Before making repairs to any plane plumbing, it is important to make accurate identification of plumbing materials. Aluminum alloy or steel tubing can be identified readily by sight where it is used as the basic plumbing material. However, it is unfriendly to determine whether a material is carbon steel or stainless steel, or whether it is 1100, 3003, 5052-0, or 2024-T aluminum alloy.

It may be vital to test samples of the material for hardness by filing or scratching considering a scriber. The magnet test is the simplest method for distinguishing between the annealed austenitic and the ferritic stainless steels. The austenitic types are nonmagnetic unless heavily cool worked, whereas the straight chromium carbon and low alloy steels are strongly magnetic. Figure 2.1 gives the methods for identifying five common metallic materials by using the magnet and concentrated nitric tart tests.


By comparing code markings of the replacement tubing taking into account the indigenous markings re the subject of the tubing alive thing replaced, it is attainable to identify extremely the material used in the original installation.
The alloy designation is stamped upon the surface of large aluminum alloy tubing. On small aluminum alloy tubing, the designation may be stamped upon the surface, but more often it is shown by a color code. Bands of the color code, not sophisticated than 4 inches in width, are painted at the two ends and in financial fable to midway amid the ends of some tubing. When the band consists of two colors, one-half the width is used for each color.
Painted color codes used to identify aluminum alloy tubing are:


Aluminum alloy tubing, 1100 (1/2-hard) or 3003 (1/2-mixture), is used for general determination lines of low or negligible shapeless pressures, such as instrument lines and ventilating conduits. The 2024-T and 5052-0 aluminum alloy materials are used in general intend systems of low and medium pressures, such as hydraulic and pneumatic 1,000 to 1,500 appendixi. systems and fuel and oil lines. Occasionally, these materials are used in tall-pressure (3,000 postscripti.) systems.

Tubing made from 2024-T and 5052-0 materials will withstand a fairly high pressure in the in the since bursting. These materials are easily flared and are soft sufficient to be formed bearing in mind hand tools. They must be handled behind care to prevent scratches, dents, and nicks.

Corrosion-resistant steel tubing, either annealed or 1/4,-well along, is used extensively in high-pressure hydraulic systems for the operation of landing gear, flaps, brakes, and the along with. External brake lines should always be made of corrosion-resistant steel to minimize uncharacteristic from rocks thrown by the tires during takeoff and landing, and from careless showground handling. Although identification markings for steel tubing differ, each usually includes the manufacturer’s declare or trademark, the SAE number, and the being condition of the metal.
Metal tubing is sized by outdoor diameter, which is measured fractionally in sixteenths of an inch. Thus Number 6 tubing is 6/16 (or 3/$ inch) and Number 8 tubing is S/16 (or 1/2 inch), etc.

In tally to auxiliary classification or means of identification, tubing is manufactured in various wall thicknesses. Thus, it is important taking into consideration installing tubing to know not without help the material and outside diameter, but along with the thickness of the wall.