What is the typical order of passes in GTAW pipe welding?

• A. Root pass, hot pass, filler pass, cover pass
• B. Root pass, filler pass, hot pass, cover pass
• C. Hot pass, root pass, filler pass, cover pass
• D. Filler pass, root pass, hot pass, cover pass

Answer: (A)

In GTAW pipe welding, the sequence of passes is chosen to establish a solid root, control heat input, and build up to the final surface with proper contour. The root pass is laid first to penetrate into the joint and create a sound foundation with minimal filler, ensuring the weld begins with a good, penetrating root. A hot pass comes next to fuse the root and help push the weld toward full penetration along the seam, while avoiding excessive filler deposition at this stage. After the root and hot passes, filler passes are added to build up the weld metal to the required thickness and strength, shaping the weld profile as needed. The final cover pass is then deposited to produce a smooth, flush surface and complete the cap, protecting the weld and achieving the desired contour. This root–hot–filler–cover order is the standard approach for balancing penetration, material deposition, and surface finish in pipe GTAW welding.