SMAW Open-Root Pass on Pipe – 1G Position

SMAW Open-Root Pass on Pipe – 1G Position

The open-root pass is the foundation of every structural and pressure pipe weld. If the root bead is incomplete, lacks fusion, or has burn-through, the entire weld joint is compromised — and no amount of fill or cap passes can fix what lies beneath. In the 1G position the pipe is laid flat and rotated by the welder or a positioner, keeping the weld pool always at or near the 12 o'clock position. This is the most accessible pipe position, making it the right starting point before you tackle fixed positions.

Why E6010 for Open-Root Work

E6010 is a fast-freeze, DC electrode with a cellulosic flux coating. Fast-freeze means the slag solidifies quickly behind the weld pool, giving you positive control over the molten metal even in a tight root opening. The forceful, digging arc penetrates deeply into the root face, reliably producing complete joint penetration when technique is correct. E6010 requires DC electrode positive (DCEP, also called reverse polarity). Always check that your power source is set to DCEP before striking an arc.

Available in 3/32 in and 1/8 in diameters, E6010 is typically run in the range printed on the electrode manufacturer's data sheet. For 3/32 in the range is commonly around 40–80 A; for 1/8 in it is commonly around 75–125 A. Your instructor will demonstrate specific settings on the shop's equipment. Dial in the lower end first — you can always increase heat, but burn-through is permanent.

Pipe Preparation and Setup

Schedule-80 pipe has thicker walls than schedule-40, giving you more material at the root face. For this joint, pipe sections are beveled to approximately 37.5° per side, leaving a land (root face) of 1/16 in, with a root opening of 1/16 to 3/32 in. These dimensions must be consistent around the full circumference.

Before welding:

• Clean the joint. Use a grinder or file to remove mill scale, rust, oil, and moisture from at least 1 in back from the bevel on both pieces.
• Tack weld. Place a minimum of four equally spaced tacks inside the root opening to hold alignment. Tacks must be sound and fully fused; grind the ends to a feathered taper so your root pass blends through them smoothly.
• Set up on pipe stands. Position the pipe so the weld zone is at a comfortable working height — roughly elbow to shoulder height — with room to rotate the pipe smoothly as you weld.

The Keyhole Technique

The keyhole is the key to complete penetration. As you establish the arc at the root, you will see a small oval or teardrop opening form just ahead of the weld pool — this is the keyhole. It forms because the arc is melting through the root face. Maintaining a consistent keyhole throughout the pass is your visual confirmation that full penetration is occurring.

Arc length: Keep it short — approximately equal to the diameter of the electrode core wire. A long arc with E6010 causes porosity and loss of penetration.

Travel speed: Move steadily. If you pause, heat builds and burn-through follows. If you move too fast, the keyhole closes and penetration is incomplete.

Electrode angle: Work angle is 90° to the pipe surface (pointing at the center of the pipe). Travel angle (drag angle) is 5–10° in the direction of travel. As you rotate the pipe in 1G, the work angle stays perpendicular to the surface beneath the arc — watch it continuously.

Whipping or steady drag: Many welders use a short whip-and-pause motion with E6010 to control heat and allow fast-freeze slag to stay ahead. Your instructor will demonstrate both a steady drag and a whip; adopt the one that gives you a consistent keyhole at your amperage setting.

Inspecting the Root Bead

After each pass, chip the slag fully with a chipping hammer — wear safety glasses during chipping. Wire-brush the bead clean. Then use a handheld mirror and flashlight to view the inside diameter (ID) of the pipe and examine the root bead.

AWS D1.1 visual acceptance criteria for root beads include:

• Complete penetration: no unfused areas along the root face edges.
• Root bead reinforcement (crown height): the bead should sit 1/16 in to 3/16 in above the ID flush surface. A sunken bead indicates incomplete penetration; excessive crown (icicles, drips) indicates too much heat or too slow travel.
• No cracks: examine the bead centerline and toes carefully.
• No burn-through beyond the allowance in your Welding Procedure Specification (WPS).

Record your observations in your personal weld log with a sketch of the cross-section profile and written notes on what you changed between passes.

Safety Points for This Lesson

PPE is non-negotiable. Wear your auto-darkening or passive welding helmet set to shade 10 or 11 for SMAW at these amperages. Leather gloves, leather jacket or sleeves, leather boots, and safety glasses under the helmet are required whenever the arc may be struck.

Chipping and grinding. Flying slag is a burn and eye hazard. Safety glasses (not just the welding lens) must be on during chipping and wire-brushing.

Electrical safety. Inspect electrode holders, cables, and ground clamp connections before each session. Never change electrodes with bare or wet hands. Keep the work area dry.

Ventilation. SMAW produces fumes containing manganese and other metal particulates. Weld only in areas with local exhaust ventilation or, if not available, wear a NIOSH-approved respirator appropriate for welding fumes. Review the SDS for E6010 electrodes.

Hot metal. Pipe and tacks remain hot long after you stop welding. Use tongs or gloves to rotate the pipe. Mark hot metal with soapstone.

Lockout/tagout. If you need to service the power source or adjust internal components, follow your shop's LOTO procedure — deenergize and verify zero energy before any contact with electrical components.