A second pass in welding should not be done if what condition exists?

Performing a second pass in welding without removing the slag from the first pass can lead to several negative consequences, making it essential to address this condition before proceeding. Slag is a byproduct of the welding process that can encapsulate impurities, which might prevent proper fusion of the second pass to the weld metal. If slag is present, it can create weak spots in the weld, reducing the strength and integrity of the final joint. Moreover, not removing the slag can lead to issues such as poor penetration and the formation of inclusions, which can compromise the quality of the weld.

It is critical in welding practice to ensure that each layer is adequately prepared before additional passes, improving the overall quality and performance of the weld. So, addressing slag removal is a fundamental step in ensuring that the welding process leads to strong and reliable joints.