Brake tubes carry pressurized air or fluids. They are located under the chassis of vehicles in highly-corrosive environments. To avoid premature failure, brake tubes must resist corrosion from road mud, salt and stone pecking. Braking failures from faulty brake tubes can be a dangerous and costly liability.
Low-cost, furnace-brazed steel tubing has been the prevalent brake tubing material in automobiles since the late 1940s. This tubing is susceptible to corrosion even when coated. Brazing voids, coating voids, poor coating adhesion, discontinuities and stone pecking can break protective coatings and expose steel to the atmosphere. This will initiate the steel corrosion process.
On the basis of quality, safety, reliability and durability, 90-10 Cu-Ni tube is a significantly better choice for automotive brake tube than low-carbon steel. Copper-nickel provides the surest protection against random service damage.
C70600, a 90-10 Cu-Ni alloy, is a proven high-quality brake tubing material. Volvo, Audi, Porsche, Rolls Royce, Lotus, Aston Martin and other performance automobiles use the alloy. Furthermore, a replacment market exists for copper-nickel tubing for brake lines, fuel and transmission systems. Copper-nickel is the preferred material for the brake tubing aftermarket.
C70600 is also common in military, firefighting and other heavy vehicles where reliability is an absolute necessity. The alloy has high resistance to corrosion from road salt and it does not need a protective coating. Its use in brake tubing has increased in recent years as automobiles are being designed to last longer and as manufacturers look for alternatives to increasingly costly corrosion-retarding coatings.
Corrosion and mechanical abuse tests were conducted to compare steel and copper-nickel for brake tubing. Steel tubes passed a 60-cycle requirement but failed well before 120 cycles. 90-10 Cu-Ni tubes completed 200 cycles with essentially no reduction in original burst strength. Further information about these tests is available.
- Automotive Hydraulic Break Tubing: The Case for 90-10 Copper-Nickel Tubing, Publication 8023-0009, CDA Inc., .
- Copper-Nickel Automotive Vehicle Brake Tubing, Publication A 8001-00/90, CDA Inc., .