Welding Basics for Emergency Repair

Understanding the Welding Processes

Three processes matter for a prepper's toolkit.

Stick welding (SMAW — Shielded Metal Arc Welding): An electrode (a stick of metal coated in flux) is clamped in a holder. You touch the electrode to the workpiece to strike an arc, then maintain a gap while the electrode melts and the flux coating burns to provide shielding gas. The most tolerant process for field conditions — it handles rusty, painted, or dirty metal better than any other arc process. Equipment is simple and cheap.

MIG welding (GMAW — Gas Metal Arc Welding): Wire fed automatically from a spool through the welding gun. A separate tank of shielding gas (typically 75% argon / 25% CO2, called C25 or 75/25) shields the weld puddle. Faster and easier to learn than stick for clean metal. Poor choice for rusty or dirty metal (porosity and inclusions result). Requires gas bottles that run out.

Flux-core wire (FCAW): Similar to MIG but uses hollow wire with flux inside — no external shielding gas required. Better for outdoor conditions than gas-shielded MIG. Less clean finish than MIG but more forgiving of gaps and imperfect fit-up.

For preparedness priority: Learn stick first. Then flux-core. MIG is a workshop luxury, not a field tool.

Equipment for Stick Welding

A used 225-amp stick welder is one of the most useful tools in any shop or homestead. Lincoln AC-225 ("tombstone") welders have been made since 1953 and are abundant at swap meets and used tool shops. They run on 230V power and produce reliable output for decades.

What you need:

• Stick welder, 150 amps minimum capacity
• Welding helmet (auto-darkening is strongly preferred over a fixed-shade helmet)
• Leather welding gloves
• Chipping hammer (to knock off slag after each bead)
• Wire brush
• Electrode selection (see below)
• Ground clamp with good cable
• Electrode holder with cable

Electrode Selection

This is where new welders get confused. The electrode (rod) selection matters for both quality and ease.

E6013: The beginner's electrode. Runs on AC or DC, produces a soft arc, forgiving of imperfect technique. Good for thin metal and light repair work. Not the best mechanical properties for structural applications.

E6011: The field repair electrode. Runs on AC (which old, cheap, buzzer-style welders produce) or DC. Digs aggressively through rust and mill scale. Excellent penetration. The best all-around choice for dirty or rusty steel in field conditions.

E7018: The structural electrode. Requires DC+ (direct current, positive polarity) and dry storage (the flux coating absorbs moisture). Produces welds with excellent mechanical properties — required by structural codes. Not ideal for dirty metal. Store in a sealed container or rod oven.

For emergency repair work, keep a pound each of E6013 and E6011. Store all electrodes dry — a zip-lock bag with silica desiccant, or a sealed plastic container. Wet electrodes cause porosity and weld defects.

Joint Preparation

The weld is only as good as the joint going in.

Remove mill scale, rust, paint, and oil from the weld zone. Contaminants cause porosity (gas bubbles trapped in the weld metal) and inclusions (slag trapped inside). A 4.5-inch angle grinder with a grinding disc or a wire cup wheel removes surface contamination in seconds.

Gap and fit-up: For butt joints (two plates end-to-end), a small gap (1/16 to 1/8 inch) allows full penetration of the weld metal through the joint. No gap means you are welding on top of the material, not through it.

Clean cuts: Fit-up is faster and easier when parts are cut squarely. A cutting wheel on an angle grinder cuts mild steel cleanly. Flame cutting (oxy-acetylene torch) works for thick stock where an angle grinder struggles.

Striking and Holding the Arc

The first lesson. The hardest to describe in words.

The electrode must maintain a specific gap from the work — about the diameter of the electrode itself (1/8 inch for a 1/8-inch electrode). Too close and the electrode sticks. Too far and the arc goes out or becomes unstable and spattery.

Striking the arc (two methods):

• Tap start: Touch the electrode straight down to the metal and lift quickly. Like striking a match.
• Scratch start: Drag the electrode across the metal at an angle and lift. More reliable for beginners.

If the electrode sticks (the most common beginner problem), twist and release the holder immediately. If you hold it there, the electrode heats up and fuses to the base metal. Give it a quick lateral twist to break it free before it has had time to fully fuse.

Running a Bead

Once the arc is struck, you are making decisions about three things simultaneously: arc length, travel speed, and electrode angle.

Arc length: Keep the gap roughly equal to the electrode diameter. Watch the puddle, not the arc. The puddle is the pool of molten metal immediately behind the arc — this is what you are controlling.

Travel speed: Move the electrode steadily along the joint. Too fast and you get a narrow, cold bead. Too slow and you pile up metal (too high crown) and risk burn-through on thin material. The bead should be slightly wider than the electrode diameter.

Electrode angle: The electrode should be angled about 10-15 degrees in the direction of travel (drag angle), perpendicular to the joint. On vertical and overhead positions, adjust the angle more aggressively to control where the puddle goes.

Reading the puddle: The molten pool should be fluid but controlled. A good puddle slightly leads the arc. Slag (the dark coating from the flux) follows behind the puddle. If slag is getting ahead of the arc, you are moving too slowly or the current is too low.

Common Metal Types and Their Considerations

Mild steel (A36, 1018): The easiest to weld. Most of what you will encounter in repair work — farm equipment, trailers, structural steel, hardware. Use E6011 or E6013. Minimal prep required.

High-strength steel (T1, Hardox, grade 80 bolts): Often found in agricultural equipment and trailers. Requires preheat for thicker sections to prevent cracking. Use E7018.

Cast iron: Very tricky. Cracks easily from thermal stress. Requires preheat to 400-500°F, slow cooling (bury in sand or wrap in insulating blanket), and special nickel electrodes (ENiFe-CI). A cast iron repair that cracks next to the weld is a thermal stress failure, not a weld failure.

Stainless steel: Requires stainless electrodes (308 or 309 series). Conducts heat poorly, warps easily, and requires clean surfaces free of carbon steel contamination. Use the lowest amperage that maintains a stable arc.

Galvanized steel: The zinc coating produces zinc fumes when heated. Zinc fumes cause metal fume fever — flu-like symptoms, sometimes severe. Grind the galvanizing off the weld zone first, and always weld galvanized in heavy cross-ventilation.

Judging Weld Quality

After each bead, chip the slag, wire brush, and examine.

Good weld indicators:

• Uniform width and height throughout the bead
• Smooth rippled surface pattern
• Fusion to the base metal on both sides of the joint (no rollover or undercut)
• No visible porosity (small holes)
• Consistent bead profile (no humps or valleys)

Problem signs:

• Porosity: gas holes in the bead. Cause: contaminated base metal, wet electrodes, or long arc length.
• Undercut: a groove burned into the base metal along the edge of the bead. Cause: too high amperage or incorrect electrode angle.
• Overlap: weld metal rolled over the base metal without fusing. Cause: too slow, too cold.
• Cracking: in the weld or adjacent heat-affected zone. Cause: incorrect electrode for the material, insufficient preheat for thick sections, or rapid cooling.

For repair work, a weld with minor porosity that fuses to both sides of the joint and carries load is functional. Reserve perfect welds for when lives depend on the joint — vehicle frames, pressure vessels, lifting equipment.

Practical First Projects

Before attempting any structural repair, practice on scrap steel until your beads are consistent.

1. Running flat beads on scrap plate: Just run parallel beads across a piece of flat stock. The first 50 beads teach you everything about arc control.
2. Butt joint (flat position): Tack two plates edge to edge, then weld the joint with one or two passes.
3. Fillet weld (T-joint): Stand one plate on another at 90 degrees and weld the joint. This is the most common joint in structural repair work.
4. Fill a gap: Find a cracked or broken piece of equipment with a simple gap. Clean, fit up, tack, weld. This is real work.