Is overlap a dimensional fault or a structural fault?

Overlap is classified as a structural fault in welding. This defect occurs when the weld metal spreads over the parent metal but fails to penetrate into the base materials. Because of this lack of proper fusion, the integrity of the weld and the overall structure can be compromised. Overlap can lead to weak points in the joint that are susceptible to failure under stress or load, thus affecting the structural integrity and performance of the welded assembly.

While dimensional faults typically involve issues related to the geometry and measurements of the weld or its components, overlap directly impacts how the materials interact with each other and their ability to support loads. This distinction is crucial in welding practices and inspections, as it helps in assessing the quality of a weld and predicting its performance in service. In essence, overlap does not merely alter the dimensions; it fundamentally affects the structural properties of the weld, making it a concern for safety and effectiveness in welded applications.