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NCCER Welding practice questions

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Question 1Welding Safety and Health

What is the main purpose of the filter lens in a welding helmet?

  1. It prevents spatter from entering the helmet through the top vent.
  2. It protects the outer cover lens from scratches during grinding.
  3. It reduces arc radiation to a safe level for the eyes. Correct answer.
  4. It keeps welding fumes out of the welder's breathing zone.

Explanation

The filter lens absorbs ultraviolet and infrared radiation and reduces visible arc intensity to protect the eyes and face. The clear cover lens protects the filter from spatter and scratches but does not provide the required arc protection.

Question 2Welding Safety and Health

After welding or cutting is finished, what is the minimum fire watch duration in an area with exposed combustibles?

  1. At least 60 minutes after the work ends
  2. Until the welder has put away the equipment
  3. At least 5 minutes after the work ends
  4. At least 30 minutes after the work ends Correct answer.

Explanation

A fire watch is required to continue for at least 30 minutes after hot work ends because concealed sparks or slag can smolder and start a fire later. The watch must have fire-extinguishing equipment and authority to stop the work.

Question 3Welding Safety and Health

Which gloves are appropriate for oxyfuel gas cutting?

  1. Rubber insulating gloves
  2. Latex exam gloves
  3. Leather gauntlet gloves Correct answer.
  4. Cotton work gloves

Explanation

Leather gauntlet gloves resist sparks, heat, and slag and cover the wrist opening during oxyfuel cutting. Other glove types either melt, burn, or are intended for electrical protection rather than heat.

Question 4Welding Safety and Health

Who should authorize a hot work permit before welding begins in a designated permit area?

  1. The site's designated hot work authorizer Correct answer.
  2. The welding consumables supplier
  3. The welder assigned to perform the work
  4. Any maintenance crew member on duty

Explanation

A hot work permit must be issued by an authorized individual who verifies that fire hazards are controlled, a fire watch is assigned, and equipment is in good condition. The welder may request the permit but cannot self-authorize it.

Question 5Welding Safety and Health

What is the main function of local exhaust ventilation at an arc welding station?

  1. It captures fumes at the arc before they reach the breathing zone. Correct answer.
  2. It cools the welding cable and the electrode holder during long passes.
  3. It filters the compressed air used by the welder's supplied-air respirator.
  4. It supplies additional shielding gas directly to the welding arc.

Explanation

Local exhaust ventilation captures welding fume close to the arc and removes it before it enters the welder's breathing zone. It supplements general ventilation but does not replace required respiratory protection in every situation.

Question 6Welding Safety and Health

What does a ground-fault circuit interrupter (GFCI) do on a portable welding circuit?

  1. It disconnects the shielding gas if the arc is lost.
  2. It limits the welding current to the electrode's rated amperage.
  3. It opens the circuit when current leaks to ground. Correct answer.
  4. It increases the open-circuit voltage to improve arc starting.

Explanation

A GFCI monitors the circuit for current leaking to ground and opens the circuit quickly to reduce the risk of electric shock. It does not regulate welding current, arc voltage, or gas flow.

Question 7Welding Safety and Health

Why is an acetylene cylinder valve opened only a small amount?

  1. To reduce the delivery pressure at the torch tip
  2. To prevent acetone from leaving the cylinder during use
  3. To keep the regulator from freezing in cold weather
  4. To allow quick shutdown if a flashback occurs Correct answer.

Explanation

An acetylene cylinder valve should be opened no more than one and one-half turns so the fuel can be shut off quickly if a flashback or hose fire occurs. The valve is not left fully open like an oxygen cylinder valve.

Question 8Welding Safety and Health

What is the purpose of a flashback arrestor installed on an oxyfuel hose?

  1. It prevents the hose from kinking at the torch connection during movement.
  2. It filters dirt and moisture from the oxygen stream before it reaches the torch.
  3. It regulates the gas pressure delivered to the torch at a steady value.
  4. It stops a flame from traveling back into the hose or cylinder. Correct answer.

Explanation

A flashback arrestor contains a flame path or check valve that stops a flame from traveling backward through the hose toward the regulator or cylinder. It is installed at the regulator outlet or torch inlet according to the manufacturer's instructions.

Question 9Welding Safety and Health

Before welding inside a confined space, which condition must be verified by atmospheric testing?

  1. The space's exit width, ladder rating, and floor slope meet construction standards.
  2. Oxygen content, flammable gas, and toxic contaminants are within acceptable limits. Correct answer.
  3. The welding machine's duty cycle, cable length, and electrode type are recorded.
  4. The space's lighting intensity, noise level, and humidity are within comfort ranges.

Explanation

Confined-space entry requires atmospheric testing for oxygen deficiency or enrichment, flammable gases, and toxic contaminants before welding begins. Testing must be repeated as conditions change, and ventilation and rescue provisions must also be in place.

Question 10Welding Safety and Health

Why must oxygen regulator fittings and cylinder valves be kept free of oil and grease?

  1. Grease changes the cylinder's pressure rating.
  2. Oil attracts moisture that corrodes the regulator seat.
  3. Hydrocarbons can ignite violently when exposed to oxygen. Correct answer.
  4. Oil causes the oxygen to burn with a cooler flame.

Explanation

Oxygen under pressure greatly accelerates combustion, and oil or grease can ignite violently when contacted by oxygen, especially with pressure or impact. Oxygen regulators, valves, and fittings must be kept clean and free of hydrocarbons.

Question 11Welding Safety and Health

Which eye and face protection is required when grinding weld slag from a completed joint?

  1. A hand-held chipping shield with no eye protection
  2. A face shield worn over safety glasses Correct answer.
  3. Safety glasses with side shields only
  4. A welding helmet with a filter lens only

Explanation

Grinding throws high-velocity particles that can strike the face and eyes from many angles, so primary impact protection is needed. A face shield worn over safety glasses provides both face coverage and secondary eye protection. A filter lens is designed for arc radiation, not for grinding impact.

Question 12Welding Safety and Health

How should oxygen and fuel-gas cylinders be stored at a welding site?

  1. Laid horizontally under a workbench
  2. Separated by at least 20 ft or a noncombustible barrier Correct answer.
  3. Side by side with the valve protection caps removed
  4. Chained together near the hot work area

Explanation

Oxygen and fuel-gas cylinders must be kept apart so a leaking cylinder cannot mix gas with the other and create a fire or explosion hazard. Accepted practice is separation by at least 20 ft or by a noncombustible barrier with a fire-resistance rating. Cylinders should also be upright and secured.

Question 13Welding Safety and Health

Which clothing practice is appropriate for arc welding?

  1. Wearing synthetic fabric shirts for easy cleaning
  2. Wearing pants legs outside boot tops Correct answer.
  3. Wearing pants with cuffs to catch sparks
  4. Rolling sleeves up to stay cool

Explanation

Sparks and slag can fall into cuffs or inside boot tops and burn the welder, so pants should cover the boot tops and have no cuffs. Sleeves should be kept down, and natural-fiber or leather clothing is preferred over synthetic fabrics that can melt.

Question 14Welding Safety and Health

A welder notices a gritty, burning sensation and sensitivity to light in both eyes several hours after arc welding without a helmet. Which hazard most likely caused these symptoms?

  1. Metal fume fever from zinc oxide
  2. Infrared radiation causing cataracts
  3. Foreign-body injury from grinding dust
  4. Ultraviolet radiation exposure causing arc eye Correct answer.

Explanation

Ultraviolet radiation from the arc can cause photokeratitis, commonly called arc eye or welder's flash, with symptoms appearing hours later. It affects both eyes and produces a gritty, burning feeling plus light sensitivity. A proper filter lens blocks this radiation.

Question 15Welding Safety and Health

When welding galvanized steel, which health effect is specifically associated with exposure to zinc oxide fume?

  1. Decompression sickness
  2. Metal fume fever Correct answer.
  3. Silicosis
  4. Lead encephalopathy

Explanation

Zinc oxide fume from galvanized coatings can cause metal fume fever, a flu-like illness with fever, chills, and muscle aches that often appears hours after exposure. Removing the coating and using ventilation or respiratory protection reduces the risk.

Question 16Welding Safety and Health

Which hose color identifies the oxygen supply in a standard oxyfuel gas welding outfit?

  1. Black
  2. Green Correct answer.
  3. Yellow
  4. Red

Explanation

In oxyfuel gas welding, green identifies the oxygen hose and red identifies the fuel-gas hose, such as acetylene. The hoses must not be interchanged because residual oil or wrong connections can create a dangerous condition.

Question 17Welding Safety and Health

When is the valve protection cap required to be on a compressed gas cylinder?

  1. At all times during welding
  2. Only while a regulator is attached
  3. Only when the cylinder is empty
  4. During transport and storage Correct answer.

Explanation

The valve protection cap shields the cylinder valve from damage that could cause a sudden release of gas, so it must be in place whenever the cylinder is moved or stored. It is removed only when the cylinder is secured and ready for use with a regulator.

Question 18Welding Safety and Health

A welding cable has a section of damaged insulation that exposes the conductor. What is the correct action before continuing work?

  1. Wrap the damaged area with electrical tape and continue welding
  2. Remove the cable from service and repair or replace it Correct answer.
  3. Continue only if the exposed section is on the work lead
  4. Keep the cable dry and reduce the amperage

Explanation

Damaged insulation can expose the welder to electric shock, especially in damp or hot conditions, and tape is not an acceptable repair for a welding cable. The cable must be taken out of service and repaired by qualified personnel or replaced.

Question 19Welding Safety and Health

Welding stainless steel can produce fume containing hexavalent chromium. Which control is the most effective for protecting the welder from this fume?

  1. Welding in a larger room without ventilation
  2. Wearing cotton gloves and a leather apron
  3. Local exhaust ventilation at the arc Correct answer.
  4. Increasing welding current to burn off the coating

Explanation

Hexavalent chromium fume is a carcinogen, and local exhaust ventilation captures it at the source before it reaches the welder's breathing zone. When local exhaust is inadequate, supplied-air or appropriate respiratory protection may also be required.

Question 20Welding Safety and Health

Which type of portable fire extinguisher should be readily available for welding hot work that may involve electrical equipment and combustible materials?

  1. Class D sodium chloride extinguisher
  2. Class ABC dry chemical extinguisher Correct answer.
  3. Carbon dioxide only
  4. Pressurized water extinguisher

Explanation

Class ABC dry chemical extinguishers are rated for ordinary combustibles, flammable liquids, and energized electrical equipment, making them suitable for welding hot work. Water is unsafe on electrical fires, and Class D agents are intended for combustible metals.

Question 21Welding Safety and Health

How should an oxyfuel gas hose connection be checked for a leak?

  1. Listen for a hissing sound and keep working.
  2. Open the cylinder valve fully and check the gauge.
  3. Apply an approved leak-detecting solution and watch for bubbles. Correct answer.
  4. Hold a lit match near the fitting and watch for a flame.

Explanation

Oxyfuel hose and fitting leaks are located with an approved leak-detecting solution; bubbles show where gas is escaping. A flame or match must never be used because fuel gas or oxygen can ignite, and listening alone will not reliably find small leaks.

Question 22Welding Safety and Health

Where should the work lead clamp be attached for arc welding?

  1. The electrical conduit
  2. Clean bare metal on the workpiece Correct answer.
  3. The painted surface of the workpiece
  4. A gas pipe near the station

Explanation

The work lead must complete the welding circuit through clean bare metal, so the clamp should be placed on the workpiece or a clean work table. Attaching it to painted, rusty, or piping systems creates resistance, poor welds, and electrical hazards.

Question 23Welding Safety and Health

What should be used to light an oxyfuel gas torch?

  1. A cigarette lighter
  2. A friction lighter or pilot flame Correct answer.
  3. A hot piece of slag
  4. A paper match held at the tip

Explanation

An oxyfuel torch is lit with a friction lighter or a stationary pilot flame while the operator keeps hands and clothing clear of the tip. Matches, cigarette lighters, and hot slag can burn the hand or ignite clothing.

Question 24Welding Safety and Health

A steel drum previously held gasoline and must be welded. What must be done before hot work begins?

  1. Fill the drum with water and weld it full
  2. Clean, purge, and test for flammable residue Correct answer.
  3. Open the bung and start welding at once
  4. Drain the drum and weld it while damp

Explanation

A container that held flammable liquid must be cleaned, purged of vapors, and tested before any hot work. Residual vapor can ignite or explode even if the drum appears empty.

Question 25Welding Safety and Health

Why must an acetylene cylinder be used in an upright position?

  1. It keeps acetone from entering the hose Correct answer.
  2. It prevents the cylinder from rusting
  3. It makes the valve easier to reach
  4. It improves the color of the flame

Explanation

Acetylene cylinders contain a porous filler and acetone; using the cylinder upright keeps liquid acetone from being drawn into the regulator and hose. Acetone in the hose can damage equipment and cause an unstable flame.

Question 26Welding Safety and Health

Welding fume containing manganese is associated with which health effect?

  1. Skin cancer
  2. Thyroid gland damage
  3. Nervous system damage Correct answer.
  4. Loss of hearing

Explanation

Manganese in welding fume is associated with damage to the central nervous system, sometimes called manganism, with symptoms resembling Parkinson's disease. Exposure is controlled by ventilation and respiratory protection.

Question 27Welding Safety and Health

Welding arcs or flames contacting chlorinated degreasing solvents can produce which toxic gas?

  1. Carbon dioxide
  2. Phosgene Correct answer.
  3. Methane
  4. Nitrogen

Explanation

Chlorinated solvents can decompose in welding heat or ultraviolet radiation to form phosgene, a highly toxic gas. Degreasing solvents must be removed and the area ventilated before welding or cutting.

Question 28Welding Safety and Health

What is the main purpose of welding screens placed around an arc welding station?

  1. To keep drafts away from the arc
  2. To reduce the noise of the arc
  3. To support the welding cables
  4. To protect nearby workers from arc radiation Correct answer.

Explanation

Welding screens block ultraviolet and visible arc radiation and help contain sparks so nearby workers are not flash burned. They also protect passersby from accidental arc exposure.

Question 29Welding Safety and Health

What is the maximum allowable working pressure for acetylene in an oxyfuel hose or torch?

  1. 50 psig
  2. 100 psig
  3. 30 psig
  4. 15 psig Correct answer.

Explanation

Acetylene is unstable under pressure, and safety standards limit its working pressure in a hose or torch to 15 psig. Higher pressures can cause decomposition or explosion.

Question 30Welding Safety and Health

Why can argon shielding gas create a hazard in a confined space even though it is non-toxic?

  1. It increases the arc's ultraviolet radiation.
  2. It can displace oxygen and cause asphyxiation. Correct answer.
  3. It is flammable and can ignite.
  4. It reacts with steel to form a toxic gas.

Explanation

Argon is an inert gas, but it is denser than air and can accumulate in low areas of a confined space, displacing oxygen. Oxygen deficiency can cause unconsciousness and death without warning.

Question 31Welding Safety and Health

After welding and cutting operations are finished, what is the minimum time a fire watch should remain in the area to check for hidden smoldering fires?

  1. 30 minutes Correct answer.
  2. 10 minutes
  3. 45 minutes
  4. 20 minutes

Explanation

A fire watch must remain at least 30 minutes after hot work ends because sparks and hot slag can smolder undetected in cracks or insulation and start a fire later. Shorter watches do not give enough time to detect a developing fire.

Question 32Welding Safety and Health

What is the primary function of a flashback arrestor in an oxyfuel gas welding outfit?

  1. It reduces cylinder pressure to the working pressure used at the torch.
  2. It stops a flame from traveling back through the hose to the cylinder. Correct answer.
  3. It filters dirt and moisture from the gas before it reaches the torch.
  4. It automatically shuts off gas flow if the torch is dropped.

Explanation

A flashback arrestor contains a flame barrier and check valve that stop a flame or pressure surge from traveling backward through the hose into the regulator and cylinder. Without this protection, a flashback could cause a cylinder explosion.

Question 33Welding Safety and Health

An engine-driven welding machine must be operated inside a building because of rain. Which precaution is required?

  1. Route engine exhaust outside and ventilate the area. Correct answer.
  2. Run the engine only at idle speed inside the building.
  3. Keep all doors and windows closed to protect the work.
  4. Place the machine as close as possible to the welding area.

Explanation

Engine exhaust contains carbon monoxide, an odorless gas that can accumulate indoors and cause unconsciousness or death. The exhaust must be routed outdoors and the space ventilated; idle speed or closed doors do not remove the hazard.

Question 34Welding Safety and Health

Before a welder enters a confined space to perform hot work, what must be done first?

  1. Open the access hatch and begin welding to check ventilation.
  2. Post a warning sign and enter without a permit.
  3. Test the atmosphere for oxygen, flammables, and toxics. Correct answer.
  4. Fill the space with argon to displace any flammable gases.

Explanation

A confined space must be tested before entry for oxygen deficiency or enrichment, flammable gases, and toxic contaminants, and monitoring must continue while welding. Welding can consume oxygen and generate carbon monoxide and other toxic gases.

Question 35Welding Safety and Health

Gas tungsten arc welding of aluminum can produce ozone. Which control best protects the welder from ozone exposure?

  1. Increase the shielding gas flow rate.
  2. Use local exhaust ventilation at the arc. Correct answer.
  3. Weld only in a large room with the doors closed.
  4. Wear a dust mask under the welding helmet.

Explanation

Ozone is a gas formed when ultraviolet radiation from the arc reacts with oxygen in the air, and it can irritate the lungs. Local exhaust ventilation captures ozone at the source before the welder breathes it; dust masks do not remove gases.

Question 36Welding Safety and Health

A welder must cut steel that is coated with lead-based paint. Which hazard control is most important?

  1. Increase the cutting oxygen pressure to speed the cut.
  2. Wipe the painted surface with solvent before making the cut.
  3. Use ventilation and a respirator for lead fume. Correct answer.
  4. Wear a faceshield over safety glasses during the cut.

Explanation

Cutting lead-painted steel vaporizes lead, and inhaling lead fume can cause acute and chronic health effects. Source ventilation and appropriate respiratory protection are required; solvent wiping is not reliable and can add fire risk.

Question 37Welding Safety and Health

Who should authorize hot work in an area where a hot work permit is required?

  1. Any welder who has completed the job.
  2. The supplier of the welding consumables used on the job.
  3. An authorized permit issuer or area supervisor. Correct answer.
  4. The local fire department, in every case.

Explanation

Hot work permits are issued by an authorized person who verifies that combustibles are protected, a fire watch is assigned, and extinguishing equipment is ready. The welder should not authorize their own hot work when a permit is required.

Question 38Welding Safety and Health

Why should a welder never dip a hot electrode holder into water to cool it?

  1. It will cause the welding cable to overheat and fail.
  2. It will contaminate the electrode coating and cause porosity.
  3. Water damages insulation and creates a shock hazard. Correct answer.
  4. The water will change the arc characteristics and reduce weld quality.

Explanation

Water can enter cracks in the electrode holder insulation and provide a conductive path from the live electrode to the welder's hand, causing a severe shock. Hot holders should be allowed to cool or be replaced rather than dipped in water.

Question 39Welding Safety and Health

A welder is using shielded metal arc welding at 140 amperes. Which minimum shade number is appropriate for the welding helmet filter lens?

  1. Shade 10 Correct answer.
  2. Shade 8
  3. Shade 12
  4. Shade 14

Explanation

For shielded metal arc welding at 60 to 160 amperes, the minimum filter lens shade is 10. A shade 8 provides too little protection for that current, while shades 12 and 14 are intended for higher currents.

Question 40Welding Safety and Health

For a manual arc welding machine operating on AC, what is the maximum allowable open-circuit voltage under standard safety requirements?

  1. 80 V Correct answer.
  2. 50 V
  3. 120 V
  4. 100 V

Explanation

Under OSHA welding standards, AC manual arc welding machines must have a maximum open-circuit voltage of 80 volts; DC machines are limited to 100 volts. Lower open-circuit voltage reduces the severity of electric shock if the welder contacts the electrode circuit.

Question 41Oxyfuel Cutting and Heating

In a standard oxyfuel cutting outfit, which color identifies the fuel-gas hose?

  1. Green
  2. Black
  3. Red Correct answer.
  4. Blue

Explanation

The standard color code uses red for the fuel-gas hose and green for the oxygen hose. Matching hoses by color helps prevent a fuel gas from being connected to an oxygen fitting, which can create a serious fire or explosion hazard.

Question 42Oxyfuel Cutting and Heating

What is the maximum allowable working pressure for acetylene in an oxyfuel hose and torch?

  1. 50 psig
  2. 5 psig
  3. 30 psig
  4. 15 psig Correct answer.

Explanation

Acetylene is unstable at higher pressures, so its working pressure in the hose and torch must never exceed 15 psig. Cylinder pressure is higher because acetylene is dissolved in acetone in a porous cylinder, but the delivery pressure must stay at or below that limit.

Question 43Oxyfuel Cutting and Heating

When lighting an oxyacetylene cutting torch, which gas should be opened and ignited first?

  1. Compressed air
  2. Acetylene Correct answer.
  3. Oxygen
  4. Both gases at the same time

Explanation

Open the fuel gas slightly, light it, and then add oxygen to adjust the flame. Lighting oxygen first or mixing both gases before ignition can produce a violent pop or uncontrolled flame.

Question 44Oxyfuel Cutting and Heating

Where should flashback arrestors be installed on an oxyfuel cutting rig?

  1. On the oxygen hose only
  2. At both hose ends Correct answer.
  3. At the torch only
  4. At the regulator only

Explanation

Flashback arrestors are placed at the regulator outlet and at the torch inlet so a flame traveling in either direction is stopped before it reaches the hose or cylinder. Check valves alone do not provide this protection.

Question 45Oxyfuel Cutting and Heating

During a cut, the torch pops repeatedly and the flame keeps going out at the tip. After shutting off the torch, what should be checked first?

  1. The regulator adjusting screw
  2. The oxygen cylinder valve position
  3. The hose color code
  4. The tip orifice condition Correct answer.

Explanation

A clogged, damaged, or overheated tip orifice is a common cause of repeated popping and flame loss. Clean the tip with the proper tip cleaner or replace it, then reset pressures before relighting.

Question 46Oxyfuel Cutting and Heating

A sharp pop occurs at the cutting tip and the flame goes out, but no flame travels back into the torch or hose. This event is best called a:

  1. Kerf
  2. Backfire Correct answer.
  3. Flashback
  4. Preheat

Explanation

A backfire is a momentary pop or explosion at the tip that extinguishes the flame without it traveling backward. A flashback is more serious because the flame moves back into the torch, hose, or regulator.

Question 47Oxyfuel Cutting and Heating

To increase delivery pressure on a typical single-stage oxygen regulator, which action is correct?

  1. Open cylinder valve farther
  2. Turn adjusting screw counterclockwise
  3. Turn adjusting screw clockwise Correct answer.
  4. Increase hose diameter

Explanation

Turning the regulator adjusting screw clockwise compresses the spring and raises delivery pressure. The cylinder valve controls supply, not the set delivery pressure, and hose diameter does not adjust pressure.

Question 48Oxyfuel Cutting and Heating

When opening an acetylene cylinder valve for cutting, how far should the valve normally be opened?

  1. One-quarter to one-half turn Correct answer.
  2. Fully open
  3. Until the gauge reads 15 psig
  4. Two full turns

Explanation

Acetylene cylinder valves are normally opened only one-quarter to one-half turn, and never more than one and one-half turns. This provides adequate flow while allowing the valve to be closed quickly in an emergency.

Question 49Oxyfuel Cutting and Heating

What is the primary function of the cutting oxygen stream in oxyfuel cutting?

  1. It stabilizes the acetylene flame
  2. It oxidizes metal and blows slag out Correct answer.
  3. It preheats the steel ahead of the cut
  4. It shields the cutting tip from spatter

Explanation

The preheat flames bring the steel to ignition temperature, and then the cutting oxygen stream oxidizes the iron and forces the molten oxide slag out of the kerf. Oxygen does not act as a shielding gas in this process.

Question 50Oxyfuel Cutting and Heating

What is the correct way to check an oxyfuel torch and hose connection for a gas leak?

  1. Apply soapy water to the connection Correct answer.
  2. Watch the pressure gauge only
  3. Use a lit match along the connection
  4. Listen for a hissing sound

Explanation

A soapy-water solution applied to the connection will bubble if gas is escaping, which locates the leak without introducing a flame. Never use a flame to test for leaks on oxyfuel equipment.