What are resistance welded pipes?
Resistance welded pipes are a process of welding metal strips into pipes through resistance heating and pressure. During welding, the current passes through the metal contact surface to generate heat, causing the material to partially melt, and then forms a weld by extrusion. This method is efficient, energy-saving, and suitable for mass production. Common resistance welded pipes include straight seam welded pipes and spiral welded pipes. This technology is widely used in the manufacture of oil and natural gas pipelines.
What is the working principle of resistance welded pipes?
Resistance welded pipes use the resistance heat effect when current passes through metal for welding. When the metal strip passes through the electrode, the high current generates high temperature on the contact surface, causing the material to reach a molten state. Subsequently, the extrusion roller applies pressure to combine the molten metal to form a strong weld. The entire process requires precise control of current, pressure, and speed. This welding method does not require filler materials and has a high weld quality.
What are the main advantages of resistance welded pipes?
Resistance welded pipes have high production efficiency and are suitable for continuous large-scale manufacturing. Its weld strength is close to that of the parent material, with good sealing, and is suitable for high-pressure pipelines. Compared with other welding methods, resistance welding has lower energy consumption and more cost advantages. In addition, the process can produce pipes of different diameters and wall thicknesses, and has strong adaptability. The welding process is highly automated and has stable quality.
What is the difference between resistance welded pipes and submerged arc welded pipes?
Resistance welded pipes use resistance heating, which has a fast welding speed and is suitable for thin-walled pipes; submerged arc welding uses arc heating and is suitable for thick-walled pipes. Resistance welding does not require flux, while submerged arc welding requires flux to protect the weld. The weld of resistance welding is narrow and the heat-affected zone is small; the weld of submerged arc welding is wider, but the penetration is greater. Both are used in fields such as petroleum and construction.
What are the common defects of resistance welded pipes?
Resistance welded pipes may have defects such as incomplete penetration, pores, and slag inclusions. Incomplete penetration is usually caused by insufficient current or pressure, which affects the strength of the weld. Porosity is formed when the gas is not completely discharged during welding. Slag inclusions are caused by impurities on the metal surface that have not been cleaned up. In addition, the weld may have cracks or misaligned edges, and quality control is required through inspection methods.
