Stud welding — specifically drawn-arc stud welding — accounts for tens of thousands of shear connector welds on every major structural steel project. It is fast, largely automated, and frequently overlooked in procedure qualification packages. AWS D1.1:2025 Clause 7 fills that gap with qualification requirements, production controls, and acceptance criteria that are separate from the groove and fillet weld procedures covered in Clause 5 and Clause 6.

Scope of Clause 7

Clause 7 applies to arc stud welding (both drawn-arc and capacitor-discharge methods) on structural steel. The most common application is headed shear connectors welded to the top flanges of steel beams to create composite action with a concrete slab. Other applications include threaded studs for railing attachment, Nelson pins, and anchor-type studs for PEMB connections.

Clause 7 does not govern resistance welding or friction-welded fasteners. Those fall outside the D1.1 scope entirely.

Procedure Variables

The stud welding procedure must document at minimum:

  • Stud diameter and type — headed shear connectors follow AWS D1.1 Annex I dimensional requirements; threaded studs follow applicable ASTM specifications.
  • Base metal — P-number equivalent and minimum thickness. Minimum base metal thickness is related to stud diameter; extremely thin flanges relative to stud diameter can cause inadequate fusion at the stud periphery.
  • Lift and plunge settings — these are the gap the stud is lifted before arc initiation and the depth it is plunged back into the molten pool. Correct settings are the primary control over heat input and flash formation.
  • Arc shield (ferrule) type — ceramic ferrules shape the flash and contain the arc. Through-deck applications require a specific ferrule geometry to accommodate the standing seam height of metal decking.
  • Position — flat (1F) is the standard for shear connectors. Overhead (4F) requires separate qualification.
  • Shielding gas — not required for short-stud CD welding but may be specified for drawn-arc studs in drafty environments.

A change in stud diameter, base metal group, or method (drawn-arc to CD) constitutes an essential variable change and requires re-qualification.

Qualification Testing

Qualification consists of welding a set of test studs and evaluating them through two methods:

Bend test. The stud is bent to 30° from its original axis using a pipe or tube as a bending bar. The weld is acceptable if there is a full flash at the root and no cracking in the weld metal or heat-affected zone. If a stud at 30° shows a crack, the engineer may require bending to 60° to confirm structural failure mode — a ductile fracture through the weld is preferable to a brittle HAZ crack.

Torque test. For threaded studs, a calibrated torque wrench loads the stud to a specified minimum torque. This supplements or replaces bend testing where bending is geometrically impractical.

Macro section examination (cross-section polish and etch) may be required by the engineer of record, particularly on critical connections or when process setup is being validated for the first time.

Production Control Test (PCT)

Unlike most structural welding where the WPS is qualified once and production begins, stud welding relies on in-process quality controls called production control tests. The PCT requirements in Clause 7 are:

  • Start of shift: weld five consecutive test studs to a piece of runoff plate or sacrificial steel before welding production studs.
  • When conditions change: any change in equipment, personnel, environment (wind, temperature), or deck thickness triggers a new PCT before continuing.
  • Bend each PCT stud to 30°. All five must pass before production resumes.

If any PCT stud fails, the cause must be identified, the equipment or settings corrected, and a new five-stud PCT completed successfully. This is the mechanism that ensures the welder, gun, and controller are dialed in before a single production stud goes down.

PCTs are a documentation artifact. The QC record for a stud-welded job should show a PCT log correlating each production run to a passing five-stud test. Third-party inspectors and AISC auditors will ask for this log.

Through-Deck Stud Welding

Composite deck construction means studs are typically welded through the steel decking rather than to bare steel. The weld burns through the decking and fuses to the beam flange below. Clause 7 permits through-deck welding with the following controls:

  • Deck steel must not exceed 0.045 in nominal thickness (G90 coating included in the thickness measurement for most interpretations).
  • The deck must be properly seated and in contact with the top flange — gaps under the deck cause erratic arc behavior.
  • Lift and plunge settings must be recalibrated from the bare-steel values because the arc must first penetrate the decking before establishing on the base metal.
  • A separate PCT must be run specifically for through-deck conditions before production.

Through-deck welds are inherently more variable than direct welds. Visual inspection of through-deck studs requires the inspector to look for the characteristic doughnut of flash that indicates penetration through the decking and proper fusion to the flange below. A bare spot — any circumferential gap in the flash — is a non-conformance requiring repair or replacement.

Visual Acceptance Criteria

After welding, every production stud receives a visual inspection. Acceptance requires:

  1. Full 360° flash — the weld fillet must be continuous around the entire base of the stud. Bare spots indicate incomplete fusion and are non-conforming.
  2. Plumb stud — the stud axis must be within 5° of its specified orientation. Off-plumb studs can indicate arc wander or misaligned equipment.
  3. No undercut — undercut at the base of the stud into the base metal is not permitted.
  4. No visible cracks — cracks in the flash, stud, or adjacent base metal are grounds for rejection.

Non-conforming studs may be replaced by welding a new stud immediately adjacent to the rejected one. Alternatively, the engineer of record may accept a reject-and-leave-in-place with the addition of a replacement, depending on the structural consequence.

Welder Qualification

Stud welding operators must be qualified per Clause 7. The qualification test is a PCT-style bend test demonstrating that the operator can consistently produce passing welds on the stud diameter and base metal type to be used in production. No separate written WPQ is required in the same form as groove and fillet weld operators, but the qualification must be documented.

Common Audit Deficiencies

CWI auditors and AISC certification reviewers most frequently cite the following stud-welding deficiencies:

  • No procedure document — Clause 7 requires a written procedure; a verbal "set it like last time" does not qualify.
  • No PCT log — shift-start tests were performed but not recorded.
  • Through-deck PCT run on bare steel — the PCT must replicate production conditions, including deck.
  • Wrong ferrule for stud diameter — using a smaller ferrule causes flash overflow and a cosmetically oversized weld that may mask incomplete fusion.

Pair this Clause 7 knowledge with a systematic pre-weld checklist by reviewing weld inspection hold points for CWI workflows and the broader WPS traceability in production weld maps.

For shops preparing for AISC certification or a large owner-furnished inspection program, a formal stud welding procedure in your audit-ready procedure library prevents last-minute scrambles when the inspector arrives.

Rule library based on AWS D1.1:2025; verify against your governing edition — the AHJ or contract may specify 2020 or earlier.

Ready to build and manage your stud welding procedures digitally? See how WPS Welding software handles Clause 7 documentation.