The design stress, which is more than the damaging stress, is the least unit stress that will render a member unfit for service before the end of its normal life. The design stress factor or factor of safety indicates the margin between design stress and the _______________ stress?

Related Mcqs:

1. Factor of safety (i.e., overdesign factor) in heat transfer equipments is about _____________ percent more than the actual/theoretical design factor?

   A. 5-10
   B. 15-20
   C. 30-35
   D. 35-40

2. Correct use of ‘factor of safety’ is very important in equipment design. It is defined as the ratio of the___________________?

   A. Ultimate stress to breaking stress
   B. Ultimate stress to working stress
   C. Working stress to ultimate stress
   D. None of these

3. A cylindrical pressure vessel of volume 6 πm3 has to be designed to withstand a maximum internal pressure of 10 atm. The allowable design stress of the material is 125N/mm2 and corrosion allowance is 2 mm. The thickness of the vessel for a length/diameter ratio of 3 will be close to________________?

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

4. Circumferential (hoop) stress in a thin cylindrical vessel under internal pressure is _____________ the longitudinal stress?

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

5. The type of stress developed in a metallic bar on subjecting it to a change in temperature without allowing it to be deformed is ______________ stress?

   A. Shear
   B. Tensile
   C. Compressive
   D. Thermal

6. In a thin cylindrical shell, the hoop stress is ________________ stress?

   A. Radial
   B. Circumferential tensile
   C. Compressive
   D. Longitudinal

7. In a cylindrical vessel subjected to internal pressure, the longitudinal stress ζL and the circumferential stress, ζn are related by___________________?

   A. ζh = 2 ζL
   B. ζh = ζL
   C. ζh = ζL/2
   D. No relation exists

8. LMTD correction factor is used in heat exchanger design for____________________?

   A. Double pipe heat exchanger
   B. Multipass shell and tube heat exchanger
   C. Fouling fluids
   D. Counter flow of hot and cold fluids

9. It is not desirable to design a heat exchanger for LMTD correction factor, FT, of less than _________________?

   A. 0.99
   B. 0.95
   C. 0.80
   D. 0.55

10. Fouling factor must be included in the calculation of overall design heat transfer coefficient, when the liquid__________________?

    A. Containing suspended solids flows at low velocity
    B. Containing suspended solids flows at high velocity
    C. Is highly viscous
    D. Is of high specific gravity