Each of these metals has its own distinct advantages or disadvantages in certain applications. Steel pipe and tubing are relatively inexpensive and are used in many hydraulic and pneumatic systems. Steel is used because of its strength, suitability for bending and flanging, and adaptability to high pressures and temperatures. Its chief disadvantage is its comparatively low resistance to corrosion. Copper pipe and tubing are sometimes used for fluid power lines.
Copper has high resistance to corrosion and is easily drawn or bent.
However, it is unsatisfactory for high temperatures and has a tendency to harden and break due to stress and vibration. Aluminum has many of the characteristics and qualities required for fluid power lines. It has high resistance to corrosion and is easily drawn or bent. In addition, it has the outstanding characteristic of light weight. Since weight elimination is a vital factor in the design of aircraft, aluminum alloy tubing is used in the majority of aircraft fluid power systems.