Double Wall Bundy Steel Tube

Bundy tubes are fully monitored during the tube fabrication, and also gone through a series of inspections to make sure they are safe and reliable for hydraulic uses.

Test and inspection items specified in standards of different countries are generally the same or very similar. We manufacture the tubes and issue test reports as per Chinese standard if no other particular requirement comes from buyers.

One thing to note is that the material listed in those standards are slightly different among countries. Low carbon steel is required commonly, but the chemical composition of the material varies, especially for carbon. In most of these countries, the steel grade exists already in their steel industry. In China, there is equivalent steel grades, but we specially developed a steel grade, BHG2, that is much more suitable for the double wall brazed steel tubing manufacture, perfect mechanical properties for the tube forming and also for the final tubes.

When tube is formed and brazed in the continuous production line, instant Eddy current automatic inspection system keeps detecting any potential imperfections of inner structure of the tube. Once the imperfections are detected, they will be automatically shown and notified by the system:

1. An alarm sound is triggered and broadcast by a loud speaker.
2. A flashing alert light on the machine shall be turned on.
3. An automatic online printer shall mark the tube sections with imperfections with ink, then the imperfect tube sections shall be cut and removed.

The following tests shall be done to make sure the tubes are suitable for hydraulic applications of automobiles.

1. Tensile test.
2. Hardness test.
3. Bending test.
4. Expansion test.
5. Developing test.
6. Flattening and bending test.
7. Pressure-proof test.
8. Burst pressure test.

The following tests shall be conducted to determine how the surface coating/plating performs when protecting the tube from corrosion.

1. Coating/plating thickness test.
2. Corrosion resistance test (neutral salt spray, i.e. NSS).
3. Film performance test (varies according to coating/plating types).

If any questions,you are more than welcome to contact sales@grandsteeltube.com

Our workshop,located in Changzhou,covers an area of 13,000 square meters equipped with the state-of-art facilities to manufacture the double wall bundy steel tubes and single wall bundy steel tubes .The monthly production capacity is 3,000,000 meters.

The materials are :SPCC,SPHC,SPCE,BHG1,BHG2,other materials can be achieved after discussion.

Mainly sizes are:4.76x0.70mm,6.35x0.70mm,8x0.70mm,9.53x0.70mm,10x0.70mm,12x0.70mm other size like:4.00x0.5mm,3.18x0.7mm,2.60x0.50mm is also produced according the requirements.other sizes can be achieved after discussion.

1. Production of  double wall bundy steel tubes & single wall bundy steel tubes since 2005.

2. Working with customers from Europe,West Asia,South America,since 2006etc

3.  Samples can be delivered within 10 days after confirmation

4.  40 days as the production period and delivery after order confirmation.

5.  200,000 meters of copper coated bundy steel tube  in stock.

6.  Sizes can be offered from OD:2.60mmxWT:0.5mm to OD:12.7mmxWT:1.24mm

7.  Third party inspection like:TUV,BV,SGS,etc accepted

8.  Professional team assists your special tube requirements.

9.  Other related tubes can be offered with competitive prices:white/yellow/olive green galvanized double wall bundy tubes,PVF bundy steel tubes;etc

We have been delivering these tubes to Peru,France,Russia,South Korea for the automotive industry,since 2006.etc.If any questions,you are more than welcome to contact sales@grandsteeltube.com

Bundy tube, also called Bundy pipe, is a double wall copper brazed steel tube. The manufacture of Bundy tube is a continuous process of rolling a copper coated steel strip through 720 degrees, brazing the outer and inner circle of the strip together by the melted copper layer to form a round tube with a continuous circular seam, and annealing. We are using fully automatic production lines with online process monitoring and continuous fabrication of the Bundy tubes.

1.A copper plated steel strip is pulled into the primary tube rollers, and become 720 degrees wrapped after going through a set of the rollers.

2.Then the wrapped tube goes into the welding chamber where the tubes are brazed. The temperature within the chamber is controlled above the copper melting temperature, so the copper layers are melted and spread into the steel surfaces. The tube is heated here in the chamber with protection gas filled so there is no oxidizing of the copper or steel, and also no water will be left to avoid any rust.

3.After the welding stage, the tube goes into the cooling section where it gets cooler, and also it is monitored online simultaneously by the Eddy current scanning device. Any abnormal section shape or un-seamed welding would be observed from the monitor screen.

4.The tubes are finally wound to be easily packed and stocked.

This process of Bundy tube production, compared with other methods, are widely accepted for its high production rate yet instant monitoring of the welding quality.

If any questions,you are more than welcome to contact sales@grandsteeltube.com