Free Plant Design and Economics MCQs with Answers

• A. Be fabricated very easily
• B. Withstand higher pressure for a given metallic shell thickness
• C. Be designed without wind load considerations
• D. Be supported very easily

Explanation: A sphere distributes internal pressure uniformly and develops lower membrane stress than a cylindrical vessel for the same wall thickness…

• A. Brackets
• B. Skirts
• C. Saddles
• D. Columns

Explanation: Saddles support horizontal vessels, whereas vertical vessels are commonly supported by skirts, brackets, or columns.

• A. Strain
• B. None of these
• C. Modular ratio
• D. Stress

Explanation: Young's modulus is stress divided by strain; since strain is dimensionless, its units are the same as stress, such as Pa or N/m².

• A. All A., B. and C.
• B. Greater cost for the reboiler heat supply
• C. Greater cost for the condenser coolant
• D. Lower fixed charges for the column

Explanation: A higher reflux ratio reduces the number of theoretical stages, so the column may require lower fixed investment, but it increases both…

• A. Torispherical
• B. Elliptical
• C. Hemispherical
• D. None of these

Explanation: A hemispherical head has the most favorable curvature and distributes membrane stress efficiently, allowing it to withstand the greatest…

• A. 30°
• B. 45°
• C. 60°
• D. 75°

Explanation: A 60° apex angle is the usual standard for conical bottom heads because it provides effective solids drainage while remaining practical to…

• A. Both A. and B.
• B. Is easy to fabricate
• C. Has greater structural strength
• D. Neither A. nor B.

Explanation: Cylindrical tanks distribute pressure and structural loads efficiently, giving greater strength than rectangular vessels, and their curved…

• A. 3 to 4
• B. 1.5 to 2
• C. 4 to 5
• D. > 5

Explanation: Hydrostatic or pressure testing is commonly carried out at about 1.5 times the design pressure to verify vessel strength and leak…

• A. Half
• B. Equal to
• C. Twice
• D. Eight times

Explanation: For a thin cylindrical vessel, hoop stress is pD/(2t), whereas longitudinal stress is pD/(4t).

• A. 5 mm
• B. 6 mm
• C. 8 mm
• D. 10 mm

Explanation: With L/D = 3, the vessel dimensions are D = 2 m and L = 6 m. The cylindrical-shell pressure thickness is about 8 mm, and adding the 2 mm…

• A. Small
• B. Tall but empty
• C. Large horizontal cylindrical
• D. Thick walled tall

Explanation: Lug supports are commonly used for relatively small vessels, where welded lugs provide a simple support without the heavier skirt…

• A. 0.01
• B. 0.3
• C. 0.75
• D. 0.95

Explanation: Structural and pressure-vessel steels have Poisson's ratio close to 0.3, meaning lateral contraction is about 30% of the axial elastic…

• A. d = 1.1 t
• B. d = 3 √t
• C. d = 1.5 t
• D. d = 1.6 √t

Explanation: Unwin’s formula for the rivet-hole diameter is d = 1.6√t, with both d and t in millimetres.

• A. Cross-sectional area
• B. Changes in temperature
• C. Both A. and B.
• D. Neither A. nor B.

Explanation: For a fully restrained bar, thermal stress is σ = EαΔT, so it depends on the temperature change and material properties but not on…

• A. Modulus of rigidity
• B. Modulus of elasticity
• C. Bulk modulus
• D. None of these

Explanation: The ratio of normal or linear stress to the corresponding linear strain is Young’s modulus, also called the modulus of elasticity.

• A. Inadequate equipment design
• B. Improper layout of the equipments
• C. Faulty operating procedures
• D. Failure of equipments

Explanation: Many chemical-plant accidents arise from faulty operating procedures, including incorrect start-up, shutdown, isolation, or emergency…

• A. None of these
• B. Axis of the load
• C. Perpendicular to the axis of the load
• D. Least radius of gyration

Explanation: A compression member buckles about the weak axis, which has the least radius of gyration and therefore the smallest critical buckling…

• A. Diamond
• B. Chain
• C. Zig-zag
• D. None of these

Explanation: In diamond riveting, the rivet rows are arranged so that their number decreases from the inner region toward the outer region, giving a…

• A. Flat
• B. Conical
• C. Dome
• D. Umbrella

Explanation: A conical roof is the standard and most commonly used roof for cylindrical storage tanks because it is simple to fabricate, drains…

• A. 2
• B. 5
• C. 10
• D. 15

Explanation: For tanks up to 15 m in diameter, the shell thickness is commonly kept at least 5 mm to prevent buckling or elastic instability, even when…