Properties of Steel Pipes

Sizing

• Steel pipes can be manufactured in almost any length, with factory welds used to join longer sections. The length of a pipe is measured in simple feet or meters. The other dimensions of a pipe are a bit more complicated. Steel pipes have both an outside and an inside diameter. These numbers can differ dramatically because of the different pipe thicknesses needed for various projects. In North America, pipe sizes are designated using a measuring system known as Nominal Pipe Size (NPS). The NPS is a number ranging from a fraction of an inch to several feet and represents the outside diameter of the pipe. Under this system, the NPS value is accompanied by a Schedule number, which represents the thickness of the pipe wall.

Manfacturing

• There are three basic manufacturing methods used to make steel pipes. Seamless pipes are made using an extrusion mold. These pipes are the most expensive, but also the most reliable. It is easier to perform calculations regarding water pressure when seamless pipes are used. Welded pipes are less expensive, but not as reliable for high-pressure situations. They are made by wrapping a sheet of steel around a form, then welding the seam. Finally, cast pipes are made using a casting mold. They are not as common today as they were in the past, and are not as fail-proof as seamless pipes.

Materials

• The most common material for steel pipe is carbon steel, which is used for potable water supplies as well as waste water systems. Alloy steel pipes, which contain metals such as nickel, chromium or tungsten, offer superior strength and resistance to chemicals. These alloy pipes are used primarily to transport chemicals like gas and oil. Stainless steel pipe is becoming more and more popular for domestic water systems and for use in the home. This material contains a large amount of chromium, which gives the steel rust-proof qualities. Finally, black steel pipe features an oxidized exterior coating and is used for gas and hot water lines in industrial settings.

Benefits

• One of the primary benefits of using steel pipe is the strength of the material. It can withstand a great deal of pressure and will not crack under most impacts. If subject to abuse, steel tends to bend, rather than break, which can reduce the risk of serious leaks and spills. This material is incredibly strong and durable and will often need no maintenance for many years after installation. Finally, it is largely resistant to rust, corrosion and chemical interaction.

Specialty Features

• There are a number of ways to treat steel pipes to make them better suited for certain uses. Galvanized steel is coated with zinc to increase the pipe's corrosion resistance. This is useful for pipes that will carry water or be installed underground. Corrugated steel pipe has a rippled texture and is often galvanized as well to protect from rust and corrosion. Corrugated piping is used for underground sewer and water lines, and the ripples in the surface help the material stand up better against the weight of the soils above. Steel tubing is also available. This flexible material is used in laboratory and industrial applications.