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Common Defects in Welding Area of ​​Spiral Welded Steel Pipe

Sources: this site    Click:    Date: 2017-5-10 1:50:49

Spiral welded steel pipe welding area of ​​the common defects are usually buried in the arc welding area prone to defects such as pores, hot cracks, and undercut.

1.bubble. Bubble occurred in the middle of the weld pipe of the welded steel pipe, the main reason is that hydrogen is still in the form of bubbles hidden in the weld metal inside, so the elimination of this defect is the first step must be removed welding wire and weld rust, oil, water And moisture and other substances, followed by the need to dry the flux to remove moisture. In addition, it is necessary to increase the current, reduce the welding speed and slow down the solidification rate of the molten metal. In addition to this defect, it is necessary to remove the rust, oil, moisture and moisture of the welding wire and weld, Heat the flux well to remove moisture. In addition, to increase the current, reduce the welding speed, slow down the melting rate of molten metal is also very effective.

2. Sulfur (sulfur-induced crack). A crack in the sulfur segregation zone in the weld segregated zone, especially in soft boiled steel. The reason for this is that there is hydrogen present in the sulfur segregation zone containing low melting point iron and steel. Therefore, in order to prevent this situation, the use of sulfur segregation with less semi-killed steel or sedative steel is also effective. Second, the steel pipe weld surface and flux cleaning and drying is also very necessary.

3.Hot crack. In submerged arc welding, hot cracks can be generated in the weld bead, especially in arcs and arcs. In order to eliminate such cracks, usually in the arc and arc at the installation of the plate, and the end of the coil at the end of welding, the spiral welded pipe can be reversed welding welding. Thermal cracking is most likely to occur when the weld stress is high, or when the weld within the weld metal is very high.

4. The slag is involved. Involved in the welding slag is in the weld metal remnants of part of the slag.

5. Poor penetration. Inside and outside the weld metal overlap is not enough, sometimes not penetration. This situation is called insufficient penetration.

6. Undercut The undercut is a V-shaped groove along the edge of the weld along the weld centerline of the welded steel pipe. The undercut is generated when the welding speed, current, voltage and other conditions are not appropriate. Where the steel pipe welding speed is too high than the current is not suitable for more likely to cause undercut defects.