Production Process and Weld Quality Control of Welded Pipes and Their Wide Application in Structural Support
Release time:
2025-04-17
Welded pipes have diverse applications in structural support, ranging from pipe trusses in building steel structures to arch ribs in bridges, from the tower bodies of power transmission towers to the booms of port machinery.
Welded pipes are manufactured using hot-rolled steel coils or plates as raw materials, undergoing processes such as forming, welding, and sizing. Weld quality control is a core aspect of ensuring product performance. Based on the forming method, welded pipes are divided into two main categories: straight seam welded pipes and spiral welded pipes. Straight seam welded pipes are produced using a continuous forming machine, gradually bending strip steel into a circular tube shape, and then welding the seam longitudinally. High-frequency resistance welding is the main welding method for small and medium-diameter welded pipes. It utilizes the skin effect of high-frequency current to rapidly heat the edges of the steel plate to a molten state, fusing them together under the pressure of extrusion rollers. This method offers high welding speed and a small heat-affected zone. Large-diameter straight seam welded pipes employ submerged arc welding, with single-sided or double-sided welding, resulting in reliable weld quality suitable for critical structural applications. Spiral welded pipes use strip steel as raw material, continuously forming and welding at a specific helix angle. This allows for the production of large-diameter steel pipes from narrower strip steel, with relatively lower equipment investment.
Weld quality control is crucial for ensuring the performance of welded pipes. Before welding, the edges of the steel plate need to be precisely machined to ensure that the bevel shape and size meet the process requirements. Welding parameters for high-frequency welded pipes, such as welding power, frequency, speed, and extrusion pressure, need precise control to ensure appropriate weld penetration and width, avoiding defects such as incomplete fusion, slag inclusions, or porosity. Submerged arc welding also requires strict management of welding materials, welding current, arc voltage, and welding speed to ensure good weld formation. Post-weld heat treatment can eliminate residual welding stress, improve the microstructure of the heat-affected zone, and enhance the weld's toughness and fatigue resistance. Non-destructive testing of the weld is an essential means of quality control. Ultrasonic testing is used to inspect internal weld defects, and X-ray inspection is used for imaging analysis of key areas to ensure that the weld quality meets standard requirements. For welded pipes used in pressure applications, a hydrostatic test is also required to verify overall strength.
Welded pipes have diverse applications in structural support, ranging from pipe trusses in building steel structures to arch ribs in bridges, from the tower bodies of power transmission towers to the booms of port machinery. Circular cross-sections possess the same moment of inertia in all directions, making them suitable for bearing multi-directional loads; square and rectangular cross-sections facilitate node connections and component arrangement, and are widely used in building structures. The internal cavities of steel pipe structures can be used for pipeline installation or filled with concrete, enabling multi-functional integrated designs. In large-space buildings such as stadiums and exhibition halls, steel pipe space frame structures cover vast spaces with their lightweight form, showcasing a perfect combination of structural aesthetics and mechanics. In municipal engineering, welded pipes are used for facilities such as streetlight poles, traffic sign poles, and guardrails, favored for their lightweight, aesthetic appeal, and durability. In the machinery manufacturing field, welded pipes are used to fabricate frames and supports for various equipment, meeting the requirements of different working conditions.
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