To determine metal jacketing stretch-out length, you multiply the diameter by which constant and add how many inches?

• A. Multiply diameter by 3.0000 and add 2 inches
• B. Multiply diameter by 3.1416 and add 3 inches
• C. Multiply diameter by 1.4142 and add 3 inches
• D. Multiply diameter by 3.1420 and add 4 inches

Answer: (B)

This question tests how stretch-out length for metal jacketing is calculated by using the circumference of the pipe plus a small fixed allowance. The jacket needs to wrap around the cylinder, so you start with the circumference, which is diameter times π. The standard practice adds a 3-inch allowance for overlaps and end conditions, giving the formula: stretch-out length = diameter × 3.1416 + 3 inches. That’s why the correct approach uses 3.1416 for pi and adds 3 inches. For example, a diameter of 12 inches gives 12 × 3.1416 + 3 ≈ 40.7 inches. The other options change either the pi value or the added allowance, which would mis-size the jacket.