Pipefitting Math and Calculations Flashcards
7 cards from real PIPEFITTER practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Pipefitting Math and Calculations flashcards as text
A pipe drops 3 inches over a 10-foot horizontal run. What is the slope expressed as inches per foot?
Answer: 0.30 in/ft
Slope = 3 inches ÷ 10 feet = 0.30 inches per foot.
How many threads per inch (TPI) are on a 2-inch NPT pipe thread?
Answer: 11.5 TPI
2-inch NPT pipe threads have 11.5 threads per inch per the ASME B1.20.1 standard.
What is the circumference of a pipe with an outside diameter of 10.75 inches (10-inch nominal)?
Answer: 33.77 inches
Circumference = π × OD = 3.1416 × 10.75 ≈ 33.77 inches.
A 5-piece equal-spread 45° offset uses 4 fittings and covers a 24-inch set. What is the spread between each fitting center?
Answer: 6 inches
In a 5-piece equal-spread offset with 4 fittings, each fitting covers 24 ÷ 4 = 6 inches of set.
A hydrostatic test requires pressurizing a system to 1.5 times the design pressure of 400 psig. What is the test pressure?
Answer: 600 psig
Test pressure = 1.5 × 400 psig = 600 psig, which is the standard hydrostatic test multiplier.
The flow velocity in a 3-inch pipe (ID = 3.068 in) is 8 ft/s. If the pipe transitions to a 6-inch pipe (ID = 6.065 in), what is the approximate velocity in the larger pipe?
Answer: 2.0 ft/s
Using continuity (A₁V₁ = A₂V₂): area ratio ≈ (3.068/6.065)² ≈ 0.256, so V₂ ≈ 8 × 0.256 ≈ 2.05 ft/s.
A pipefitter calculates that 3 inches of pipe is needed per degree of bend on a 2-inch pipe. How long a pipe section is needed to fabricate a 30° bend?
Answer: 90 inches
Required length = 3 inches/degree × 30 degrees = 90 inches of pipe.