In a pressure vessel containing multiple openings of various dimensions at diffe

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Question
In a pressure vessel containing multiple openings of various dimensions at different parts, stress concentration at the edges of the opening is maximum which becomes negligibly small beyond the area covered by __________ times the hole diameter.
Options
A. two
B. five
C. ten
D. twenty

Correct Answer

two

3. 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
Options
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.

6. Pick out the wrong statement.
Options
A. Lug supports are less expensive than other type of supports.
B. A pipe is differentiated from a tube by the fact that a pipe has a greater wall thickness compared to the tube.
C. A reducer is used to change the direction of a pipe in a straight run.
D. The method of fixing tubes to a tube sheet by expanding is called 'tube rolling'.

8. Elastic failure of a material occurs, when the tensile stress equals yield strength, yield point or the elastic limit. Also, the elastic failure occurs according to maximum strain theory, when the maximum tensile strain equals (where, ? = yield strength and E = modulus of elasticity)
Options
A. E
B. ?
C. ?/E
D. E/?

9. Pick out the wrong statement.
Options
A. If sufficient residence time (around 8 seconds) is not proivided to the downcoming liquid in the downcomer, it may entrain some vapour.
B. The liquid head in the downcomer should not be greater than one half the plate spacing to avoid flooding.
C. The dischare end of the downcomer must project far enough into the tray liquid so that no gas bubbles can enter the open end and by pass the bubble caps.
D. none of these.

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