3g Weld Position 【VERIFIED • BREAKDOWN】

Here’s a comprehensive guide to the 3G Welding Position (Groove Weld, Vertical), a key certification test for structural and pipe welders.

Guide to the 3G Weld Position 1. What Is 3G?

G = Groove weld (as opposed to F for fillet weld). 3 = Vertical position (the weld axis is approximately vertical). So 3G means: a groove weld made on a vertical surface , with the weld progression either vertical-up or vertical-down .

Common test configurations:

3G (plate) : Plate is vertical, groove runs horizontally. 3G (pipe) : Pipe axis is vertical, weld is circumferential (also called 5G or 2G depending on orientation – but pure 3G pipe is rare; usually 5G or 6G).

In this guide, we focus on plate 3G – the most common certification test.

2. 3G Positions: Up vs. Down | Type | Direction | Common Process | Difficulty | Penetration | Best For | |------|-----------|----------------|------------|--------------|----------| | 3G Up | Root to top (vertical up) | SMAW, FCAW, GTAW | Higher | Deep | Thick plate, structural steel | | 3G Down | Top to root (vertical down) | GMAW (short arc) | Lower | Shallow | Thin sheet, production welding | 3g weld position

Note : Many codes (e.g., AWS D1.1) require vertical-up for structural steel. Vertical-down is often not permitted for root passes on thick plate.

3. Joint Preparation (Typical for 3G Test)

Plate thickness : 3/8″ (10 mm) to 1″ (25 mm) Groove angle : 60° included (30° bevel each side) Root opening : 1/4″ (6 mm) – may vary by code Land (root face) : 1/16″ – 3/32″ (1.5–2.5 mm) Backing : Copper or steel backing bar (or no backing for open-root) Here’s a comprehensive guide to the 3G Welding

4. Techniques for 3G Vertical-Up (Most Critical) 4.1. Electrode/Process Selection

SMAW (stick) : E7018 (1/8″ or 3/32″) – low hydrogen FCAW (flux core) : E71T-1 (0.045″ or 1/16″) GMAW (MIG) : Short-circuit transfer only (spray transfer not possible vertically) GTAW (TIG) : 3/32″ tungsten, ER70S-6 filler