Mastering 4F welding requires a combination of strict arc length control, proper electrode angles, and, usually, a multi-pass approach. 1. Body Position and Comfort
| Defect | Appearance | Root Cause | Solution | | :--- | :--- | :--- | :--- | | | A groove melted into the vertical plate just above the weld toe. | Welding too hot; pausing too long on the vertical plate; wrong angle. | Reduce amperage. Tighten the weave. Pause less on the vertical side. | | Lack of Fusion | The weld metal doesn't bond to the vertical plate. | Too cold; moving too fast; poor technique. | Increase heat. Slow down. Ensure you are washing the puddle into the vertical plate. | | Convex (Ropy) Weld | The weld bulges outward like a rope. | Travel speed too slow; amperage too low. | Increase amperage or move faster. Pause on the sides to flatten the center. | | Slag Inclusion | Slag trapped inside the weld (SMAW/FCAW). | Not cleaning between passes; weaving too wide; welding over slag. | Grind every pass. Keep weave width under 3x electrode diameter. | | Overlap | Weld metal rolls over the base metal without fusing. | Too cold; improper angle (pointing down instead of into the corner). | Increase heat. Adjust electrode angle to 45° into the corner. |
Keep arc focused strictly at the 45-degree intersection line. Safety and Personal Protective Equipment (PPE) 4f welding position full
In this position, the welder works from the underside of a joint, facing upward toward the ceiling or overhead structure. The letter designates a fillet weld, which is used to join two pieces of metal perpendicular or nearly perpendicular to each other, creating a T-joint, lap joint, or corner joint.
The weld axis is horizontal, but the welding is performed from the underside. Mastering 4F welding requires a combination of strict
In the world of welding, standardization is key to quality and safety. The American Welding Society (AWS) and the ISO (International Organization for Standardization) have developed a numerical system to classify welding positions. Among these, the stands out as one of the most challenging yet common positions welders face on the job site.
Unlike the flat (1F) or horizontal (2F) positions, gravity is actively working against you in 4F. Molten metal wants to drip downward. Controlling the weld pool requires skill, proper technique, and the right machine settings. | Welding too hot; pausing too long on
The weld is performed on a T-joint, lap joint, or corner joint where the weld axis is horizontal and the weld is deposited from the underside of the joint.
When welding a fillet weld on a vertical plate (commonly mistaken as 4F), you have two choices: traveling upward or traveling downward. The choice depends on the welding process, material thickness, and desired penetration.