Groove Welds on Plate — Flat and Horizontal (1G, 2G)

Groove Welds on Plate — Flat and Horizontal (1G, 2G)

Why Groove Welds Matter

Groove welds join members edge-to-edge through the full thickness of the base metal. In structural work governed by AWS D1.1, complete joint penetration (CJP) groove welds carry the full design load of the connection. Getting the root pass right and building sound fill and cap passes is the difference between a joint that performs in service and one that fails inspection — or worse, fails in the field.

This lab covers the single-V groove weld in the flat (1G) and horizontal (2G) positions using GMAW. Both positions appear on the AWS D1.1 Certified Welder qualification test and in NCCER performance evaluations.

Joint Preparation and Fit-Up

A single-V groove requires a bevel angle of 37.5° on each plate edge, producing a 75° included angle when the two pieces are brought together. Use an angle grinder with a grinding disc to form the bevel. Maintain a root face (land) of approximately 1/8" — this small flat shelf at the bottom of the bevel supports the root pass and prevents burn-through.

After grinding, check your work with a fit-up gauge before assembly:

• Root opening (root gap): Typically 1/8" for short-circuit GMAW on 1/4" plate. Confirm the dimension called out on your Welding Procedure Specification (WPS).
• Root face: Consistent around the joint — too thin invites blow-through; too thick risks lack of penetration.
• Bevel angle: Use the gauge or a protractor to verify 37.5° ± a small tolerance.

Align the pieces on a flat surface, set the root gap with a root gap gauge or drill bit of the correct diameter, and apply tack welds at each end and the center. Tacks must be strong enough to hold alignment under thermal distortion. Stop and present your fit-up to the instructor before striking an arc. A poor fit-up cannot be fixed after welding begins without cutting apart the joint.

Welding Sequence: Root, Fill, and Cap

Root pass — Use short-circuit transfer (low voltage, lower wire feed speed) to control heat input and fill the narrow root opening without burning through. Travel straight or use a slight weave, watching the leading edge of the puddle drop into the root. Listen for the characteristic frying sound of short-circuit transfer. On 1G (flat), gravity helps the puddle fill the root; on 2G (horizontal), the puddle wants to sag, so keep travel speed up slightly and angle the gun upward 5–10° into the joint.

After the root pass, stop and clean thoroughly. Wire-brush the entire pass to remove silicon islands (the glassy residue from ER70S-6 deoxidizers). Grind any high spots, convex humps, or areas of suspected lack of fusion before continuing. Never bury a defect under fill passes.

Fill passes — Increase voltage and wire feed speed as needed per the WPS for a larger, more fluid puddle. Use a slight side-to-side weave or stringer beads depending on the WPS. Pause at each sidewall to ensure fusion into the groove face. Each pass should be cleaned before the next is deposited.

Cap pass — The cap should be flat to slightly convex, with reinforcement not exceeding 1/8" above the base metal surface per AWS D1.1. Blend the toes smoothly into the base metal — sharp or undercut toes are rejectable. On 2G, gravity pulls the cap bead down; keep a slight uphill gun angle and controlled travel speed to avoid sagging.

Safety in This Lab

• PPE required: Auto-darkening or fixed-shade welding helmet (appropriate lens shade for GMAW amperage), leather welding gloves, flame-resistant (FR) jacket or sleeves, leather boots, and safety glasses under the helmet.
• Angle grinder safety: Wear a full face shield over safety glasses when grinding. Inspect grinding discs for cracks before mounting. Never exceed the disc's rated RPM.
• Ventilation: GMAW produces fumes from the wire, base metal, and shielding gas displacement. Work with local exhaust ventilation at the source or in a well-ventilated bay. Do not weld galvanized or coated steel without enhanced ventilation and engineering controls.
• Hot metal: Plate stays hot long after welding. Use pliers or tongs; mark hot pieces with soapstone as a warning to others.
• Lockout/tagout: If a machine malfunction requires internal inspection or repair, follow your shop's LOTO procedure before touching internal components.

Guided-Bend Testing

Visual inspection alone does not prove internal soundness. AWS D1.1 requires guided-bend tests to verify fusion and ductility. After the coupon cools:

1. Cut two specimens to the dimensions specified in your bend specimen template — one for a face bend (weld face in tension) and one for a root bend (weld root in tension).

2. Grind both surfaces flush with the base metal. Remove all reinforcement.

3. Place each specimen in the guided-bend jig with the correct face toward the plunger.

4. Apply load until the specimen wraps around the mandrel to the angle required by the jig.

5. Inspect the convex surface for cracks or open defects.

Acceptance criteria (AWS D1.1): No single crack or open defect may exceed 1/8" measured in any direction on the convex surface after bending. Corner cracks arising from the edge of the specimen, not from a weld defect, are typically not counted. Record your findings on the inspection report form.

Connecting to Your Credentials

The 1G and 2G groove weld in GMAW directly maps to AWS D1.1 Certified Welder qualification testing and NCCER Welding Level 2 performance tasks. Passing both the visual and bend test in this lab builds the exact skills evaluated on those credential assessments.