Pipefitting Trade Math Flashcards

A pipe run requires a 45° offset with a travel distance of 14.14 inches. What is the approximate offset rise?

Answer: 10 inches

For a 45° offset, the rise equals the travel multiplied by 0.707; 14.14 × 0.707 ≈ 10 inches.

A circular pipe has an outside diameter of 6.625 inches. What is its circumference? (Use π = 3.1416)

Answer: 20.81 in

Circumference = π × D = 3.1416 × 6.625 ≈ 20.81 inches.

A pipe is to be cut to leave a 3/8-inch gap for a weld. If the overall run is 120 inches and there are 4 welds, what is the total cut allowance?

Answer: 1-1/2 inches

Total cut allowance = 4 welds × 3/8 inch = 1-1/2 inches.

What is the volume of a cylindrical pipe section with an inside diameter of 4 inches and a length of 24 inches? (Use π = 3.1416)

Answer: 301.59 in³

Volume = π × r² × L = 3.1416 × 4 × 24 = 301.59 in³.

If a 6-inch pipe carries flow at 500 GPM, and you reduce to a 3-inch pipe, what is the approximate velocity ratio change?

Answer: Flow quadruples

Halving the diameter reduces the area by a factor of 4, so velocity must quadruple to maintain the same flow rate.

A welder needs to wrap a pipe with 2-inch-wide insulation tape at a 45° helix angle. If the pipe OD is 10 inches, how many linear inches of tape are needed per foot of pipe?

Answer: 53.41 in

At 45° helix the pitch equals the tape width; inches of tape per foot ≈ (12/2) × π × 10 = 6 × 3.1416 × 10 ≈ 188.5 / wrap, requiring ≈ 53.41 in total per lineal foot given the helix geometry.

A system uses 300 feet of 2-inch Schedule 40 pipe weighing 3.65 lb/ft. What is the total weight of the piping?

Answer: 1,095 lb

Total weight = 300 ft × 3.65 lb/ft = 1,095 lb.