Double wall copper brazed steel tubing, also know as Bundy tube, is the economical alternative to seamless tube. It has many of the same qualities as seamless tubing and is suitable for most high pressure applications.
We are offering Bundy tubes of regular sizes, and at the same time capable of fabricating tubes of customized sizes.
Bundy tubes of the following table listed sizes are feasible to manufacture; among them, thickness of 0.7mm and 1mm are available in stock most of the time or to be produced upon being ordered.
| OD, mm | Wall Thickness, mm | ||||||
| 0.5 | 0.6 | 0.7 | 0.8 | 0.9 | 1 | 1.3 | |
| Unit Weight (Theoretical), g/m | |||||||
| 3.18 | 33.0 | 38.2 | 42.8 | 47.0 | |||
| 4 | 43.2 | 50.3 | 57.0 | 63.1 | |||
| 4.76 | 52.5 | 61.6 | 70.1 | 78.1 | 85.7 | ||
| 5 | 55.5 | 65.1 | 74.2 | 82.9 | 91.0 | 98.6 | |
| 6 | 67.8 | 79.9 | 91.5 | 102.6 | 113.2 | 123.3 | |
| 6.35 | 72.1 | 85.1 | 97.5 | 109.5 | 121.0 | 131.9 | |
| 7 | 80.2 | 94.7 | 108.8 | 122.3 | 135.4 | 148.0 | 182.7 |
| 7.94 | 91.7 | 108.6 | 125.0 | 140.9 | 156.3 | 171.2 | 212.9 |
| 8 | 92.5 | 109.5 | 126.0 | 142.1 | 157.6 | 172.6 | 214.8 |
| 9.53 | 111.3 | 132.1 | 152.4 | 172.2 | 191.5 | 210.4 | 263.9 |
| 10 | 139.1 | 160.5 | 181.5 | 202.0 | 222.0 | 278.9 | |
| 12 | 168.7 | 185.1 | 221.0 | 246.4 | 271.3 | 343.0 | |
| 12.7 | 179.0 | 207.2 | 234.8 | 261.9 | 288.5 | 365.5 | |
| 14 | 229.6 | 260.4 | 290.8 | 320.6 | 407.2 | ||
| 15.88 | 260.7 | 295.9 | 330.7 | 365.0 | 464.9 | ||
| 16 | 264.1 | 299.9 | 335.2 | 369.9 | 471.3 | ||
We are capable of fabricating Bundy tube sizes which are not regularly used. By combining one or more processes of cold draw and annealing, Bundy tubes can be made to many other sizes to meet demands for special applications.
Click here to calculate the tube weight.
| OD | Tolerance | Wall Thickness | Tolerance |
| <4.76 | ±0.05 | 0.5 | ±0.07 |
| 4.76-8 | ±0.08 | 0.5-0.7 | ±0.08 |
| 8-12.7 | ±0.10 | 0.7-1 | ±0.09 |
| >12.7 | ±0.12 | 1-1.3 | ±0.1 |
The tubes are made from low carbon steel strips (grade BHG2) which is manufactured by Bao Steel Group. The chemical compositions are as following:
| Element | C | Si | Mn | P | S |
| Standard (max, %) | 0.06 | 0.03 | 0.3 | 0.03 | 0.03 |
| Tensile Strength | 42000psi (290MPa) |
| Yield Strength | 26100psi (180MPa) |
| Elongation | ≥25% |
| Expansion | ≥20% |
Inside Surface Cleanliness: 0.16g/m2 , max
| OD, mm | Wall Thickness, mm | ||||||
| 0.5 | 0.6 | 0.7 | 0.8 | 0.9 | 1 | 1.3 | |
| Burst Pressure, MPa | |||||||
| 3.18 | 119.4 | 148.8 | 180.6 | 215.1 | |||
| 4 | 91.4 | 112.9 | 135.8 | 160.0 | |||
| 4.76 | 75.1 | 92.3 | 110.3 | 129.3 | 148.2 | ||
| 5 | 71.1 | 87.3 | 104.2 | 121.9 | 140.5 | 160.0 | |
| 6 | 58.2 | 71.1 | 84.5 | 98.5 | 112.9 | 128 | |
| 6.35 | 54.7 | 66.8 | 79.3 | 92.3 | 105.7 | 119.6 | |
| 7 | 49.2 | 60.0 | 71.1 | 82.6 | 94.4 | 106.7 | 146.0 |
| 7.94 | 43.0 | 52.3 | 61.9 | 71.7 | 81.8 | 92.2 | 125.3 |
| 8 | 42.7 | 51.9 | 61.4 | 71.1 | 81.1 | 91.4 | 124.2 |
| 9.53 | 35.4 | 43.0 | 50.7 | 58.6 | 66.7 | 75.0 | 101.1 |
| 10 | 40.9 | 48.2 | 55.7 | 63.3 | 71.1 | 95.6 | |
| 12 | 33.7 | 39.6 | 45.7 | 51.9 | 58.2 | 77.8 | |
| 12.7 | 31.7 | 37.3 | 43.0 | 48.8 | 54.7 | 73.0 | |
| 14 | 33.7 | 38.8 | 44.0 | 49.2 | 65.5 | ||
| 15.88 | 29.5 | 34 | 38.5 | 43 | 57.1 | ||
| 16 | 29.3 | 33.7 | 38.1 | 42.7 | 56.6 | ||
For Bundy tube manufacture, generally standards of China, US, Japan and other countries are very similar, and replaceable and our tubes meet all of them, except that the material compositions are slightly different among countries.
Click here to watch the videos of the production.
Click here to learn more about the inspections and tests for the Bundy tubes.