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Pipe and Tubular Products of Steel

May 22, 2021

What to Know About Pipe and Tubular Products of Steel

All steel hollow products are steel pipe and tubular products. Therefore, any steel hollow product you find around comes under the pipe and tubular steel products category. These products usually have a cylindrical shape. Though, they get alteration frequently with different techniques to produce rectangular, symmetrical, oval, and square forms.

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These products are suitable for various applications. However, their most common use is in fluid conveyance and structural members. They are usually produced using alloy steel or wrought carbon and are designed by terms pipes, especially OCTG and tubing, etc.

In this article, we will discuss steel pipes and tubular products and their classifications. We will also share some examples of these products and their use for a better understanding.

Dimensions of Steel Pipes and Tubular Products

Pipes and tubular products of steel have one inside dimension, one outside dimension, and a wall thickness. The tubular products and steel pipe have broad classification as tube and pipe. Tube and pipe terms have inconsistent application.

Normally, ‘pipe’ defines cylindrical products with a combination of wall thickness and outside diameter. A clear difference between a tube and a pipe is the design of the tube or pipe diameter. A pipe normally has a “nominal pipe design that depends on the inside diameter (ID) of the wall thickness.

On the other hand, the design of tubes has one outside diameter (OD). For instance, a steel pipe of 20mm with a thickness of 4mm has 28mm outside diameter, while a steel tube of 20mm has a 20mm outside diameter.

Classifications of Tubular Products and Steel Pipe

The two extensive classifications of steel pipes and tubular products are further divided into various user groups. For instance, three groups come under the tubes, such as pressure tubes, mechanical tubing, and structural tubing. Similarly, there are five groups under pipes, such as standard pipe, OCTG, line pipe, pressure pipe, and water well pipe. Several other pipes are also available for various special applications. These pipes include tube piling and conduit pipe.

Such special groups have various uses in different applications. Some examples of such special applications include gas and oil transmission pipes, casing pipes, drill pipes, and main water supply pipes, etc. The development of these pipes is regardless of their manufacturing method, finish degree, wall thickness, and size range. Mechanical and structural tubing doesn’t follow this nomenclature system. Instead, their names are obtained from the finish degree and fabrication method, like seamless-hot finished or cold-formed welded.

Steel pipe and tubular products manufacture through the formation of the flat skelp, strip, plate, or a sheet into the hollow cylinder while welding the resultant spiral or longitudinal seam together. You can also make them by developing a hole in the solid cylinder by elongating and piercing the resulting hollow cylinder.

The first product group is known as welded pipes, while the second product group is known as seamless pipes. Let’s quickly go through the production processes of these products.

1. Welding Processes

To manufacture welded pipes and tubular products of steel, we work plate, sheet, strip, or skelp into the cylinder. Then, it combines at the spiral or longitudinal seam by different processes. Those processes are as follow:

  • Electric-Resistance Welding
  • Continuous Welding
  • Fusion Welding
  • Submerged Arc Welding

You can pick any of the above-listed welding processes according to the application requirements.

2. Seamless Processes

Then, we have seamless processes for pipes and tubular products of steel. Below is the list of the seamless processes for steel tubular products and pipes. Seamless processes help produce up to 1200mm products with the help of the hot-extrusion method.

  • Hot Extrusion
  • Rotary Piercing
  • Drawing and Cupping

We can also produce products up to 2000mm in diameters with the help of the rotary piercing technique.

Cold Finishing

You can cold finish both welded and seamless tubular products and pipes of appropriate sizes. You can decrease or increase the diameter with cold finishing for producing different shapes. It also allows you to produce a closer dimensional tolerance or smoother surface, or to alter mechanical properties.

Cold drawing is the most common and frequently adapted process in which a descaled hot pipe is deformed plastically by die-drawing and mandrel drawing. Cold drawing without the mandrel is known as sinking or drawing.

In swaging and pipe reducing through pilgering or rotorolling, reducing dies take the hollow pipe over the mandrel. However, the mandrel is not dependent on swaging. Pipe reducing has great commercial significance because it allows heavy reductions to a mill-length pipe. It also helps in refactoring alloys, which are hard to draw cold due to greater power requirements.

You can cold finish round cross-section pipes and tubular products of steel on their outside through polishing, grinding, or turning. Or, you can also do it by combining any of the discussed processes.

They can be honed, skived, or bored on their inside diameter. The product’s mechanical properties cannot enhance because these operations include just stock removal with insignificant plastic deformation.

Mostly, the standard specs of these products and pipes involving strength rely on cold-worked or hot-rolled material properties. A few OCTG of high strength is treated with heat for achieving high strength, SSCC resistance, and ductility by intended applications.

You can employ cold drawing for improving surface finish and strength and also the product’s dimensional accuracy. However, you can also achieve the prescribed levels of strength in a few specifications with cold working.

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Conclusion

Any steel hollow product you see around comes under steel pipes and tubular products. Further, steel pipes and tubular products are classified into different groups. These products include three groups, involving mechanical tubing, structural tubing, and pressure tubes. On the other hand, pipes have five groups including OCTG, water well pipes, pressure pipes, line pipes, and standard pipes.

Then, there two types of processes; seamless and welded. Welded processes include electro-resistant welding, submerged arc welding, fusion welding, and continuous welding. On the other hand, the seamless processes are rotary piercing, drawing and cupping, and hot extrusion.

We hope this article has helped you develop a basic understanding of these steel products. For further details or information about this topic, you can feel free to contact us, anytime. We always feel happy to assist.

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