Carbon Steel Copper Coated Bundy Tube Double Walled Steel Bundyweld Tube
Carbon Steel Copper Coated Bundy Tube Double Walled Steel Bundyweld Tube
Bundy tube is type of double-walled low-carbon steel tube manufactured by rolling a copper-coated steel strip through 720°F and resistance brazing the overlapped seam in a process called Bundywelding. It may be zinc coated for corrosion protection. It is primarily used in automotive hydraulic brake lines in cars. We can supply any type and diameter of Bundy Tube your requirement calls for.
Bundy Tube
- Double-Walled Construction: It is made from two layers of low-carbon steel strip.
- Copper Brazing: The unique process involves coating one strip of steel with a layer of copper. The two strips are then rolled into a tube and passed through a furnace. The heat melts the copper, which bonds the two layers together seamlessly along the entire length of the tube. This creates an extremely strong, leak-proof, and consistent tube.
- Strength and Durability: The double-wall design makes it much stronger than a single-wall tube of the same thickness, allowing it to withstand high pressures and resist vibration and fatigue.
- Smooth Interior: The manufacturing process results in a very smooth inner surface, which is ideal for fluid flow.
| Standard | Region / Organization | Description |
| SAE J527 | SAE (Society of Automotive Engineers, USA) | Covers double-walled, copper-coated, steel, resistance-brazed tubing for automotive and hydraulic use. |
| SAE J356 | SAE | Covers single-wall welded low-carbon steel tubing, sometimes used as alternative to Bundy. |
| ASTM A254 | ASTM (USA) | Covers copper-brazed steel tubing (also known as Bundy tubing). |
| DIN 74234 | DIN (Germany) | Specification for double-walled brazed steel tubing (Bundy tube) for brake lines. |
| EN 10305-2 | European Norm | Welded cold-drawn steel tubes for precision applications (sometimes used for Bundy-type tubes). |
Size and Tolerance
| Outer diameter (mm) |
Diameter tolerance (mm) |
Wall thickness(mm) | Wall thickness tolerance(mm) | Pressure resistance(MPa) | Burst pressure (MPa) |
| 4.76 | ±0.05 | 0.7 | +0.05/-0.08 | 41.2 | 110 |
| 6 | ±0.08 | ±0.08 | 32.7 | 85 | |
| 6.35 | ±0.08 | ±0.08 | 30.9 | 78 | |
| 8 | ±0.1 | ±0.08 | 24.5 | 67.5 | |
| 9.52 | ±0.1 | ±0.08 | 20.6 | 57 | |
| 10 | ±0.1 | ±0.08 | 19.6 | 55 | |
| 12 | ±0.1 | ±0.08 | 16.3 | 32 | |
| 10 | ±0.1 | 1 | ±0.08 | 28 | 65 |
| 12 | ±0.1 | ±0.08 | 23.3 | 56 |
Common Applications
Bundy tube is famous for its use in automotive and refrigeration systems where reliability is critical:
Automotive: Brake lines and fuel lines are the most common applications. Its strength and resistance to corrosion (especially when coated or plated) make it ideal for these safety-critical systems.
Refrigeration & AC: Used for refrigerant lines in domestic refrigerators, air conditioners, and heat pumps because it is strong and can be easily bent to fit tight spaces.
Hydraulic Lines: Used in various hydraulic systems for machinery.
General Industrial Applications: Anywhere a durable, small-diameter, pressure-resistant tube is needed.
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