SMAW Technique: Flat and Horizontal Positions

Mastering the flat (1G/1F) and horizontal (2G/2F) positions in Shielded Metal Arc Welding (SMAW) is the cornerstone of all structural welding. These positions allow you to build foundational skills in puddle control, bead placement, and parameter management before tackling more challenging overhead or vertical work. Achieving a sound weld here is not just about making metal stick together; it’s about consistently producing a bead with proper profile, penetration, and mechanical properties that will pass both visual inspection and destructive testing.

The Fundamental Variables: Arc, Angle, and Speed

Every successful weld is a careful balance of three interdependent variables. Neglecting one will compromise the entire operation. The first is arc length, which is the distance between the tip of the electrode and the weld puddle. Maintaining a short, consistent arc length—roughly equal to the diameter of the electrode’s core wire—is critical. A long arc creates excessive spatter, poor penetration, and allows atmospheric contamination (nitrogen, oxygen) to enter the weld, leading to porosity and brittleness. You should hear a steady, crisp cracking sound, not a sputtering or hissing.

Second is electrode angle. This is typically described in two components: travel angle and work angle. The travel angle is the angle along the axis of the joint, usually a 5- to 15-degree drag (backhand) angle for flat and horizontal positions. This angle helps shield the molten puddle with the flux coating and directs the arc force for better penetration. The work angle is the angle perpendicular to the travel direction. For a flat fillet weld in the horizontal position (2F), this is typically a 45-degree angle between the two pieces. An incorrect work angle will cause the weld metal to favor one plate over the other, creating an unequal leg and potential lack of fusion.

Third is travel speed. Your speed must be consistent and matched to the heat input from your amperage setting. Moving too fast results in a narrow, ropey bead with insufficient penetration and possible slag inclusions. Moving too slow produces an excessively wide, convex bead that can lead to overlap at the toes and excessive heat input, which may distort the base metal. The ideal speed creates a bead width approximately 2-3 times the electrode diameter, with a flat to slightly convex profile that smoothly blends into the base metal.

Bead Placement Techniques: Stringer vs. Weave

With the fundamentals in hand, you apply them through specific bead placement techniques. A stringer bead is made by moving the electrode straight along the joint with no lateral oscillation. This is the preferred technique for root passes and hot passes, as it provides deep, focused penetration with lower heat input and minimizes the risk of slag entrapment. It requires excellent control of arc length and travel speed to maintain a uniform bead width.

A weave bead involves moving the electrode from side to side in a controlled pattern as you travel forward. This technique is used for fill and cover passes to deposit more metal and widen the bead. Common patterns include the crescent, “Z,” and “J” weaves. The key is to pause momentarily at each side (the toe of the weld) to ensure proper fusion and prevent undercut, a groove melted into the base metal that is not filled. In the horizontal position (2G/2F), gravity pulls the molten metal downward. Therefore, you use a slight uphill angle or adjust your weave to hold the puddle, often employing a “step” or “ladder” pattern where you move upward slightly, then across, then forward.

Multipass Welding and Sequencing

Single-pass welds are rare in structural work. Multipass welding is the process of depositing a sequence of weld beads to fill a joint. Correct sequencing is vital to control heat input, manage distortion, and ensure complete fusion between all passes. The general sequence is: root pass, hot pass, fill passes, and cover (cap) pass.

The root pass is the first bead in the joint’s groove. Its sole job is to achieve complete penetration at the root without burning through. It is almost always a stringer bead. The hot pass follows immediately, done before the root pass cools completely. It serves to burn out any trapped slag from the root and ensure sidewall fusion. Subsequent fill passes are used to build up the weld metal to just below the surface. These can be stringers or weaves, but you must clean all slag thoroughly between each pass. Finally, the cover pass is the final, cosmetic layer. It must have a uniform appearance and completely cover the previous passes, with proper reinforcement and no defects.

Adjusting for Electrode Types and Positions

Not all SMAW electrodes behave the same, and your technique must adapt. A fast-freezing E6010 electrode (cellulosic coating) requires a tight, dragging arc and whipping motions for root passes on pipe, but for fill passes in flat/horizontal, a steady drag is used. In contrast, a E7018 (low-hydrogen, iron powder) electrode is a “drag rod” designed to be held with a very short, steady arc. Its thick flux creates a deep slag layer that must be completely removed between passes.

The transition from flat (1G/1F) to horizontal (2G/2F) introduces gravity as a primary factor. In the horizontal position, molten metal wants to sag. To combat this:

• Reduce amperage by 5-10% compared to flat position.
• Use a slightly higher work angle, pointing the arc more toward the upper piece to prevent the puddle from dripping.
• Employ weave patterns with deliberate pauses at the top toe to build a “shelf” that supports the puddle below it.
• For horizontal groove welds (2G), weld the bottom side of the groove first, creating that supporting shelf for subsequent passes.

Common Pitfalls

Undercut: This is a groove melted into the base metal at the toe of the weld that remains unfilled. It is a critical stress riser.

• Cause: Too high amperage, too long an arc, or moving too fast without pausing at the edges during a weave.
• Correction: Reduce amperage slightly, maintain a proper arc length, and ensure a brief pause at each side of your weave to fill the groove.

Slag Inclusions: Non-metallic solid material trapped in the weld metal or between weld beads.

• Cause: Failure to remove all slag from a previous pass, incorrect electrode angle that buries slag in the puddle, or a travel speed that is too fast.
• Correction: Chip and wire-brush every pass meticulously. Use a proper travel angle to let the slag float behind the arc. Ensure complete slag removal before depositing the next bead.

Poor Bead Profile (Excessively Convex or Concave): A convex bead creates stress concentrations at the toes, while a concave bead lacks throat thickness in fillet welds.

• Cause: Convexity is from too low amperage or too slow travel speed. Concavity is from too high amperage, too long an arc, or improper horizontal technique causing sag.
• Correction: Adjust amperage and travel speed in tandem to achieve a flat profile. In horizontal positions, adjust your work angle and travel speed to control the fluid puddle.

Lack of Fusion: Failure of weld metal to fuse completely with the base metal or the previous weld bead.

• Cause: Insufficient amperage, improper travel speed (too fast), or incorrect electrode angle that does not direct heat into the sidewall or previous pass.
• Correction: Increase amperage within range, slow down, and angle the electrode deliberately toward the area you need to fuse—point it at the sidewall or the toe of the previous bead.

Summary

• Control the Triad: Success in flat and horizontal SMAW depends on meticulously balancing arc length, electrode angle, and travel speed to manage the weld puddle.
• Match Technique to Purpose: Use tight, straight stringer beads for root and hot passes to ensure penetration, and controlled weave patterns for fill and cover passes to fill the joint, always pausing at the toes to prevent undercut.
• Follow a Logical Sequence: Execute multipass welds in the correct order (root, hot, fill, cover) and clean all slag thoroughly between every single pass to prevent inclusions.
• Adapt to Conditions: Adjust your parameters and technique for the specific electrode type (e.g., E6010 vs. E7018) and to counteract the effects of gravity when moving from the flat to the horizontal position.
• Diagnose and Correct: Common defects like undercut, slag inclusions, and poor bead profile have direct technical causes. Systematically checking and adjusting your amperage, angle, and speed is the path to producing clean, sound, and structurally reliable welds.