NCCER Plasma Arc Cutting - Module 3

In plasma arc cutting, plasma is created by ____ .

• combining acetylene with acetone

• exposing cutting gas to radioactive material

• passing fuel gases through a large orifice inside the torch

• superheating gas in an electric arc

Answer explanation

Page Ref: Sec. Ref. 1.0.0 Objective: 1a

In most cases, plasma arc cutting is ___ .

• slower and less efficient than other cutting methods

• faster and more efficient than other cutting methods

• more likely to create large amounts of dross than other cutting methods

• more likely to create a large heat-affected zone than other cutting methods

Answer explanation

Page Ref: Sec. Ref. 1.0.0 Objective: 1a

Which of the following PPE is considered optional for plasma arc cutting?

• Hearing protection

• Safety glasses

• A full leather hood

• High-top shoes or boots

Answer explanation

Page Ref: Sec. Ref. 1.2.1 Objective: 1b

Which of the following safety statements related to plasma arc cutting is true?

• A hot-work permit is not required for plasma arc cutting due to the nature of the process.

• Both methane and propane are lighter than air and rise quickly from the work area if released.

• Never carry matches or gas-filled lighters in your pockets.

• Unlike oxyfuel cutting, a vessel can be cut safely with plasma regardless of its contents.

Answer explanation

Page Ref: Sec. Ref. 1.2.2 Objective: 1b

The simplest plasma arc cutting units use filtered .

• carbon dioxide

• nitrogen

• compressed air

• helium

Answer explanation

Page Ref: Sec. Ref. 2.1.0 Objective: 2a

Industrial plasma cutting units can cut carbon steel up to .

• 1" thick

• 3" thick

• 5" thick

• 7" thick

Answer explanation

Page Ref: Sec. Ref. 2.1.0 Objective: 2a

The most common plasma arc cutting torch uses .

• a pilot arc with the transferred arc process

• a pilot arc with the nontransferred arc process

• contact starting with the oxyfuel pilot process

• discharge starting with the common arc process

Answer explanation

Page Ref: Sec. Ref. 2.2.0 Objective: 2b

The typical plasma arc cutting torch contains a .

• deflector, retaining cup, extended nozzle, and extended electrode

• gouge shield, retaining cup, gouging nozzle, and standard bronze electrode

• deflector, gouge shield, retaining cup, and copper electrode

• retaining cup, copper electrode with a hafnium or thoriated tungsten insert, gas swirl ring, and nozzle

Answer explanation

Page Ref: Sec. Ref. 2.2.0 Objective: 2b

The term standoff distance refers to the .

• distance between the torch internal arc and the workpiece

• length of the plasma arc

• distance between the area being cut and the workpiece clamp

• distance between the torch tip and the workpiece

Answer explanation

Page Ref: Sec. Ref. 2.2.0 Objective: 2b

Most heavy-duty plasma arc cutting systems require one gas cylinder containing the cutting gas and another containing ___ .

• shielding or cooling gas

• water vapor

• acetylene

• a mixture of cutting gas and shielding gas

Answer explanation

Page Ref: Sec. Ref. 2.3.2 Objective: 2c