Structural Welding Guide

Structural welding builds the steel skeleton that holds up buildings, bridges, equipment, and infrastructure. AWS D1.1 (Structural Welding Code, Steel) governs the process from joint design through final inspection. Working under code means every weld has documented procedures, qualified welders, and inspection requirements.

The code uses prequalified joint details for common configurations. A prequalified joint (like a single-V groove with 60-degree included angle, 1/4 inch root opening, and backing bar) can be used without separate procedure qualification testing. Non-prequalified joints require a PQR (Procedure Qualification Record) with destructive testing to prove the joint works.

A WPS (Welding Procedure Specification) documents every parameter for a specific joint: process, filler metal classification, shielding gas, preheat, interpass temperature, amperage range, voltage range, travel speed, and position. Welders follow the WPS for every structural weld. Deviating from the WPS means the weld doesn’t meet code.

Welder qualification tests prove the individual can produce acceptable welds per the WPS. The test coupon (plate or pipe, depending on the production work) gets a visual inspection, then destructive testing: guided bend tests for groove welds, macro etch for fillet welds. A 3G/4G plate qualification covers all plate positions. A 6G pipe qualification covers all pipe and plate positions.

Inspection criteria in D1.1 set specific limits for defects. Visual inspection checks for undercut (max 1/32 inch), porosity, cracks (zero tolerance), incomplete fusion, and proper profile. More critical connections require NDT (non-destructive testing) per the engineer’s specifications.

Common structural welds include fillet welds on beam connections, CJP (complete joint penetration) groove welds on moment connections, and PJP (partial joint penetration) groove welds on columns. The guides below cover prequalified joint details, WPS development, and practical test preparation.