There’s probably nothing more critical to the success of modern infrastructure than simple steel pipes. Steel pipes are used widely in applications from underground water and power lines to sewers and drains. There are over 2.5 million miles of pipe in the oil and natural gas industry alone, not counting millions of miles more in water systems and other infrastructure networks.

But how are those pipes manufactured? How did the industry grow to be able to provide almost countless miles of pipes and tubes? The process of manufacturing stainless steel tubes and pipes has evolved along with advancements in industrial technology. In this article, we’ll outline some of that process.

Which Raw Materials Are Used?

The basic raw material used in the production of tubes and pipes is steel. Steel is an alloy composed of aluminum, titanium, manganese, zirconium, vanadium, and tungsten. Finished pipes frequently have an outer coating as well. This coating can be an advanced carbon coating to increase the durability of the pipe, or something as simple as a coat of paint.

The Tube and Pipe Manufacturing Processes

Steel pipes can be produced by a number of different methods. Here are some of the most common and efficient pipe manufacturing processes.

Mannesmann Plug Mill Manufacturing Process

This method was founded by Mannesmann, a German engineer. It starts with a cylindrical steel billet, which is pierced and fed between two rollers. At the same time, a cone-shaped mandrel is inserted into the billet. After being pierced, the billet undergoes another rolling stage in which it is elongated. A third rolling process in a plug mill completes the initial stage of the pipe manufacture. It finishes with heat treatment and undergoes a cooling, slicing, and straightening process.

Mandrel Mill Process

Like the Mannesmann process, mandrel mill pipe manufacturing begins with a hot steel billet. After heating, the billet is pierced and fed into a mandrel mill through multiple pairs of rollers. Afterward, the pipe is heat-treated and stretched, before being cooled, cut, and straightened. Unlike the Mannesmann milling process, in most cases, the desired diameter is achieved in a single attempt.

Extrusion Process

Extrusion pipe manufacturing uses hydraulic power to push a mandrel through a heated billet. By doing this within a large die, excess material is trapped between the mandrel and the walls of the die, extending and hollowing-out the billet and producing a pipe.

Forged Seamless Pipe Manufacturing Process

A heated billet is used in the process. The hot billet is placed in the forging die, which has a slightly larger diameter than the finished pipe. A hydraulic building hammer with matching interior diameter helps to create a cylindrical forged pipe. The pipe is then machined to arrive at the final dimensions. The process is efficient in the production of seamless pipes with large diameters.

Welded Pipe Manufacturing Process

Unlike some of the other processes mentioned, welded pipes are made using metal plates or coils, rather than billets. The coil or plate is rolled into a circular section. After rolling the circular section from the plate, the plate is welded. Advantages of this method include a less complicated manufacturing process and easily available material. The pipes can be produced in large sizes without any restrictions. Pipes that are welded with filler materials can be used in the manufacturing of long radius elbows and bends.

These are some of the methods that are currently used to produce large-diameter industrial metal pipes and tubing. These processes are constantly evolving, and new methods – such as 3D printing – show promise.

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Bailey Hudson is a freelance industrial writer who focuses on quality industrial equipment and modern manufacturing. Bailey is currently writing for SummitMT.