Final answer:
The joint that uses equally spaced tack welds to prevent the edges from being drawn together during the welding process is known as a tack weld joint. These welds are critical for maintaining alignment and spacing between components to avoid deformation due to thermal expansion.
Step-by-step explanation:
The joint that uses equally spaced tack welds to prevent the edges from being drawn together is known as a tack weld joint in the field of welding. Tack welds are small welds used to hold components in place until the final weld is completed. Their purpose is to ensure proper alignment and spacing during the welding process. By using them at regular intervals, the welder can mitigate the effects of heat, which can cause the metal to warp or the edges to move closer together, resulting in an uneven or deficient joint.
The phenomenon described by Beth, where the columns on the edges are slightly closer to one another than the columns in the center of each side, can be related to the thermal expansion that occurs during welding. As the metal heats and cools, it can expand and contract, leading to movement if not properly controlled. Tack welds serve to counteract this movement by fixing the pieces in position across the span of the material being joined.