Red Seal Metal Fabricator cheat sheet

Hierarchy of controls, most to least effective: elimination, substitution, engineering controls, administrative controls, personal protective equipment.

Arc flash boundary: the distance at which incident energy equals 1.2 cal/cm² (5 J/cm²), the onset of second-degree burn; approach only in rated PPE.

Welding fume: manganese and hexavalent chromium are the key concerns on stainless and hardfacing; local exhaust ventilation at the arc is the primary control, respirators are secondary.

Compressed gas cylinders: oxygen and fuel gas stored at least 6 m (20 ft) apart, or separated by a fire-rated barrier at least 1.5 m (5 ft) high with a 30-minute fire rating.

Acetylene: never exceed 15 psi (103 kPa) gauge delivery pressure, and withdraw no more than 1/7 of cylinder contents per hour to avoid acetone carryover.

Noise: 85 dBA Lex 8-hour exposure triggers a hearing conservation program; exchange rate 3 dB means each 3 dB increase halves permissible exposure time.

WHMIS 2016/GHS labels carry six elements: product identifier, hazard pictograms, signal word, hazard statements, precautionary statements, and supplier identifier; SDS has 16 sections.

Spent pickling acid, chromate conversion coatings, and cadmium-bearing fume are hazardous wastes; segregate and manifest, never discharge to storm drains.

Speeds and feeds for drilling: RPM = (cutting speed × 4) / diameter in inches, with cutting speed in surface feet per minute (HSS in mild steel ≈ 100 sfpm).

Tap drill size for a 75% thread ≈ major diameter − (1 / threads per inch); use the nearest standard drill at or below that value.

Ironworker capacity: rated tonnage applies at the thickest material; punching requires roughly 1 ton per 25 mm (1 in) of hole diameter per 3 mm (1/8 in) of plate thickness in mild steel.

Bandsaw blade selection: coarse teeth (3–6 TPI) for thick solid sections, fine teeth (10–14 TPI) for tube and thin plate; keep at least three teeth in the cut.

Shear and press brake tonnage rises with material tensile strength; multiply mild-steel ratings by about 1.4 for stainless and 1.5 or more for abrasion-resistant plate.

Grinding wheel ring test: suspend the wheel by its bore and tap it lightly; a clear ring indicates soundness, a dull thud means discard.

Never exceed the marked maximum RPM on a grinding wheel or wire brush; guard exposure must not exceed 90 degrees on bench and pedestal grinders.

Hand and power tool inspection: check cords and grounding, remove damaged tools from service, and match abrasive type to material (no ferrous-contaminated wheels on aluminum).

First-angle projection (ISO/CSA) places the top view below the front view; third-angle projection (ASME) places the top view above the front view.

A weld symbol: reference line with arrow, fillet size to the left of the fillet symbol, length to the right, pitch after a hyphen; tail holds the process specification.

Weld symbol side rule: symbol below the reference line means arrow side, above means other side, both sides means both.

Geometric tolerancing: a feature control frame reads symbol, tolerance, then datum references in order of precedence (primary, secondary, tertiary).

Allowance for bend: bend allowance BA = (π/180) × A × (R + K × T), where A is bend angle in degrees, R inside radius, T thickness, K the K-factor (typically 0.33–0.50).

Flat pattern length = sum of outside leg lengths − bend deductions (BD = 2 × outside setback − bend allowance) for each bend.

Scale reading: verify the stated scale (1:1, 1:10, 1:50) before measuring; never scale critical dimensions from a drawing, use stated dimensions.

Surface finish symbols: the check mark alone means any process; a number after the check mark is the maximum Ra in micrometres; a bar over the symbol means no material removal.

AISI/SAE 1018 is low-carbon (≈0.18% C) mild steel, readily welded and formed; 1045 is medium carbon (≈0.45% C) and needs preheat for crack-free welding.

A36 structural steel: minimum yield 250 MPa (36 ksi), tensile 400–550 MPa (58–80 ksi); ASTM A992 for wide-flange beams: yield 345 MPa (50 ksi).

Stainless families: 304 (18% Cr, 8% Ni) general purpose; 316 adds 2–3% Mo for chloride resistance; 430 is ferritic and magnetic; 410 is martensitic and hardenable.

Aluminum: 6061-T6 is heat-treatable and weldable with 4043 or 5356 filler; 5052 is non-heat-treatable, excellent formability and marine corrosion resistance.

Carbon equivalent (CE = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15) above about 0.40% indicates preheat and controlled heat input are needed.

Material test report (MTR) traceability: match heat number on the mill certificate to the plate stamp; verify chemistry and mechanicals against the specification.

Preparation: remove mill scale, oil, and moisture 25 mm (1 in) or more from the joint; hydrogen from moisture and paint causes underbead cracking in high-strength steels.

Thermal cutting leaves a heat-affected zone; grind or machine to sound metal before welding on thick plate or when the cut edge will carry primary stress.

Oxy-fuel cutting: preheat to the material's ignition temperature, then introduce the oxygen jet; cutting oxygen pressure and tip size scale with plate thickness.

Kerf is the width of material removed by a cut; allow for it when laying out parts and nesting, typically 1.5–3 mm on plasma and 2–5 mm on oxy-fuel.

Plasma cutting produces a slight bevel on one side of the cut; the good (square) side usually faces the direction of travel on the right side of the kerf.

Minimum bend radius for mild steel ≈ 1 × thickness; for aluminum 6061-T6 it is roughly 2–3 × thickness because of lower ductility.

Bend deduction accounts for the stretch of the neutral axis; K-factor is the neutral axis position as a fraction of thickness and shifts with radius-to-thickness ratio.

Springback: overbend to compensate; mild steel springs back about 1–2 degrees, high-strength and stainless about 5–10 degrees for the same radius.

Press brake tonnage per metre rises with thickness squared; doubling thickness roughly quadruples the required force for the same V-die opening.

Edge quality: laser gives the narrowest kerf and best edge; waterjet cuts without a heat-affected zone, useful for heat-sensitive alloys.

Fit-up tolerance: root gap and root face control penetration; a gap that is too wide increases dilution and distortion, too tight causes lack of fusion.

Tack welds must be of the same quality as the finished weld and be sized to hold the joint; remove or feather tacks that will not be fused into the final pass.

Distortion control: balance welding about the neutral axis, use backstep or skip sequence, preset the joint, and clamp or fixture to restrain movement.

Shrinkage allowance: butt welds pull about 1–2 mm per metre of weld length in mild steel; account for it when setting overall lengths.

Alignment checks: use a spirit level, plumb line, laser, or dial indicator; verify squareness with a 3-4-5 triangle or a machinist square.

Hole alignment: ream or drill matched holes with parts clamped; never enlarge a structural bolt hole beyond the specified oversize without engineering approval.

Preheat and interpass temperature control reduces shrinkage stress and hydrogen cracking; measure with contact thermometers or temperature-indicating crayons.

Assembly sequence: locate and fix the datum face first, then build outward; check diagonals of rectangular frames to confirm square before final welding.

SMAW electrode classification E7018: E = electrode, 70 = 70 ksi minimum tensile, 1 = all-position, 8 = low-hydrogen with iron powder, current and polarity per the last two digits.

Low-hydrogen electrodes (7018, 8018) must be stored in a holding oven at 120 °C (250 °F) or higher and reconditioned per manufacturer limits.

GMAW transfer modes: short circuit for thin sheet, globular for mid-range, spray for high deposition at high current; short circuit is not suitable for thick plate.

GTAW uses a non-consumable tungsten electrode and separate filler; DCEN for steel, AC for aluminum to break the oxide, and pure argon or argon-helium shielding.

Brazing vs. soldering: brazing filler melts above 450 °C (840 °F) but below the base metal; soldering is below that temperature.

Preheat is required for thick sections and high-carbon or alloy steels; interpass temperature caps prevent loss of toughness in quenched-and-tempered steels.

Post-weld heat treatment relieves residual stress and tempers the HAZ; typical for pressure vessels and thick sections per the applicable code.

Filler metal selection: match strength and chemistry to the base metal; use 4043 for 6061 general work and 5356 for higher-strength or anodized aluminum welds.

Visual inspection (VT) is the most common first-line method and must be done before other NDT, after cleaning to sound metal.

Liquid penetrant (PT) detects surface-breaking discontinuities in non-porous materials; clean, apply penetrant, remove excess, develop, and inspect under proper light.

Magnetic particle (MT) detects surface and near-surface flaws in ferromagnetic materials only; not applicable to austenitic stainless or aluminum.

Ultrasonic testing (UT) detects internal flaws and measures thickness; requires a couplant and a calibrated reference standard for sizing.

Radiographic testing (RT) shows internal density differences; radiation safety controls and qualified interpreters are mandatory.

Weld acceptance criteria and NDT extent come from the applicable code (e.g., CSA W47.1/W59, ASME Section IX, AWS D1.1) and the project specification, not from shop preference.

Destructive tests: bend test for ductility, tensile test for strength, macro-etch for penetration and HAZ; procedure and performance qualification follow the code.

Dimensional inspection: verify against the drawing's tolerances, use calibrated instruments, and record results before release to the next operation.

Sling tension in a two-leg lift: tension = (load / 2) ÷ cos(angle from vertical per leg); as the angle widens, tension rises sharply.

Sling angle factor: at 30 degrees from horizontal, capacity is roughly 50% of the vertical rating; at 60 degrees, about 87%; never exceed the rated angle.

Working load limit (WLL) is the maximum load a rigging component may carry; the WLL is stamped on the hardware and is the basis for inspection.

Shackle and hook inspection: reject for cracks, deformation, excessive wear (typically 10% of original dimension), or missing safety latches.

Center of gravity: a load lifts level only when the hook is directly above the CG; off-center lifts cause load tilt and unequal leg tension.

Rigging hardware: never side-load a hook beyond its rated capacity; use a swivel or shackle to align the load.

Tag lines control rotation and swing; keep personnel out of the fall zone and never walk or stand under a suspended load.

Inspection intervals: slings and hardware are inspected before each use and at intervals set by the employer; damaged gear is tagged out of service immediately.