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Spiral steel pipe welding area common defects

Spiral welded pipe is a major transmission fluid welded steel pipe, spiral welded pipe production by a coil of width continuous molding welding is easy to implement production automation, and double-sided submerged arc welding automatic welding type, there are a variety of The testing method checks checks to ensure the quality of the welds, laying oil and gas pipelines, has been widely applied to the spiral welded pipe. But in forming the welding process, due to operational mistakes or process due to mature etc., lead to the the welded pipe produces a wide variety of defects.

Spiral steel pipe welding area common defects porosity, hot cracking and undercut.

  • bubbles. Bubbles occurred in the center of the weld bead, the main reason is that the hydrogen is still hidden in the form of bubbles within the weld metal, therefore, to eliminate this defect measures must first remove the wire and weld the rust, oil, water and moisture and other substances, and secondly they must be well dried flux removing moisture. In addition, an increased current, reducing the welding speed, and is also very effective to slow down the solidification rate of the molten metal.
  • sulfur bifida (sulfur caused cracks). Sulfur segregation with the sulfides into the weld metal when welding sulfur segregation with a strong plate (especially soft boiling steel) generated cracks. The reason is that the presence of hydrogen in a low melting point of iron sulfide and steel containing sulfur segregation band. So, in order to prevent the situation, to use sulfur segregation band semi-killed steel or killed steel Ming efficiency. Secondly, the weld surface clean and dry and flux is necessary.
  • hot cracking. In submerged arc welding, weld hot cracking prone to crack, particularly in the arcing and the arc-quenching at the crater. To eliminate such cracks, usually in arcing and arc-quenching at equipped with a pad, and when the plate roll to the end of welding, the reverse spiral welded and the welding feed stitch welding. Hot cracking in the weld stress big time, or weld metal si high when most prone.
  • welding slag involvement. Involved in the weld slag is the remaining part of the weld slag in the weld metal.
  • degrees poor penetration. The degree of overlap of the internal and external weld metal is not enough, and sometimes lack of penetration. This is called penetration degree.
  • undercut. The undercut is a V-shaped groove along the weld centerline at the edge of the weld. The undercut is generated in the case of improper welding speed, current, voltage, and other conditions. High welding speed than the current is not suitable for easier Undercuts.

ASTM A213 T11 Seamless alloy pipes
+ ASTM A335 alloy pipe
ASMT A333 Grade 6 seamless pipes
+ ASTM A333 Alloy pipe


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