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Mechanical Interview Questions 4 contains questions about Piston Ring,  Power plant,  Hydrostatic system,  Ductile-Brittle Transition Temperature in metals, Hydrodynamic Cavitation,  Powder Technology,  Stress Strain curve for Steel, difference between Pipe and Tube, Welding damage Eye sight, BCC, FCC, CPH.

31. What will be the position of Piston Ring?

32. What is Heat rate of a Power plant?

33. What is a Hydrostatic system?

34. How to find a Ductile-Brittle Transition Temperature in metals?

35. What is Hydrodynamic Cavitation?

37. What are the points in the Stress Strain curve for Steel?

38. What is the difference between Pipe and Tube?

39. How does Welding damage Eye sight?

40. Explain why BCC, FCC and CPH lattice packing and features of grain structure affect the Ductility and Brittleness of parent metallic materials?

31. What will be the position of Piston Ring?

In 180 degree angle the Top ring, Second ring and Oil ring are fixed. Position the ring approximately 1 inch gap below the neck.

32. What is Heat rate of a Power plant?

Heat rate is a measure of the turbine efficiency. It is determined from the total energy input supplied to the Turbine divided by the electrical energy output.

33. What is a Hydrostatic system?

Hydrostatics is the study of fluid bodies that are

• At rest
• Moving sufficiently slowly so there is no relative motion between adjacent parts of the body

For hydrostatic situations

• There are no shear stresses
• There are only pressure forces that act perpendicular to any surface.

It’s a closed loop hydraulic systems. It comprises of motor and pump. Here pump supplies energy to motor and motor gives return energy to pump supply.

34. How to find a Ductile-Brittle Transition Temperature in metals?

The point at which the fracture energy passes below a pre-determined point for a standard Impact tests.

DBTT is important since, once a material is cooled below the DBTT, it has a much greater tendency to shatter on impact instead of bending or deforming.

35. What is Hydrodynamic Cavitation?

Hydrodynamic cavitation describes the process of vaporization in a constrained channel at a specific velocity.

Bubble generation and Bubble implosion which occurs in a flowing liquid as a result of a decrease and subsequent increase in pressure.

Powder technology is one of the ways of making bearing material. In this method metals like bronze, Al, Fe are mixed and compressed to make an alloy.

37. What are the points in the Stress Strain curve for Steel?

Proportional limit, elastic limit or yield point, ultimate stress and stress at failure.

38. What is the difference between Pipe and Tube?

Ex. Iron Pipe, Carbon Tube, Steel Tube etc.

Tube is defined by Outer diameter and Wall thickness (OD and WT). While Pipe is defined by Inner diameter (ID).

Example:

2 inch pipe have 2.375 inch outer diameter, where 2 inch tube have same 2 inch outer diameter.

· Tube is easily shaped by bending, where Pipe needs some mechanical work to shape it.

· Tube is tight then Pipe.

· Tube is applicable to non cylindrical sections like Square and Rectangular.

39. How does Welding damage Eye sight?

An Electric welding arc produces Ultraviolet light and the UV light (Sun burn) will damage the retina. Welding shields or Goggles with the proper shade (Automatic shading) of lens is the best protection for welders.

Light filtering curtains and reduced reflective surfaces help protect both welders and observers in the area.

40. Explain why BCC, FCC and CPH lattice packing and features of grain structure affect the Ductility and Brittleness of parent metallic materials?

Ductility is the mechanical property of a material. (It is the material’s ability to deform under the tensile stress without fracture).

So it is depends on the atoms how they arranged in a lattice and its grain size.

The ability to absorb the energy of the impact and fracture resistance depends on the arrangement of the atoms in a lattice and features of grain structure.