Engineering companies have materials engineers to determine materials to be used in piping systems. Most pipe is of carbon steel (depending on service) is manufactured to different ASTM standards.

The carbon-steel pipe is strong, ductile, weldable, machinable, reasonably, durable and is nearly always cheaper than pipe made from other materials. If a carbon-steel pipe can meet the requirements of pressure, temperature, corrosion resistance, and hygiene, it is a natural choice.

Iron pipe is made from cast-iron and ductile-iron. The principal uses are for water, gas and sewage lines.

Plastic pipe may be used to convey actively corrosive fluids and is especially useful for handling corrosive or hazardous gases and dilute mineral acids.

Other Metals and Alloys pipe made from copper, lead, nickel, brass, aluminum and various stainless steels can be readily obtained. These materials are relatively expensive and are selected usually either because of their particular corrosion resistance to the process chemical, their good Heat Transfer, or for their tensile strength at high temperatures. Copper and copper alloys are traditional for instrument lines, food processing, and Heat Transfer equipment. Stainless steels are increasingly being used for these.

Lined Pipe

Some materials described above, have been combined to form lined pipe systems.

For example, a carbon steel pipe can be internally lined with a material able to withstand chemical attack permits its use to carry corrosive fluids. Linings can be applied after fabricating the piping, so it is possible to fabricate whole pipe spools before lining.

Other internal layers can be: glass, various plastics, concrete, etc., also coatings, like Epoxy, Bituminous Asphalt, Zink, etc. can help to protect the inner pipe.

Many things are important in determining the right material. The most important of these are pressure, temperature, product type, dimensions, costs, etc..