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: The weld is made on the underside of a horizontal surface where two pieces of metal meet at a right angle (T-joint or lap joint).

This article provides a full, deep dive into the 4F welding position—covering its definition, techniques for different processes (SMAW, GMAW, FCAW), common defects, troubleshooting, and certification tips.

In all cases, the , but the weld face is below the welder (overhead).

The is a specialized designation for an overhead fillet weld . In this configuration, the welder works from underneath the joint, depositing weld metal onto the underside of a horizontal surface and against a vertical surface. Because gravity pulls the molten metal away from the joint, 4F is widely considered one of the most difficult and technical positions to master. Core Definition and Standards