welded and seamless steel pipe

Steel Pipe: The Choice of Welded and Seamless Variations

Hollow metal with a round or oval cross-section is commonly classified as either “pipe” or “tube”, even though there are distinct technical contrasts between the two. Pipe fabrication is typically achieved by extruding or piercing a hot rolled bar, while tubes stem from piercing a hot rolled coil.

A wide range of sizes and grades of pipe are available for purchase that are typically designated as Nominal Bore or Nominal Diameter. Apart from the usual Carbon Steel and Stainless Steel options, many Alloy Steel and metal variants can be found. For Carbon Steel and Stainless Steel pipes, the wall thickness is given according to Schedule numbers, while the thickness for Alloy Steel and other metals is specified in inches.

The production of pipes is carried out in two distinct ways. Welded pieces are shaped by forming a plate or ribbon into a cylinder and welding the edges together. Seamless pipes, meanwhile, are formed by puncturing a heated roll of steel to create a hollow cylinder.

Welded and Seamless pipes each boast their own set of advantages – while Welded pipes are formed from a flat plate or strip and welded along the seam, Seamless pipes are made by piercing a hot rolled coil to form a hollow cylinder. Although it is generally more expensive to manufacture, the Seamless variant offers enhanced mechanical properties and finish.

From slender circumference to outsized diameters and beyond, the spectrum of welded pipes is expansive. In stark contrast, larger sizes of the more costly seamless variety are a rarity.

A flat plate or strip is twisted into a cylindrical shape and its edges are then affixed together in the welding process to create welded pipe. Welding this tube together instead of forming it in one single piece results in much more affordable pipe when compared to seamless options. Yet, due to such economical methods, the finished item’s mechanical properties may not be quite as optimal and its appearance more than likely falls below that of seamless pipe due to imperfect sealant applications.

Crafted from a single hot-rolled coil that is punctured to form a hollow cylinder, seamless pipe has proven to be advantageous in terms of both its mechanical properties and its pristine finish. However, its fabrication usually comes with a more extended price tag.

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