There are two general categories for pipes: seamless and welded. There are multiple methods of making pipes, but there are four main procedures that most manufacturers in the U.S. prefer to use. These are the Seamless Method, the Double Submerged Arc Weld, the Electric Resistance Weld, and the Continuous Weld.

1. The Newly Welds
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2. There are two general categories for pipes: seamless and welded. There are multiple methods of making pipes, but there are four main procedures that most manufacturers in the U.S. prefer to use. These are the Seamless Method, the Double Submerged Arc Weld, the Electric Resistance Weld, and the Continuous Weld.
Here is a comparison between the Continuous Weld and the Electrical Resistance Weld. Knowing the difference between these different methods not only provides the advantages of each procedure, but will explain why these are the better options as well.
The Continuous Weld
The continuous weld pipe starts as a coiled skelp with the required width and thickness for the eventual pipe. Successive steel coils are welded end-to-end to create a long ribbon of steel, which is fed into a roll leveler, and a gas furnace. The machine heats the metal to a temperature that makes it easier to manipulate, and the forming rolls roll the skelps into the dimensions of the pipe.
Manufacturers like this method because they do not have to add any metal to the formation of the pipe than what they already had. This is also an assembly line’s dream method because one the coiled skelps starts going into the machine, the process does not stop unless they run out of metal. This allows them to make more pipes with no downtime and greater efficiency.

3. The Electrical Resistance Weld
There are two very important differences between the Continuous Weld and the Electrical resistance Weld. The latter method uses electricity and cold forming to form its pipes instead of the heat and hot forming of the former. An electric current runs through the edges of the strip for the fusion weld, copper discs then raise the temperature to make the weld more effective.
Similar to the Continuous weld, the electric resistance weld does not use any added metal in its pipe production. In fact, the procedure actually creates unneeded metal at the weld points called flashes. Cutters remove these flashes at finishing stations, and make the pipe smoother and easier to handle overall.

4. RESOURCES:
Steel Tube Fabrication: http://servicesteel.com/steel-tube-fabrication-services/
Pipe Manufacturing Process –
http://primis.phmsa.dot.gov/comm/FactSheets/FSPipeManufacturingProcess.htm
Continuous Welded Pipes and Tubes –
http://www.prnewswire.com/news-releases/continuous-welded-pipes-and-tubes--- global-strategic-business-report-214715771.html