Weld Cracks and Repair Causes of LSAW Steel Pipe

In the pipeline installation and construction, often encounter the phenomenon of weld cracks, if not timely detection and repair, there is a serious risk, particularly the transportation of flammable, explosive and toxic media pipeline, the danger is very serious of. This requires the construction unit, in construction of lsaw steel pipe, welding quality must not be ignored.

Cracks in the welding operation encountered are varied. Sometimes the distribution of crack in the weld, sometimes located in the heat affected zone; sometimes appears on the surface of the weld, the weld may appear inside; sometimes you can see the macro, it is sometimes necessary to see under a microscope; transverse cracks, longitudinal cracks; sometimes breaking arc in place a so-called crater cracks; immediately after welding has occurred, but also take some time to appear (the so-called delayed cracking), there is a sudden cooling in the winter when the cracks, so-called embrittlement . Despite the variety of types of cracks, but the nature of the crack, the often encountered are as follows: hot cracking: at high temperatures generated, and all along the austenite grain boundary cracking, its main form of crystalline crack . That weld during crystallization, in the vicinity of the solidus solidification shrinkage due to the metal, liquid film between grains not subjected to tensile stress, so that the cracking along the grain boundaries. Cold crack: That is in the vicinity of martensitic transformation temperature at a relatively low temperature of about 200e ~ 300 degrees Celsius, due to stress, hardened tissue and hydrogen bound cracks welded joints produced guilty of cold cracking.