A boiler operated with a pressure of 350 psi; the boiler drum is 12 ft long and a diameter of 5 ft. What is the total force acting on the boiler drum? (Use P x (area of head + area of drum)).

• A. 11,000,000
• B. 11,474,610
• C. 12,000,000
• D. 9,800,000

Answer: (B)

The pressure on the drum creates a force equal to the pressure times the total area the pressure acts on. For a closed cylinder, that includes the two circular ends and the curved surface. Use consistent units: the pressure is in psi, so convert lengths to inches.

Radius is 2.5 ft (30 in) and length is 12 ft (144 in). End areas: two circular heads give 2 × πr^2 = 2 × π × 30^2 = 1800π in^2. Side (lateral) area: 2πr × L = 2π × 30 × 144 = 8640π in^2. Total area is 1800π + 8640π = 10,440π in^2 ≈ 32,798 in^2.

Multiply by the pressure: 350 psi × 32,798 in^2 ≈ 11,479,000 lbf. So the total force on the boiler drum is about 11.48 million pounds-force, which matches the given answer.