AWS D1.1 Acceptance Criteria: Visual, UT and RT Limits
AWS D1.1 acceptance criteria in one place: undercut, porosity and profile limits for visual inspection, UT and RT criteria, and static vs cyclic loading.
AWS D1.1/D1.1M, Structural Welding Code — Steel, sets its weld acceptance criteria in Clause 8, Inspection. Three things decide which limit applies to a weld: the examination method, whether the connection is statically or cyclically loaded, and whether it is tubular or nontubular. Cracks are the one constant: the code rejects them at any size, in any location, under every loading case.
Choosing the volumetric method in the first place is covered in our RT vs UT comparison.
Which edition your procedure cites
AWS renumbered the code in the 2020 edition. Inspection moved from Clause 6 to Clause 8, so the visual criteria moved from Table 6.1 to Table 8.1 and the ultrasonic acceptance tables from Table 6.2 and 6.3 to Table 8.2 and 8.3. A procedure or inspection test plan that still cites Clause 6 was written against the 2015 or an earlier edition. The current edition is D1.1/D1.1M:2025, which revised the 2020 edition and updated the Table 8.1 visual criteria for undercut and piping porosity, so confirm the edition named in the contract documents before you accept or reject a weld against the limits below.
Visual acceptance criteria (Table 8.1)
Visual inspection is the only method D1.1 requires on every weld. The limits below summarise Table 8.1 for nontubular connections as published in the 2020 edition; tubular connections carry their own criteria, and the contract documents may set tighter limits, which they often do on fracture-critical work.
| Discontinuity | Statically loaded | Cyclically loaded |
|---|---|---|
| Cracks | Rejected at any size and location | Rejected at any size and location |
| Weld and base-metal fusion | Complete fusion required | Complete fusion required |
| Crater cross section | Craters filled to the full weld cross section, except at the ends of intermittent fillet welds outside their effective length | Craters filled to the full weld cross section |
| Undercut, base metal under 1 in. thick | 1/32 in. maximum, with 1/16 in. allowed for an accumulated 2 in. in any 12 in. of weld | 0.01 in. maximum where the weld is transverse to tensile stress; 1/32 in. in all other cases |
| Undercut, base metal 1 in. and thicker | 1/16 in. maximum for any length of weld | Same as above: the limit follows the stress direction, not the thickness |
| Piping porosity, complete-joint-penetration butt weld transverse to computed tensile stress | No visible piping porosity | No visible piping porosity |
| Piping porosity, other groove welds and fillet welds | Sum of diameters of 1/32 in. and larger not over 3/8 in. in any linear inch, and not over 3/4 in. in any 12 in. of weld | Not more than one in each 4 in. of weld length, maximum diameter 3/32 in. |
| Undersized fillet weld | Underrun of 1/16 in. for a nominal size of 3/16 in. or less, 3/32 in. for 1/4 in., and 1/8 in. for 5/16 in. or more, over no more than 10% of the weld length; none at the ends of girder web-to-flange welds for a length of twice the flange width | Underrun of 1/16 in. for a nominal size of 3/16 in. or less, 3/32 in. for 1/4 in., and 1/8 in. for 5/16 in. or more, over no more than 10% of the weld length; none at the ends of girder web-to-flange welds for a length of twice the flange width |
Magnetic particle and penetrant testing
D1.1 does not require MT or PT on its own account. When the contract documents call for them, the indications they reveal are judged against the visual acceptance criteria for the loading case, so a surface crack found by MT is rejected exactly as a visible crack would be. The 2025 edition added definitions that split MT and PT indications into linear and rounded.
Ultrasonic acceptance criteria (Tables 8.2 and 8.3)
D1.1 does not size an ultrasonic indication. It rates it in decibels: the indication rating d equals the indication level a minus the reference level b minus an attenuation factor c, which allows two decibels per inch of sound path beyond the first inch. The rating is read against weld thickness and probe angle to place the indication in a severity class from A to D, with Table 8.2 covering statically loaded and Table 8.3 cyclically loaded nontubular connections. The criteria apply to complete-joint-penetration groove welds from 5/16 in. through 8 in. thick. Material outside that band, tubular T-, Y- and K-connections, and other joint types need the tubular provisions or an alternative technique qualified by demonstration and approved by the Engineer. A worked explanation of the rating is in our guide to D1.1 ultrasonic acceptance criteria.
Radiographic acceptance criteria
Radiography has its own part of Clause 8. Its acceptance criteria are drawn as figures that show the permitted size of an elongated discontinuity against weld thickness, together with rules on the sum of discontinuity dimensions in a length of weld and the minimum clearance between neighbouring discontinuities and to the edge of the weld. As with the other methods, the statically loaded, cyclically loaded and tubular cases are judged separately, and cracks are rejected outright. Read the figure for the loading case of the joint in front of you rather than a summary value.
What the code does not decide
D1.1 sets how a weld is judged, not how much NDT a structure receives. Ultrasonic, radiographic, magnetic particle and penetrant testing apply only when the contract documents call for them; the drawings and project specification, or the building code that invokes D1.1, set the extent. Once NDT is called for, D1.1 supplies both the procedure requirements and the acceptance criteria.
Scope: when D1.1 is the right code
D1.1 covers carbon and low-alloy structural steel 1/8 in. and thicker. Thinner sheet steel falls under AWS D1.3, stainless steel under D1.6, aluminum under D1.2, reinforcing steel under D1.4, and highway bridges under AASHTO/AWS D1.5. Pressure vessels and process piping follow ASME rules instead; our comparison of AWS and ASME weld acceptance criteria covers where the two differ.
Who inspects and who performs the NDT
D1.1 recognises three routes for the inspector: current or previous certification as an AWS Certified Welding Inspector under AWS QC1, current or previous certification as a welding inspector under the Canadian Welding Bureau scheme to CSA W178.2, or an engineer or technician whose training and experience the Engineer accepts. Personnel who perform the NDT are qualified separately, under ASNT SNT-TC-1A, and the 2025 edition rewrote how that NDT personnel certification is established.
Need D1.1 welds examined or a UT procedure approved?
For weld inspection, first establish the construction code, edition, permitted examination technique and acceptance criteria. TOFD is not automatically interchangeable with conventional UT acceptance tables. Our ASNT Level III consulting supports procedure review and qualification for the agreed scope.
Frequently asked questions
Q1: Are cracks ever acceptable under AWS D1.1?
No. Cracks are rejected at any size and in any location, for statically and cyclically loaded connections alike. The crack is removed, the joint repaired to a qualified procedure and the repair examined again by the same method.
Q2: Why does the undercut limit change with loading?
Undercut is a notch at the weld toe, and under cyclic loading a notch transverse to the stress is where fatigue cracks start. That is why cyclically loaded members allow only 0.01 in. where the weld is transverse to tensile stress, while statically loaded members are judged mainly on base-metal thickness.
Q3: Does AWS D1.1 require ultrasonic or radiographic testing?
No. Visual inspection is required on all welds; UT, RT, MT and PT apply only when the contract documents call for them. Once they are called for, the code supplies the procedure requirements and the acceptance criteria.
Q4: What weld thickness range do the D1.1 ultrasonic criteria cover?
Complete-joint-penetration groove welds from 5/16 in. through 8 in. thick. Outside that band, and for tubular T-, Y- and K-connections, the tubular provisions or a technique qualified by demonstration and approved by the Engineer apply.
Q5: Why do older procedures cite Table 6.1 instead of Table 8.1?
The 2020 edition moved inspection from Clause 6 to Clause 8. The technical content largely carried over; the numbering did not. A procedure still citing Clause 6 was written against the 2015 or an earlier edition and should be checked against the edition the contract invokes.
Keeping the weld quality record defensible
WPS, PQR and welder qualification continuity, NDT results tied to specific joints, and material traceability by heat number are what a fabrication audit actually examines. ERP for welding and fabrication shops and inspection management software cover holding that record as structured data rather than attached PDFs.