Welded Steel Pipe: Classification and Production Methods

North American clients favor welded steel pipe based on economics, quick availability and a more consistent thickness. The characteristics arise from the material and, of course the production methods.

Producing Welded Steel Pipes: Classification

Companies produce welded steel pipes by taking such flat substrates as steel plate or HR coil, and shaping and welding them. Classification of the pipes can be the result of different approaches. Professionals consider whether the steel pipe is straight seam or spiral welded. Others may divide the material into its purpose e.g. mining, oil drilling, agricultural, or manufacturing.

One of the more common ways of classifying welded steel pipes is by looking at the process. In other words, classifying steel pipes according to production methods and/or sub-processes. The results fall into one of three classifications. These are:

1. Electric-Resistance Welded (ERW): ERW is either high or low frequency. Restricted to a size of a maximum of approximately 24” in diameter, this type of welded steel pipe is the result of longitudinally welded HR coil.
2. Longitudinal (LSAW or DSAW): The main substrate for this method is heavy steel plate. Producers use one of two methods, submerged arc welded (SAW) and the double submerged arc welded (DSAW). The resulting flat plate features a straight seam stretched the full length of the pipe. Standard sizes for this type of pipe range between 12m and 18m. By using this method, the weld quality is high with few defects.
3. Spiral Welded or Spiral Welded Longitudinal: Spiral welded, like the name indicates, is the result of a circular motion. The manufacturer takes the plate, and winds and welds the substrate of an HR coil or steel plate in a spiral. This method is called helical submerged arc welded (HSAW). The resulting product is longer and thicker than other methods. Overall, this method is favored because it proves to be simple, efficient, cost-effective and fast.

No matter how you classify welded steel pipe, the market for both producers and distributors remains strong. Diversification is one means of maintaining consistency in profits. Quality, and meeting and even exceeding the specifications of such organizations as the API, are essential for ensuring the producers and distributors remain competitive globally. Kelly Pipe continues to provide the quality welded steel pipe its clients have come to expect, including OCTG and water well pipes from its extensive inventory.