456A SMAW, GMAW, FCAW, GTAW and SAW practice questions.

Five free practice questions on SMAW, GMAW, FCAW, GTAW and SAW: block D of the Red Seal 456A Welder exam, about 54 of its 125 questions. They are in the exam's format: four options, one correct answer. Answer each one before opening the explanation. No account, no email.

01The questions

1. Procedural · Sets up FCAW, MCAW and GMAW equipment

   Welding overhead with FCAW-G on a shipyard deckhead, the welder finds spatter built up inside the nozzle, bridging it to the contact tip. What is the correct action?

   1. Raise the gas flow to push past the build-up
   2. Knock the nozzle on the work to break it loose
   3. Keep welding; nozzle spatter is only cosmetic
   4. Stop, clean the nozzle, apply anti-spatter
   Show the answer

   D. Correct. Spatter narrows the gas path and disturbs the shield, which causes porosity. Bridged to the tip, it also makes the nozzle live, and it can arc to the work. Clean with nozzle pliers or a reamer, check the diffuser ports and insulator, and apply anti-spatter to slow the build-up.

   Why not the others

   A. More flow through a clogged nozzle makes turbulence that draws air into the shield. It also leaves the tip-to-nozzle short in place. Clean the nozzle.

   B. Rapping the gun dents the nozzle and cracks the insulator. It usually leaves spatter behind, too. Clean with nozzle pliers or a reamer, then apply anti-spatter.

   C. Nozzle spatter affects gas coverage, which causes porosity. Once it bridges to the tip it is an electrical fault as well, so it has to be cleaned out.

2. Recall · Sets up SMAW equipment

   When does an SMAW power source put its highest voltage at the electrode holder?

   1. When it is on but not welding, at open-circuit voltage
   2. During welding at the highest amperage setting
   3. Only when set to AC above 200 A
   4. While the welder holds a very long arc
   Show the answer

   A. Correct. With the machine on and no arc, the holder sits at open-circuit voltage, commonly 50–80 V and higher than the voltage during welding. That is why changing rods barehanded or in wet conditions is a shock hazard and why voltage-reducing devices exist.

   Why not the others

   B. Current is highest while welding, but the voltage across the arc then drops to arc voltage (typically about 20–30 V). The highest voltage appears when no current is flowing.

   C. Open-circuit voltage is present on AC and DC at any current setting whenever the machine is on and the arc is out. AC shock is more dangerous at a given voltage, but it is not the only time voltage is high.

   D. A long arc raises the arc voltage, but it is still below the open-circuit voltage; once current flows, the CC machine's voltage falls from its no-load value.

3. Procedural · Sets up GTAW equipment

   An open-root GTAW joint on 50 mm (2 in) Schedule 10 304L tube for a food plant must have a smooth, bright root. How is the inside of the joint protected?

   1. Purge for a fixed 30 seconds, then strike
   2. Purge with CO₂ because it is heavier than air
   3. Raise the torch flow so gas reaches the root
   4. Dam each side, purge with argon, check the oxygen level
   Show the answer

   D. Correct. Dams or plugs on each side of the joint contain the purge, argon displaces the air, and an oxygen analyzer confirms the level is below the WPS limit before striking. Vent the purge so it cannot pressurize the tube and blow out the root.

   Why not the others

   A. A fixed time ignores the volume, flow and leaks, so oxygen may still be far above the limit. The purge is confirmed with an oxygen analyzer before welding.

   B. CO₂ is an active gas; at welding temperature it oxidizes the stainless and adds carbon, damaging corrosion resistance. Stainless back purges use argon or another gas the WPS lists.

   C. Torch gas cannot reach and stay on the inside of the tube; more flow just becomes turbulent. The root side needs its own contained back purge.

4. Procedural · Sets up SAW equipment

   A longitudinal SAW butt seam is being set up on a pressure-vessel shell course. How are the start and end of the weld handled?

   1. Start 25 mm (1 in) in from the end and back-weld
   2. Start at the plate edge with extra current
   3. Tack run-on and run-off tabs to the joint ends
   4. Stop short of the end and fill it by SMAW
   Show the answer

   C. Correct. Tabs of the same material and joint preparation let the arc settle before it reaches the part and carry the crater beyond it, so start porosity, lack of fusion and crater cracks end up in the tabs. They are removed afterwards by cutting and grinding, not by knocking them off.

   Why not the others

   A. Starting on the part puts the unstable start and its defects in the seam, and back-welding to the edge is awkward with a mechanized head. Run-on tabs take the start off the part.

   B. Extra current at the edge melts it away and still leaves the start defects in the seam. Run-on and run-off tabs keep the start and the crater off the part.

   D. Finishing the end by hand leaves an unplanned tie-in and a joint section the SAW procedure does not cover. Run-off tabs let the SAW bead run the full length.

5. Procedural · Sets operating parameters for FCAW, MCAW and GMAW

   The data sheet for an E491T-8 (E71T-8) self-shielded wire lists 19–32 mm (3/4–1-1/4 in) CTWD. A welder used to GMAW holds about 10 mm (3/8 in). What should they do?

   1. Keep 10 mm and add shielding gas to be safe
   2. Extend to the data-sheet range and hold it steady
   3. Extend to about 50 mm (2 in) for more deposition
   4. Keep 10 mm; a shorter stickout gives better control
   Show the answer

   B. Correct. Self-shielded wires are designed around a longer electrical stickout, which preheats the wire and sets the current, arc and shielding the classification assumes. Hold 19–32 mm steady and set voltage and WFS from the same data sheet; many FCAW-S guns use a guide tube or insulated nozzle to help hold it.

   Why not the others

   A. A self-shielded wire is not classified with gas, and gas does not correct the stickout. Hold the data-sheet extension.

   C. Going past the listed range drops the current further and makes the arc wander and fusion poorer. Deposition gains are not worth leaving the data-sheet range. Hold 19–32 mm.

   D. A short stickout suits short-circuit GMAW, not this wire. The self-shielded formulation is designed around the resistance preheat of the listed extension. Held short, it runs off its intended current and arc characteristics.

02Answer key

03What block D covers

This block covers the welding processes themselves. It includes SMAW electrodes such as E4918 and E4310, power sources, polarity and duty cycle, GMAW, FCAW and metal-cored wires, shielding gases and transfer modes, GTAW tungstens, AC balance and back purging, submerged arc fluxes and settings, and the defects each process produces, from arc blow and porosity to undercut, cold lap and crater cracks.

The Red Seal Occupational Standard names this block “Performs welding processes”. It carries 43.2% of the exam, about 54 of the 125 questions, split across four tasks. The share column is each task's weight within the block, as the standard publishes it.

04What the questions turn on

Reading electrode designations

In E4918, the 49 is the minimum tensile strength in tens of MPa, the same electrode as E7018 in imperial. The 1 means all positions, and the 8 means a low-hydrogen potassium iron-powder coating for DCEP or AC.

Polarity by process

Solid GMAW wire, gas-shielded flux-cored and metal-cored wires all run DCEP. Self-shielded wires such as T-8 and T-11 run DCEN, and GTAW on carbon and stainless steel runs DCEN so the tungsten stays cool.

CV voltage versus wire feed

On a CV machine, wire feed speed sets the current. Voltage too low for the feed speed stubs the wire into the pool and gives a narrow, ropey bead. Voltage too high gives large drops, a flat, wide bead and undercut.

Hydrogen from damp consumables

Moisture in exposed E4918 rods or flux-cored wire breaks down into hydrogen in the arc. It shows as porosity or wormtracks, and on Q&T steel welded without preheat, as a delayed crack at the toe in the HAZ.

05The other blocks

The 456A exam has four blocks. Each has its own page of free questions:

The 456A Welder practice exam page describes the full question bank. How these questions are written and checked: how our questions are made. Found a mistake? Tell us and we will fix it.