Content Extraction Summary

**Hook Options:** 1. Most welding schools start students on MIG because it is easier — this produces welders who cannot troubleshoot a failed weld under field conditions. 2. A 7018 electrode deposited at correct amperage produces a weld stronger than the base metal it joins. The joint is not a weakness. It is an upgrade. 3. Ninety percent of weld defects trace back to preparation, not technique. A perfect bead on a dirty joint will fail.

**Key Mechanism:** Fusion welding works by creating a shared molten pool between two pieces of base metal and (usually) a filler material. The pool solidifies into a metallurgical bond — atoms from both pieces interlock into a single crystal structure. Every process variable (amperage, voltage, travel speed, shielding) exists to protect that pool from contamination during the seconds it takes to freeze.

**Misconception to Correct:** MIG welding is not "easy welding" and stick welding is not "old welding." Stick (SMAW) remains the most versatile process on earth — it works in wind, rain, on rusty metal, underwater, and in remote locations with no gas supply. Learning it first builds the hand-eye coordination and arc-reading skills that transfer to every other process. Starting on MIG teaches wire-feeding, not welding.

**Practical Application:** A person who masters stick welding on 3/8" plate in the 3G (vertical) position can learn MIG in an afternoon, TIG in a week, and pass a structural certification within months. The reverse path — MIG first — typically takes three times longer to reach the same endpoint.

**Citation-Ready Claims:**

  • AWS D1.1 structural code requires minimum 60 ksi tensile strength for qualifying welds — E7018 electrodes exceed this at 70 ksi (AWS A5.1, Table 1).
  • Lincoln Electric's published data shows E7018 low-hydrogen electrodes reduce hydrogen-induced cracking by 70–80% compared to cellulosic electrodes like E6010 (Lincoln Electric Technical Brief, "Low Hydrogen Electrodes," 2019).
  • OSHA 29 CFR 1926.351 requires fire watch for a minimum of 30 minutes after welding operations cease in areas with combustible materials.
  • The Bureau of Labor Statistics reports median pay for welders at $47,010/year (2023), with pipeline and structural welders earning $70,000–$120,000+ depending on certification level and travel willingness (BLS Occupational Outlook Handbook, 2024).

Introduction

Every metal structure you trust with your life — bridges, buildings, pressure vessels, pipelines — holds together because someone created a metallurgical bond between two pieces of steel. Not a mechanical fastener. Not an adhesive. A bond where atoms from both pieces fuse into a single continuous structure.

Four processes dominate modern welding. Each exists because no single method handles every situation.

**Stick welding (SMAW)** uses a consumable electrode coated in flux. The flux burns to create shielding gas and slag, protecting the weld pool. It works anywhere — outdoors, in wind, on dirty or rusty metal, in the rain. No external gas supply needed. This is the process that built American infrastructure and still dominates pipeline, structural, and field repair work.

**MIG welding (GMAW)** feeds a continuous solid wire through a gun while flowing shielding gas from an external tank. It is faster than stick and easier to learn. It dominates shop fabrication, automotive work, and manufacturing. It does not work well outdoors because wind disperses the shielding gas.

**TIG welding (GTAW)** uses a non-consumable tungsten electrode to create the arc while the welder feeds filler rod by hand. It produces the highest-quality welds with the most precise heat control. It is the slowest process and the hardest to learn. It dominates aerospace, nuclear, food-grade piping, and any application where weld appearance and X-ray quality matter.

**Flux-core (FCAW)** uses a tubular wire filled with flux instead of a solid wire. Self-shielded flux-core works outdoors like stick welding but runs on a wire-feed machine. Dual-shield flux-core adds external gas for even higher quality. It dominates structural steel erection and shipbuilding because it deposits metal faster than any other manual process.

Why Learn Stick First

Stick welding is harder to learn than MIG. The electrode burns down, changing arc length constantly. The flux coating must be held at the correct angle or it contaminates the weld. Restarts require chipping slag and re-striking.

This difficulty is the point.

Stick welding forces you to read the arc — the sound, the color, the shape of the puddle. You learn what a good weld pool looks like because you have no choice. There is no wire feed speed to compensate for poor technique. There is no gas flow to mask contamination.

Every skill learned on stick transfers directly to other processes. The reverse is not true. A MIG welder who switches to stick starts from near-zero. A stick welder who picks up a MIG gun is running quality beads within hours.

Professional welding programs at institutions like Hobart Institute of Welding Technology and Tulsa Welding School start students on stick for exactly this reason. The harder entry point produces more capable welders faster.

1. Stick Welding (SMAW)

Shielded Metal Arc Welding is the backbone of field welding. The equipment is simple: a power source, a stinger (electrode holder), a ground clamp, and consumable electrodes. No gas bottles. No wire feeders. No regulators.

Electrode Selection

Electrodes are classified by a four-digit numbering system. Example: E7018.

  • **E** = Electrode
  • **70** = Minimum tensile strength in thousands of psi (70,000 psi)
  • **1** = All-position capability (1 = all positions, 2 = flat and horizontal only)
  • **8** = Flux coating type and current type

**Core Electrode Selection Chart:**

| Electrode | Tensile Strength | Position | Current | Primary Use | |-----------|-----------------|----------|---------|-------------| | E6010 | 60 ksi | All | DC+ only | Root passes, pipe welding, dirty/rusty steel. Deep penetration. Cellulosic coating burns fast and hot. The "farmer rod" — works on anything. | | E6011 | 60 ksi | All | AC or DC+ | Same as 6010 but runs on AC. Use when your machine does not have DC output. Slightly less penetration than 6010. | | E6013 | 60 ksi | All | AC or DC± | General purpose, sheet metal, light fabrication. Easy arc start, smooth bead, shallow penetration. Good for beginners learning bead placement. | | E7014 | 70 ksi | All | AC or DC± | Iron powder coating for higher deposition rate. Flat and horizontal fillet welds. Smooth, easy to run. | | E7018 | 70 ksi | All | AC or DC+ | Structural work, code welding, pressure vessels. Low-hydrogen coating minimizes cracking risk. Required by most structural codes. Must be stored in a rod oven at 250–300°F after opening. | | E7024 | 70 ksi | Flat/Horiz | AC or DC± | High deposition, flat fillets. Iron powder coating. "Drag rod" — lay it against the joint and drag. Not for vertical or overhead. |

The Three Rods Every Welder Needs

**6010** for getting into tight spots and burning through contamination. It digs deep and runs fast. The bead is rough — that is by design. It is a penetration rod, not a cover pass rod.

**6013** for general fabrication and learning. Smooth arc, easy starts, forgiving. It does not penetrate as deeply, which makes it better for thinner material where burn-through is a risk.

**7018** for anything structural. This is the rod that code welding is built on. Low-hydrogen coating means less risk of hydrogen cracking in thick or high-strength steel. It produces a smooth, strong bead with excellent mechanical properties. The tradeoff: 7018 is hygroscopic — the flux absorbs moisture from air. Exposed rods must be re-dried in a rod oven (250–300°F for one hour minimum per AWS D1.1 Section 5.3.2.1) or they will introduce hydrogen into the weld.

Amperage Settings by Rod Diameter

| Rod Diameter | Amperage Range | Typical Setting | Notes | |-------------|---------------|-----------------|-------| | 3/32" (2.4mm) | 40–90A | 65A | Sheet metal, thin wall tube, out-of-position work on thin stock. | | 1/8" (3.2mm) | 75–130A | 110A | Most common size. General fabrication. Good balance of deposition and control. | | 5/32" (4.0mm) | 110–170A | 140A | Heavy fabrication, flat and horizontal fills. Higher deposition rate. | | 3/16" (4.8mm) | 140–210A | 175A | Thick plate, production welding. Requires larger machine (200A+). | | 1/4" (6.4mm) | 200–320A | 260A | Heavy structural, large fillets. Industrial machines only. |

**Rule of thumb:** Multiply rod diameter in thousandths by 1. A 1/8" rod (125 thousandths) runs at roughly 125 amps. Adjust from there based on position (reduce 10–15% for vertical and overhead) and fit-up.

AC vs DC

**DC+ (DCEP — reverse polarity):** Electrode is positive, workpiece is negative. Two-thirds of the heat goes into the electrode, which melts the filler and drives penetration into the base metal. Standard for 6010, 7018, and most structural work.

**DC- (DCEN — straight polarity):** Electrode is negative. Two-thirds of heat goes into the workpiece. Used for surfacing/buildup applications and some TIG welding.

**AC (Alternating Current):** Polarity switches 120 times per second on 60Hz power. Useful for arc blow correction (DC creates magnetic fields that can deflect the arc) and for running 6011 and 6013 on transformer-based machines. AC machines are simpler and cheaper.

2. MIG Welding (GMAW)

Gas Metal Arc Welding feeds a continuous solid wire through a contact tip while shielding gas flows from a nozzle around the arc. The welder controls the gun trigger and travel speed. The machine controls wire feed speed (which sets amperage) and voltage.

The Wire Speed / Voltage Relationship

MIG welding has two primary adjustments. Understanding their interaction is the key to tuning.

**Wire feed speed (WFS)** controls amperage. More wire = more current required to melt it = higher amperage. On most machines, WFS is the primary heat control.

**Voltage** controls arc length. Higher voltage = longer arc = wider, flatter bead. Lower voltage = shorter arc = narrower, taller bead with more penetration.

**Tuning procedure:** Set WFS to produce the amperage needed for your material thickness. Then adjust voltage until the arc sounds like frying bacon — a steady, consistent crackle. A buzzing sound means voltage is too low. A hissing sound means voltage is too high.

Shielding Gas Selection

| Gas Mixture | Application | Characteristics | |------------|-------------|-----------------| | 75% Argon / 25% CO₂ (C25) | Mild steel — general purpose | Most popular mix. Good bead profile, moderate spatter, moderate penetration. The default choice for shop fabrication. | | 90% Argon / 10% CO₂ | Mild steel — thin gauge, appearance work | Less spatter than C25. Slightly less penetration. Cleaner bead appearance. | | 100% CO₂ | Mild steel — maximum penetration | Deepest penetration, most spatter. Cheapest gas. Used in heavy fabrication and structural work where penetration matters more than appearance. | | 100% Argon | Aluminum, stainless steel | Required for non-ferrous metals. Does not work well on mild steel (unstable arc, poor penetration). | | 98% Argon / 2% CO₂ | Stainless steel | Minimizes carbon pickup that would reduce corrosion resistance. Some shops use tri-mix (90% He / 7.5% Ar / 2.5% CO₂) for better penetration on thick stainless. |

Wire Diameter Selection

| Wire Diameter | Material Thickness | Amperage Range | Gas Flow Rate | |--------------|-------------------|---------------|---------------| | 0.023" (0.6mm) | 24 gauge – 16 gauge | 30–90A | 15–20 CFH | | 0.030" (0.8mm) | 22 gauge – 3/16" | 40–145A | 20–25 CFH | | 0.035" (0.9mm) | 16 gauge – 3/8" | 50–180A | 25–30 CFH | | 0.045" (1.1mm) | 3/16" – 1/2"+ | 75–250A | 25–35 CFH |

**Default recommendation:** 0.030" wire for material under 3/16", 0.035" wire for 3/16" and above. Most hobbyist and small-shop welders will use 0.030" for 90% of their work.

Transfer Modes

**Short circuit transfer** — The wire touches the workpiece and short-circuits, depositing metal in small droplets. Low heat input. Used for thin material and out-of-position work. Voltage: 14–22V.

**Globular transfer** — Large droplets form on the wire tip and fall into the puddle by gravity. Flat and horizontal only. Messy, high spatter. Exists between short circuit and spray — avoid this range.

**Spray transfer** — Above a threshold amperage/voltage, the wire produces a stream of tiny droplets that spray across the arc. High deposition, deep penetration, low spatter. Flat and horizontal only (too much heat for vertical/overhead). Requires argon-rich gas (80%+ Ar). Voltage: 24–34V.

**Pulsed spray** — The machine alternates between peak and background current, producing spray transfer at lower average heat input. Allows spray-quality welds in all positions. Requires an inverter-based power source with pulse capability.

3. TIG Welding (GTAW)

Gas Tungsten Arc Welding is the most precise welding process. The welder holds a torch with a non-consumable tungsten electrode in one hand and feeds filler rod with the other, while operating a foot pedal to control amperage in real time. The learning curve is steep. The results are unmatched.

Tungsten Selection

| Tungsten Type | Color Code | Current | Application | |--------------|-----------|---------|-------------| | 2% Thoriated (WT20) | Red | DC only | Steel, stainless, chromoly, titanium. Easiest to start. Best arc stability. Mildly radioactive — do not grind without ventilation. | | 2% Ceriated (WC20) | Gray/Orange | AC or DC | All metals. Non-radioactive alternative to thoriated. Excellent for low-amperage DC work. | | 2% Lanthanated (WL20) | Blue | AC or DC | All metals. Non-radioactive. Good all-around tungsten. Handles higher amperages than ceriated. | | Pure (WP) | Green | AC only | Aluminum. Forms a ball on AC, which provides good arc cleaning. Being replaced by ceriated and lanthanated. | | Tri-mix / E3 | Purple | AC or DC | All metals. Multi-oxide tungsten designed as universal replacement. Non-radioactive. |

**Recommendation:** Lanthanated (blue) for DC work on steel and stainless. Ceriated (gray) or E3 (purple) for AC aluminum. Thoriated works well but the radioactivity concern is real — avoid grinding thoriated tungsten indoors without a ventilation system.

Tungsten Preparation

For DC welding, grind the tungsten to a point. The taper length should be 2–2.5 times the electrode diameter. Grind lengthwise (parallel to the electrode axis), not across. Cross-grinding creates ridges that cause arc wander.

For AC welding on aluminum, start with a slight point, then strike an arc on a piece of scrap. The AC current will form a ball on the end. The ball diameter should not exceed 1.5 times the tungsten diameter. If it gets too large, re-grind and restart.

Filler Rod Selection

| Filler Rod | Base Metal | Notes | |-----------|-----------|-------| | ER70S-2 | Mild steel, low-alloy steel | Triple-deoxidized. More forgiving on contaminated steel than ER70S-6. | | ER70S-6 | Mild steel | Most common steel filler. Good wetting on clean material. | | ER308L | 304 stainless steel | "L" = low carbon, prevents sensitization (chromium carbide precipitation at grain boundaries). | | ER309L | Dissimilar metals (stainless to mild steel) | Higher chromium/nickel content bridges the composition gap. | | ER316L | 316 stainless steel | Matches 316 base metal. Contains molybdenum for pitting resistance. | | ER4043 | Aluminum (general, castings) | Easier to feed, less crack-sensitive. Lower strength than 5356. Good for 6061. | | ER5356 | Aluminum (structural, marine) | Higher strength, better corrosion resistance. Preferred for 5052, 5083, marine applications. Do not use on 6061 — cracking risk. | | ERCuSi-A | Silicon bronze | Brazing/welding copper, brass, dissimilar metals. Low heat input preserves base metal properties. |

Gas Lens vs Standard Collet

A standard collet body creates turbulent gas flow. The shielding gas exits the nozzle in a cone that breaks down into turbulence within about 3/8" of the cup.

A **gas lens** replaces the collet body with a brass fitting containing layered stainless mesh screens. These screens straighten the gas flow into a laminar column that extends 2–3 times farther from the cup. This means better shielding coverage, the ability to extend the tungsten further from the cup for better joint access, and lower gas consumption for equivalent protection.

Gas lenses cost $15–30. They are not optional for serious TIG work. Every professional TIG torch setup uses them.

AC vs DC for TIG

**DC Electrode Negative (DCEN):** Standard for steel, stainless, chromoly, copper alloys. Concentrates heat on the workpiece (about 70% of arc energy). Tungsten stays cool and holds a point. Deep, narrow penetration profile.

**AC:** Required for aluminum and magnesium. The electrode-positive half-cycle provides "cleaning action" — it breaks up the aluminum oxide layer (Al₂O₃, melting point 3,762°F) that sits on top of the aluminum (melting point 1,221°F). Without this cleaning, the oxide layer blocks fusion to the base metal. The electrode-negative half-cycle provides penetration. Modern inverter machines let you adjust the AC balance — more EN for deeper penetration, more EP for more cleaning.

**AC Frequency:** Higher frequency (80–250 Hz vs the default 60 Hz) focuses the arc into a tighter cone, giving more directional control and narrower bead. Lower frequency (20–40 Hz) widens the arc and cleaning zone. Adjustable AC frequency is an inverter-only feature.

4. Flux-Core Welding (FCAW)

Flux-core uses a tubular wire with flux inside instead of a solid wire. It runs on the same equipment as MIG — a wire feeder and constant-voltage power source. The difference is what happens at the arc.

Self-Shielded (FCAW-S)

The flux inside the wire generates its own shielding gas and slag when it burns. No external gas bottle needed. This makes self-shielded flux-core the only wire-feed process that works reliably outdoors in wind. It is the standard for structural steel erection, bridge work, and field welding where stick is too slow and MIG gas would blow away.

Common wires: E71T-8 (all position, code-rated), E71T-11 (all position, general purpose).

**Tradeoff:** Self-shielded flux-core produces more fume, more spatter, and a rougher bead than MIG or dual-shield. The slag must be chipped between passes. Penetration is moderate.

Dual-Shield (FCAW-G)

Combines flux-core wire with external shielding gas (usually 75/25 or 100% CO₂). The gas provides additional shielding while the flux provides deoxidizers and alloying elements. This produces the highest deposition rates of any semi-automatic process — up to 25+ lbs/hr on large groove welds.

Common wires: E71T-1 (all position), E71T-12 (all position, low spatter).

**When to choose flux-core over solid MIG wire:**

  • Material thickness over 3/8" — flux-core deposits more metal per pass
  • Outdoor work with any wind — self-shielded FCAW-S eliminates gas loss
  • Structural work requiring code compliance — certain flux-core wires are qualified for seismic and bridge applications
  • Overhead and vertical welding on thick plate — flux-core slag supports the puddle in out-of-position work

5. Joint Types and Preparation

Every weld joint requires specific preparation. The geometry of the joint determines how the weld metal fills the gap and fuses to both pieces. Poor fit-up causes more weld defects than poor technique.

Butt Joint

Two pieces aligned edge-to-edge in the same plane. The most tested joint type in code welding.

  • **Material up to 3/16":** Square edges, 1/16" root gap, no bevel required. Full penetration achievable from one side.
  • **Material 3/16" to 3/8":** Single-V groove. Bevel each piece 30° (60° included angle). Leave 1/16"–3/32" root face (the unbeveled flat at the bottom of the groove). Root gap 1/16"–3/32". First pass (root pass) with 6010 or TIG. Fill and cap with 7018, MIG, or flux-core.
  • **Material over 3/4":** Double-V groove (bevel both sides). Reduces filler metal required by 50% compared to single-V. Requires access to both sides.
  • **Root face** too thin = burn-through. Root face too thick = lack of penetration. Target 1/16" for most applications.

Lap Joint

One piece overlaps the other. Welded with fillet welds along one or both edges. No beveling required. The most common joint in structural steel and fabrication.

  • Clean the overlap area — contaminants trapped between plates cause porosity.
  • Minimum overlap should be 3x the thinner material thickness (AWS D1.1 recommendation).
  • Gap between plates should be less than 1/16" for optimal fillet weld quality.

T-Joint

One piece perpendicular to another, forming a T shape. Welded with fillet welds on one or both sides.

  • No beveling required for fillets up to 3/4" leg size.
  • For full-penetration T-joints (code-required in some applications), bevel the vertical member to 45° and weld a groove weld with fillet reinforcement.
  • Ensure the vertical member is truly square — a 2° lean compounds across a long weld.

Corner Joint

Two pieces meet at a corner. Open corner (pieces at 90° with edges exposed) or closed corner (one piece overlaps the end of the other).

  • **Open corner on thin material:** Fuse the edges together with no filler (autogenous weld) or light filler pass.
  • **Open corner on thick material:** Bevel exterior side 30–45° for groove weld access.
  • **Closed corner:** Fillet weld the interior. Stronger configuration because the overlap adds bearing area.

Edge Joint

Two pieces side by side with edges aligned upward. Used mainly for sheet metal, flanges, and non-structural joining. Not suitable for load-bearing applications — the weld only penetrates the edges, not the full thickness.

6. Equipment Selection

Machine Selection Guide

| Budget | Machine Type | Output | Best For | Limitations | |--------|-------------|--------|----------|-------------| | $200–$400 | Transformer stick (AC only) | 100–225A AC | Farm/ranch repair, learning stick, fence posts, trailers. | No DC output. Cannot run 6010. Heavy (80–120 lbs). | | $400–$700 | Inverter stick (AC/DC) | 140–200A AC/DC | Field repair, fabrication, structural practice. | No wire feed capability. | | $500–$900 | MIG (wire feed, 120/240V) | 140–210A | Home shop, auto body, furniture, light fabrication. | 120V models limited to ~140A (thin material only). | | $800–$1,500 | Multi-process inverter | 200A AC/DC | Stick + TIG + MIG capability. Best value for learning all processes. | Jack-of-all-trades machines may compromise on individual process quality. | | $1,500–$3,000 | Industrial MIG or TIG | 250–350A | Production shop, code welding, aluminum TIG. | Dedicated to one process. Requires 240V single-phase or 3-phase. | | $3,000–$8,000 | Synergic MIG / Pulse TIG | 300–500A | Professional fabrication, aerospace, pipe welding. | Requires 240V. Often needs 3-phase power for full output. |

Duty Cycle Explained

Duty cycle is the percentage of a 10-minute period that the machine can weld at rated output before overheating. A machine rated "200A at 30% duty cycle" can weld at 200 amps for 3 minutes, then must cool for 7 minutes.

**Critical detail:** Most hobbyist machines are rated at 20% duty cycle at maximum output. At lower amperages, duty cycle increases. A 200A/20% machine might deliver 100% duty cycle at 120A. Check the manufacturer's duty cycle curve, not just the headline number.

For home shop and farm use, 20–30% duty cycle is adequate — most welds take 30–60 seconds. For production environments, 60–100% duty cycle at working amperage is the minimum.

Input Power Requirements

**120V (standard household outlet):** Limits maximum output to roughly 140A. Adequate for MIG welding material up to 3/16" and stick welding with 3/32" and 1/8" rods. Requires a dedicated 20A circuit — do not share with other tools.

**240V single-phase:** Standard for most shop welders. Provides full output capability (200–300A). Requires a dedicated 50A breaker and 6-gauge wire (for 50A) or 8-gauge (for 40A). A dryer outlet (NEMA 14-30 or 14-50) works for most 240V welders.

**240V or 480V three-phase:** Industrial machines. Higher efficiency, smoother arc. Requires commercial electrical service or a phase converter (rotary phase converters work; static converters do not work well with welders).

Essential Accessories

  • **Auto-darkening helmet** — Shade 9–13 variable, with grind mode. Minimum $80 for reliable sensors. Cheap helmets have slow reaction times that cause arc flash exposure. Lincoln Viking, Miller Digital Infinity, and ESAB Sentinel are industry standards.
  • **Welding gloves** — Stick/MIG: heavy leather gauntlets. TIG: thin goatskin for dexterity. Never use damaged gloves — a pinhole burns through.
  • **Angle grinder** — 4.5" with flap discs (40 and 80 grit), grinding wheels, and cut-off wheels. Non-negotiable. You will use this more than the welder.
  • **Chipping hammer and wire brush** — For slag removal on stick and flux-core welds.
  • **Welding clamps and magnets** — Strong-hand clamps, C-clamps, magnetic squares. Good fixturing is half the job.
  • **Soapstone or welding marker** — For marking cut lines and joint positions.
  • **Square and tape measure** — You cannot weld what you cannot measure. A combination square checks 90° and 45° — carry one at all times.

7. Safety

Welding creates hazards in four categories: radiation, heat, fume, and electricity. All four can injure or kill. None are optional to address.

Arc Flash — Shade Selection

The welding arc produces ultraviolet radiation intense enough to burn the cornea (photokeratitis, or "arc flash") in seconds. Infrared radiation causes retinal damage with longer exposure. Proper shade selection is not preference — it is medical necessity.

| Process | Amperage Range | Minimum Shade | Recommended Shade | |---------|---------------|---------------|-------------------| | SMAW (Stick) | Under 60A | 7 | 10 | | SMAW (Stick) | 60–160A | 8 | 10–11 | | SMAW (Stick) | 160–250A | 10 | 12 | | SMAW (Stick) | 250–550A | 11 | 14 | | GMAW (MIG) | Under 60A | 7 | 10 | | GMAW (MIG) | 60–160A | 10 | 11 | | GMAW (MIG) | 160–250A | 10 | 12 | | GMAW (MIG) | 250–500A | 10 | 14 | | GTAW (TIG) | Under 50A | 8 | 10 | | GTAW (TIG) | 50–150A | 8 | 10–12 | | GTAW (TIG) | 150–500A | 10 | 14 | | FCAW (Flux-core) | 60–160A | 10 | 11 | | FCAW (Flux-core) | 160–250A | 10 | 12 |

Shade guide based on ANSI Z49.1:2012, Table 1.

Fume Extraction

Welding fume contains metal oxides, fluorides (from 7018 flux), manganese compounds, and (on certain base metals) hexavalent chromium. Long-term exposure causes manganism (a Parkinson's-like neurological condition), lung fibrosis, and cancer.

**Minimum protection:** Weld outdoors or in a well-ventilated space with natural cross-ventilation. Position yourself upwind of the plume.

**Better:** Portable fume extractor with a flexible arm, positioned 12–18 inches from the arc. HEPA or activated carbon filter rated for welding fume (MERV 15+).

**Best:** Overhead hood extraction system pulling 150+ CFM per welding station, ducted to exterior exhaust.

**Respirator requirements:** When ventilation is inadequate, wear a P100 half-face respirator at minimum. For stainless steel, galvanized steel, or any coated metal, an air-purifying respirator with combination OV/P100 cartridges is the minimum. Galvanized steel (zinc-coated) produces zinc oxide fume that causes "metal fume fever" — flu-like symptoms within 4–12 hours of exposure.

Fire Watch and Hot Work Permits

Per OSHA 29 CFR 1926.352:

  • Remove all combustible material within a 35-foot radius of the welding operation, or protect it with fire-resistant covers.
  • A fire watch must be maintained for a minimum of 30 minutes after welding ceases.
  • Fire extinguisher rated minimum 2A:10B:C must be immediately accessible.

**Hot work permits** are required in many commercial and industrial settings before any welding, cutting, or grinding operation. The permit documents: location, hazards identified, precautions taken, fire watch assignment, and the time window for the work.

PPE Checklist

  • [ ] Auto-darkening helmet with correct shade for process and amperage
  • [ ] Safety glasses worn under the helmet (UV protection for peripheral exposure)
  • [ ] Welding gloves appropriate to process (gauntlet for stick/MIG, goatskin for TIG)
  • [ ] Long-sleeve welding jacket or flame-resistant shirt — cotton minimum, leather preferred
  • [ ] Leather boots — no synthetic uppers (they melt). Steel toe required in industrial settings.
  • [ ] Hearing protection in high-amperage or grinding operations
  • [ ] Welding cap or bandana to protect scalp from overhead sparks
  • [ ] No synthetic clothing under welding gear — polyester melts to skin

8. Troubleshooting

Every weld defect has a cause. Finding it requires understanding what went wrong in the molten pool. Here are the most common defects, their root causes, and fixes.

Porosity

**Appearance:** Small round holes (gas pockets) scattered through or on the surface of the weld.

**Causes:**

  • Contamination — oil, paint, rust, moisture, zinc coating on base metal
  • Insufficient shielding gas flow (MIG/TIG) — check regulator, hose connections, and nozzle for spatter blockage
  • Excessive shielding gas flow — turbulence at the nozzle pulls in atmospheric contamination. More gas is not better. Stay within recommended CFH range.
  • Wind disrupting gas coverage (MIG/TIG outdoors)
  • Wet electrodes (stick — 7018 absorbs moisture)
  • Arc length too long — the arc outruns the gas shield

**Fix:** Clean the joint to bright metal within 1" of the weld zone. Check gas flow rate. Shorten arc length. Dry electrodes. Block wind or switch to a flux-shielded process.

Undercut

**Appearance:** A groove melted into the base metal along the edge of the weld, unfilled by weld metal. Creates a stress riser that concentrates fatigue cracking.

**Causes:**

  • Amperage too high
  • Travel speed too fast — the arc melts the base metal edge but the puddle moves on before filling it
  • Incorrect torch/electrode angle — directing the arc at the base metal edge instead of the joint root
  • Arc length too long

**Fix:** Reduce amperage 5–10%. Slow travel speed. Direct the arc into the joint, not the sidewalls. Shorten arc length. On multipass welds, pause at the toes (edges) of the bead to allow fill.

Lack of Fusion

**Appearance:** The weld metal sits on top of the base metal without actually melting into it. May look acceptable on the surface but will fail under load. Only reliably detected by bend test or X-ray.

**Causes:**

  • Amperage too low — insufficient heat to melt base metal
  • Travel speed too fast — not enough time for the puddle to wet out
  • Improper joint preparation — insufficient root gap or bevel angle
  • Cold lap — the puddle rolls over unmelted base metal, common on MIG welds with too much wire speed relative to voltage
  • Oxide layer on aluminum blocking fusion (insufficient AC cleaning in TIG, or MIG without oxide removal)

**Fix:** Increase amperage. Slow travel speed. Ensure proper bevel angle and root gap. Watch the leading edge of the puddle — you should see the base metal melting ahead of the advancing pool. If the pool is just rolling over the surface, you have a fusion problem.

Burn-Through

**Appearance:** Holes melted completely through the base metal. Common on thin sheet metal and root passes on pipe.

**Causes:**

  • Amperage too high for material thickness
  • Travel speed too slow
  • Root gap too wide
  • Root face too thin or absent

**Fix:** Reduce amperage. Increase travel speed. Tighten root gap. On thin sheet metal, use skip-welding (tack, skip, tack) to control heat input. On pipe root passes, use the "keyhole" technique — maintain a visible keyhole at the leading edge of the puddle and keep it a consistent size by modulating amperage with the foot pedal (TIG) or adjusting travel speed.

Excessive Spatter

**Appearance:** Small metal droplets scattered around the weld, adhered to the base metal surface.

**Causes:**

  • Voltage too low (MIG) — the wire stubs into the puddle instead of transferring smoothly
  • Voltage too high (MIG) — excessive arc length creates large unstable droplets
  • Wire feed speed mismatched to voltage
  • Contaminated or rusty wire
  • Wrong gas mixture or insufficient gas flow
  • Arc length too long (stick)

**Fix:** Adjust voltage to achieve a smooth crackling sound. Clean or replace wire. Check gas flow and mixture. Apply anti-spatter spray to surrounding surfaces if needed (does not fix root cause, only eases cleanup).

Cracking

The most serious weld defect. A cracked weld is a failed weld. Period.

**Hot cracking** occurs while the weld is solidifying. Caused by high sulfur or phosphorus content in the base metal, excessive restraint on the joint, or a concave bead profile (creates tension on the surface as it shrinks).

**Cold cracking (hydrogen-induced)** occurs hours or days after welding. Caused by hydrogen trapped in the weld from moisture in electrodes, flux, or shielding gas. Most common in high-strength steels and thick sections. This is why 7018 electrodes must be kept dry and why preheat is specified for thick or high-carbon steel.

**Fix:** For hot cracking — reduce travel speed to produce a convex bead. Check base metal chemistry (mill cert). Reduce restraint by changing weld sequence. For cold cracking — use low-hydrogen electrodes (7018), store rods in oven, preheat base metal per code requirements (typically 200–400°F for steels over 1" thick or carbon content above 0.30%), and allow slow cooling (post-heat or insulating blankets).

9. Certification Path

AWS D1.1 Structural Welding Code

AWS D1.1 is the dominant structural welding code in the United States. It governs welding on buildings, bridges, and other steel structures. Passing a D1.1 qualification test proves you can produce a sound weld under controlled conditions.

**What the test involves:**

  • Weld a test coupon (plate or pipe) in a specified position using a specified process
  • The coupon is cut into specimens and subjected to guided bend tests (face bend, root bend, side bend) or tensile tests
  • On critical applications, radiographic (X-ray) examination is used instead of or in addition to bend tests
  • A single defect exceeding 1/8" in any dimension on a bend specimen is cause for failure

Positions

| Position Code | Description | Difficulty | |--------------|-------------|------------| | 1G / 1F | Flat groove / Flat fillet | Lowest — gravity helps pool the metal | | 2G / 2F | Horizontal groove / Horizontal fillet | Moderate — gravity pulls puddle down on grooves | | 3G / 3F | Vertical groove / Vertical fillet | High — must work against gravity (uphill technique) | | 4G / 4F | Overhead groove / Overhead fillet | Highest — gravity pulls puddle away from joint | | 6G | Pipe, 45° fixed (all positions combined) | Master qualification — passing 6G qualifies all positions |

**Qualification logic:** Passing a higher-position test qualifies you for all lower positions. A welder who passes 3G and 4G plate is qualified for 1G, 2G, 3G, and 4G. A welder who passes 6G pipe is qualified for all plate and pipe positions.

Career Value

The Bureau of Labor Statistics reports 427,300 welding jobs in the United States with a median salary of $47,010 as of 2023. That median obscures significant range. Code-certified structural welders earn $60,000–$80,000 in shop environments. Pipeline welders with 6G qualifications and travel willingness earn $70,000–$120,000+. Underwater welders, nuclear welders, and aerospace TIG specialists can exceed $150,000.

Certification is the dividing line. An uncertified welder competes on price. A certified welder competes on capability. AWS certification costs $300–$1,000 for testing and is valid for 6 months (must be maintained through continued employment or retesting). The return on that investment is measured in multiples, not percentages.

1. **Learn stick welding** on mild steel plate. Run pads of beads until they are consistent. Move to T-joints (fillets), then butt joints (grooves). Master flat position, then horizontal, then vertical-up with 7018. 2. **Pass 3G and 4G plate tests** with 7018. This qualifies all plate positions and proves structural competency. 3. **Learn MIG and flux-core** for production efficiency. The stick foundation makes this fast. 4. **Learn TIG** on steel first (DCEN, lanthanated tungsten, ER70S-2 filler). Then move to stainless. Then aluminum (AC). 5. **Pursue 6G pipe** if pipeline or pressure vessel work is the goal. This is the highest-value single certification in the trade.

10. Sources

1. AWS A5.1/A5.1M:2012 — Specification for Carbon Steel Electrodes for Shielded Metal Arc Welding. American Welding Society. 2. AWS D1.1/D1.1M:2020 — Structural Welding Code — Steel. American Welding Society. 3. Lincoln Electric. "Low Hydrogen Electrodes." Technical Brief, 2019. 4. ANSI Z49.1:2012 — Safety in Welding, Cutting, and Allied Processes. American Welding Society. 5. OSHA 29 CFR 1926.351 — Arc Welding and Cutting. Occupational Safety and Health Administration. 6. Bureau of Labor Statistics. "Welders, Cutters, Solderers, and Brazers." Occupational Outlook Handbook, 2024. 7. Miller Electric. "Guidelines for Gas Metal Arc Welding (GMAW)." Application Guide, 2021. 8. Lincoln Electric. "The Procedure Handbook of Arc Welding." 14th Edition, 2000. 9. Hobart Institute of Welding Technology. "Welding Electrode Classification Systems." Training Reference, 2020. 10. NIOSH Publication No. 88-110 — "Criteria for a Recommended Standard: Welding, Brazing, and Thermal Cutting." National Institute for Occupational Safety and Health.

`[practical-skills]` `[facility-design]` `[advanced]`