A certain pressure vessel manufacturer avoids doing reinforcements calculations for openings by always providing a reinforcing pad extending upto double the diameter of the opening and of the same material and thickness as that of the shell wall. If area compensation is accepted as a code guideline, his approach leads to safe design____________________?

Related Mcqs:

1. In case of a shell and tube heat exchanger, the minimum shell thickness for carbon steel (inclusive of corrosion allowance) depends on shell diameter and is in the range of ________________ mm?

   A. 3-5
   B. 5-11
   C. 8-15
   D. 12-18

2. A pressure vessel is said to be made of ‘thick’ shell, if the ratio of its diameter to wall thickness is_______________?

   A. < 10
   B. > 10
   C. > 20
   D. < 20

3. Tube wall thickness depends on the corrosiveness of the fluids and their operating pressure & temperature and is specified by Birmingham wire gauge (B.W.G)-a number which varies from 8 to 18 with the numbers 14 and 16 being more commonly used. Outside diameter of tubes varies from about 15 to 50 mm; however a tube of less than _____________ mm outside diameter is generally not recommended for fouling fluids ?

   A. 16
   B. 19
   C. 28
   D. 38

4. For a cylindrical vessel of moderate height, the weld joint efficiency for joints parallel to the cylindrical axis is given as 1.0; while for joints along the girth (circumference) it is given as 0.8. In calculating the shell wall thickness using code formula for an internally pressurised cylindrical vessel, what value of weld joint efficiency should be used ?

   A. 0.8
   B. 0.9
   C. 1.0
   D. (0.8)0.5

5. In a shell and tube heat exchanger having square pitch, the shell side equivalent diameter is given by (where, P = pitch, d = outside diameter of the tube) ?

   A. 4(P2 – πd2/4)/πd
   B. (P2 – rd2/4)/rd
   C. 4P2/πd
   D. πd/4P2

6. 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

7. In a shell and tube heat exchanger for a given heat transfer surface area, smaller diameter tubes are favoured as compared to larger diameter ones; because the smaller diameter tubes ______________?

   A. Are easier to clean
   B. Are less prone to fouling
   C. Can be fitted into a smaller shell diameter hence the cost of the heat exchanger would be less
   D. None of these

8. In case of a ‘thin’ pressure vessel, the ratio of its diameter to wall thickness is_________________?

   A. < 10
   B. > 10
   C. > 20
   D. 30

9. For a cylindrical shell, (subject to the thickness of uppermost course being more than the minimum for dia of the tank in question), the thickness of the courses of shell_________________?

   A. Decreases upwards
   B. Increases upwards
   C. Remains same throughout
   D. May decrease or increase upwards depending upon whether vacuum or positive pressure
   would be maintained inside the shell

10. The wall thickness of thin cylindrical shell with hemispherical ends is ______________ that of the spherical ends?

    A. Equal to
    B. More than
    C. Less than
    D. Either B. or C.; depends on maximum permissible internal pressure