Certified Welder Base Metal Preparation 3

Question 1

Which tool is most appropriate for removing mill scale from a narrow weld groove prior to GTAW on carbon steel?

Accepted Answer

Die grinder with carbide burr

Answer

A die grinder with a carbide burr can reach into tight grooves and remove mill scale without leaving abrasive particles that could contaminate the weld.

Question 2

When performing an oxy-fuel cut on carbon steel plate, the cut edge should be ground before welding primarily to remove:

Accepted Answer

Drag lines and hardened surface layer

Answer

Oxy-fuel cutting produces a hardened surface layer from rapid quenching and drag lines that can act as stress risers if not removed prior to welding.

Question 3

Interpass cleaning between weld passes is required mainly to prevent:

Accepted Answer

Slag inclusions in the completed weld

Answer

Removing slag between passes prevents slag entrapment, which would appear as inclusions in radiographic or ultrasonic inspection of the finished weld.

Question 4

What is the correct fit-up root opening for a standard single-V butt joint when using SMAW on ¼-inch plate?

Accepted Answer

1/16 to 3/32 in

Answer

A root opening of 1/16 to 3/32 inch provides adequate access for the electrode to achieve root fusion without excessive melt-through.

Question 5

A welder is preparing aluminum base metal for GTAW. Which preparation step is unique to aluminum compared to steel?

Accepted Answer

Mechanical removal of the oxide layer immediately before welding

Answer

Aluminum's oxide layer (Al₂O₃) has a much higher melting point than the base metal and must be freshly removed immediately before welding to prevent oxide inclusions.

Certified Welder Practice Test

Certified Welder Practice Test

Certified Welder Base Metal Preparation 3