420B Red Seal — Ironworker

About the 420B Red Seal Exam — Ironworker

The 420B Ironworker Red Seal exam is Canada's national certification for ironworkers who erect structural steel, place reinforcing rod, and perform rigging and hoisting on construction sites. A Red Seal 420B endorsement proves your skills meet the national standard and is recognized in every province without re-examination.

The exam has approximately 120 multiple-choice questions based on the 2023 RSOS, with a 70% passing score. Exam time is 4 hours.

Official 420B Exam Breakdown (red-seal.ca)

Red Seal publishes how the 120 questions on the real 420B exam are distributed across its Major Work Activities:

• A — Occupational skills — 15 questions (12%)
• B — Rigging and hoisting — 22 questions (18%)
• C — Cranes — 11 questions (9%)
• D — Reinforcing — 19 questions (16%)
• E — Pre-stresses/post-tensions — 8 questions (7%)
• F — Erection, assembly and installation — 34 questions (28%)
• G — Maintenance and upgrading — 11 questions (9%)

Every question is four-option multiple choice with one correct answer, the writing time is four hours and the pass mark is 70%. Source: 420B exam information, red-seal.ca. Exams are periodically rewritten to updated occupational standards, so check that page before you book.

What this question bank covers

These are the topic areas in this practice bank and what each one covers. The real 420B exam has 120 questions and a four-hour writing time. How those questions are distributed across the official blocks is published by Red Seal — see the 420B exam information page.

• Structural Steel Erection — Column setting, beam connections, high-strength bolt installation (turn-of-nut, DTI), plumbing and levelling, temporary bracing, AISC/CISC code. The heaviest block.
• Rigging & Hoisting — Wire rope inspection, sling angle derating, WLL calculations, shackles, hooks, taglines, crane hand signals, load chart reading. Expect math questions.
• Welding & Cutting — SMAW/FCAW for structural steel, preheat on A36/A572, CSA W47.1 certification, weld symbols, fillet weld sizing, OFC and plasma cutting.
• Blueprint Reading & Layout — Structural drawing symbols, column grids, elevation marks, piece marks, connection details, section views, anchor bolt layout.
• Reinforcing Steel — Rebar designation/grades (400/500), development length, lap splices, hooks, cover requirements, tying, placement tolerances (CSA A23.1).
• Safety & Fall Protection — 100% tie-off, PFAS components, controlled decking zones, safety netting, leading edge work, anchor strength, fall clearance math.
• Tools & Equipment — Spud wrenches, drift pins, ironworker machines, come-alongs, beam clamps, burning bars, tensioning tools.

Exam Strategy for 420B

Rigging math comes up reliably. Practice sling angle calculations and two-leg bridle sling WLL problems — these are straightforward marks once you know the formula.

Fall protection rules = free marks. Memorize controlled decking zone rules, 100% tie-off requirements, and PFAS components. These questions are specific and testable.

Blueprint reading is on every exam. Practice reading structural drawing symbols, piece marks, and weld symbols from a connection detail.

How to Use This Tool

121 questions across all 7 blocks with full explanations. Use Topic Filter to drill weak areas; use Mock Exam Mode 2–3 weeks before exam day.

Related reading: How to Pass the 420B Exam | Ironworker Salary Guide | Ironworker Career Guide