Groove Welds on Plate — 2G and 3G Positions

Groove Welds on Plate — 2G and 3G Positions

Why These Positions Matter

Structural steel fabrication and building construction rarely let you weld in the flat (1G) position. Beams, columns, and connections are often fixed in place, so you weld horizontally across a joint (2G) or vertically up a wall or column (3G). AWS D1.1 — the Structural Welding Code for Steel — requires welder qualification tests in the positions that match the work. Earning a passing coupon in 2G and 3G is a direct step toward your AWS Certified Welder credential and is recognized by every structural employer that works under D1.1.

Joint Fit-Up: Getting It Right Before the Arc Starts

A sound groove weld begins with accurate fit-up. For a single-V groove on 3/8 in. A36 plate you will grind each plate edge to produce the specified included angle — typically 60° total (30° bevel per side) for SMAW. Use a weld gauge or protractor to confirm the bevel angle. Set the root opening (the gap between the two pieces) using a small spacer or tack. A root opening in the range of 1/16 in. to 3/32 in. is common for 3/8 in. plate with E6010 root passes; confirm the exact dimension your instructor specifies. Check squareness with a combination square so the joint face is not bowed or misaligned. Tack weld at each end and, on longer coupons, in the middle to hold fit-up during welding. Tacks must be sound; remove or blend any cracked tacks before proceeding.

Electrode Selection and Storage

E6010 is a cellulosic, fast-freeze electrode well suited for root passes because it gives the welder control of a small, penetrating arc and freezes quickly — important when gravity is working against you. E7018 is a low-hydrogen, iron-powder electrode used for fill and cap passes; it produces a smooth bead with excellent mechanical properties. E7018 is moisture-sensitive. Store it in a rod oven at the manufacturer's recommended temperature (typically around 250 °F to 300 °F) and never leave it on the bench for more than the time specified on the label or by your instructor. Using damp E7018 can cause porosity and hydrogen-induced cracking — both rejectable under D1.1.

2G Position: Horizontal Groove Weld

In the 2G position the plate is vertical and you weld horizontally. Gravity pulls molten metal downward, which tends to cause overlap on the bottom toe and underfill on the top. Combat this by:

• Angling the electrode slightly upward (a small lead/drag angle of about 5°–10°) and pointing it slightly into the joint.
• Keeping a short arc length; a long arc widens the puddle and makes sag worse.
• Using the lower end of the amperage range for the electrode diameter.
• Pausing briefly at the top toe of each pass to ensure fusion before moving on.

Run the root pass first, then chip and brush thoroughly. Run fill passes in sequence, staggering starts and stops. The cap pass should be flush to slightly convex; crown reinforcement must not exceed the limit stated in D1.1 Table — typically no more than 1/8 in. above the base metal surface for most thicknesses.

3G Position: Vertical-Up Groove Weld

In the 3G position the plate is vertical and you weld upward. Vertical-up produces excellent fusion and penetration because the puddle stays against the joint wall as you progress. Key technique points:

• Use a slight weave or a triangular motion (pause at each side, faster across the middle) to tie in the toes.
• Keep the arc tight and the puddle small; if the puddle starts to sag, pause travel and let it solidify slightly.
• E6010 at lower amperage is common for the root; E7018 fill and cap passes benefit from a slightly whipping or weave motion depending on pass width.
• Work upward steadily; do not allow a large, fluid puddle to build because it will roll out of the joint.

Multi-Pass Sequence and Interpass Cleaning

Every pass must be cleaned before the next one. Use a chipping hammer to break slag, then a wire brush to expose clean metal. Failure to remove slag causes slag inclusions — a rejectable discontinuity. Check interpass temperature with a contact or infrared thermometer. D1.1 limits maximum interpass temperature for carbon steel; do not begin a new pass if the coupon exceeds that limit, as excessive heat input can degrade mechanical properties. Allow the coupon to cool to the acceptable range, then resume.

AWS D1.1 Visual Acceptance Criteria

After completing each coupon, your instructor will perform a visual inspection. The main criteria for visual acceptance under D1.1 include:

• No cracks of any kind.
• Complete fusion at toes and along the root — no cold lap visible.
• Crown reinforcement within code limits (not excessively convex or concave).
• Undercut along the toes not exceeding the permitted depth or length specified in the code.
• No overlap (weld metal rolled over base metal without fusing).
• Porosity limited per code; visible surface porosity clusters are rejectable.

Weld Log

Document each coupon in your lab log: electrode classification, diameter, amperage and voltage as read from the machine, estimated travel speed, number of passes, position, and your visual inspection result. This habit mirrors industrial practice and prepares you for the procedure qualification records used in real fabrication shops.

Safety

• PPE: welding helmet (appropriate shade lens for SMAW — typically shade 10 or 11), leather gloves, flame-resistant jacket, leather boots, and ear protection when grinding.
• Grinding: use a face shield over safety glasses when grinding; inspect wheels before use and never exceed rated RPM.
• Electrical safety: keep the work clamp close to the weld area; inspect electrode holder and cables for damaged insulation before each session.
• Ventilation: SMAW on carbon steel produces fumes; ensure local exhaust ventilation is operating and position your head out of the fume plume.
• Hot metal: coupons remain dangerously hot long after welding; use pliers or tongs and mark hot pieces with soapstone.