Welding
Processes and electrodes
Boilermaker welding covers SMAW (stick), GMAW/FCAW (wire), and GTAW (TIG) for root passes and tube work. The most-tested knowledge is electrode identification. In E7018, the first two digits give minimum tensile strength in ksi (70,000 psi), the third digit gives position (1 = all positions), and the last digit gives coating/current characteristics (8 = low-hydrogen, iron-powder coating, usable on AC or DC electrode positive). Compare E6010 - a cellulosic, deep-penetrating electrode used on DC electrode positive for root passes and dirty pipe - and E7024, a high-iron-powder, high-deposition electrode used flat and horizontal on AC or DCEN.
Storage matters. Low-hydrogen electrodes (7018, 8018) absorb moisture; keep them in a holding oven (typically 250–300°F) and use portable ovens in the field. Electrodes that have been wet or baked incorrectly cause hydrogen-assisted cracking.
Technique and defects. Set amperage in the range on the electrode chart, hold a short arc (arc length roughly the diameter of the bare end of the electrode), and keep the correct travel and work angles. Traps to recognize: an arc that is too long causes spatter, porosity, and undercut; too much current causes undercut and a concave bead; too little causes lack of fusion and a high, narrow bead. Travel too fast gives a thin bead with undercut; too slow gives excessive reinforcement and slag entrapment. Clean each pass - slag inclusions are the classic stick-welding defect.
Distortion control. Use balanced welding (backstep, skip, or alternating sides), correct fit-up and tack placement, and preheat per procedure. Don't confuse preheat with interpass temperature.
Worked example. A WPS calls for E7018 at 1/8 in diameter. Decode it: 70 ksi minimum tensile, all-position, low-hydrogen, AC or DCEP. That tells you to pull it from the oven, not a damp toolbox.
Rule of thumb. Fit-up and cleanliness fix more welds than amperage does.