1. Working Principle (Manufacturing)
The process varies depending on the welding technology:
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ERW Process: A cold-rolled strip is passed through a series of rollers to form a tube. High-frequency electrical current is applied to the edges. The heat generated by the material’s electrical resistance melts the edges, which are then squeezed together by “pressure rolls” to create a forged weld.7
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LSAW Process: A heavy plate is bent into a “U” shape, then an “O” shape (the UOE process).8 A welding machine then performs an arc weld on both the inside and outside of the seam using a consumable wire.
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Finishing: The “weld bead” (the raised portion of the weld) is often trimmed or “scarfed” to make the pipe smooth.9
2. Primary Use
The primary use of welded pipe is for Low to Medium Pressure Fluid Transport and Structural Applications.
It is preferred over seamless pipe when:
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Cost is a factor: Welded pipe is significantly cheaper to produce.10
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Large Diameters are needed: It is much easier to roll a large plate into a 48-inch pipe than it is to pierce a solid 48-inch billet.
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Wall Thickness Uniformity: Because it starts as a flat, precisely rolled plate, the wall thickness is often more consistent than seamless pipe.
3. Common Applications
Welded pipes are the “veins” of modern infrastructure:
| Type | Common Application |
| ERW Pipe | Water mains, fencing, scaffolding, and low-pressure gas lines in housing. |
| LSAW Pipe | High-pressure oil and gas transmission pipelines over long distances. |
| SSAW (Spiral) | Large-diameter water transport and piling for bridges and building foundations. |
| Automotive | Exhaust pipes, chassis components, and seat frames. |
| HVAC | Ductwork and cooling water circulation in large buildings. |
