Open welding can be caused by several factors. Some of the most common causes may be:
Incorrect nitrogen injector setting: It is important to check the nitrogen injector setting to ensure that the correct amount is being injected.
Lack of nitrogen or insufficient flow: If there is insufficient nitrogen or insufficient flow, the weld may not form properly.
Welding too hot: If the welding current is too high, it can cause the weld to open.

Insufficient current: Low welding current can result in a cold weld, which can lead to an open weld.
Poor geometry of the welding rollers: If the welding rollers are not aligned correctly, this can result in an open weld.
These are just some of the possible causes, and the solution may vary depending on the specific problem.