Journeyman Plumbers Exam Isometric Analysis and Math 2 — Questions and Answers
Question 1: On an isometric drawing, a pipe running parallel to the right front edge of the cube is drawn at what angle from horizontal?
- 30 degrees (Correct answer)
- 45 degrees
- 60 degrees
- 90 degrees
Correct answer: 30 degrees
In isometric drawing, the three primary axes are drawn at 30 degrees above horizontal (left and right) and vertical.
Question 2: A plumber needs to offset around a beam using 45-degree elbows. The diagonal (travel) distance is 18 inches. What is the set (offset) distance?
- 12.73 inches (Correct answer)
- 18.00 inches
- 25.46 inches
- 9.00 inches
Correct answer: 12.73 inches
For a 45-degree offset, the set equals the travel multiplied by 0.707, so 18 × 0.707 ≈ 12.73 inches.
Question 3: What is the constant used to calculate the travel of a 60-degree offset?
- 1.155 (Correct answer)
- 0.707
- 1.414
- 0.866
Correct answer: 1.155
The travel constant for a 60-degree offset is 1.155, meaning travel = set × 1.155.
Question 4: In an isometric plumbing diagram, what does a line drawn vertically represent?
- A pipe running plumb (vertical) (Correct answer)
- A pipe running horizontal north-south
- A pipe running horizontal east-west
- A pipe running at 45 degrees
Correct answer: A pipe running plumb (vertical)
In isometric drawing conventions, vertical lines represent pipes that run plumb (true vertical).
Question 5: A drain pipe drops 1/4 inch per foot over a run of 32 feet. What is the total drop?
- 8 inches (Correct answer)
- 6 inches
- 10 inches
- 4 inches
Correct answer: 8 inches
Total drop = 32 feet × 0.25 inches/foot = 8 inches.
Question 6: On an isometric drawing, which axis represents pipes running left-to-right (east-west) in the field?
- The right-leaning 30-degree axis (Correct answer)
- The left-leaning 30-degree axis
- The vertical axis
- The 45-degree axis
Correct answer: The right-leaning 30-degree axis
By convention, the right-leaning 30-degree axis on an isometric drawing represents east-west (left-to-right) pipe runs.
Question 7: A plumber must make a parallel offset of 6 inches using 45-degree fittings. What length of pipe is needed between the two elbows (the travel)?
- 8.49 inches (Correct answer)
- 6.00 inches
- 4.24 inches
- 12.00 inches
Correct answer: 8.49 inches
Travel = set × 1.414, so 6 × 1.414 = 8.49 inches.
