Spiral steel pipes are made by bending strip steel in a spiral direction using a coiling machine, followed by capacitive double-sided submerged arc welding. During the production process of spiral steel pipe welding, issues such as incomplete welds and misaligned edges are common. However, the most difficult issue to control is the appearance of pinholes at the butt welds of spiral steel pipes.


Spiral submerged arc welded steel pipe manufacturers analyze the causes of pinholes as follows:


1. Insufficient current supplied to the welding torch and too short a capacitance time during welding. The weld surface hardens before the capacitance is fully penetrated, resulting in unpenetrated sand particles or air bubbles inside.


2. Improper alignment of the strip steel when entering the bending section, resulting in an excessively large gap between the strip steel sections.


3. Failure to promptly clean rust or oxide scale from both sides of the strip steel during butt welding.


4. Lack of timely maintenance and upkeep of production equipment. Dust or dirt on the workbench may accidentally fall into the welding seam of the steel strips.


5. Low or excessively humid temperatures in the work area can affect the temperature and dryness of the welding point.