Spiral welded steel
pipe pile defective area prone to porosity, thermal cracking and weakening. Spiral steel pipe pile weld porosity affects not only dense, leading to leakage and corrosion of the pipeline will be called point seriously reduce the weld strength and toughness. Weld porosity factors: water, dust, oxidation and iron filings, welding ingredients and cover thickness, surface quality and plate steel, welded steel casting process flow.
Flux components. The CaF 2 and SiO 2, which contains a suitable amount of solder, the reaction will absorb a lot of H 2, HF High stable insoluble in the liquid metal, thereby preventing the formation of bubbles of hydrogen gas holes. Bubbles occur in the weld center, the main reason is still hidden in the weld metal in the form of hydrogen bubbles inside, so measures to eliminate such defects must be cleared wires and welding rust, oil, water and moisture and other substances, and the flow should be sufficiently dried to remove moisture. In addition, to increase the current, lower welding speed, slowing down the solidification rate of molten metal is also effective.
The thickness of the mass flow, usually, 25-45mm, large solder particle size, pipe pile bulk density withstand the maximum thickness h, while the minimum value, high current, low welding rate savings to withstand the maximum thickness and the minimum value of the adder or summer air humidity, the magnetic flux recovery should be dried before use. Sulfur cause cracking, welding sulfur segregation with a strong board (especially soft boiling steel) sulfide sulfur segregation zone in the weld metal derived cracks. The reason for this is the presence of hydrogen sulfide-containing steel of sulfur segregation with a low melting point. Therefore, to prevent this generates, uses less sulfur segregation band semi-killed or killed invention is also effective. Then clean the welding and soldering of surface and drying is also very necessary.
Steel Surface treatment: Avoid decoiling flat scale and other contaminants when making decisions, the Board must install purification device. Hot crack. In arc welding, can produce cracks in the crater during welding thermal cracking, particularly arc suppression and prone. To resolve this crack, usually in the arc extinguishing plate and equipment and welding the coil end can reverse spiral welded steel pipe welds. Thermal cracking surfacing in stressful times, or at the most vulnerable to high weld metal B.
Steel edge treatment: Steel must be installed on the end plate rust and burr removal device to reduce the possibility of generating holes. Removing means mounted milling plate sheared better location, the structure of the device is active rolls down the gap on the two upper clamping plate and the lower edge of the position adjustment. Participation waste. Participation in the weld metal slag remaining slag.
Weld: weld forming factor is too small, narrow and deep seams to form a gas leak include difficult to easily form pores and slag. Weld than the overall control of 1.3-1.5, thick-walled spiral pipe maximum thin-walled minimum. Penetration is poor. Internal and external weld metal is not enough overlap, and sometimes a lack of penetration. It is the lack of penetration.