Stainless steel pipe does not corrode easily and is useful in gas and oil refineries. It could be used in other projects but is quite expensive.
Black steel, which gets its name from a black oxide scale that forms on the surface, is subject to rust and corrosion. Factories apply a protective coating of oil to make it more rust-resistant. It can be welded or threaded for fittings and is widely used in oil pipelines and for sewage projects. At times, black steel pipes are lined with concrete for added protection and durability.
Alloy steel pipe, which may contain nickel, chromium, manganese, boron, vanadium, silicon, zirconium, aluminum, tin, copper, tungsten, titanium, cobalt or tin in addition to iron, is used in projects that require the particular properties of a specific alloy. Projects using alloy steel pipe include gas drilling, spacecraft, transformers and nuclear plant applications.
Carbon steel is an alloy of iron and carbon with small amounts of silicon, sulphur and manganese. The amount of carbon in the alloy determines its hardness, strength and ductility, which is the ability to be shaped into a new form. Low-carbon steel can be welded and does not melt easily. High-carbon steel is difficult to weld. Carbon steel is one of the most-used types of steel. One of the many projects for which it is used is a project involving pipes that can withstand high pressure. Schedule 40 steel, which is a mild carbon steel often used to transport water and gas, also is a good choice for projects such as bumpers and roll cages for off-road vehicles
Galvanized or painted steel pipes offer added protection against rust and corrosion. They come in a variety of diameters and lengths and can be threaded for assembly with various fittings to form many do-it-yourself projects. Such projects are limited only by imagination and budget. A steel pipe bookcase is one example. With careful planning and wise choice of materials, a project made from coated steel pipe will need little maintenance and last many years.