few considerations like your joint size, operating environment, budget constraints, and skill level.
Joint Size/Geometry
Each technique excels in specific joint cases. Among the techniques, torch brazing is quite versatile – it can handle large, irregular, or hard-to-reach joints, such as those found in HVAC systems or plumbing repairs. Due to its manual scale, it’s easy to make adjustments on the fly.
Induction brazing excels with small and standardized joint diameters. This method is limited to geometries that fit within the induction coil, or a custom joint has to be made. Still, it’s a great option for HVAC piping.
Furnace brazing is best suited for medium to large batches of components with consistent joint designs.
Environment
The external factors also have a role in method usage. Torch brazing is well-suited for fieldwork or repairs but should be avoided in confined, flammable, or oxygen-sensitive spaces due to the open flame.
Induction brazing, on the other hand, is a flame-free option and can be freely used indoors in cleanrooms, hospitals, or explosive atmospheres.
Furnace brazing is an industry-limited option.
Budget
Torch brazing setup is comparatively less complex and cheaper than the other techniques. But if we consider safety as well as affordability, portable induction brazing equipment is a good option. Furnace brazing has an expensive setup, but that’s viable when you need to batch product parts.
Skill Level
Torch brazing demands advanced manual skills, including precise flame control and timing when feeding the filler metal. Mistakes, such as overheating or uneven heating, can lead to weak joints.
CAB is also technically demanding as it requires knowledge of furnace operation, gas management, and thermal cycles. It’s typically used by trained professionals in industrial settings.
Among the three, induction brazing requires the most minimal operator expertise once the system is programmed, making it accessible for workers with basic training.
Choose FOCO Induction Equipment for Brazing Copper Pipes
If you’re convinced that induction heating is the ideal solution for your brazing needs, we recommend exploring FOCO’s lineup of induction heating systems.
Our range includes portable units for small-scale operations and robust industrial systems designed for high-volume production. With frequency options ranging from 1 kHz to 800 kHz and power outputs from 6 kW to 200 kW, FOCO equipment is engineered to meet diverse brazing requirements.
Contact us today to discuss your specific needs, and let our experts guide you in selecting the perfect induction heating solution.
