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Red Seal Pass › Welder (456A) › Ontario

Welder (456A) Red Seal Exam in Ontario

Certifying authority: Skilled Trades Ontario (STO). Last checked 2026-09-10.

Certification is voluntary in Ontario

This trade is not on Ontario’s compulsory list, so you may work in it without a certificate. The Red Seal still travels across Canada as a recognised credential, and employers frequently ask for it — but in Ontario it is a qualification, not a licence.

Source: Skilled Trades Ontario — Compulsory Trades (23 trades)

Preparing for the Welder (456A) exam in Ontario?

Start with 10 free interactive Welder (456A) questions with worked explanations, or take a full 125-question timed mock exam weighted to the official RSOS breakdown.

Try the 10-Question Interactive Welder (456A) Quiz & Free PDF → Take Full 125-Question Timed Mock Exam ($14.99 CAD) →

Or unlock all Welder (456A) questions with the 7-Day Pass ($9.99) or 3-Month Pass ($69.99, Free-Until-You-Pass Guarantee).

Whether it is required or not, the exam itself is the same paper everywhere in Canada. What your province decides is whether you must hold the certificate, how you apply, and where you sit it.

The exam: 125 questions, 4 Major Work Activities

The Red Seal Occupational Standard sets the split below. It does not change by province.

Major Work ActivityWeightingQuestions
MWA A: Performs Common Occupational Skills 16% 20 Qs
MWA B: Performs Layout and Fabrication of Components for Welding 22% 28 Qs
MWA C: Performs Cutting and Gouging 18% 23 Qs
MWA D: Welding Processes 43% 54 Qs

Source: Red Seal Exam Breakdown — Welder (456A), red-seal.ca

Time allowed and pass mark

4 hours, and a 70% pass mark (88/125). These are set provincially rather than by the Red Seal standard, and the four hours is the same whether your paper is 100 or 150 questions.

Confirmed against Skilled Trades Ontario’s Exam Preparation Guide and SkilledTradesBC. Check your own authority before exam day.

Quick 3-Question Welder (456A) Readiness Check

Click any option (A–D) below to grade yourself immediately and view the worked explanation:

Sample Question 1 of 3
A welder at a fabrication shop in Sarnia is sent to run SMAW with E7018 electrodes on baffle repairs inside a small storage tank. The tank is a confined space with one small access opening, and the entry permit has been issued after atmospheric testing. The crew lead asks what must be set up for fumes before and during the welding. What ventilation is needed?
A) Continuous mechanical exhaust that pulls the fumes away from the welder's breathing zone in the tank
B) Natural airflow through the access opening, with a pedestal fan set outside the tank at all times
C) A supplied-air respirator for the welder, with no ventilation running inside the tank at all
D) General shop ventilation switched on for just a few minutes between each of the welding passes
Correct answer: A

Fumes build up quickly in a confined space, so continuous mechanical ventilation that captures fumes at the source and keeps fresh air at the welder is required. Natural or intermittent airflow is not enough, and a respirator does not replace ventilation.

Sample Question 2 of 3
A welder in a Kingston fabrication shop is back gouging a column splice with an air carbon arc torch. Suddenly the gouge starts popping loudly, molten metal sprays everywhere, and the groove becomes ragged and bridged with metal that is not blown out. The current and carbon size have not changed. What supply fault is the most likely cause?
A) The travel speed is about half again faster than normal gouging
B) The carbon is too small for the current set on the power source dial
C) The compressed air supply has dropped and no longer clears the groove
D) The power source has switched itself from DCEP to DCEN polarity
Correct answer: C

Air carbon arc gouging depends on a strong air jet to blow the molten metal out of the groove. If the air supply drops, the molten metal stays under the arc, causing popping, spatter and slag bridges. Speed, carbon size and polarity do not fit the current and carbon that have not changed.

Sample Question 3 of 3
A shop in Sarnia is welding a Cr-Mo pipe spool after finishing a carbon steel job. The apprentice plans to use the same 50 degrees C preheat as on the carbon steel. The WPS for the alloy lists a higher preheat and interpass range, along with a post-weld heat treatment. What should the welder do?
A) Use the 50 degrees C from the carbon steel job, since steel is steel at any grade
B) Use the highest preheat the torch can reach, so as to be sure the alloy is warm
C) Leave out the preheat, and do only the post-weld heat treatment after the weld
D) Follow this alloy's WPS for preheat, interpass and post-weld heat treatment
Correct answer: D

Different alloys have different temperature needs, so the WPS for this alloy is followed. Cr-Mo steels harden readily and need more than a carbon steel's preheat. Too much heat can also harm properties, and post-weld heat treatment does not replace preheat for preventing cracks during welding.

Where you write it in Ontario

Booking is handled by Skilled Trades Ontario (STO); confirm current locations and dates with them.

Preparing for the Welder (456A) exam

Our Welder (456A) question bank is built to the official RSOS weighting above, with a worked explanation and code citation on every question.

Continue to Full 10-Question Interactive Welder (456A) Quiz → Take the full 125-question timed mock exam →

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