Welding fabrication joins metal components through fusion processes, creating pressure vessels, piping systems, structural assemblies, and process equipment. Welding quality directly determines fabricated equipment integrity, making qualified procedures, skilled welders, and rigorous quality control essential.

Fabrication welding encompasses diverse processes: SMAW (stick) for versatility and field capability, GMAW (MIG) for productivity on production welding, GTAW (TIG) for quality root passes and exotic materials, FCAW for high deposition rates, SAW for automated high-quality production, and specialized processes for specific applications.

For pressure vessel fabrication, welding typically involves tacking components for alignment, root pass welding establishing weld foundation (often TIG for quality), fill passes building weld thickness (often MIG or FCAW for productivity), cap passes providing acceptable surface (sometimes TIG for appearance), and post-weld heat treatment when required for code or service.

Welding quality requirements for code fabrication include qualified welding procedures per ASME Section IX, certified welders qualified for required processes and positions, documented welding parameters, systematic inspection and NDE, and comprehensive documentation. Quality programs demonstrate consistent compliance.

Welding challenges in fabrication include diverse materials requiring specific procedures, thick sections demanding multiple passes, position restrictions in complex assemblies, distortion control maintaining tolerances, and schedule pressure requiring productivity without quality compromise. Proper planning, procedures, and workforce capabilities overcome challenges.