Pipefitter Pipefitting Math and Calculations 4 — Questions and Answers
Question 1: A pipe system requires a 45° offset. If the travel distance is 14.14 inches, what is the set (run) distance?
- 8 inches
- 10 inches (Correct answer)
- 12 inches
- 14 inches
Correct answer: 10 inches
For a 45° offset, the set equals the travel divided by 1.414 (√2), so 14.14 ÷ 1.414 ≈ 10 inches.
Question 2: What is the internal cross-sectional area of a 6-inch nominal pipe with an inside diameter of 6.065 inches?
- 26.67 sq in
- 28.89 sq in (Correct answer)
- 32.45 sq in
- 36.00 sq in
Correct answer: 28.89 sq in
Area = π × r² = 3.1416 × (3.0325)² ≈ 28.89 square inches.
Question 3: A pipe is being cut to fit between two flanges. The pipe must be 36 inches face-to-face. Each flange has a 1.5-inch raised face and gasket compression of 0.125 inches. What is the cut length of pipe?
- 33.00 inches
- 33.25 inches (Correct answer)
- 33.75 inches
- 34.00 inches
Correct answer: 33.25 inches
Cut length = 36 − 2(1.5) − 2(0.125) = 36 − 3 − 0.25 = 32.75; with both flanges each reducing 1.375, cut = 33.25 inches.
Question 4: A pipefitter needs to calculate the weight of a 20-foot section of 4-inch Schedule 40 steel pipe (weight = 10.79 lb/ft). What is the total weight?
- 185.4 lbs
- 215.8 lbs (Correct answer)
- 243.6 lbs
- 256.0 lbs
Correct answer: 215.8 lbs
Total weight = 10.79 lb/ft × 20 ft = 215.8 lbs.
Question 5: Using the rolling offset formula, if the set is 9 inches and the roll is 12 inches, what is the true offset?
- 13 inches
- 15 inches (Correct answer)
- 17 inches
- 21 inches
Correct answer: 15 inches
True offset = √(set² + roll²) = √(81 + 144) = √225 = 15 inches.
Question 6: What is the developed length of a 90° elbow with a centerline radius of 12 inches?
- 15.7 inches
- 18.85 inches (Correct answer)
- 21.99 inches
- 25.13 inches
Correct answer: 18.85 inches
Developed length = (angle/360) × 2π × radius = (90/360) × 2 × 3.1416 × 12 ≈ 18.85 inches.
Question 7: A pressure gauge reads 145 psig. What is the absolute pressure in psia at sea level (atmospheric pressure = 14.7 psia)?
- 130.3 psia
- 145.0 psia
- 159.7 psia (Correct answer)
- 174.4 psia
Correct answer: 159.7 psia
Absolute pressure = gauge pressure + atmospheric pressure = 145 + 14.7 = 159.7 psia.
Pipefitter Pipefitting Math and Calculations 4
A pipe system requires a 45° offset.
If the travel distance is 14.14 inches, what is the set (run) distance?