Welding, Cutting & Steel Finishing

Welding is one of the most skilled trades on any job site, and on a church project it’s everywhere — moment connections on steel frames, base plates anchored to foundations, handrail assemblies in sanctuaries, and miscellaneous metals that tie the whole building together. This guide covers the core welding, cutting, and finishing skills our crews and subtrades use in the field and in the shop. Whether you’re a CWB-qualified journeyperson or an apprentice picking up your first stinger, there’s something in here for you.

1. SMAW (Stick) Welding — Skill 3.03

Shielded Metal Arc Welding — the process that built every bridge, building, and pipeline in this country before fancy wire feeders showed up. SMAW uses a consumable electrode coated in flux that melts to form a protective slag over the weld pool. It’s portable, versatile, and works in positions and conditions that make other processes cry.

Electrode Selection

E7018 is the workhorse of structural welding. It’s a low-hydrogen electrode that produces 70 ksi (480 MPa) tensile strength weld metal with excellent ductility. The “18” designation means it runs on AC or DCEP in all positions. E7018 is required for virtually all structural connections on church construction projects.

E6010 is a cellulosic electrode that digs deep — it’s the root pass rod of choice when you need penetration through mill scale, rust, or less-than-perfect fit-up. It runs on DCEP only and produces a forceful, digging arc. You’ll see E6010 used for root passes on open-root groove welds, followed by E7018 fill and cap passes.

Other electrodes you may encounter: E7024 (iron powder, flat/horizontal only, high deposition for shop work), E6011 (AC version of E6010 for field generators without DC capability), and E4918 (CSA equivalent designation for low-hydrogen electrodes meeting CSA W48).

Rod Storage — This Actually Matters

Low-hydrogen electrodes like E7018 are extremely moisture-sensitive. Absorbed moisture introduces hydrogen into the weld metal, causing hydrogen-induced cracking (also called “cold cracking” or “underbead cracking”). CSA W59 Clause 5.3 has strict requirements:

• Hermetically sealed containers: Electrodes in unopened, factory-sealed cans may be used directly without reconditioning.
• Holding ovens: Once opened, E7018 rods must be stored in a holding oven at 120 °C (250 °F) minimum. Portable rod ovens on the ironworker’s belt keep rods warm in the field.
• Exposure limits: E7018 rods may be out of the oven for a maximum of 4 hours (CSA W59). After that, they must be reconditioned at 370 °C (700 °F) for 1 hour, and this can only be done once.
• E6010/E6011: These are cellulosic electrodes and actually need some moisture to run properly. Do not put them in a rod oven — store at room temperature in a dry area.

Amperage, Travel Speed & Bead Patterns

Amperage settings depend on electrode diameter, position, and joint type. Here are starting points for E7018:

• 3/32″ (2.5 mm): 70–110 A — used for thin material, root passes, out-of-position work
• 1/8″ (3.2 mm): 110–150 A — the most common size for field structural work
• 5/32″ (4.0 mm): 140–200 A — higher deposition for flat and horizontal fillets
• 3/16″ (4.8 mm): 180–255 A — flat position only, heavy structural shop work

Travel speed controls bead width and heat input. Too fast and you get a skinny, convex bead with poor tie-in. Too slow and you build up excess reinforcement, overheat the base metal, and risk undercut. A good rule: the arc should stay at the leading edge of the puddle, not behind it.

Bead patterns: For flat and horizontal fillets, a slight weave or “Christmas tree” pattern gives good fusion to both legs. For vertical-up, a triangular weave with pauses at each side wall ensures proper tie-in. Overhead, keep it tight — stringer beads with minimal weave prevent the puddle from dripping on your neck.

Multi-Pass Technique

Any weld larger than about 8 mm (5/16″) in a single pass is asking for trouble — incomplete fusion, excessive heat input, and distortion. Multi-pass welding builds the weld in layers:

1. Root pass: The first bead in the joint. Must achieve full fusion to both members. Often done with E6010 for penetration on open-root joints, or E7018 on backing-bar joints.
2. Hot pass: Immediately follows the root pass to burn out any slag inclusions and refine the root profile. Run hot and fast.
3. Fill passes: Build up the joint to near-flush. Use stringer beads or slight weave. Each pass must be cleaned of slag before the next.
4. Cap pass: The final, visible bead. Should be uniform in width, slightly convex, with smooth tie-in to the base metal. This is what the inspector sees first.

2. GMAW (MIG) Welding — Skill 3.04

Gas Metal Arc Welding feeds a continuous solid wire electrode through a gun, shielded by an externally supplied gas. It’s faster than stick, produces less slag, and requires less operator skill for basic joints. On HCMI projects, you’ll see MIG welding primarily in shop fabrication, though it shows up in the field for miscellaneous metals and lighter structural work.

Wire Types & Shielding Gas

ER70S-6 is the standard wire for structural carbon steel. The “S-6” designation means it has higher silicon and manganese deoxidizers, which improve wetting and produce a smoother bead — especially useful on mill scale. Common diameters: 0.035″ (0.9 mm) for thin material, 0.045″ (1.2 mm) for general structural work.

Shielding gas: The standard mix for structural steel is 75% Argon / 25% CO₂ (often called “C-25”). This mix gives a stable arc, good penetration, and minimal spatter. Flow rate: 35–45 CFH (16–21 L/min). Pure CO₂ is cheaper and gives deeper penetration but produces significantly more spatter. Pure argon is used for aluminum and stainless — never for carbon steel structural work.

Transfer Modes

Short-circuit transfer operates at lower voltage and wire feed speed. The wire physically touches the puddle and shorts out, transferring metal in small droplets. Best for thin material (under 6 mm), root passes, and out-of-position work. Settings: 17–22 V, 150–250 IPM wire feed.

Spray transfer operates at higher voltage and wire feed. Tiny droplets stream across the arc in a fine spray — no short-circuiting. High deposition rates and excellent fusion, but it produces a large, fluid puddle that limits use to flat and horizontal positions. Settings: 26–32 V, 300–500 IPM wire feed. This is the production mode for shop welding.

Shop vs. Field Use

MIG welding dominates in the fabrication shop because of speed and consistency. In the field, it’s limited by one major weakness: wind. Even a light 10 km/h breeze can blow the shielding gas away from the weld pool, causing porosity. Field MIG work requires wind screens or sheltered conditions. For exposed field structural welding, FCAW (flux-cored) is almost always the better choice.

3. FCAW (Flux-Cored) Welding — Skill 3.05

Flux-Cored Arc Welding is the go-to process for field structural welding in Ontario. It uses a tubular wire electrode filled with flux, giving you the deposition rate of MIG welding with the wind tolerance of stick. It’s what built most of the steel churches, schools, and commercial buildings across this province.

Self-Shielded vs. Gas-Shielded

Self-shielded FCAW (FCAW-S): The flux core generates its own shielding gas when it burns — no external gas bottle required. This makes it the king of field work. Wires like E71T-8 (all-position, low hydrogen) and E70T-6 (flat/horizontal, high deposition) are standard. Wind tolerance is excellent — usable in winds up to 35 km/h, far beyond what any gas-shielded process can handle.

Gas-shielded FCAW (FCAW-G): Uses an external shielding gas (typically 75/25 Ar/CO₂ or 100% CO₂) in addition to the flux core. Wires like E71T-1 give better bead appearance and lower spatter than self-shielded, but have the same wind sensitivity as MIG. Used primarily in shop fabrication or sheltered field conditions.

Slag Removal & Common Defects

FCAW produces slag just like stick welding, and it must be completely removed between passes. The slag from self-shielded wires can be particularly tenacious — use a chipping hammer followed by a wire brush, then inspect before the next pass. Common FCAW defects:

• Worm tracks: Small, elongated porosity that looks like worm holes on the surface. Usually caused by moisture in the wire or excessive contact-tip-to-work distance (stickout).
• Slag inclusions: Trapped slag between passes from inadequate cleaning. Detectable by UT inspection.
• Excessive spatter: Usually caused by voltage too high for the wire feed speed, or wrong polarity. Self-shielded FCAW runs on DCEN (electrode negative) — check your leads.

4. GTAW (TIG) Welding — Skill 3.06

Gas Tungsten Arc Welding is the precision process — the one you pull out when the work is visible, the material is exotic, or the tolerances are surgical. On church projects, TIG welding shows up in some very specific places.

When TIG Shows Up on Church Projects

• Stainless steel handrails and guardrails: Lobby and sanctuary railings that must be both structural and beautiful. No grinding allowed — the weld is the finish.
• Ornamental metalwork: Crosses, decorative screens, artistic features. Often thin-gauge stainless or mild steel.
• Aluminum: Curtain wall framing repairs, storefront modifications, signage supports.
• Stainless kitchen equipment: Commercial kitchen counter and equipment connections in church kitchens and fellowship halls.

Filler Rod & Gas

Filler rods: ER308L for 304 stainless, ER316L for 316 stainless, ER70S-2 for carbon steel, ER4043 for general aluminum, ER5356 for structural aluminum. Rod diameter should match or be slightly less than material thickness — 1/16″ (1.6 mm) and 3/32″ (2.4 mm) are most common for church construction work.

Shielding gas: 100% Argon, always. Flow rate: 15–25 CFH (7–12 L/min). For aluminum, increase to 20–30 CFH. Use a gas lens in the torch cup for better gas coverage — it produces a wider, more laminar gas flow that protects more of the weld zone. Cup size: #6 (3/8″) minimum, #8 (1/2″) preferred.

Heat Control on Thin Material

TIG welding thin stainless (1.5–3 mm) is where skill really matters. Too much heat and you blow through or cause excessive discolouration (purple/black oxide instead of the golden straw colour that indicates proper heat). Techniques:

• Use a foot pedal for amperage control — allows real-time heat modulation.
• Pulse settings: 1–5 pulses per second on thin stainless lets the base metal cool between pulses. Set background current to 20–30% of peak current.
• Back-purge the inside of stainless tube and pipe with argon to prevent oxidation (sugaring) on the back side of the weld.
• Heat sinks: Copper backing bars or wet rags behind the weld area draw heat away.

5. Oxy-Fuel Cutting — Skill 3.07

Oxy-fuel (oxy-acetylene) cutting has been on construction sites since before your grandfather was born, and it’s still here because it does things nothing else can — cuts thick steel in remote locations with no electricity, heats frozen bolts, bends plates, and preheats joints. Every ironworker and welder needs to be proficient with a torch.

Equipment Setup

1. Cylinder inspection: Check for damage, proper caps, secure chain restraint (cylinders must be chained upright per O. Reg. 213/91 s. 123). Verify test dates — cylinders must be re-tested every 10 years (TSSA).
2. Regulator installation: Crack the cylinder valve momentarily to clear debris (stand to the side). Install regulators — right-hand thread for oxygen (green), left-hand thread for acetylene (red/brass with notched nut).
3. Regulator settings: Oxygen — 25–40 psi working pressure for cutting, up to 60 psi for heavy cuts. Acetylene — never exceed 15 psi (103 kPa). Above 15 psi, acetylene becomes unstable and can spontaneously decompose (explode). This is not a guideline — it’s physics.
4. Flashback arrestors: Must be installed at both regulators. Check-valves alone are not sufficient. Inspect and replace per manufacturer’s recommendations.
5. Tip selection: Match the tip size to the material thickness. For a Victor-style torch: #0 tip for up to 6 mm (1/4″), #1 for 6–12 mm, #2 for 12–25 mm, #3 for 25–50 mm, #4 for 50–100 mm, #5 for 100–150 mm.

Cutting Technique

Oxy-fuel cutting works by preheating steel to its kindling temperature (~870 °C / 1,600 °F) and then blasting it with a high-pressure oxygen jet. The steel doesn’t melt — it oxidizes (burns) and the oxygen stream blows the molten oxide out the bottom of the cut. This is why oxy-fuel only works on ferrous metals — stainless, aluminum, and copper don’t oxidize the same way.

1. Light the torch with acetylene only, then add oxygen to get a neutral preheat flame (equal-length inner cones).
2. Hold the preheat flames 3–5 mm above the steel surface at the starting edge until it reaches bright cherry red.
3. Slowly press the cutting oxygen lever. The steel should start cutting immediately with a shower of sparks out the bottom.
4. Move the torch along the cut line at a steady speed. The preheat flames lead slightly — about 3–5 mm ahead of the cut.
5. Kerf width: Approximately 1.5–3 mm for thin material, up to 5–6 mm for plate over 50 mm thick. Account for kerf when measuring your cuts.

6. Plasma Cutting — Skill 3.08

Plasma cutting uses a constricted arc to ionize compressed air (or nitrogen/argon) into a plasma jet reaching 20,000 °C. It melts and blows through metal faster and cleaner than oxy-fuel on material under 25 mm, and it cuts stainless and aluminum that oxy-fuel can’t touch.

Amperage vs. Thickness

Plasma cutter sizing is rated by maximum severance cut thickness, but the rated cut thickness (where you get a quality edge) is typically 60–70% of the maximum:

• 30 A unit: Quality cut up to 8 mm (5/16″), severance to 12 mm — sheet metal and light gauge
• 45 A unit: Quality cut up to 12 mm (1/2″), severance to 16 mm — most miscellaneous steel on site
• 65 A unit: Quality cut up to 20 mm (3/4″), severance to 25 mm — structural angles and plates
• 85–105 A unit: Quality cut up to 25–32 mm (1–1-1/4″), severance to 38 mm — heavy structural

When Plasma Beats Oxy-Fuel

Use plasma when: the material is under 25 mm (faster, cleaner edge), the material is stainless or aluminum (oxy-fuel won’t work at all), you need precision on complex shapes (tighter kerf, less heat distortion), or you’re doing high-volume repetitive cuts (especially on CNC tables). Use oxy-fuel when: the material is over 25 mm thick, you don’t have electricity, you also need to heat or bend material, or you’re in a remote location with only cylinders available.

7. CWB Certification & Welding Procedure Specifications

The Canadian Welding Bureau (CWB) is the national certification body for welding in Canada. If you’re welding structural steel on any HCMI project, you must be qualified through CWB. There are no shortcuts, no exceptions, and no “yeah but I’ve been welding for 20 years” exemptions. The code doesn’t care about your experience — it cares about your test coupons.

What CWB Certification Means

CWB certification operates at two levels:

• Company certification (Division 1 or 2): The welding company must be CWB-certified, with documented quality control, qualified welding supervisors, and approved Welding Procedure Specifications (WPS). Structural steel subtrades must hold valid CWB company certification per CSA W47.1.
• Welder qualification: Each individual welder must pass performance qualification tests for specific processes, positions, and material thicknesses. Qualification is valid for 2 years, provided the welder continues to use the process. Qualification records and welder ID stamps must be available on site.

Welding Procedure Specifications (WPS)

A WPS is the recipe for a weld. It documents every variable: process, electrode/wire, shielding gas, preheat, interpass temperature, amperage range, voltage range, travel speed, joint design, and position. Every structural weld must be made in accordance with a written WPS that has been qualified by procedure qualification testing per CSA W59.

Position Qualifications

CWB qualification testing is position-specific. A welder qualified in the flat position (1G/1F) is not qualified for vertical (3G/3F) or overhead (4G/4F). Position qualifications and what they cover:

• 1G/1F (Flat): Flat position groove and fillet welds only.
• 2G/2F (Horizontal): Covers flat and horizontal.
• 3G/3F (Vertical): Covers flat, horizontal, and vertical.
• 4G/4F (Overhead): Covers all four positions — the full qualification.

AWS equivalence: CWB qualifications are based on CSA W47.1 and CSA W59, while AWS uses AWS D1.1 (Structural Welding Code — Steel). The processes and positions are similar, but the codes are not interchangeable. American-qualified welders working in Ontario on CSA W59 projects must re-qualify under CWB.

Welder ID Stamps

Each CWB-qualified welder is assigned a unique identification stamp. This stamp must be applied adjacent to every structural weld they make. The stamp links the weld to the welder, so if an inspection reveals a defect, the responsible welder can be identified. It’s quality control and accountability in a single punch mark.

8. Weld Inspection & Defects

Every structural weld is subject to inspection. Some get a visual look from the welding supervisor. Some get an ultrasonic scan from a CWB inspector that reveals every buried flaw. Knowing what inspectors look for — and how defects happen — makes you a better welder.

Visual Inspection Criteria

Visual inspection (VT) is the first and most common inspection method. The CWB inspector or welding supervisor checks for:

• Undercut: A groove melted into the base metal along the toe of the weld. CSA W59 limits undercut to 1 mm depth for statically loaded structures. Caused by excessive heat, wrong electrode angle, or travel speed too fast.
• Porosity: Gas pockets trapped in the weld metal. Surface porosity is visible; subsurface porosity requires UT or RT. Caused by moisture (wet rods, damp base metal), contamination (oil, paint, rust), or loss of shielding gas.
• Incomplete fusion (cold lap): The weld metal sits on top of the base metal without actually fusing to it. Extremely dangerous in structural connections. Caused by insufficient heat, wrong electrode angle, or excessive travel speed.
• Crater cracks: Small cracks at the end of a weld bead where the arc was terminated too abruptly. The crater shrinks as it cools and cracks. Prevented by filling the crater before breaking the arc (back-stepping technique).
• Excessive reinforcement: Weld face built up too high. CSA W59 limits reinforcement to 3 mm for groove welds. Wastes material and creates stress concentrations.
• Weld size: Inspector measures fillet weld legs with a fillet gauge. Undersized welds are rejected. Welds must meet the size specified on the drawings — no smaller, and not excessively larger.

Non-Destructive Testing (NDT) Methods

When visual inspection isn’t enough, NDT methods reveal subsurface defects:

• Ultrasonic Testing (UT): A transducer sends high-frequency sound waves through the weld. Defects reflect the sound back, showing up on a screen. UT is the most common NDT method for structural steel in Ontario — fast, portable, and no radiation hazard. Per CSA W59, UT is required for all CJP (complete joint penetration) groove welds on primary structural members.
• Magnetic Particle Testing (MT): Magnetizes the steel and applies iron particles to the surface. Cracks and near-surface defects disrupt the magnetic field, attracting particles to form a visible indication. Excellent for finding surface and shallow subsurface cracks. Often used on fillet welds and areas inaccessible to UT.
• Radiographic Testing (RT): X-ray or gamma ray exposure through the weld onto film or digital detector. Provides a permanent image of the internal weld structure. Less common on structural steel in Ontario (UT is preferred), but used for piping and critical connections. Requires controlled area and radiation safety protocols.

Rejection & Repair Procedures

When a weld is rejected by inspection, the repair process follows a specific sequence:

1. Inspector marks the defect location and type on the weld (typically with paint marker and measurement references).
2. The defective area is removed by grinding or air-arc gouging to sound metal.
3. The repair weld is made using the same WPS as the original weld (or an approved repair WPS).
4. The repair is re-inspected using the same method that found the original defect.
5. All repairs are documented in the weld inspection records.

Weld Defects — How They Happen & How to Prevent Them

Understanding why defects occur is the first step to eliminating them. Here’s a field-practical rundown:

9. Reading Weld Symbols

Weld symbols on structural drawings are the universal language between the engineer and the welder. If you can’t read them, you’re guessing — and guessing on structural welds is how buildings get red-tagged. The good news: the basic system is logical once you learn the parts.

The Symbols You’ll See Most Often

• Fillet weld (triangle): By far the most common on structural drawings. The number next to it is the leg size in mm. A “8” next to a fillet symbol means 8 mm legs (with a throat of 8 × 0.707 = 5.7 mm).
• Groove welds: V-groove, bevel, J-groove, and U-groove each have their own symbol. The angle and root opening are noted. CJP (complete joint penetration) groove welds on moment connections are the critical ones — they’re tested by UT.
• Field weld flag: A flag at the junction of the arrow and reference line means the weld is to be made in the field (not in the shop). If there’s no flag, it’s a shop weld.
• All-around symbol: A circle at the arrow/reference line junction means the weld goes continuously around the entire joint. Common on tube-to-plate connections and column base plates.
• Length and pitch: Numbers to the right of the weld symbol indicate length and spacing of intermittent welds. For example, “50–150” means 50 mm welds spaced at 150 mm centre-to-centre.

10. Preheat Requirements

Preheating the base metal before welding slows the cooling rate in the heat-affected zone (HAZ), reducing the risk of hydrogen-induced cracking and improving ductility. It’s not optional — CSA W59 Table 5.3 specifies minimum preheat temperatures based on material thickness, carbon equivalent, and welding process.

Why Preheating Matters

When steel cools too quickly after welding, the HAZ can transform into martensite — a hard, brittle microstructure that’s susceptible to cracking. Hydrogen trapped in this brittle zone migrates to high-stress areas and initiates cracks, sometimes hours or days after welding. Preheat gives hydrogen time to diffuse out and prevents the hard microstructure from forming in the first place.

Minimum Preheat Temperatures (CSA W59 Table 5.3)

For the most common structural steels on church construction projects (CSA G40.21 350W, ASTM A992, A572 Gr. 50 — all with similar carbon equivalents):

• Up to 19 mm thickness: No preheat required (0 °C minimum — meaning the steel must be above freezing)
• 19–38 mm thickness: 66 °C (150 °F) minimum preheat
• 38–64 mm thickness: 107 °C (225 °F) minimum preheat
• Over 64 mm thickness: 150 °C (300 °F) minimum preheat

These are minimums for low-hydrogen processes (E7018, FCAW with H8 or lower diffusible hydrogen). For non-low-hydrogen processes (E6010, E6011), preheat requirements increase by approximately 28 °C (50 °F) per thickness range.

How to Verify Preheat Temperature

• Temperature-indicating crayons (temp sticks): Marks that melt at a specific temperature. Draw on the steel 75 mm from the joint — when the mark melts, you’ve reached that temperature. Common sticks: 66 °C (150 °F), 107 °C (225 °F), 150 °C (300 °F). Measure on the opposite side from the heat source for accurate reading.
• Infrared thermometer (IR gun): Point and read. Fast and non-contact, but can be affected by surface finish and emissivity. Set emissivity to 0.95 for bare steel. IR guns are excellent for quick field checks but temp sticks remain the CWB-accepted primary method.
• Contact thermocouple: Most accurate. Used for critical applications and when interpass temperature must also be monitored (max interpass is typically 230 °C / 450 °F per CSA W59).

11. Touch-Up Painting — Skill 3.14

Structural steel arrives on site with a shop-applied primer coat. During erection, bolting, welding, and handling, that primer gets damaged — scratched, burned off in weld zones, and scuffed by rigging and come-alongs. Touch-up painting restores the corrosion protection and must be done before the steel is enclosed.

Primer Selection

• Zinc-rich primer: Used for touch-up on galvanized or zinc-primed steel. Provides cathodic (sacrificial) protection — the zinc corrodes before the steel. ZRC (zinc-rich compound) cold galvanizing spray is the most common field product. Zinc content must be minimum 92% in the dry film per ASTM A780 (referenced in CSA W59 and CSA S16).
• Alkyd / red oxide primer: Used for standard shop-primed structural steel. Match the shop primer — if the shop coat is red oxide, touch up with compatible red oxide. If the shop coat is a grey universal primer, use the same system. Check the project spec and the steel fabricator’s coating data sheet.
• Inorganic zinc: High-performance primer for aggressive environments. Requires near-white blast cleaning (SSPC-SP 10) for full adhesion — not typically a field touch-up product. Used primarily in shop application.

Surface Preparation

Touch-up primer is only as good as the surface under it. Minimum preparation for field touch-up is SSPC-SP 3 (Power Tool Cleaning): remove all loose mill scale, rust, weld spatter, slag, and damaged paint using a wire wheel, flap disc, or needle scaler. The surface should have a metallic sheen with no visible contamination. For zinc-rich primers, SSPC-SP 11 (Power Tool Cleaning to Bare Metal) is required — no rust or old paint remaining.

Application & DFT

• Application method: Brush or spray for most field touch-up. Brush application is preferred for small areas, weld toes, and bolt heads because it works the primer into surface irregularities.
• Dry film thickness (DFT): Typical specification is 50–75 μm (2–3 mils) per coat. Zinc-rich touch-up: 50–100 μm (2–4 mils). Measure with a magnetic DFT gauge after drying — at least 3 readings per area.
• Environmental limits: Do not apply primer when surface temperature is below 10 °C (50 °F), when relative humidity exceeds 85%, or when surface temperature is less than 3 °C (5 °F) above the dew point. Paint applied outside these limits may not cure properly and will fail prematurely.
• Coverage area: Touch up all field welds (the entire weld plus 25 mm on each side), all bolt heads and nuts at connections, any area where shop coat is scratched to bare metal, and any area of visible rust.