Red Seal Welder cheat sheet

CSA W117.2 governs welding safety in Canada; it requires a hazard assessment before hot work and a written permit where the employer's program demands one.

Hot-work permit rule: the fire watch stays in place during welding and for at least 30 minutes after the last arc, then the area is re-inspected for smouldering material.

Combustibles are kept at least 11 m (35 ft) from hot work, or protected by a fire-resistant shield or wet-down when that distance cannot be met.

Cylinder storage: oxygen and fuel gas cylinders separated by at least 6 m (20 ft) or by a non-combustible barrier at least 1.5 m (5 ft) high with a fire-resistance rating of at least 30 minutes.

Cylinders are stored upright, valve caps on, secured against falling, away from heat and ignition; acetylene is never laid down or used from a horizontal position.

Fume control hierarchy: source extraction or ventilation first; an air-supplied respirator is required for confined-space welding and for metals such as stainless or galvanized steel where local exhaust cannot control exposure.

Confined-space entry requires a written entry permit, atmospheric testing for oxygen (19.5-23%), flammables and toxics, an attendant outside, and a retrieval system.

Eye and face protection: a welding helmet with the correct shade for the process and current, plus safety glasses with side shields worn underneath for chipping and grinding.

Lifting rule of thumb: keep the load close, back straight, lift with the legs; two workers or mechanical assistance for anything above the employer's single-person limit.

A welding machine's duty cycle is the percentage of a 10-minute period it can run at rated output; at 60% duty cycle a 200 A machine runs 6 minutes and rests 4 minutes.

Constant-current (drooping) characteristic suits SMAW and is set by amperage; constant-voltage (flat) characteristic suits GMAW/FCAW and is set by voltage and wire-feed speed.

OCV is open-circuit voltage; it is higher than arc voltage and is limited by standards (typically 80 V for SMAW, 100 V for some engine drives) for operator safety.

An AC transformer welder needs a high-frequency or scratch start for TIG; a DC machine allows lift-arc or high-frequency start and gives a stable arc at low current.

Regulator vs flowmeter: a regulator reduces cylinder pressure to a working pressure; a flowmeter sets shielding-gas flow in L/min or CFH at the torch.

GMAW gun liner, contact tip and drive rolls must match the wire size and type; a worn contact tip causes arc wander and porosity.

Plasma cutting consumables (electrode, swirl ring, nozzle, shield) wear as a set; replacing one worn part while leaving others worn shortens life of the new part.

Oxy-fuel torch tips are sized by number and marked for the fuel gas and plate thickness; a sooty flame or popping indicates the wrong tip or contaminated seat.

Grinder wheels are matched to the tool's RPM rating; a wheel rated below the tool speed must never be mounted.

Travel speed (mm/min) = wire-feed speed (mm/min) x wire cross-section area / weld cross-section area, for a given deposition efficiency.

Heat input (kJ/mm) = voltage (V) x current (A) x 60 / (1000 x travel speed in mm/min); keep within the procedure's range to control toughness.

Deposition rate (kg/h) = wire cross-section (mm2) x wire-feed speed (mm/min) x density (g/cm3) x 60 / 1,000,000.

Dilution (%) = area of base metal melted / total weld area x 100; relevant to cladding and repair procedures.

Circumference = pi x diameter; a 508 mm (20 in) pipe has a circumference of about 1596 mm, so a full root pass needs that much filler travel.

Right-triangle layout for a 45-degree offset: offset = run x tan(45) = run; for a 22.5-degree miter, setback = radius x tan(11.25).

Taper allowance for pipe: total taper = (outside diameter - wall thickness) x 0.4142 (for 90-degree cut) or use the standard cut-back formulas for miters.

Conversion: 1 in = 25.4 mm; 1 psi = 6.895 kPa; 1 CFH = 0.472 L/min; 1 kJ/mm = 25.4 kJ/in.

Weight of a steel plate (kg) = length (m) x width (m) x thickness (mm) x 7.85 (density of steel in g/cm3).

A welding symbol: reference line, arrow, tail (process/spec reference), and above/below the line for the side of the joint the weld is on.

Fillet weld symbol: triangle on the reference line; size to the left of the symbol, length to the right; a dimension in parentheses is the pitch of intermittent welds.

Groove weld symbols: V, bevel, U, J, square; the root opening, groove angle and root face are placed on the symbol or in the tail notes.

Supplementary symbols: all-around circle at the joint, field-weld flag at the bend, tail for process, and finish symbol (G, M, C, F, R) on top of the reference line.

A dimension shown in parentheses on a weld symbol is a reference dimension; the controlling dimension is the one without parentheses.

Weld-all-around and field-weld symbols override the side-of-line placement: the weld is made on both sides and at the site, not in the shop.

A welding procedure specification (WPS) is the controlling document; the drawing calls the joint and symbol, the WPS calls the process, current, preheat and pass sequence.

Isometric drawings show pipe runs in three axes; use the north arrow and line numbers to orient, and check for a bill of materials with pipe schedule and material spec.

A revision cloud and triangle on a drawing flag a change; the current revision is the one in the title block, and superseded drawings are removed from the shop floor.

Carbon equivalent (CE) for steel: CE = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15; above about 0.40 the steel needs preheat to avoid hydrogen cracking.

Preheat slows cooling, lowers the martensite transformation temperature range and gives hydrogen time to escape; interpass temperature is controlled to protect toughness.

Austenitic stainless steel (300 series) is welded with low heat input, stringer beads and no preheat; excessive heat causes sensitization (chromium carbide precipitation) and intergranular corrosion.

Duplex stainless requires controlled heat input and interpass temperature (typically below 150 C) to keep the ferrite-austenite balance near 50/50.

Aluminum: remove the oxide layer immediately before welding, use AC for TIG to break the oxide, and use a filler (4043 or 5356) matched to the alloy and service.

Hydrogen is the main cause of cold cracking in steel; control it with dry electrodes, clean wire, preheat and a post-weld hydrogen bake-out where specified.

Hot cracking (solidification cracking) is driven by sulfur, phosphorus and segregation; low dilution and a filler with more manganese help resist it.

Weldability is reduced by high carbon, high sulfur (free-machining steels) and high alloy content; these need a qualified procedure and often a different filler.

Galvanized steel produces zinc fume; remove the coating at least 25-50 mm from the joint and use ventilation or respiratory protection.

SMAW: electrode classification E4918 means 490 MPa minimum tensile, all-position, 18 = low-hydrogen iron-powder coating and the current/polarity indicated by the last digits.

GMAW transfer modes: short-circuit (low current, thin material), globular (transition zone, avoid), spray (high current, argon-rich gas), and pulsed (controlled spray at lower average current).

GMAW gas selection: 100% CO2 is deep-penetrating and cheap; 75% Ar/25% CO2 is a common mild-steel mix; argon-rich mixes are needed for spray transfer.

FCAW: self-shielded wire uses no external gas and is suited to field work; gas-shielded wire uses CO2 or a mix and gives higher deposition and better toughness.

GTAW: DCEN puts heat in the work for steel; AC is used for aluminum; the electrode is tungsten (2% thoriated or ceriated), ground to a point for DC and balled for AC.

SAW: high deposition, deep penetration, uses granular flux; the flux must be dry and the wire/flux combination is qualified as a pair.

Resistance spot welding: current, time and electrode force control the nugget; clean surfaces and correct electrode shape determine weld size.

FCAW/SMAW polarity: DCEP (electrode positive) is standard for most electrodes; DCEN is used for some self-shielded wires and for TIG on steel.

Shielding-gas flow for GMAW is typically 12-20 L/min (25-40 CFH); too much causes turbulence and porosity, too little allows atmospheric contamination.

Pipe fit-up: root gap, land (root face) and bevel angle are set by the WPS; a common root gap is 2-3 mm with a 1.5-2 mm land on a 37.5-degree bevel.

Tack welds must be made with a qualified procedure and consumed by the root pass; a cracked tack is removed, not welded over.

Fit-up sequence: square and level the assembly, tack in a balanced order, check diagonal dimensions, then complete welds in a sequence that balances shrinkage.

Pipe offset layout: mark the pipe with a wrap-around and soapstone, cut with the bevel set by a pipe beveler, and check the cut with a square and a bevel gauge.

For a 90-degree branch, the cut line is set from the centerline of the header and the saddle is ground to fit; a gap at the saddle is not filled with a bridge.

Assembly jigs and strongbacks hold parts against distortion during welding; strongbacks are removed only after the weld has cooled to the specified temperature.

Bolted and welded joints in the same assembly: complete and cool the welds before final bolt-up to avoid locked-in stress.

A fit-up check with a straightedge or feeler gauge: a gap over the code limit is corrected by re-fit, not by adding filler to bridge it.

Visual inspection (VT) is the first and most used method: it checks bead profile, undercut, overlap, spatter, arc strikes and fit-up before any NDT.

Penetrant testing (PT) finds surface-breaking defects in non-porous materials; the surface must be clean and dry, and the penetrant dwell time is per the procedure.

Magnetic particle testing (MT) finds surface and near-surface defects in ferromagnetic materials only; it does not work on austenitic stainless or aluminum.

Radiographic testing (RT) finds volumetric defects (porosity, slag, incomplete penetration) and is read against a code acceptance standard; it is not good for tight planar cracks normal to the beam.

Ultrasonic testing (UT) finds planar defects (cracks, lack of fusion) and measures depth; it requires a qualified operator and a calibration block.

Destructive tests: tensile, bend (face and root), nick-break, macro-etch and hardness; a bend test exposes lack of fusion and porosity at the root or face.

Weld defect names: lack of penetration, lack of fusion, undercut, overlap, porosity, slag inclusion, spatter, arc strike, and crater crack.

Acceptance criteria come from the applicable code (for example CSA W47.1 for structural steel or ASME Section IX for procedure qualification); the inspector applies the code, not personal preference.

A weld that fails inspection is repaired only after the cause is identified; repeated repair of the same area can require a new procedure qualification.

Oxy-fuel cutting: preheat the steel to its ignition temperature, then a jet of pure oxygen oxidizes the iron; the cut is a chemical reaction, not a melt.

Neutral flame: equal acetylene and oxygen; an oxidizing flame (excess O2) is used for cutting and a carburizing flame (excess acetylene) for some brazing and hardfacing.

Cutting tip size and oxygen pressure are selected by plate thickness; too much pressure causes a rough, gouged kerf and too little causes a slow, drossy cut.

Kerf: the width of material removed by the cut; layout allowances add half the kerf to each side of the cut line.

Plasma cutting works on any conductive metal including stainless and aluminum; it uses a constricted arc and a shielding gas, and produces a narrow, fast cut.

Air-carbon-arc gouging removes metal with a carbon electrode and compressed air; it is used to back-gouge a root for re-welding and to remove defects.

Gouging rules: use DC electrode positive, keep the electrode at a shallow angle, and stop before the gouge gets deeper than the defect; the gouged surface is ground clean before welding.

Liquid-oxygen or oxygen-lance cutting is used for thick sections and for piercing; it requires special training and is not a routine shop process.

Thermal cutting leaves a heat-affected zone; on hardenable steel, preheat and a post-cut inspection are required before welding over a cut edge.

Distortion control: balance the welding around the neutral axis, use back-step or skip sequence, and keep the heat input low and uniform.

Back-step welding: weld short beads starting at the end and progressing toward the start, so each bead shrinks against the previous one and pulls the part straight.

Presetting (pre-bending) the part opposite the expected shrinkage is a common method for controlling angular distortion in a tee or butt joint.

Shrinkage allowance for a butt weld is roughly 1-2 mm per metre of weld length for a single-V groove; the exact value is set by the procedure.

Peening reduces tensile stress in the weld cap but is not allowed on the root pass or on the final pass where the code prohibits it.

Repair procedure: gouge or grind out the defect to sound metal, confirm with PT or MT, re-weld with a qualified procedure, and re-inspect to the original acceptance criteria.

A crack repair requires the crack ends to be drilled or ground out before gouging, so the crack does not propagate ahead of the repair.

Post-weld heat treatment (PWHT) relieves residual stress and tempers the HAZ; it is applied at a controlled rate with thermocouples and recorded on a chart.

Maintenance of equipment: check cables for damage, keep the work clamp and lead clean, and verify the machine's calibration and duty cycle before production work.