Pipefitter Pipefitting Trade Math 2

Question 1

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

Accepted Answer

10 inches

Answer

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

Question 2

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

Accepted Answer

20.81 in

Answer

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

Question 3

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?

Accepted Answer

1-1/2 inches

Answer

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

Question 4

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)

Accepted Answer

301.59 in³

Answer

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

Question 5

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?

Accepted Answer

Flow quadruples

Answer

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

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