Are weld tabs required on all groove welds in AWS D1.1 structural work?

AWS D1.1:2025 fabrication requirements call for extension bars on butt joint groove welds where the weld must be full length. The default is that tabs are required; the Engineer of Record must waive the requirement in writing for them to be omitted. Not all joint types need tabs — tee and corner joints with natural weld terminations are different from butt joints.

What material must weld tabs be made from?

Weld tabs must be made from the same base metal group as the work being welded — they cannot be random scrap of unknown chemistry. Using unverified scrap creates a heat-affected zone in unknown material tack-welded to your production joint, which can introduce cracking that propagates into the joint during cooling.

How are weld tabs removed, and what surface condition is required?

Tabs are removed by mechanical cutting followed by grinding flush with the base metal surface. Flame cutting alone is not acceptable — it leaves a rough, hardened surface. The finished zone must be smooth and free of notches, steps, or undercut that could act as fatigue initiators. This area is then subject to the same visual acceptance criteria as the rest of the weld.

Do weld tab removal areas require NDE?

If the project specification requires MT or PT on the groove weld, that requirement typically extends to the tab removal areas. Transverse cracks at weld ends — particularly crater cracks — are a common defect that magnetic particle testing picks up at these locations. The inspection record should specifically document the tab removal area inspection.

Weld tabs and runoff plates: AWS D1.1 requirements

When AWS D1.1:2025 requires extension bars on groove welds, how to size and position them, and what CWIs check at removal and final surface condition.

Weld tabs — sometimes called runoff plates, extension bars, or starting tabs — are short pieces of base metal tacked to the ends of a joint before welding begins. The welder starts the arc on the tab, runs the full bead through the production joint, and terminates on the far tab. The arc start and stop — where defects concentrate — are left on the tabs, which are then removed and discarded.

This sounds straightforward, but shops make consistent errors with weld tabs: using the wrong geometry, leaving them in place after welding, or removing them in a way that damages the base metal. All three show up regularly on CWI inspection punchouts.

Why weld ends are the highest-risk zone

When an arc is struck, initial heat input and puddle stability are erratic. The first fraction of an inch of weld is statistically the most likely location for porosity and lack of fusion. At the stop end, a crater forms as the arc extinguishes; an unfilled crater is a stress concentration that can crack under load — a serious concern in cyclically loaded connections and moment frames.

For CJP groove welds connecting beam flanges to column flanges, or for full-penetration butt splices in primary tension members, end defects are categorically unacceptable. The weld must be sound across its full length. Tabs move the inevitable transition zone outside the production joint.

The same principle applies to fillet welds on built-up sections like plate girder flanges, where a continuous weld is specified and a crater at the end of a run would land at a stress concentration.

When AWS D1.1:2025 requires weld tabs

AWS D1.1:2025 fabrication requirements specify that groove welds in butt joints — where the weld is required to be full length — must use extension bars unless the Engineer of Record (EOR) waives the requirement in writing or unless the joint geometry makes tab use impractical. The default is that tabs are required; waiver is the exception.

Tee joints and corner joints where the weld terminates naturally at a return or at an edge condition may not require tabs, but any groove or fillet weld that terminates abruptly on a primary load path warrants scrutiny. When demand-critical welds are required by the contract under AWS D1.8 seismic provisions, requirements for weld tabs are stricter still.

The contract documents or project specification may impose additional requirements beyond the code minimum. On public infrastructure, bridge work governed by AWS D1.5, or owner-specified inspection and test plans (ITPs), weld tab requirements may be spelled out in detail independently of the base code.

Geometry: the tab must match the joint

This is the most frequently violated requirement. A weld tab is not simply a piece of scrap steel of roughly the right thickness. It must be prepared with the same joint geometry as the production weld — the same groove angle, the same root opening, the same root face dimension.

If the production joint is a 45° single-bevel CJP on 1 in. plate, the tab is also a 45° single-bevel on material of the same or greater thickness. If the joint has a 3/16 in. root face and a 1/4 in. root opening, the tab matches those dimensions.

Why does geometry matter? Because the welder must execute the same cross-section through the tab as through the production joint. A flat-bar tab attached to a beveled joint forces the welder to change technique at the transition — which is exactly where quality problems originate. The tab exists to absorb the transition. It only works if the joint preparation is continuous through the tab.

Material matters equally. Tabs must be of the same base metal group (matching the prequalified base metal groupings per AWS D1.1:2025) as the work. Using a piece of random scrap with unknown chemistry creates a heat-affected zone adjacent to your production joint that may crack during cooling, particularly if the unknown material has elevated carbon or sulfur content. A crack in the tab that runs to the tack weld can propagate into the production joint.

Removal: method, sequence, and surface condition

Weld tabs are removed after the weld is complete and cooled — or after post-weld heat treatment if PWHT is specified. The method is mechanical cutting followed by grinding. Flame cutting alone is not acceptable; the thermal cut surface is rough, hardened from the rapid thermal cycle, and not flush. Grinding brings the weld end flush with the base metal and eliminates any remaining tab or cut surface.

The finished zone at the former tab location must be smooth and flush. AWS D1.1:2025 requires the transition to be free of notches, undercut, or irregular geometry that could act as a fatigue initiator. A CWI uses visual inspection — and a straight-edge or weld gauge across the end condition if needed — to confirm the surface. Any step, groove, or notch visible at the tab removal zone is a finding.

After grinding, the tab removal zone is subject to the same visual acceptance criteria as the rest of the weld. If MT or PT is specified for the project, that requirement typically extends here. Transverse cracks at weld ends are a recognized defect mode; this is where poor tab practice turns into a reject, not just a cosmetic issue.

What the CWI checks at each stage

A structured CWI review of weld tabs covers three stages:

Pre-weld (before arc strike): Confirm tabs are present on both ends. Verify that the tab geometry matches the production joint — groove angle, root opening, root face. Confirm that the tab material is documented as the correct base metal group. This is the cheapest inspection hold point: catching a wrong tab before welding costs nothing; catching it after requires weld removal to access the end zone.

In-process: Verify that the welder is starting and stopping on the tabs, not on the production joint. On multi-pass work, intermediate passes should also start and stop on tabs where the run extends the full joint length.

After tab removal: Surface flush and smooth with no notches at the transition from weld to base metal? No cracking visible at the weld end — particularly crater cracks or transverse cracks? Color and surface texture consistent with the adjacent weld? MT or PT acceptance confirmation if specified?

The CWI record should document tab removal as an inspected item. An owner's third-party auditor reviewing records months after fabrication will ask for this documentation. For how this step fits into the full quality and NDE record, see NDE documentation and audit packets and the CWI hold point framework at weld inspection hold points.

Common shop errors

Wrong tab geometry: A shop cuts a flat plate and tacks it to a beveled joint because the welder "just needs somewhere to start." The result is a joint discontinuity at the transition and no benefit at the actual arc strike location.

Skipping tabs on interior butt splices: A plate girder flange splice in the middle of a span doesn't have a free edge to attach tabs to. Shops sometimes skip tabs here because it's inconvenient. The correct approach is to use strongbacks or fixturing to hold the tabs in position — not to waive them by default.

Leaving tabs in place: Field-welded connections sometimes see "temporary" tabs left permanently because removal was inconvenient after erection. Unless the EOR has accepted them in writing, they are a non-conformance. Tabs create crevice corrosion risk at the tack weld interface and can mask weld end defects from visual inspection.

Grinding into the base metal: Aggressive removal can produce a surface gouge below the base metal thickness. That creates a stress concentration — exactly what tabs were installed to prevent. Grinding flush means level with the parent metal surface, not below it.

Documentation in the inspection record

A complete CJP groove weld inspection record should include, for each joint: tab geometry and material confirmed; weld completed; tabs removed; end condition ground flush; visual acceptance confirmed; MT/PT (if required) accepted. This chain of custody supports the as-built record if an engineer of record or owner's inspector reviews the work after the fact.

For the pre-weld steps that set up a successful tab installation, see joint fit-up tolerances in AWS D1.1. If your shop is managing these inspection records on paper or spreadsheets and looking for a more auditable approach, see what purpose-built welding procedure software provides.

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