SSAW Steel Pipe Weld Defect and Detection

Because SSAW pipe can be continuously formed by the coil width of the welding production, easy to automate the use of double-sided submerged arc welding, there are a variety of test methods to check the quality inspection of the weld. Therefore, the laying of pipelines, spiral welded pipe has been widely used. However, during the forming process, various pipe defects are generated due to process errors or due to other reasons that cause the operation to mature.


Lack of integration
There is no weld between the base metal and the base metal, not the space left by arc melting, which is usually a double-sided spiral welded pipe produced in the middle of the weld. Due to the use of double-sided spiral submerged arc welded pipe, it is not the reason for automatic welding penetration joints, it is too small for the gap, the welding current is too small and the welding speed too fast, or improper welding wire arc is due to partial local blowing Cracked and caused.


Stomata and slag inclusion
The stomata in the bath absorb a large amount of hot gas, whereas the cooling gas drops sharply in the molten metal and the residual gas escapes too late, which is formed in the weld metal. Pores can be divided into isolated pores, pore densities, porosities, and wormhole chains, and there are generally several factors that contribute to the genesis of the pores in the gas welding process. The formation of pores in the weld is mainly hydrogen and carbon monoxide, of which the ray intensity attenuation tends to zero, therefore, black holes appear larger than the background image patchy blackness, blackness is generally larger, the image is clear, easy to identify.


crack
Cracks are bad for severe weld defects and common defects in welds. Welding cracks caused by stress brittleness and other factors together, the bonding strength of the metal atom welded joint local damage, the formation of a new interface (gap). According to its causes can be divided into thermal cracking, cold cracking, reheating cracks, layered tearing, stress corrosion cracking. Spiral welded pipe is generally high-quality carbon steel and low alloy steel materials, welding and heat treatment is no longer carried out, so most of the hot cracking and cold cracking.