A structural fabrication shop completed beam-to-column connections for a mezzanine addition on an industrial building. The inspector evaluated 12 CJP groove welds on W14×53 members, statically loaded. Weld W7 was rejected for undercut at the root toe: depth measured at 3/64″ (0.047″), exceeding the statically loaded limit of 1/32″ (0.031″) for material ≤1″ thick. The contractor ground the toe, applied a repair pass, and re-inspection confirmed acceptance.
Frequently Asked Questions
What is undercut and why did it cause a rejection?
Undercut is a groove melted into the base metal at the weld toe. AWS D1.1 Cl. 6.9.6 limits undercut depth to 1/32" for material 1" thick or less on statically loaded structures. Weld W7 measured 3/64" — about 50% over the limit. The correction is to grind the undercut area and apply a fill pass to restore the base metal profile, then re-inspect.
How is undercut depth measured?
Undercut is measured perpendicular to the base metal surface using calibrated bridge cam gauges or an undercut gauge. Depth is compared against the Table 6.1 limit for the applicable service category and material thickness.
When can a rejected weld be re-inspected?
After corrective action is completed per AWS D1.1 Cl. 5.25 (repair welding) or grinding to remove the rejectable condition. The CWI must re-inspect and accept the weld before final sign-off.