Visual acceptance criteria for structural welds: AWS D1.1
AWS D1.1 sets specific visual acceptance criteria for groove and fillet welds. Here's how CWIs apply them on statically and cyclically loaded structures.
Visual inspection is the first and most common inspection method on a structural weld. It costs nothing beyond a calibrated gauge and a trained eye, and it catches the most common rejectable conditions before they're buried under subsequent passes or covered by coating. AWS D1.1 defines what passes and what fails — but the criteria are not uniform. They vary by structure type, weld type, and loading condition.
Why loading type changes the acceptance criteria
AWS D1.1 separates acceptance criteria for statically loaded and cyclically loaded structures. The underlying logic is mechanical: a surface discontinuity that has negligible effect on a statically loaded beam may act as a fatigue crack initiation site in a dynamically loaded connection.
CWIs on structural jobs should confirm at the pre-job meeting which acceptance criteria apply. Most building steel governed by AISC is treated as statically loaded. Bridge structures, crane runways, and offshore platforms typically invoke the cyclically loaded criteria, which are tighter.
This distinction drives decisions about which criteria the inspector applies when measuring undercut, evaluating weld profile, and accepting or rejecting surface porosity. Applying static criteria on a cyclic structure is not a conservative error — it's a code compliance failure.
Rule library based on AWS D1.1:2025; verify against your governing edition.
Cracks — no tolerance
No crack of any type is acceptable in a finished structural weld. This is one of the few absolute rules in the code, with no size threshold or loading-type variation. Rejectable cracks include:
Longitudinal cracks in the weld bead
Transverse cracks crossing the weld axis
Toe cracks at the weld-to-base-metal boundary
Root cracks in partial-penetration groove welds
Crater cracks at weld terminations
Crater cracks are a chronic problem on SMAW when the welder breaks the arc without filling the crater. The procedural fix: weld back into the crater, fill it, then break the arc on the filled bead. Any termination that shows cracking must be ground out and repaired before re-inspection.
Undercut
Undercut is a groove melted into the base metal or previously deposited weld metal that is not filled by weld metal. It concentrates stress at the weld toe — the most common fatigue initiation site in structural welds.
AWS D1.1 sets undercut limits based on loading type and weld orientation relative to the primary stress direction. For cyclically loaded structures, the permissible undercut depth is more restrictive than for statically loaded work. Weld orientation (parallel versus transverse to stress) also affects the applicable limit.
A CWI measuring undercut uses a V-WAC gauge or equivalent calibrated tool. Visual estimate is insufficient for accepting or rejecting a borderline case. Undercut that exceeds the applicable limit must be repaired by depositing additional weld metal and blending the toes smoothly into the base metal.
Porosity
Surface porosity appears as round pits on the weld face. AWS D1.1 limits cumulative surface porosity — not just individual pore size, but the sum of pore diameters in a defined weld length. Isolated small pores may be within limits while a cluster of the same-size pores over a short span is rejectable.
Common production causes:
Moisture in the electrode covering, flux, or base metal surface
Contamination (oil, paint, mill scale) left in the joint
Loss of shielding gas coverage from drafts or a nozzle held too far from the work
Inadequate pre-cleaning on coated or thermally cut surfaces
Surface porosity that exceeds code limits must be repaired. Grinding out the pores and re-welding is acceptable if the rewelded area meets criteria. Subsurface porosity requires volumetric testing — radiographic or ultrasonic — to characterize.
Groove weld profile
Acceptance criteria for complete-joint-penetration (CJP) groove welds cover both the weld face and, where accessible, the weld root:
Weld face reinforcement: must not exceed the code limit for the applicable thickness range. Excessive reinforcement creates an abrupt profile transition that concentrates stress at the weld toes.
Root pass: on accessible roots (two-sided welds, backgouged roots), excessive root reinforcement or melt-through has code-specific limits.
Weld toe geometry: abrupt transitions — high crowns that drop sharply to the base metal, or weld beads with irregular starts and stops — are workmanship issues that may require grinding even when dimensional limits are met.
For partial-joint-penetration (PJP) groove welds, the effective throat must meet the minimum specified on the WPS and drawing. PJP welds are acceptable with incomplete penetration by design, but the throat is not negotiable.
Fillet weld profile
Fillet weld acceptance criteria cover four main conditions:
Throat size: must equal or exceed the minimum specified. Use a fillet weld gauge — not visual estimate — for acceptance decisions.
Concavity: a concave fillet may have an effective throat below the specified minimum. Measure the theoretical throat from the root to the lowest point on the weld face.
Convexity: excessive convexity (a raised, rounded bead cross-section) concentrates stress at the weld toes and is rejectable beyond code limits.
Overlap: weld metal that rolls over the base metal surface without fusion is a cold lap condition — rejectable regardless of loading type.
Fillet weld length must meet the specified weld length after accounting for starts and stops. A weld called out as 6 in that ends up as three 2-in runs with gaps is not equivalent.
Incomplete fusion
Incomplete fusion — weld metal that failed to bond to the base metal or the preceding pass — is rejectable under all loading conditions. At the surface it appears as a linear seam or cold lap along the weld toe. Subsurface incomplete fusion is not detectable by visual inspection; it requires ultrasonic or radiographic testing.
A WPS that specifies correct preheat, interpass temperature, and travel speed reduces the risk of incomplete fusion. When visual inspection identifies surface incomplete fusion, the weld must be repaired before the joint is accepted. The repair WPS should be the same qualified WPS used for the original weld or a qualified repair WPS.
The inspection record
AWS D1.1 requires that inspection results be documented. A visual inspection record should include:
Weld identification referenced to the weld map or drawing
Inspection date and inspector certification number
Applicable acceptance criteria (statically vs. cyclically loaded)
Any rejection, the specific basis for rejection, and the weld location
Repair disposition, the repair WPS used, and the re-inspection result
Shops that manage NDE records alongside visual inspection reports in a single retrievable audit packet reduce re-inspection requests and audit exposure significantly. See pricing for how WPS software handles inspection documentation.
FAQ
Frequently asked.
Where are the visual acceptance criteria in AWS D1.1:2025?
Visual inspection acceptance criteria are in the Inspection section of the code. Criteria differ for statically loaded versus cyclically loaded structures and for groove welds versus fillet welds. Always work from the edition referenced by your contract or AHJ, and verify clause references directly — the 2025 edition renumbered several sections from 2020.
Is any amount of undercut rejectable, or is there a defined limit?
AWS D1.1 allows undercut up to specified limits that depend on loading type and weld orientation relative to applied stress. The limit for cyclically loaded members is more restrictive than for statically loaded structures. A CWI measuring undercut uses a calibrated weld gauge — visual estimate alone is insufficient for borderline cases.
Can a welder grind a rejected area and present it for re-inspection?
Yes. Grinding to remove surface discontinuities is a permitted repair method. The repaired area must be re-inspected and meet acceptance criteria. Document the original rejection, the corrective action taken, and the re-inspection result — all three entries belong in the inspection record.
Do visual acceptance criteria apply to tack welds?
Tack welds that will be incorporated into the final weld are subject to inspection requirements under AWS D1.1. Cracked tack welds must be removed. Tack welds that will be completely remelted by the final pass are typically held to less stringent visual standards, but the fabrication section of the code governs — not assumption.