Question Set 172

11) What is caustic embrittlement?

Caustic embrittlement is a physical change in metal. In this phenomenon, the boiler becomes brittle because of accumulation of caustic soda.

12) Name the boiler that does not need a steam drum.

Supercritical pressure boiler does not need a steam drum.

13) Explain the Otto cycle in brief.

Otto cycle describes the functioning of a typical spark-ignition four-stroke engine. Otto cycle is a description of what happens to gas as it is subjected to changes of volume, temperature, addition, or removal of heat.

14) What do you mean by annealing?

Annealing is the process of heating any material above the recrystallization temperature and cooling after some time. This process increases the hardness and strength of metal material. The result you will get is a reduction of dislocations in the crystal structure of metal being annealed.

15) Explain enthalpy.

It is the heat content of a thermodynamic system.

16) Define a uniformly distributed load.

A uniformly distributed load is a load which is spread over a region of the beam. Here the magnitude of the load remains similar throughout the element.

17) Explain different types of fits.

Fits can be categorized into three groups: 1) clearance fit, 2) interference fit, and 3) transition fit.

·          Clearance fit: This fit is identified by the occurrence of clearance between the two similar parts.

·          Interference fit: In this fit, the size of the mating parts is predefined to occur interference between these parts. Here the hole tolerance zone is completely below shaft tolerance zone.

·          Transition fit: It is a comptonization between clearance and interface fit. In this case of fit, the tolerance zone of the shaft and hole overlaps.

18) Explain important rules that must be kept in mind while designing castings?

Following are the points that you should keep in mind:

·          Keep section thickness uniform as much as possible.

·          Sudden changes in the thickness should be averted at all costs.

·          Design casting by keeping simplicity.

·          Avoid large flat surfaces as true large spaces are difficult to create.

·          Use a curved shape to improve the stress handling of the cast.

19) What is universal coupling?

Universal coupling is used to connect two shafts whose axes are inclined to each other. It consists of a pair of hinges, connected by a cross shaft.

20) Why would you use pneumatics?

Pneumatic systems are significantly cheaper than other streams, i.e., hydraulic system. It can move faster and do not leak oil if they develop a leak.