AIT Trade Theory 3 — Questions and Answers
Question 1: Which hand tool is used to measure and mark a 90-degree angle on material?
- Speed square or try square (Correct answer)
- Combination level
- Plumb bob
- Chalk line
Correct answer: Speed square or try square
A speed square or try square is specifically designed to check or mark 90-degree (right) angles on material, making it essential for layout work in many trades.
Question 2: In welding, what is the purpose of a flux coating on a shielded metal arc welding (SMAW) electrode?
- To increase the amperage of the welding machine
- To cool the base metal during welding
- To protect the molten weld pool from atmospheric contamination (Correct answer)
- To add color coding for electrode identification only
Correct answer: To protect the molten weld pool from atmospheric contamination
The flux coating on SMAW electrodes melts during welding to create a protective gas shield and slag layer that prevents oxygen and nitrogen from contaminating the molten weld pool.
Question 3: What is the main function of a pressure relief valve in a hydraulic or plumbing system?
- To increase system pressure when needed
- To prevent system pressure from exceeding a safe maximum (Correct answer)
- To filter contaminants from the fluid
- To regulate the flow rate of fluid
Correct answer: To prevent system pressure from exceeding a safe maximum
A pressure relief valve opens automatically when system pressure reaches a preset maximum, releasing excess pressure to prevent equipment damage or dangerous ruptures.
Question 4: When measuring with a vernier caliper, what does the vernier scale allow you to do?
- Measure weight of small objects
- Take measurements in metric only
- Read fractional measurements more precisely than the main scale alone (Correct answer)
- Automatically convert between metric and imperial
Correct answer: Read fractional measurements more precisely than the main scale alone
The vernier scale on a caliper allows the user to read fractional increments (typically 0.02 mm or 0.001 inch) that fall between the main scale divisions, greatly increasing measurement precision.
Question 5: In construction trades, what is the purpose of a vapor barrier?
- To provide structural support in walls
- To prevent moisture from migrating through walls, floors, or ceilings (Correct answer)
- To improve the R-value of insulation by 50%
- To act as a fire-resistant membrane
Correct answer: To prevent moisture from migrating through walls, floors, or ceilings
A vapor barrier (or vapor retarder) is a material used to slow or prevent moisture vapor from passing through building assemblies, preventing condensation and moisture damage within walls and structures.
Question 6: What type of thread is most commonly used on plumbing pipe fittings in North America?
- Metric thread (M)
- National Pipe Taper thread (NPT) (Correct answer)
- Unified National Coarse thread (UNC)
- British Standard Pipe thread (BSP)
Correct answer: National Pipe Taper thread (NPT)
National Pipe Taper (NPT) threads are the standard thread type used on most plumbing pipe fittings in North America; the tapered design creates a seal as the fitting is tightened.
Question 7: What does the term 'load-bearing' mean when referring to a wall in a building?
- The wall contains electrical wiring and outlets
- The wall is made of concrete or masonry only
- The wall supports the weight of the structure above it (Correct answer)
- The wall is located on the exterior of the building
Correct answer: The wall supports the weight of the structure above it
A load-bearing wall is a structural element that carries and transfers the weight of the floors, roof, and other structural components above it down to the foundation.
AIT Trade Theory 3
Which hand tool is used to measure and mark a 90-degree angle on material?