SMAW Technique and Welding in All Positions
Starting, running and restarting
Strike by scratching or tapping. On restart, strike slightly ahead of the crater and come back into it to prevent a cold lap and porosity at the joint. Hold an arc length about equal to the electrode core diameter - roughly 2.5 mm for a 3.2 mm electrode. Work angle is 90 degrees for a butt joint, about 45 degrees for a fillet, with a 10-15 degree drag angle for most covered electrodes. Keep bead width to about three times the electrode diameter or less; some codes reduce that limit. Deslag completely between passes.
Positions
1G/1F flat uses the highest current and gives the best deposition. 2G/2F horizontal needs attention to undercut on the upper leg. 3G/3F vertical: E7018 is run uphill with a short arc, slightly reduced current and a brief pause at each toe; cellulosic electrodes are run downhill for open-root pipe roots at high travel speed and thin deposit. 4G/4F overhead uses about 10-15% less current, a shorter arc, faster travel and smaller beads to stop the puddle sagging.
Worked example
Vertical uphill E7018 on 10 mm plate: start near 30-35 A per mm of electrode diameter, so about 100-120 A for a 3.2 mm electrode. Work angle 90 degrees, drag angle 0-10 degrees uphill, arc length about 2.5 mm, weave no wider than 9 mm, pausing briefly at each toe to fuse the sidewall.
Traps
- Lengthening the arc to see the puddle - causes spatter, porosity and undercut.
- Weaving wide to fill a groove quickly - lack of fusion at the toes.
- Restarting without feathering the crater.