Final answer:
The edge preparation for butt joints on metals over a certain thickness is necessary.
Step-by-step explanation:
The edge preparation for butt joints on metals is only required on metals over a certain thickness. This is because thicker metals require a greater degree of beveling or chamfering to ensure proper weld penetration and a strong joint.
The specific thickness at which edge preparation becomes necessary can vary depending on several factors, such as the type of metal being used and the welding process being employed. However, as a general guideline, edge preparation is typically required on metals that are around ½ inch thick or more.
For example, if you are welding two pieces of steel together and each piece is ¾ inch thick, you would need to properly bevel the edges before welding to ensure a strong, high-quality joint.