What is the typical sequence of passes for a GTAW butt weld on steel, from root to cover?

What is the typical sequence of passes for a GTAW butt weld on steel, from root to cover?

• A. Root pass to ensure fusion; multiple fill passes; final cover pass
• B. Root pass; final cover pass; multiple fill passes; verify toe fusion and flush
• C. Multiple fill passes; root pass; cover pass
• D. Root pass; cover pass; fill passes

Answer: (A)

In GTAW butt welds on steel, you begin with a root pass to establish proper fusion at the joint and to secure a sound root bead. This first pass ensures the weld penetrates to form a solid root and helps you verify fit-up and alignment. Next come the fill passes. These adds layers of weld metal to build up the joint to the required height. Using multiple fill passes helps manage heat input, control distortion, and reduce the risk of burn-through on thin sections while achieving the desired weld thickness and profile. The final pass is a cover (or cap) pass. This last layer smooths and brings the weld to its final contour, provides a uniform top surface, and helps ensure full joint fill and a good appearance. It also can improve corrosion resistance at the weld and helps seal any surface irregularities. So the typical sequence is root pass first, followed by one or more fill passes, and finished with a cover pass.

In GTAW butt welds on steel, you begin with a root pass to establish proper fusion at the joint and to secure a sound root bead. This first pass ensures the weld penetrates to form a solid root and helps you verify fit-up and alignment.

Next come the fill passes. These adds layers of weld metal to build up the joint to the required height. Using multiple fill passes helps manage heat input, control distortion, and reduce the risk of burn-through on thin sections while achieving the desired weld thickness and profile.

The final pass is a cover (or cap) pass. This last layer smooths and brings the weld to its final contour, provides a uniform top surface, and helps ensure full joint fill and a good appearance. It also can improve corrosion resistance at the weld and helps seal any surface irregularities.

So the typical sequence is root pass first, followed by one or more fill passes, and finished with a cover pass.