Alloy tubing is a type of metal tubing made from an alloy, or a specific mixture of metals. Certain alloys are better suited to certain applications than others, so the mixtures used in alloy tubing are specifically defined. For example, 4130 steel alloy is defined as that which contains 0.30 percent carbon by weight, as well as specific amounts of other elements.
The varieties of alloy tubing available are virtually unlimited. In addition to the many different alloy mixtures, tubing of many different dimensions can be made. Wholesalers and retailers of these metal parts often organize their inventory by the alloy type, as well as the diameter of the tubing. Both the outside diameter of the tubing and its wall thickness are measured and carefully controlled during the manufacturing process. Alloy tubing can be purchased in numerous combinations of these two parameters.
Steel is not the only metal used as the primary component of alloy tubing. Aluminum and copper alloys are used in the same way, and brass tubing is also common. Copper alloy tubing is usually used in plumbing applications. Being more flexible than steel, copper tubing is more easily adjusted and manipulated in small spaces and around corners. Aluminum tubing is great for making bicycle frames, and both brass and aluminum tubing are commonly used in the building of models.
There are certain applications, however, for which steel is ideally suited. Its hardness, strength, and wear resistance make a great deal of difference where these attributes are important. Alloy tubing used in roll cages, for example, is almost always made from a steel alloy. Steel tubing is also the metal of choice for most other automotive applications, especially in engine parts. When used in these contexts, it can hold up well and for long periods of time under the heat and pressure that is present in engines.
Other than carbon, the elements used to produce steel alloy include chromium, molybdenum, vanadium, nickel, and boron. There is a significant percentage of chromium in stainless steel, which gives this particular alloy some of its signature properties, particularly its well-known luster. Stainless steel alloy tubing comes in many different varieties, each having a slightly different composition, which is denoted by a numbered code. For instance, the 321 alloy has 18 percent chromium, and 11 percent nickel, which is stabilized by the addition of titanium. This particular alloy is best suited for applications such as aircraft hydraulics and electrical instruments.