CPM CPM - Certified Plant Mechanic Welding and Fabrication Techniques

Question 1

What does the acronym MIG stand for in the MIG welding process?

Accepted Answer

Metal Inert Gas

Answer

MIG (Metal Inert Gas) welding, also called GMAW (Gas Metal Arc Welding), uses a continuously fed wire electrode shielded by an inert or semi-inert gas.

Question 2

What shielding gas mixture is most commonly used when MIG welding mild steel in a plant maintenance setting?

Accepted Answer

75% argon / 25% CO2 (C25)

Answer

C25 (75% Ar / 25% CO2) provides a stable arc, good penetration, and reduced spatter, making it the most common choice for mild steel MIG welding.

Question 3

Which welding process uses a non-consumable tungsten electrode and is best suited for precision welds on stainless steel and aluminum?

Accepted Answer

GTAW (TIG)

Answer

GTAW (Gas Tungsten Arc Welding), commonly called TIG, uses a non-consumable tungsten electrode and filler rod added separately, allowing precise, high-quality welds.

Question 4

In SMAW (Stick) welding, what is the primary function of the flux coating on the electrode?

Accepted Answer

Protect the weld pool from atmospheric contamination

Answer

The flux coating melts and forms a slag that shields the molten weld pool from oxygen and nitrogen in the atmosphere, preventing porosity and oxidation.

Question 5

What is the purpose of preheating base metal before welding in plant maintenance applications?

Accepted Answer

Reduce the risk of hydrogen cracking in high-carbon or thick materials

Answer

Preheating slows the cooling rate after welding, reducing thermal shock and the formation of hard, brittle microstructures that can crack in high-carbon or alloy steels.

CPM - Certified Plant Mechanic Practice Test

CPM - Certified Plant Mechanic Practice Test

CPM CPM - Certified Plant Mechanic Welding and Fabrication Techniques