Modern welding techniques have been able to weld welds with no internal or external defects and mechanical properties equal to or higher than those of the connected bodies. The mutual position of the welded body in the space is called a welded joint. The strength at the joint is not only affected by the quality of the weld but also related to its geometry, dimensions, stress conditions and working conditions. The basic forms of joints are butt joints, lap joints, T-joints (cross joints) and corner joints.