Thick welds are:

Thick welds are typically done in multiple passes to ensure proper penetration and fusion of the materials being joined. When welding thicker materials, a single pass often does not provide enough heat or penetration for a strong joint. Therefore, multiple passes allow the welder to build up the weld gradually, ensuring that each layer properly melts into the base metal and achieves the necessary strength and integrity.

This approach is essential in preventing issues such as incomplete fusion or excessive heat input, which can lead to warping or structural weaknesses. While it is possible to have other configurations and practices in welding, the technique of utilizing multiple passes specifically addresses the challenges presented by thickness in the materials being welded, making it the most effective choice for thick welds.