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Free Red Seal Sheet Metal Worker (308A) Practice Test
30 original questions with explanations. Pick an answer to check it instantly.
Question 1 · A – Performs common occupational skills
A sheet metal worker is about to MIG weld galvanized steel duct supports indoors. What is the main health hazard to control?
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Answer: C. Zinc oxide fume, which can cause metal fume fever, so use local exhaust and suitable respiratory protection
Heating galvanized steel vaporizes the zinc coating, forming zinc oxide fume. Breathing it can cause metal fume fever (flu-like chills and fever). Remove the coating where practical, use local exhaust ventilation and wear appropriate respiratory protection.
Check it: RSOS task A-1 (safety-related functions)
Question 2 · A – Performs common occupational skills
Before clearing a jam in a power squaring shear, what must the worker do first?
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Answer: A. Shut off and lock out the machine's energy sources, then verify it cannot start
Lockout isolates all energy sources (electrical, hydraulic, pneumatic, stored mechanical) and verifying zero energy prevents an unexpected stroke. Relying on a co-worker or the stop button is not an acceptable substitute for lockout.
Check it: RSOS task A-1 (safety-related functions)
Question 3 · A – Performs common occupational skills
Aviation snips are often colour-coded by handle. Which snip is designed to cut a curve to the left most easily?
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Answer: D. Red-handled snips
By common convention, red-handled aviation snips cut left (counterclockwise) curves, green-handled snips cut right curves and yellow-handled snips cut straight lines and gentle curves. Check the maker's marking, because conventions can vary.
Check it: RSOS task A-2 (tools and equipment)
Question 4 · A – Performs common occupational skills
Which machine is normally used to form the pocket of a Pittsburgh lock seam on straight duct sections?
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Answer: D. A Pittsburgh (lock-forming) roll former
A Pittsburgh lock-former rolls the pocket (female) half of the seam along the edge of the sheet. The flanged (male) edge is then inserted and the pocket is hammered or closed over. Slip rolls form cylinders, and beaders stiffen panels.
Check it: RSOS task A-2 (tools and equipment)
Question 5 · A – Performs common occupational skills
On a mechanical drawing drawn at a scale of 1:50, a duct run measures 84 mm. What is its actual length?
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Answer: A. 4.2 m
At 1:50, every millimetre on the drawing represents 50 mm on site: 84 × 50 = 4200 mm = 4.2 m. Always confirm the scale shown on that particular view, since details are often drawn at a different scale.
Check it: RSOS task A-3 (organizing work)
Question 6 · A – Performs common occupational skills
An apprentice is learning to set up a box and pan brake. Which mentoring approach best confirms the skill has been learned?
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Answer: A. Demonstrate, then have the apprentice do it while you observe and give feedback
Effective trade mentoring follows a show, practise and give feedback cycle. Watching the apprentice perform the task is the only reliable way to confirm the skill and correct errors before they become habits or cause injury.
Check it: RSOS task A-4 (communication and mentoring)
Question 7 · B – Performs fabrication
Which pattern development method is used for fittings whose surfaces are made of parallel lines, such as elbows and tees made from cylinders or prisms?
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Answer: A. Parallel line development
Parallel line development uses element lines that run parallel to each other on the surface, which fits cylinders and prisms such as round elbows, mitred fittings and pipe tees. Cones and pyramids use radial line; irregular transitions use triangulation.
Check it: RSOS task B-5 (pattern development)
Question 8 · B – Performs fabrication
A square-to-round transition has no common apex and its surface lines are not parallel. Which method develops its pattern?
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Answer: D. Triangulation
Triangulation breaks the surface into small triangles, finds the true length of each side and lays them out in sequence. It handles transitions, offsets and other shapes that have neither parallel elements nor a common apex.
Check it: RSOS task B-5 (pattern development)
Question 9 · B – Performs fabrication
A right cone has a base diameter of 500 mm and a vertical height of 600 mm. What is the slant height used as the pattern radius?
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Answer: B. 650 mm
The slant height is the hypotenuse of a right triangle formed by the base radius (250 mm) and the height (600 mm): √(250² + 600²) = √422,500 = 650 mm. Using the diameter instead of the radius gives 781 mm, which is wrong.
Check it: RSOS task B-5 (pattern development)
Question 10 · B – Performs fabrication
A cone with a base radius of 250 mm has a slant height of 650 mm. What is the included angle of its flat sector pattern?
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Answer: B. 138.5°
The arc of the pattern must equal the base circumference, so the sector angle is 360 × r ÷ slant height = 360 × 250 ÷ 650 = 138.5°. The other values come from halving the angle or using the vertical height.
Check it: RSOS task B-5 (pattern development)
Question 11 · B – Performs fabrication
Which longitudinal seam is commonly used on rectangular duct and is closed by hammering the pocket flange over the inserted edge?
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Answer: A. Pittsburgh lock seam
The Pittsburgh lock is a corner seam: one edge is formed into a pocket and the other into a single 90° flange. The flange is inserted and the pocket edge is hammered over to lock it. A button punch snap lock instead locks with punched dimples and needs no hammering.
Check it: RSOS task B-6 (fabricating air and material handling components)
Question 12 · B – Performs fabrication
Why are flat panels of larger rectangular duct often cross-broken or beaded?
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Answer: B. To stiffen the panel so it resists drumming and deflection under pressure
Cross-breaking (a shallow X) or beading puts a slight bend into the flat panel, raising its stiffness. This reduces drumming, noise and deflection when the system runs, and it is one of the reinforcement options recognized in duct construction standards such as SMACNA's.
Check it: RSOS task B-6 (fabricating air and material handling components)
Question 13 · B – Performs fabrication
A transverse joint on rectangular duct is made with flat drive slips on the short sides and S-slips on the long sides. What is the main purpose of these slip connectors?
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Answer: B. To join duct sections end to end with a mechanical connection that can then be sealed
S and drive slips connect duct sections at transverse joints. They are simple and economical for lower-pressure systems; joints are then sealed to the required sealing class. Higher pressure classes and larger ducts often use flanged connectors such as TDC/TDF or angle flanges.
Check it: RSOS task B-6 (fabricating air and material handling components)
Question 14 · B – Performs fabrication
When fabricating a kitchen grease exhaust duct, how are the seams and joints typically made?
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Answer: C. Continuously welded so the duct is liquid-tight
Grease ducts must contain grease and resist fire, so standards such as NFPA 96 call for liquid-tight, continuously welded (or listed) joints in heavier steel or stainless steel. Mechanical locks and tape can leak grease and fail in a fire.
Check it: RSOS task B-6 (fabricating air and material handling components)
Question 15 · B – Performs fabrication
Why should copper flashing not be installed in direct contact with galvanized steel or aluminium?
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Answer: A. Galvanic corrosion: the less noble zinc or aluminium corrodes when wet with an electrolyte
Dissimilar metals in contact with moisture form a galvanic cell. Zinc and aluminium are less noble than copper, so they corrode. Runoff from copper onto galvanized or aluminium surfaces causes the same damage. Separate them or use compatible metals.
Check it: RSOS task B-7 (flashing, roofing, sheeting and cladding)
Question 16 · B – Performs fabrication
When fabricating stainless steel food-service equipment, why should carbon steel brushes and tools that have touched carbon steel be kept off the work?
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Answer: C. Embedded iron particles rust and stain the stainless surface
Stainless resists corrosion because of a thin chromium oxide layer. Iron particles from carbon steel tools become embedded and rust, leaving stains and starting corrosion. Use dedicated stainless tools and brushes, and passivate where required.
Check it: RSOS task B-8 (specialty products)
Question 17 · C – Installs air and material handling systems
A load is lifted with a two-leg sling. As the angle between each leg and the horizontal decreases, what happens to the tension in each leg?
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Answer: B. It increases
Each leg's tension equals (load ÷ 2) ÷ sin(angle to horizontal). As the sling angle gets flatter, the sine gets smaller and the leg tension rises sharply. At 30° to horizontal, each leg carries the full load.
Check it: RSOS task C-9 (preparing the installation site)
Question 18 · C – Installs air and material handling systems
A Category I natural-draft gas furnace is to be vented with a factory-built vent. Which type of vent is normally used?
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Answer: C. Type B gas vent
Category I appliances operate with non-positive vent pressure and non-condensing flue temperatures, and are normally vented with listed Type B double-wall gas vent. Condensing Category IV appliances use the special venting the appliance maker specifies.
Check it: RSOS task C-10 (chimneys, breeching and venting)
Question 19 · C – Installs air and material handling systems
Why must a single-wall vent connector from a draft-hood appliance rise toward the chimney or vent?
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Answer: C. So the buoyant flue gases flow freely and do not spill at the draft hood
Natural-draft venting relies on hot, buoyant flue gases. A connector that dips or runs flat slows the flow and can cause spillage of combustion products at the draft hood. Gas and oil codes such as CSA B149.1 and CSA B139 require connectors to rise toward the vent.
Check it: RSOS task C-10 (chimneys, breeching and venting)
Question 20 · C – Installs air and material handling systems
Where should a fire damper be installed in relation to a fire-rated wall?
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Answer: C. Within the plane of the rated wall, in a sleeve secured with retaining angles as listed
A fire damper must be installed as its listing and the manufacturer require, normally within the plane of the fire separation in a steel sleeve with retaining angles on both sides. An access door is provided so the damper and fusible link can be inspected and reset.
Check it: RSOS task C-11 (air handling system components)
Question 21 · C – Installs air and material handling systems
A 600 × 400 mm duct carries 1200 L/s. What is the average air velocity?
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Answer: D. 5.0 m/s
Convert flow to m³/s (1.2) and area to m² (0.6 × 0.4 = 0.24). Velocity = 1.2 ÷ 0.24 = 5.0 m/s. Forgetting to convert litres to cubic metres produces the 50 m/s answer, ten times too high.
Check it: RSOS task C-11 (air handling system components)
Question 22 · C – Installs air and material handling systems
Why is a flexible connector installed between a fan and its ductwork?
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Answer: A. To isolate fan vibration and noise from the duct system
A flexible connection (fabric collar) stops the fan's vibration from travelling into the duct system, where it would be amplified as noise. It must be installed with some slack but not stretched or twisted, and must not be used to correct misalignment.
Check it: RSOS task C-11 (air handling system components)
Question 23 · C – Installs air and material handling systems
What is the purpose of turning vanes installed in a square-throat rectangular elbow?
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Answer: B. To reduce turbulence and pressure loss as air turns the corner
Air turning a square-throat elbow separates from the inner wall, creating turbulence, noise and a large pressure loss. Turning vanes divide the turn into several small, efficient elbows, which greatly lowers the loss.
Check it: RSOS task C-11 (air handling system components)
Question 24 · C – Installs air and material handling systems
In a dust collection system, why should branches join the main at an angle such as 30° or 45° rather than at 90°?
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Answer: D. To reduce turbulence and pressure loss and keep material conveying smoothly
Angled entries merge the branch air in the direction of flow. A 90° entry creates turbulence and higher losses and can let material drop out or build up. Material handling systems also use long-radius elbows for the same reason.
Check it: RSOS task C-12 (material handling system components)
Question 25 · C – Installs air and material handling systems
Supply duct carrying cold air runs through a warm, humid unconditioned space. Where must the vapour retarder be on its insulation?
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Answer: B. On the outside (warm side) of the insulation, with all joints and penetrations sealed
Moisture moves from warm to cold. The vapour retarder goes on the warm side, which for cold supply duct is the outside of the insulation. Any gaps let humid air reach the cold duct, where it condenses and soaks the insulation.
Check it: RSOS task C-13 (insulation, lagging, cladding and flashing)
Question 26 · C – Installs air and material handling systems
A pitot tube reading shows a velocity pressure of 24 Pa. With air density 1.2 kg/m³ (Pv = 0.6 × v²), what is the velocity?
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Answer: D. 6.3 m/s
Rearrange Pv = 0.6 × v²: v = √(Pv ÷ 0.6) = √(24 ÷ 0.6) = √40 = 6.3 m/s. Forgetting the square root gives 40, which is far too high for a typical duct.
Check it: RSOS task C-14 (leak testing, air balancing and commissioning)
Question 27 · D – Installs roofing and specialty products
Why are concealed sliding (expansion) cleats used on long standing-seam metal roof panels?
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Answer: B. To let panels expand and contract with temperature while staying held down
Long metal panels change length noticeably with temperature. Sliding clips hold the panel against wind uplift but let it move, preventing buckling (oil-canning) and fastener elongation. Fixed points are set in one zone, usually near the ridge or mid-length, per the system design.
Check it: RSOS task D-15 (metal roofing and cladding/siding)
Question 28 · D – Installs roofing and specialty products
When installing an exterior aluminium composite or metal panel rainscreen, what is the purpose of the cavity behind the panels?
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Answer: D. To drain and ventilate water that gets past the panel joints
A rainscreen accepts that some water will pass the open or sealed joints. The cavity lets that water drain out and the space ventilate and dry, with the air and water barrier on the backup wall behind the cavity.
Check it: RSOS task D-17 (specialty products)
Question 29 · E – Performs maintenance and repair
During scheduled maintenance of a kitchen exhaust hood system, what should be checked at the hood?
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Answer: C. Grease filters and the grease buildup in the hood and duct, cleaning as scheduled
Grease buildup in filters, the hood plenum and exhaust duct is a major fire risk. NFPA 96 sets inspection frequencies based on the type and volume of cooking, and accumulations found must be cleaned by qualified people. Refrigerant and gas work belong to other trades.
Check it: RSOS task E-18 (scheduled maintenance)
Question 30 · E – Performs maintenance and repair
A newly fabricated duct section drums loudly whenever the fan starts. What is the most likely fix?
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Answer: A. Add reinforcement such as cross-breaking, beading or stiffening angles to the panel
Drumming (oil-canning) happens when a large flat panel snaps in and out as pressure changes. Stiffening the panel with cross-breaks, beads or reinforcement angles stops it. More speed raises the pressure swing and makes drumming worse.
Check it: RSOS task E-19 (repairing faulty systems and components)
These are VoltExam questions written for the Red Seal Sheet Metal Worker Interprovincial Exam, not official exam questions. Each shows the rule or standard to check it against. New to this exam? Read the Red Seal Sheet Metal Worker (308A) guide.
Last checked against Red Seal Program (with provincial and territorial apprenticeship authorities) on .
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Official sources
- Red Seal – Sheet Metal Worker trade page ↗
- Red Seal – Sheet Metal Worker exam information (breakdown) ↗
- Red Seal – Overview of the Red Seal Examination ↗
- Skilled Trades Ontario – Sheet Metal Worker ↗
- Skilled Trades Ontario – Sheet Metal Worker (308A) 2025 trade report ↗
Sources checked November 3, 2026. VoltExam is independent and not affiliated with Red Seal Program (with provincial and territorial apprenticeship authorities). Rules change: confirm details with the official source before your exam.