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Free Red Seal Welder (456A) Practice Test
30 original practice questions with explanations, written for the Red Seal Welder Interprovincial Exam. Pick an answer to check it instantly.
Last checked against Red Seal Program (with provincial and territorial apprenticeship authorities) on .
These are VoltExam questions, not official exam questions. Each shows the rule or standard to check it against. New to this exam? Read the Red Seal Welder (456A) guide.
Question 1 · A – Performs common occupational skills
Before mounting a new abrasive disc on a 125 mm angle grinder, what must you confirm about the disc's marked maximum speed?
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Answer: A. It is equal to or greater than the grinder's rated no-load speed
A disc spun faster than its rated maximum speed can burst from centrifugal force and throw fragments at high velocity. The disc's marked r/min must be at least the grinder's no-load speed, and the guard must stay in place.
Check it: RSOS task A-1 (maintains tools and equipment)
Question 2 · A – Performs common occupational skills
Why must acetylene cylinders be stored and used in an upright position?
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Answer: B. Because acetylene is dissolved in acetone, which can be drawn out through the valve if the cylinder lies on its side
Free acetylene is unstable under pressure, so it is dissolved in acetone held in a porous filler. If the cylinder is on its side, liquid acetone can be withdrawn with the gas, damaging regulators and creating a hazardous flame. A cylinder that has been lying down should stand upright before use.
Check it: CSA W117.2 (safety in welding, cutting and allied processes)
Question 3 · A – Performs common occupational skills
A welder is repairing galvanized steel brackets in a poorly ventilated area. What specific health hazard does this create?
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Answer: C. Zinc oxide fumes that can cause metal fume fever
Galvanized steel is coated with zinc, which vaporizes and oxidizes in the arc. Inhaling zinc oxide fume can cause metal fume fever, with flu-like symptoms. Remove the coating near the joint where permitted and use local exhaust ventilation or suitable respiratory protection.
Check it: RSOS task A-3 (performs safety-related activities)
Question 4 · A – Performs common occupational skills
On a standard welding symbol, a fillet weld symbol is drawn below the reference line. Where is the weld made?
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Answer: D. On the arrow side of the joint
By convention, a weld symbol below the reference line means the weld goes on the arrow side, the side the arrow points to. A symbol above the line means the other side, symbols on both sides mean both sides, and a flag at the junction indicates a field weld.
Check it: AWS A2.4 (standard welding symbols)
Question 5 · A – Performs common occupational skills
Why is preheat specified for welding thick, higher-carbon or high-strength steels?
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Answer: A. To slow the cooling rate so the heat-affected zone is less hard and hydrogen can diffuse out, reducing the risk of cracking
Thick or hardenable steels cool quickly after welding, which can form hard, brittle microstructures in the heat-affected zone. Combined with hydrogen and restraint, this causes cold (hydrogen) cracking. Preheat slows cooling and gives hydrogen time to escape.
Check it: RSOS task A-5 (performs routine trade activities); CSA W59
Question 6 · B – Performs layout and fabrication of components for welding
You need to wrap a template around NPS 6 pipe with an outside diameter of 168.3 mm. What is the outside circumference?
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Answer: B. About 529 mm
Circumference = π × diameter = 3.1416 × 168.3 ≈ 528.7 mm. 337 mm is just twice the diameter, 1057 mm uses 2π × diameter (that would need the radius), and 264 mm is half the circumference.
Check it: RSOS task B-7 (performs layout)
Question 7 · B – Performs layout and fabrication of components for welding
A rectangular frame is laid out 1200 mm by 1600 mm. To check that it is square, what should each diagonal measure?
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Answer: C. 2000 mm
By the Pythagorean theorem, diagonal = √(1200² + 1600²) = √(1 440 000 + 2 560 000) = √4 000 000 = 2000 mm. If both diagonals are equal the frame is square; 2800 mm is simply the sum of the two sides.
Check it: RSOS task B-7 (performs layout)
Question 8 · B – Performs layout and fabrication of components for welding
A single-sided fillet weld on a T-joint keeps pulling the vertical plate out of square toward the weld. Which fit-up technique best counters this?
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Answer: D. Preset the plate at a slight angle away from the weld so shrinkage pulls it back to square
Weld metal shrinks as it cools and pulls the joint toward the weld side. Presetting the part by the expected amount in the opposite direction lets shrinkage bring it into position. Larger welds add more shrinkage and make distortion worse.
Check it: RSOS task B-8 (fabricates components)
Question 9 · B – Performs layout and fabrication of components for welding
Why should tack welds be made with the same care, filler metal and preheat as the final weld?
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Answer: A. Because tack welds are usually incorporated into the final weld, so any defect in them becomes a defect in the joint
Tack welds are normally fused into the root or later passes. A cracked, porous or cold tack becomes part of the finished weld, so tacks should meet the same quality requirements, and cracked tacks should be removed before welding.
Check it: RSOS task B-8 (fabricates components); CSA W59
Question 10 · B – Performs layout and fabrication of components for welding
Two plates are each bevelled at 30° for a single-V groove butt joint. What is the included groove angle?
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Answer: B. 60°
The groove angle is the total included angle between the two bevelled faces. Two 30° bevels give 30° + 30° = 60°. The bevel angle refers to one member only.
Check it: RSOS task B-8 (fabricates components)
Question 11 · B – Performs layout and fabrication of components for welding
What is the backstep welding sequence?
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Answer: C. Depositing short weld segments in the direction opposite to the overall progression of the weld
In backstep welding, each short segment is welded back toward the previous one while the joint as a whole progresses forward. Spreading heat this way limits the build-up of shrinkage in one direction and helps control distortion.
Check it: RSOS task B-8 (fabricates components)
Question 12 · B – Performs layout and fabrication of components for welding
Steel has a density of about 7850 kg/m³. What is the approximate mass of a plate 2 m × 1 m × 10 mm thick?
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Answer: D. 157 kg
Volume = 2 m × 1 m × 0.010 m = 0.02 m³. Mass = 0.02 × 7850 = 157 kg. Converting millimetres to metres correctly is the key step; knowing the mass lets you choose suitable lifting equipment.
Check it: RSOS task B-8 (fabricates components); RSOS task A-2 (material handling)
Question 13 · C – Performs cutting and gouging
Why is oxy-fuel gas cutting not effective on stainless steel?
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Answer: A. The chromium oxide that forms melts at a higher temperature than the base metal and does not blow away as slag
OFC works by rapidly oxidizing preheated iron and blowing out the fluid oxide. In stainless steel, chromium forms a refractory oxide with a melting point above that of the steel, so the cut cannot proceed cleanly. Plasma arc cutting is used instead.
Check it: RSOS task C-10 (oxy-fuel gas cutting)
Question 14 · C – Performs cutting and gouging
What is the generally accepted maximum working pressure for withdrawing acetylene from a cylinder or regulator?
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Answer: B. 103 kPa (15 psi)
Acetylene becomes unstable and can decompose explosively above about 103 kPa (15 psi) gauge. Regulators should never be set above this, and most cutting is done well below it.
Check it: CSA W117.2 (safety in welding, cutting and allied processes)
Question 15 · C – Performs cutting and gouging
A shop needs to cut 12 mm aluminum plate with a thermal process. Which process is suitable?
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Answer: C. Plasma arc cutting
Plasma arc cutting melts metal with a constricted high-temperature arc and blows it away, so it cuts any electrically conductive metal, including aluminum and stainless steel. Oxy-fuel processes rely on oxidizing iron and do not work on aluminum.
Check it: RSOS task C-11 (plasma arc cutting)
Question 16 · C – Performs cutting and gouging
Which current and polarity are normally used for air carbon arc gouging with DC copper-coated carbon electrodes?
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Answer: D. DCEP (electrode positive)
Air carbon arc gouging with standard DC electrodes uses DCEP, which gives a stable arc and efficient metal removal. The compressed air jet blows the molten metal out of the groove. AC requires special AC electrodes and is less common.
Check it: RSOS task C-12 (air carbon arc cutting and gouging)
Question 17 · C – Performs cutting and gouging
Why should grinding discs and wire brushes used on stainless steel be kept separate from those used on carbon steel?
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Answer: A. Carbon steel particles embedded in stainless steel can rust and reduce its corrosion resistance
Iron particles transferred from carbon-steel tools contaminate the stainless surface and rust, causing staining and pitting. Dedicated discs and stainless steel brushes protect the passive chromium oxide layer.
Check it: RSOS task C-9 (non-thermal cutting and grinding)
Question 18 · D – Welding processes
In the CSA W48 electrode classification E4918, what does '49' indicate?
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Answer: B. A minimum tensile strength of 490 MPa for the weld metal
CSA W48 uses metric classifications. In E4918, '49' is the minimum weld-metal tensile strength of 490 MPa, '1' means all positions, and '8' means a low-hydrogen potassium coating with iron powder, usable on AC or DCEP. It is the metric equivalent of E7018.
Check it: CSA W48 (filler metals and allied materials for metal arc welding)
Question 19 · D – Welding processes
After a can of E4918 electrodes is opened, why are unused electrodes kept in a heated holding oven?
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Answer: C. To keep the low-hydrogen coating from absorbing moisture, which would add hydrogen to the weld
Low-hydrogen coatings pick up moisture from the air. That moisture breaks down in the arc and puts hydrogen into the weld, raising the risk of hydrogen-induced cracking and porosity. Storage ovens and limited exposure times keep the coating dry.
Check it: RSOS task D-13 (shielded metal arc welding); CSA W48
Question 20 · D – Welding processes
While SMAW welding with DC near the end of a heavy steel member, the arc keeps deflecting and spattering. Which change is most likely to correct this arc blow?
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Answer: D. Switch to AC with an electrode suited to AC
Arc blow is caused by unbalanced magnetic fields around a DC arc, especially near ends and corners. Alternating current reverses the field many times a second, which largely eliminates arc blow. Shortening the arc, angling the electrode and relocating the work connection can also help; a longer arc makes it worse.
Check it: RSOS task D-13 (shielded metal arc welding)
Question 21 · D – Welding processes
Which CSA W48 electrode has a cellulose-sodium coating, gives deep penetration, and is commonly run on DCEP for open-root pipe passes?
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Answer: A. E4310
E4310 (metric equivalent of E6010) has a high-cellulose sodium coating that produces a forceful, deep-penetrating arc and runs on DCEP, making it popular for open-root passes. E4918 is low-hydrogen, E4924 is a high-deposition iron-powder rod for flat and horizontal work, and E4313 is a soft-arc rutile electrode.
Check it: CSA W48 (filler metals and allied materials for metal arc welding)
Question 22 · D – Welding processes
Which GMAW metal transfer mode has the lowest heat input and is best suited to thin sheet and out-of-position work?
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Answer: B. Short-circuiting transfer
In short-circuiting transfer, the wire touches the weld pool and shorts many times per second at low voltage and current. The small, cool weld pool suits thin material and all positions, but it is prone to lack of fusion on thick sections if misused.
Check it: RSOS task D-14 (FCAW, MCAW and GMAW)
Question 23 · D – Welding processes
To achieve axial spray transfer with GMAW on carbon steel, which shielding gas is required?
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Answer: C. An argon-rich mixture, such as 90% argon and 10% carbon dioxide
Spray transfer needs a high-argon shielding gas (typically above about 80% argon) and current above the transition level. Pure CO₂ produces globular transfer with more spatter at high currents. Nitrogen is not a shielding gas for steel GMAW.
Check it: RSOS task D-14 (FCAW, MCAW and GMAW)
Question 24 · D – Welding processes
What is the main advantage of self-shielded flux-cored arc welding (FCAW-S) for outdoor field work?
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Answer: D. It does not need an external shielding gas, so wind is less likely to cause porosity
FCAW-S generates its own shielding from the core ingredients, so there is no gas cylinder and no gas shield to be blown away by wind. It still produces slag and fairly high fume, so cleaning between passes and ventilation are needed.
Check it: RSOS task D-14 (FCAW, MCAW and GMAW)
Question 25 · D – Welding processes
A GMAW welder starts getting porosity after moving to a station next to an open bay door. What is the most likely cause?
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Answer: A. Drafts are blowing away the shielding gas
Wind and drafts disturb the gas shield, letting air reach the molten pool. Nitrogen and oxygen from the air cause porosity. Use screens, reduce drafts, check gas flow and nozzle condition, or switch to a self-shielded process outdoors.
Check it: RSOS task D-14 (FCAW, MCAW and GMAW)
Question 26 · D – Welding processes
Why is alternating current normally used for GTAW on aluminum?
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Answer: B. The electrode-positive half of the cycle breaks up the surface aluminum oxide (cleaning action)
Aluminum is covered by a tough oxide that melts far above the base metal. During the electrode-positive part of the AC cycle, the arc breaks up this oxide; during the electrode-negative part, more heat goes into the work for penetration. Argon shielding is still required.
Check it: RSOS task D-15 (gas tungsten arc welding)
Question 27 · D – Welding processes
When preparing a tungsten electrode for DC GTAW, why should the grinding marks run lengthwise toward the point?
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Answer: C. To give a stable, focused arc; circumferential marks can make the arc wander
Grinding along the electrode's length leaves ridges that direct the arc straight off the tip, giving a stable, focused arc. Grinding around the circumference can cause the arc to wander. Use a dedicated wheel to avoid contaminating the tungsten.
Check it: RSOS task D-15 (gas tungsten arc welding)
Question 28 · D – Welding processes
Which polarity is normally used for GTAW on carbon steel and stainless steel, and why?
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Answer: D. DCEN, because most of the heat goes into the work and the tungsten stays cooler
With DCEN (electrode negative), electrons flow from the tungsten to the work, putting most of the heat into the work for good penetration while the tungsten stays relatively cool. DCEP overheats the tungsten, and AC cleaning action is only needed on metals with refractory oxides such as aluminum.
Check it: RSOS task D-15 (gas tungsten arc welding)
Question 29 · D – Welding processes
When GTAW welding a stainless steel pipe root, why is the inside of the pipe purged with argon?
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Answer: A. To prevent heavy oxidation (sugaring) on the root side, which harms corrosion resistance and weld quality
Hot stainless steel exposed to air on the back of the root oxidizes into a rough, granular 'sugared' surface that reduces corrosion resistance and can hide defects. Back purging displaces the air with inert gas until the root and hot pass are complete.
Check it: RSOS task D-15 (gas tungsten arc welding)
Question 30 · D – Welding processes
Why is submerged arc welding generally limited to the flat position and horizontal fillet welds?
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Answer: B. The granular flux and large molten pool must be held in place by gravity
In SAW the arc is buried under a blanket of granular flux, and the weld pool and slag are large and fluid. Gravity is needed to keep the flux on the joint and support the pool, so SAW is used mostly flat or for horizontal fillets unless special flux-retaining equipment is used. No shielding gas is used.
Check it: RSOS task D-16 (submerged arc welding)
Official sources
- Red Seal – Welder trade page ↗
- Red Seal – Welder exam information (breakdown) ↗
- Red Seal – Welder exam breakdown ↗
- Red Seal – Red Seal Occupational Standard: Welder ↗
- Red Seal – Overview of the Red Seal Examination ↗
- Skilled Trades Ontario – Welder (456A) ↗
- Skilled Trades Ontario – Welder practical assessment advisory (PDF) ↗
- Saskatchewan Apprenticeship – Welder Interprovincial Journeyperson Examination Information 2026 (PDF) ↗
- CWB Group – What is a Red Seal trade qualification? ↗
Sources checked November 2, 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.