The Welded Tubing Process
The manufacturing process for as-welded mechanical
tubing begins with coils of steel, which are slit to the proper
width for the desired tube size. The cut strip, or skelp, passes
through a series of rolls that progressively cold-form it into a
tubular shape. It then passes through an electric resistance welder
which joins the edges together, under pressure, to complete the
tubular shape. In-line equipment then tests the tube's weld for
integrity.
No filler is added in the welding process, so the
composition of the weld is the same as the parent material. Welding
leaves a small amount of flash on the tube's outer and inner
surfaces. The outer flash is removed to provide a smooth contour and
maintain OD tolerance. Depending upon customer specifications, the
inner flash can also be removed.
Following flash removal, the tube is cooled and
sized to specified dimensions by a series of finishing rolls Or, if
it has been ordered in square or rectangular shape, it passes
through shaping rolls to give it the desired shape and dimensions.
Then it is cut to the length ordered.
Source: Steel Tube Institute of North America
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