What is used to depict internal features on a drawing?

Hidden lines are utilized in technical drawings to indicate features that are not directly visible due to obstruction by other components. When creating a welding print or any engineering drawing, a hidden line typically consists of a dashed line representing edges or surfaces that lie behind or within another object. This is particularly important in depicting internal features, such as holes, slots, or interior parts of a weldment, allowing the viewer to understand the complete structure without requiring a separate view.

In contrast, visible lines are used to show edges that can be seen directly, dimension lines convey measurements, and center lines indicate the axes of symmetrical features. Each of these has specific roles in a drawing, but none fulfill the purpose of clearly demonstrating internal features as effectively as hidden lines do. Therefore, the use of hidden lines is crucial for providing clarity in complex designs where internal details need to be understood for accurate fabrication and assembly.