Nickel is an often alloyed element, since it is able to alloy to almost any metal, and as a result, nickel tubing is predominantly fabricated from nickel alloys.
Some common nickel alloys used for tubing include nickel-chromium alloys (Nichrome), nickel-titanium alloys (Nitinol), nickel superalloys (Inconel), and nickel-copper alloys (Monel). Due to the wide range of nickel alloys, nickel tubing can offer a variety of characteristics that appeal to diverse industries including: residential, for use in plumbing, refrigerators and air conditioning systems; medical, for applications requiring hypodermic tubing; automotive, for internal systems tubing such as vehicle brake tubing; industrial manufacturing, for use in material handling and processing applications as well as equipment such as heat exchangers and furnaces; and petrochemical for oil and gas extraction and processing.
An attractive and durable metal, some additional characteristics of nickel include malleability, ductility, sanitary, and excellent strength and toughness in extreme environments.
Nickel tubing can refer to tubing that is wholly fabricated from nickel alloys, or it can refer to tubing that has been fabricated from a different material and then nickel coated. When the tube is completely fabricated from nickel alloys, the two most common processes of tube fabrication are tube rolling and tube extrusion. In tube rolling, pre-impregnated nickel alloys are cut and rolled around a mandrel.
Next, the nickel is wrapped around the mandrel in order to eliminate any retained air and lastly, the nickel is heat-cured and will form a hollow tube once the mandrel is removed. In tube extrusion, a round nickel billet is pressed through a die, which is a hollow profile that shapes the nickel into a hollow tube-shape by means of a pin attached to the die as the billet is squeezed through.
For tubing that is nickel-coated rather than wholly nickel, electroplating is the most common. In electroplating, an electric current is used to reduce positively-charged ions of nickel from a solution and thus, coat the metal tubing with a layer of nickel. Electroless nickel plating may also be used, in which a catalytic process is used to reduce the nickel ions from a solution, which results in the coating of the tube with nickel without having to use electrical energy.