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MTTC Welding Trade Test practice questions

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Question 1Welding Safety, Health, and Environmental Practices

Which type of fire extinguisher is specifically designed for use on energized electrical equipment?

  1. Class C extinguisher Correct answer.
  2. Class B foam extinguisher
  3. Class D extinguisher
  4. Class A water-based extinguisher

Explanation

Class C extinguishers use non-conductive agents such as carbon dioxide or dry chemical to smother fires involving energized electrical equipment without exposing the operator to shock. Water and foam conduct electricity and must never be used on live circuits. Class D agents are formulated for combustible metals and are not rated for electrical hazards.

Question 2Welding Safety, Health, and Environmental Practices

What is the primary purpose of a welding fume extraction system at the arc?

  1. To supply shielding gas to the weld pool
  2. To capture airborne metal fumes and gases before they enter the welder's breathing zone Correct answer.
  3. To reduce the intensity of ultraviolet radiation from the arc
  4. To cool the weld joint and reduce distortion

Explanation

Local exhaust ventilation captures contaminants at or near the source, preventing metal fume and shielding-gas decomposition products from reaching the welder's breathing zone. It does not cool the weld, deliver shielding gas, or filter arc radiation. Effective capture depends on hood placement and airflow rate.

Question 3Welding Safety, Health, and Environmental Practices

Before arc welding on a metal part, a welder should verify that the work lead is securely connected to the workpiece. What is the main safety reason for this check?

  1. To maintain the correct arc voltage for the welding process
  2. To prevent the welding current from traveling through unintended paths such as building steel or grounding conductors Correct answer.
  3. To keep the electrode from sticking to the work
  4. To ensure the shielding gas flows at the correct rate

Explanation

A poor or missing work connection forces welding current to seek alternative paths, which can overheat conductors, damage equipment, or create shock and fire hazards. Proper connection keeps the circuit confined to the intended welding leads and workpiece. Gas flow, electrode sticking, and arc voltage are unrelated to work-lead connection safety.

Question 4Welding Safety, Health, and Environmental Practices

A welder must perform gas tungsten arc welding inside a confined space. Which practice is required before entry?

  1. Starting the arc immediately to burn off any accumulated gases
  2. Testing the atmosphere for oxygen content and flammable or toxic gases Correct answer.
  3. Leaving the space open to the shop floor for natural ventilation
  4. Using a self-contained breathing apparatus only if the welder feels dizzy

Explanation

Confined spaces can accumulate argon or helium that displaces oxygen, and welding can generate toxic fumes, so atmospheric testing must be performed before and during entry. Natural ventilation alone is unreliable in a confined space. Respiratory protection and a written entry plan with an attendant are typically required.

Question 5Welding Safety, Health, and Environmental Practices

Which type of eye and face protection is appropriate for a welder using shielded metal arc welding?

  1. Sunglasses with UV-blocking lenses
  2. A face shield with a clear visor
  3. A welding helmet with a filter lens of the correct shade number Correct answer.
  4. Clear safety glasses alone

Explanation

Arc welding emits intense ultraviolet and infrared radiation that can cause arc eye and skin burns, so a welding helmet with a properly selected filter shade is required. Clear safety glasses or face shields do not block the radiation. Sunglasses are not impact-rated and do not provide adequate arc protection.

Question 6Welding Safety, Health, and Environmental Practices

What is the primary hazard associated with welding on galvanized steel?

  1. Release of asbestos fibers from the coating
  2. Generation of carbon monoxide from the zinc coating
  3. Production of ozone that is harmless at any concentration
  4. Exposure to zinc oxide fume that can cause metal fume fever Correct answer.

Explanation

Galvanized steel carries a zinc coating that vaporizes at welding temperatures, producing zinc oxide fume; inhaling it can cause metal fume fever with flu-like symptoms. Asbestos is not present in galvanized coatings. Ozone is an irritant and is not harmless, and carbon monoxide is not generated from zinc.

Question 7Welding Safety, Health, and Environmental Practices

Which statement correctly describes the use of compressed gas cylinders in a welding shop?

  1. Cylinders may be laid horizontally during storage as long as caps are on.
  2. Cylinders must be secured upright to prevent them from falling. Correct answer.
  3. Cylinders should be stored near a heat source to keep regulators from freezing.
  4. Cylinders may be used as rollers to move heavy workpieces.

Explanation

Compressed gas cylinders must be secured in an upright position to prevent tipping, which can damage the valve and cause a violent release of gas. Storing them near heat raises internal pressure and is prohibited. Using cylinders as rollers or supports can damage them and is unsafe.

Question 8Welding Safety, Health, and Environmental Practices

In gas welding, which device prevents a flashback from traveling back into the fuel gas hose and cylinder?

  1. A pressure regulator
  2. A flashback arrestor Correct answer.
  3. A flowmeter
  4. A cylinder valve

Explanation

A flashback arrestor contains a check valve and a flame barrier that stop a flame from propagating backward through the hose into the regulator and cylinder. Regulators reduce pressure but do not stop flame travel. Flowmeters indicate gas flow, and cylinder valves simply open or close the supply.

Question 9Welding Safety, Health, and Environmental Practices

A welder notices the smell of acetylene near a leaking hose connection. What is the appropriate immediate action?

  1. Wrap the connection with tape and resume welding
  2. Close the cylinder valves, ventilate the area, and repair or replace the leaking component before further use Correct answer.
  3. Increase the acetylene pressure to clear the leak
  4. Continue welding while monitoring the smell

Explanation

Acetylene is highly flammable and forms explosive mixtures with air, so a leak must be isolated by closing the cylinder valves and the area must be ventilated. The faulty hose or fitting must be repaired or replaced before work resumes. Increasing pressure or taping a leak does not eliminate the ignition hazard.

Question 10Welding Safety, Health, and Environmental Practices

What is the purpose of a hot work permit in a welding operation?

  1. To document the welder's certification level
  2. To record the welding procedure specification used for the job
  3. To schedule the welder's lunch and rest breaks
  4. To verify that fire hazards have been controlled and that fire watch and authorization are in place before hot work begins Correct answer.

Explanation

A hot work permit is a formal authorization that confirms combustible materials are removed or protected, fire extinguishing equipment is available, and a fire watch is assigned. It is not a certification record, a welding procedure document, or a break schedule. The permit helps prevent fires from sparks and slag.

Question 11Welding Safety, Health, and Environmental Practices

When welding overhead, which personal protective equipment is most important to prevent burns from falling sparks and slag?

  1. Leather cape, sleeves, and a flame-resistant head covering Correct answer.
  2. A disposable dust mask
  3. A cotton T-shirt and shorts
  4. Rubber boots and a raincoat

Explanation

Overhead welding allows molten slag and sparks to fall onto the welder, so leather or flame-resistant cape, sleeves, and head protection are needed to prevent burns. Cotton clothing can ignite, and rubber raincoats can melt or conduct heat. A dust mask provides no protection against hot particles.

Question 12Welding Safety, Health, and Environmental Practices

Which gas is commonly used as a shielding gas for gas metal arc welding and can displace oxygen in a confined space?

  1. Argon Correct answer.
  2. Hydrogen
  3. Oxygen
  4. Acetylene

Explanation

Argon is an inert shielding gas widely used in gas metal arc welding, and because it is heavier than air it can accumulate in low areas and displace oxygen. Oxygen supports combustion and is never used as a shielding gas. Acetylene is a fuel gas, and hydrogen is not a common inert shielding gas for this process.

Question 13Welding Safety, Health, and Environmental Practices

What is the correct way to move a compressed gas cylinder short distances on a shop floor?

  1. Roll the cylinder on its side
  2. Drag the cylinder by the hose
  3. Use a cylinder cart with the cylinder secured Correct answer.
  4. Carry the cylinder by its valve

Explanation

Cylinders should be moved on a properly designed cart with the cylinder secured and the valve cap in place when possible. Rolling or dragging a cylinder can damage the valve or shell, and lifting by the valve can break it off and cause a violent release. The valve is not a handle.

Question 14Welding Safety, Health, and Environmental Practices

A welder is using a grinder to prepare a joint. Which hazard control is most important for preventing eye injury?

  1. Wearing a welding helmet with a dark filter lens
  2. Wearing a dust mask
  3. Wearing tinted sunglasses
  4. Wearing safety glasses with side shields and a face shield Correct answer.

Explanation

Grinding produces high-velocity abrasive particles and sparks, so safety glasses with side shields plus a face shield provide the required impact protection. A welding helmet's dark filter reduces visibility for grinding and is not a substitute for impact-rated eye protection. Sunglasses and dust masks do not protect the eyes from flying debris.

Question 15Welding Safety, Health, and Environmental Practices

Which of the following is a correct practice for storing oxygen and fuel gas cylinders?

  1. Store oxygen cylinders at least 20 feet from fuel gas cylinders or separate them with a noncombustible barrier at least 5 feet high Correct answer.
  2. Store oxygen and acetylene cylinders together without separation
  3. Store all cylinders lying flat on the floor
  4. Store cylinders near oily rags to prevent rust

Explanation

Oxygen and fuel gas cylinders must be separated by at least 20 feet or by a noncombustible barrier at least 5 feet high with a fire-resistance rating. Keeping them together without separation increases the risk of a combined fire or explosion. Cylinders should be stored upright and away from combustible materials such as oily rags.

Question 16Welding Safety, Health, and Environmental Practices

What is the primary reason for wearing a respirator during welding when local exhaust ventilation is inadequate?

  1. To reduce noise from the welding arc
  2. To provide oxygen in an oxygen-deficient atmosphere
  3. To protect against exposure to metal fumes and toxic gases Correct answer.
  4. To keep the welding helmet from fogging

Explanation

When ventilation cannot keep airborne contaminants below exposure limits, a respirator filters or supplies clean air to protect the welder from metal fume and toxic gases. It does not prevent helmet fogging, supply oxygen unless it is a supplied-air type, or reduce arc noise. Respirator selection must match the contaminant and concentration.

Question 17Welding Safety, Health, and Environmental Practices

A welder is working near a sprinkler system and needs to perform hot work. What should be done to protect the sprinkler heads?

  1. Turn off the entire sprinkler system for the shift
  2. Remove the sprinkler heads temporarily
  3. Cover the sprinkler heads with a noncombustible shield or use a heat-resistant blanket Correct answer.
  4. Paint the sprinkler heads with heat-resistant paint

Explanation

Sprinkler heads can be activated by welding heat or sparks, causing water damage and disabling fire protection, so they should be shielded with a noncombustible cover. Removing heads or shutting off the system disables fire protection and is not permitted without proper authorization. Painting a sprinkler head can interfere with its operation.

Question 18Welding Safety, Health, and Environmental Practices

Which statement about the use of a fire watch during welding is correct?

  1. A fire watch is responsible for welding the joint.
  2. A fire watch must remain in the area for a specified period after welding ends to detect smoldering fires. Correct answer.
  3. A fire watch is only required when welding inside a building.
  4. A fire watch may leave the area once the arc is turned off.

Explanation

A fire watch monitors for sparks and smoldering materials during and after hot work, typically for at least 30 minutes after completion, to catch delayed ignition. The watch must not leave immediately when the arc stops. Fire watch duties are separate from welding, and outdoor work may also require a watch.

Question 19Welding Safety, Health, and Environmental Practices

What is the main hazard of using carbon dioxide as a shielding gas in a poorly ventilated area?

  1. It reacts with steel to form toxic phosgene.
  2. It causes immediate skin burns on contact.
  3. It is flammable and can ignite.
  4. It is heavier than air and can displace oxygen, causing asphyxiation. Correct answer.

Explanation

Carbon dioxide is heavier than air and can accumulate in low-lying areas, displacing oxygen and creating an asphyxiation hazard in poorly ventilated spaces. It is not flammable. Phosgene can form from chlorinated solvents exposed to arc radiation, not from carbon dioxide reacting with steel, and cold gas contact is not a primary burn hazard.

Question 20Welding Safety, Health, and Environmental Practices

A welder is preparing to weld on a metal drum that may have contained flammable liquid. What is the correct safety procedure?

  1. Weld immediately because the drum is empty.
  2. Fill the drum with water and weld without further testing.
  3. Vent the drum by opening the bung and begin welding.
  4. Purge and clean the drum according to a documented procedure, test the atmosphere, and obtain authorization before welding. Correct answer.

Explanation

Empty containers can hold flammable vapor or residue that may explode when heated, so they must be cleaned, purged, and tested before hot work. Filling with water alone does not remove flammable vapor from all areas. Simply opening a bung does not make the atmosphere safe.

Question 21Welding Safety, Health, and Environmental Practices

Which of the following is a correct practice for preventing electric shock when welding in a damp area?

  1. Weld barefoot to improve grounding
  2. Use equipment with damaged insulation as long as the welder wears gloves
  3. Increase the open-circuit voltage to improve arc starting
  4. Stand on a dry wooden board and wear rubber-soled boots Correct answer.

Explanation

Damp conditions lower body resistance and increase shock severity, so the welder should stand on a dry insulating surface and wear dry rubber-soled boots. Bare feet or damaged insulation increase the risk of electrocution. Higher open-circuit voltage raises the shock hazard and is not a control measure.

Question 22Welding Safety, Health, and Environmental Practices

What is the purpose of a ground fault circuit interrupter (GFCI) in a welding shop?

  1. To filter electromagnetic interference from the welding machine
  2. To detect a ground fault and quickly interrupt power to prevent electrocution Correct answer.
  3. To reduce the welding current to a safe level
  4. To stabilize the arc during welding

Explanation

A GFCI monitors the difference between current leaving and returning through the circuit; when a ground fault is detected, it interrupts power quickly enough to reduce the risk of electrocution. It does not regulate welding current, stabilize the arc, or filter interference. GFCIs are especially important for portable tools and damp locations.

Question 23Welding Safety, Health, and Environmental Practices

Which factor most strongly influences the selection of a filter shade number for a welding helmet?

  1. The ambient noise level in the shop
  2. The type of base metal being welded
  3. The color of the welder's clothing
  4. The welding process, current, and arc time Correct answer.

Explanation

Filter shade selection is based on the welding process, the amperage or current level, and the duration of arc exposure, with higher currents requiring darker shades. Clothing color, base metal type, and noise level do not determine the required shade. Using too light a shade can cause arc eye and skin burns.

Question 24Welding Safety, Health, and Environmental Practices

A welder using a fuel gas torch notices a pop and the flame goes out at the tip. What should be done before relighting?

  1. Increase the fuel gas pressure and relight
  2. Immediately relight the torch while the gas is still flowing
  3. Close the torch valves, allow accumulated gas to dissipate, and check the equipment for the cause Correct answer.
  4. Point the torch at the work and strike a spark

Explanation

A pop and flameout can leave unburned fuel gas flowing, so the torch valves must be closed and the area allowed to ventilate before relighting. Relighting immediately can cause a flash fire or explosion. The equipment should be inspected for a loose tip, incorrect pressures, or a blocked orifice.

Question 25Welding Processes and Equipment

Which welding process uses a continuously fed consumable wire electrode and a shielding gas supplied through the gun, with the wire feed speed controlling the current?

  1. Oxyfuel gas welding
  2. Gas metal arc welding Correct answer.
  3. Gas tungsten arc welding
  4. Shielded metal arc welding

Explanation

Gas metal arc welding (GMAW) feeds a bare consumable wire from a spool through the gun, and the operator sets wire feed speed, which largely determines the welding current. A separate shielding gas protects the molten puddle. The other processes either use a non-consumable electrode, a coated stick electrode, or a fuel gas flame.

Question 26Welding Processes and Equipment

In shielded metal arc welding, what is the primary function of the flux coating on the electrode?

  1. It increases the deposition rate by adding iron powder only
  2. It generates shielding gas and forms a protective slag over the weld Correct answer.
  3. It cools the weld puddle to prevent distortion
  4. It conducts the welding current to the base metal

Explanation

The flux coating decomposes in the arc heat to release shielding gases and to form a slag layer that blankets the cooling weld and excludes atmospheric oxygen and nitrogen. It also stabilizes the arc and can add alloying elements. Current is carried by the metal core, not the coating.

Question 27Welding Processes and Equipment

What does the term 'duty cycle' mean for an arc welding power source rated at 200 amps, 60 percent duty cycle?

  1. The machine can run at 200 amps for 6 out of every 10 minutes without overheating Correct answer.
  2. The machine can weld 60 percent of each minute at 200 amps continuously
  3. The machine delivers 60 percent of 200 amps as its average output
  4. The machine must rest 60 percent of its total service life

Explanation

Duty cycle is the percentage of a 10-minute period that a power source can operate at its rated current without exceeding its thermal limit. A 60 percent rating at 200 amps therefore permits 6 minutes of welding at 200 amps followed by 4 minutes of idling or lower-current work in each 10-minute cycle.

Question 28Welding Processes and Equipment

Which current type is required for the self-regulating 'digging' arc behavior that lets a constant-voltage GMAW power source maintain arc length automatically?

  1. Pulsed alternating current with variable frequency
  2. Direct current electrode negative with a rising characteristic
  3. Direct current electrode positive with a constant-voltage characteristic Correct answer.
  4. Alternating current with a drooping characteristic

Explanation

In GMAW the power source holds voltage nearly constant, and DCEP provides stable metal transfer with good penetration. Because voltage tracks arc length, a self-regulating arc keeps the arc length nearly fixed as the gun-to-work distance changes. Constant-current drooping sources behave differently and do not self-regulate in this way.

Question 29Welding Processes and Equipment

A welder is using the short-circuiting transfer mode in GMAW. Which combination of settings best describes this mode?

  1. High voltage and low current with a large globular droplet
  2. High voltage and high current with a spray of fine droplets
  3. Medium voltage with helium-rich gas and a long arc
  4. Low voltage and low current with the wire touching the puddle each cycle Correct answer.

Explanation

Short-circuiting transfer uses relatively low voltage and low current so the wire tip contacts the puddle, extinguishes the arc, and transfers metal by short circuit many times per second. It suits thin sheet and out-of-position work but produces more spatter. Spray transfer needs high current and high voltage with argon-rich gas.

Question 30Welding Processes and Equipment

Why is alternating current often preferred over direct current for welding aluminum with gas tungsten arc welding?

  1. AC produces a narrower heat-affected zone than any DC polarity
  2. The electrode-positive half cleans the oxide while the electrode-negative half provides penetration and electrode cooling Correct answer.
  3. AC completely eliminates the need for any shielding gas
  4. AC allows the use of a smaller tungsten electrode at higher current

Explanation

In AC GTAW the electrode-positive portion of the cycle bombards the work with positive ions, breaking up the tenacious aluminum oxide, while the electrode-negative portion delivers heat for penetration and keeps the tungsten from melting. This balance of cleaning and penetration is why AC is standard for aluminum.

Question 31Welding Processes and Equipment

In gas tungsten arc welding of steel, what is the consequence of using direct current electrode positive (DCEP)?

  1. Deep penetration with a long electrode life
  2. Improved shielding gas coverage at the arc
  3. Excellent cleaning action with shallow penetration and risk of melting the tungsten Correct answer.
  4. Increased travel speed with no change in penetration

Explanation

With DCEP the work is the cathode and receives heavy positive-ion bombardment, which cleans the surface but concentrates heat at the tungsten. Penetration is shallow and the electrode tends to overheat and melt, so DCEP is rarely used for steel. DCEN is the normal choice for steel.

Question 32Welding Processes and Equipment

What is the main purpose of a backing gas or purge when welding the root pass of stainless steel pipe?

  1. To preheat the pipe to reduce residual stress
  2. To speed up the cooling rate of the weld metal
  3. To prevent oxidation and loss of corrosion resistance on the inside surface Correct answer.
  4. To increase the deposition rate of the root pass

Explanation

The root surface of a stainless pipe is exposed to air on the inside while it is molten, and oxygen causes oxidation, discoloration, and chromium depletion that destroys corrosion resistance. Purging with argon or another inert gas displaces air until the root has cooled enough to stay bright.

Question 33Welding Processes and Equipment

A welder notices porosity concentrated along the centerline of a gas metal arc weld made on galvanized steel. Which cause is most likely?

  1. Travel angle held too far in the push position
  2. Too much preheat applied to the joint
  3. Zinc vapor from the coating entering the molten puddle Correct answer.
  4. Excessive shielding gas flow rate only

Explanation

Galvanized steel carries a zinc coating that vaporizes well below the steel melting point, and the vapor can be trapped in the solidifying puddle as porosity. Removing the coating near the joint, increasing gas coverage, or adjusting technique reduces the problem. Zinc fume also poses a health hazard requiring ventilation.

Question 34Welding Processes and Equipment

Which shielding gas blend is most commonly used for spray-transfer GMAW of carbon steel?

  1. A mixture of argon with 10 to 20 percent carbon dioxide Correct answer.
  2. Pure carbon dioxide
  3. Pure helium
  4. A mixture of argon with 25 percent oxygen

Explanation

Argon-rich blends with 10 to 20 percent CO2 give a stable spray arc on carbon steel with good penetration and bead appearance. Pure CO2 is cheaper but produces a harsher, more spattery globular arc and does not support true spray transfer. Helium is used mainly for high-conductivity metals or thick sections.

Question 35Welding Processes and Equipment

In flux-cored arc welding, what distinguishes a self-shielded wire from a gas-shielded wire?

  1. Self-shielded wire requires an external argon cylinder
  2. Self-shielded wire uses a non-consumable electrode
  3. Self-shielded wire can only be run on alternating current
  4. Self-shielded wire generates its own shielding from the flux core and needs no external gas Correct answer.

Explanation

Self-shielded FCAW wires contain fluxing and gas-forming ingredients in the core that protect the arc without an external gas supply, which suits outdoor and windy sites. Gas-shielded FCAW wires require an external shielding gas such as CO2 or an argon blend. Both use a continuously fed consumable tubular electrode.

Question 36Welding Processes and Equipment

What is the primary role of the orifice or gas lens in a GTAW torch?

  1. To cool the tungsten electrode by water circulation
  2. To feed filler wire automatically into the puddle
  3. To increase the welding current capacity of the torch
  4. To deliver shielding gas in a smooth, laminar flow that covers the weld zone Correct answer.

Explanation

The gas lens uses fine screens to straighten the gas flow so it emerges as a smooth, laminar column that resists turbulence and gives better coverage, especially with a longer electrode extension. It does not carry current, feed wire, or cool the torch.

Question 37Welding Processes and Equipment

A welder is preparing to weld 1/4 inch thick carbon steel plate with SMAW using E7018 electrodes. What electrode condition is most important for avoiding porosity?

  1. The electrodes should be bent slightly to improve arc starting
  2. The electrodes should be stored in a low-hydrogen oven and kept dry before use Correct answer.
  3. The electrodes should be dipped in water to improve conductivity
  4. The electrodes should be cooled below freezing before use

Explanation

E7018 is a low-hydrogen electrode whose coating absorbs moisture readily, and moisture in the coating introduces hydrogen that causes porosity and hydrogen cracking. Electrodes must be kept in a holding oven after opening and dried per the manufacturer's recommendations. Water or freezing would damage the coating.

Question 38Welding Processes and Equipment

What is the primary reason for using direct current electrode negative (DCEN) with gas tungsten arc welding on carbon steel?

  1. It concentrates heat in the work for deeper penetration and reduces tungsten overheating Correct answer.
  2. It allows the use of a larger nozzle diameter
  3. It provides the strongest oxide cleaning action
  4. It eliminates the need for filler metal

Explanation

With DCEN the work is positive and receives the electron bombardment, so most of the arc heat goes into the work, giving deeper penetration while the tungsten stays relatively cool. The trade-off is that DCEN offers little oxide cleaning, which is why reactive metals and aluminum often use AC.

Question 39Welding Processes and Equipment

Which of the following is the best description of the plasma arc welding process?

  1. It uses a constricted arc through a nozzle to produce a high-energy-density column Correct answer.
  2. It uses friction between a rotating tool and the workpiece
  3. It uses a consumable wire fed into a gas flame
  4. It relies on a fuel gas flame impinging on the joint

Explanation

Plasma arc welding forces the arc through a small orifice, constricting it into a high-temperature, high-velocity column with high energy density. This allows keyhole welding of thicker sections in a single pass. It is distinct from oxyfuel, GMAW, and friction stir processes.

Question 40Welding Processes and Equipment

What is the primary function of the pilot arc in plasma arc cutting?

  1. To cool the torch after cutting
  2. To establish a conductive path between the electrode and the nozzle so the main arc can transfer to the work Correct answer.
  3. To preheat the workpiece to reduce cracking
  4. To supply additional shielding gas to the cut

Explanation

In plasma cutting, a pilot arc is struck between the electrode and the nozzle, ionizing the gas so the main transferred arc can jump to the workpiece. This is especially important for cutting painted, rusty, or non-conductive surfaces where the arc would otherwise be hard to start.

Question 41Welding Processes and Equipment

A welder is setting up a submerged arc welding (SAW) operation for a long straight seam on thick plate. Which characteristic makes SAW well suited to this job?

  1. It uses a granular flux blanket and high currents for deep penetration at high deposition rates Correct answer.
  2. It is a manual process requiring no automated carriage
  3. It is limited to thin sheet metal below 1/8 inch
  4. It uses no filler metal and relies on fusing the base metal

Explanation

SAW buries the arc under a blanket of granular flux, allowing very high currents and deposition rates with deep penetration and good arc stability. Because the arc is hidden, it is typically run mechanically on flat or horizontal positions. It is not a thin-sheet or manual process.

Question 42Welding Processes and Equipment

What does the number '70' represent in the SMAW electrode classification E7018?

  1. The minimum tensile strength of the deposited weld metal in thousands of psi Correct answer.
  2. The percentage of iron powder in the coating
  3. The maximum plate thickness in sixteenths of an inch
  4. The welding current in amperes

Explanation

In the AWS electrode classification, the first two digits after the E give the minimum tensile strength of the deposited weld metal in thousands of pounds per square inch. The next digit indicates position, and the last digit indicates coating type and current. So E7018 deposits at least 70,000 psi tensile strength.

Question 43Welding Processes and Equipment

In gas metal arc welding, what happens to the arc if the contact-tip-to-work distance is increased significantly while all other settings stay the same?

  1. The transfer mode changes to spray regardless of settings
  2. The welding current rises sharply because resistance drops
  3. The arc becomes longer and less stable, and the current tends to drop because of increased resistance in the extended wire Correct answer.
  4. The shielding gas flow increases automatically

Explanation

Increasing the contact-tip-to-work distance lengthens the electrically resistive wire extension, which reduces current for a given voltage setting and makes the arc harder to control. The arc becomes longer and more prone to wandering and spatter. Good practice keeps the distance short and consistent.

Question 44Welding Processes and Equipment

Which type of power source characteristic is best suited for shielded metal arc welding with a constant-current (drooping) output?

  1. A rising voltage curve that increases current with arc length
  2. A pulsed curve that alternates polarity at high frequency
  3. A flat constant-voltage curve that holds voltage steady
  4. A steeply dropping voltage curve that limits current when the arc length changes Correct answer.

Explanation

SMAW uses a drooping constant-current characteristic so that small changes in arc length produce only small changes in current, giving the welder a stable, controllable arc. The open-circuit voltage is high enough to strike the arc, and the steep curve limits current during a short circuit. Flat constant-voltage sources are used for GMAW.

Question 45Welding Processes and Equipment

A welder is using oxyfuel gas welding with an oxyacetylene torch. Which flame type should be used for a neutral weld on mild steel?

  1. A carburizing flame with an excess of acetylene
  2. A neutral flame with equal proportions of oxygen and acetylene Correct answer.
  3. A soft flame with only acetylene
  4. An oxidizing flame with excess oxygen

Explanation

A neutral flame has approximately equal oxygen and acetylene, producing a well-defined inner cone and a clean, balanced combustion that neither adds carbon nor oxidizes the steel. It is the standard choice for mild steel. Carburizing and oxidizing flames are used for special purposes but can harm the weld.

Question 46Welding Processes and Equipment

What is the primary reason that pulsed GMAW is used for out-of-position welding on thin material?

  1. It lowers the average current while maintaining a stable spray transfer during the high-current pulses Correct answer.
  2. It increases the wire feed speed to the maximum machine setting
  3. It eliminates the need for shielding gas
  4. It changes the polarity to electrode negative during the pulse

Explanation

Pulsed GMAW alternates a high-current pulse, which produces spray transfer and good fusion, with a low background current that lets the puddle cool. The reduced average heat input makes the puddle easier to control in vertical and overhead positions on thin material. Shielding gas and polarity remain essentially unchanged.

Question 47Welding Processes and Equipment

What is the purpose of the slope control on a constant-current welding power source?

  1. It determines the duty cycle of the machine
  2. It controls how quickly the current rises or falls when the arc length changes, affecting arc stability and spatter Correct answer.
  3. It adjusts the wire feed speed in GMAW
  4. It sets the shielding gas flow rate

Explanation

Slope control adjusts the dynamic response of the power source, influencing how rapidly current changes when the arc length varies. A suitable slope helps stabilize the arc, reduce spatter, and improve restart behavior. It does not control gas flow, wire feed, or duty cycle.

Question 48Welding Processes and Equipment

Which of the following is a characteristic advantage of the gas tungsten arc welding process?

  1. It produces very high deposition rates for thick plate
  2. It uses a consumable electrode that is easy to feed
  3. It requires no shielding gas and can be used in windy outdoor conditions
  4. It gives precise control of the arc and heat input with excellent weld quality on thin material Correct answer.

Explanation

GTAW uses a non-consumable tungsten electrode and an independent arc, giving the welder fine control over heat input and filler addition. This yields clean, high-quality welds on thin sections and root passes, though deposition rates are low compared with GMAW or SAW.

Question 49Welding Processes and Equipment

A weld made with GMAW shows a narrow, ropey bead with poor fusion at the edges. Which parameter change is most likely to correct this?

  1. Decrease the shielding gas flow to near zero
  2. Reduce the voltage and increase the wire feed speed
  3. Increase the voltage to widen and flatten the bead while keeping current adequate Correct answer.
  4. Increase the travel speed significantly

Explanation

A narrow, ropey bead with poor edge fusion often indicates too low a voltage, which produces a short, stiff arc that does not wet out the toes. Raising the voltage lengthens and widens the arc, flattening the bead and improving fusion, provided current and travel speed remain suitable.

Question 50Welding Processes and Equipment

Which welding process uses a continuous consumable electrode fed through a gun with a shielding gas supplied around the arc?

  1. Shielded metal arc welding
  2. Gas metal arc welding Correct answer.
  3. Submerged arc welding
  4. Oxyfuel gas welding

Explanation

Gas metal arc welding feeds a continuous consumable wire electrode through a gun while a shielding gas flows around the arc to protect the molten metal. This continuous wire feed distinguishes it from processes using covered stick electrodes or granular flux. The shielding gas is externally supplied rather than generated by flux decomposition.