800+ Mechanical Engineer Interview Questions and Answers

There are three types of lubrication: boundary, mixed, and hydrodynamic.

• Boundary lubrication occurs when there is direct contact between two surfaces and a lubricant is used to reduce friction.

• Mixed lubrication is a combination of boundary and hydrodynamic lubrication.

• Hydrodynamic lubrication occurs when a fluid film is created between two surfaces, reducing friction and wear.

• Examples of lubricants include oil, grease, and graphite.

• The type of lubrication used depends on the ...read more

I have used the Single-stage ejector system and the Multi-stage ejector system.

• Single-stage ejector system: This system uses a single ejector stage to create a vacuum or low-pressure environment. It is commonly used in applications such as vacuum cleaners and air conditioning systems.

• Multi-stage ejector system: This system uses multiple ejector stages in series to achieve higher levels of vacuum or lower pressures. It is often used in industries like power generation and chem...read more

Stainless steel pipelines are commonly used for transporting hazardous chemicals due to their corrosion resistance and durability.

• Stainless steel pipelines are preferred for their resistance to corrosion from hazardous chemicals.

• PVC pipelines are not suitable for hazardous chemicals as they can degrade and leak.

• Carbon steel pipelines can be used for some hazardous chemicals, but may require additional coatings or linings for protection.

• Specialized materials like PTFE (Teflon)...read more

The formula to calculate module in gears is the ratio of pitch diameter to the number of teeth.

• Module = Pitch Diameter / Number of Teeth

• Module is a measure of the size of the teeth on a gear.

• It is commonly used in gear design and manufacturing to ensure proper meshing of gears.

• For example, if a gear has a pitch diameter of 40 mm and 20 teeth, the module would be 40 mm / 20 = 2 mm.

The basic combinations of coating in plastic include single layer coating, multi-layer coating, and functional coating.

• Single layer coating: A single layer of coating is applied to the plastic surface for protection or decoration.

• Multi-layer coating: Multiple layers of coatings are applied to the plastic surface for enhanced properties like scratch resistance or UV protection.

• Functional coating: Coatings with specific functions like anti-bacterial, anti-static, or self-cleani...read more

Troubleshooting of centrifugal pump involves identifying and resolving issues to ensure optimal performance.

• Start by checking for common issues such as leaks, low flow rate, or abnormal noise

• Inspect the pump components including impeller, casing, and seals for wear or damage

• Verify proper alignment of the pump with the motor and check for any blockages in the system

• Use diagnostic tools like pressure gauges or vibration sensors to pinpoint the problem

• Refer to the pump manual or...read more

The slope given to a 200 mm dia drainage pipe depends on the specific requirements and regulations of the project.

• The slope of a drainage pipe is typically expressed as a percentage or a ratio.

• The slope is necessary to ensure proper flow and prevent the accumulation of debris or stagnant water.

• The slope is determined based on factors such as the pipe material, pipe length, and the expected flow rate.

• For example, a common slope for a drainage pipe is 0.5% or 1:200, which means...read more

Heat treatment involves heating and cooling of metals to alter their properties. FE-C equilibrium diagram shows the relationship between carbon content and temperature in steel.

• Heat treatment is used to improve the mechanical properties of metals.

• It involves heating the metal to a specific temperature and then cooling it at a specific rate.

• FE-C equilibrium diagram shows the phases of steel at different temperatures and carbon content.

• It helps in determining the microstructure...read more

Comments on shop drawing for mechanical engineer

• Check dimensions and tolerances

• Ensure proper material selection

• Verify compliance with industry standards

• Confirm accuracy of assembly instructions

• Identify potential manufacturing issues

HDPE piping is used for water and gas distribution due to its flexibility and corrosion resistance, while CS piping is used for high temperature and pressure applications due to its strength and durability.

• HDPE piping is commonly used for water and gas distribution systems due to its flexibility, corrosion resistance, and ability to withstand low temperatures.

• CS piping, or carbon steel piping, is used for high temperature and pressure applications such as steam lines, oil and...read more

Cost and estimation are calculated by analyzing project requirements, materials, labor, and overhead costs.

• Determine project requirements and scope

• Identify necessary materials and their costs

• Estimate labor costs based on project timeline and required skillset

• Calculate overhead costs such as rent, utilities, and insurance

• Consider any potential risks or unforeseen expenses

• Use software tools such as Excel or specialized cost estimation software

• Regularly review and update cost es...read more

Gear box maintenance involves regular inspection, lubrication, and replacement of worn-out parts.

• Regular inspection of gear teeth and bearings

• Lubrication of gears and bearings

• Replacement of worn-out parts such as seals and bearings

• Checking oil levels and changing oil as needed

• Cleaning and inspecting filters

• Checking alignment and adjusting as needed

A diesel engine works by compressing air in the cylinder, which heats up and ignites the fuel injected into the cylinder.

• Air is drawn into the cylinder and compressed by the piston

• The compressed air heats up and ignites the fuel injected into the cylinder

• The explosion pushes the piston down, which turns the crankshaft and powers the engine

• Diesel engines are more efficient than gasoline engines because they compress the air instead of relying on a spark to ignite the fuel

The number of stages of turbine blades varies depending on the specific turbine design and application.

• Turbine blades are used in various applications such as gas turbines, steam turbines, and wind turbines.

• The number of stages in a turbine refers to the number of sets of rotating and stationary blades.

• Each stage of turbine blades helps to extract energy from the fluid passing through the turbine.

• Gas turbines typically have multiple stages, ranging from 1 to 20 or more, to ac...read more

Bearings are of various types such as ball, roller, plain, etc. Furnace maintenance includes cleaning, inspection, and replacement of parts.

• Different types of bearings are used in mechanical systems depending on the load and speed requirements.

• Ball bearings are commonly used in high-speed applications while roller bearings are used in heavy load applications.

• Plain bearings are used in low-speed and high-load applications.

• Furnace maintenance includes regular cleaning of the fu...read more

Types of fits include clearance and interference fits, each with different characteristics.

• Clearance fit allows for clearance between the shaft and hole, providing easy assembly and disassembly.

• Interference fit has interference between the shaft and hole, creating a tight connection with high friction.

• Transition fit falls between clearance and interference fits, providing a balance between clearance and interference.

• Examples: Press fit (interference), Sliding fit (clearance),...read more

PSL 2 has stricter requirements than PSL 1. Gas pipelines use PSL 2 pipes.

• PSL 2 has higher minimum yield strength and stricter chemical composition requirements than PSL 1

• PSL 2 also has non-destructive inspection requirements

• Gas pipelines use PSL 2 pipes due to their higher strength and durability

• PSL 1 pipes are typically used for low-pressure applications

Laser beam welding is a process of joining two metal pieces using a laser beam.

• Laser beam welding is a non-contact process.

• It uses a high-energy laser beam to melt and fuse the metal pieces together.

• It is commonly used in the automotive, aerospace, and electronics industries.

• It produces a narrow and deep weld with minimal distortion.

• Examples include welding of car body parts, aircraft engine components, and electronic circuit boards.

The solar system refers to the sun and all the celestial objects that orbit around it. There are two types: ongrid and offgrid systems.

• The solar system consists of the sun, planets, moons, asteroids, comets, and other celestial bodies.

• Ongrid systems are connected to the main electrical grid and feed excess energy back into the grid.

• Offgrid systems are not connected to the main grid and rely on batteries or other storage methods to store excess energy.

• Ongrid systems are common...read more

I have been working as a piping engineer for 5 years.

• I have 5 years of experience working specifically as a piping engineer.

• During this time, I have gained expertise in designing, analyzing, and implementing piping systems.

• I have worked on various projects that involved piping design, layout, and maintenance.

• I have also collaborated with other engineers and professionals to ensure the successful completion of projects.

Coke density and water consumption are important factors in coke production.

• Coke density is typically measured in kg/m³ and can vary depending on the type of coke being produced.

• Water consumption for coke production can vary depending on the production process and the quality of the raw materials.

• Efficient use of water in coke production is important for both environmental and economic reasons.

• Coke density and water consumption are closely related, as the amount of water used...read more

Pump lineup is crucial for efficient operation. Proper selection and maintenance can improve efficiency.

• Pump lineup should be selected based on the required flow rate and head

• Centrifugal pumps are commonly used for low viscosity fluids while positive displacement pumps are used for high viscosity fluids

• Efficiency can be improved by proper maintenance such as regular cleaning and lubrication

• Variable frequency drives can also improve efficiency by adjusting the pump speed to ma...read more

Basic laws of thermodynamics

• First law: Energy cannot be created or destroyed, only transferred or converted

• Second law: Entropy of a closed system always increases over time

• Third law: Absolute zero cannot be reached

• Examples: car engine, refrigerator, power plant

Heat variation in HF plant can be controlled through various methods.

• Maintaining proper insulation in the plant

• Using heat exchangers to transfer heat from one process to another

• Implementing a control system to monitor and adjust temperature

• Regular maintenance and cleaning of equipment to prevent heat buildup

• Using cooling towers or water sprays to reduce temperature

• Optimizing the plant layout to minimize heat transfer between processes

There are three types of maintenance: corrective, preventive, and predictive.

• Corrective maintenance involves fixing a problem after it has occurred.

• Preventive maintenance involves regularly scheduled maintenance to prevent problems from occurring.

• Predictive maintenance involves using data and analysis to predict when maintenance will be needed.

• Examples of maintenance tasks include oil changes, equipment inspections, and software updates.

To apply for JSW Steel Plant, visit their official website and look for job openings. Submit your resume and application online.

• Visit JSW Steel Plant's official website

• Look for job openings and requirements

• Submit your resume and application online

• Prepare for interviews and assessments

I would ensure your medical insurance is properly managed and utilized.

• Review the coverage provided by the insurance plan

• Ensure timely payment of premiums to avoid any lapses in coverage

• Keep track of medical expenses and file claims accurately

• Stay informed about any changes in the insurance policy or network providers

Welding rod specification refers to the detailed information about the type, composition, and properties of a welding rod.

• Welding rod specification includes information about the type of welding rod, such as whether it is a coated electrode or a bare electrode.

• It also includes details about the composition of the welding rod, such as the type and percentage of filler metal and flux used.

• The specification provides information about the diameter and length of the welding rod.

• It...read more

There are various types of gearboxes such as manual, automatic, CVT, DCT, etc. Conveyors can use gearboxes for power transmission.

• Types of gearboxes include manual, automatic, CVT, DCT, etc.

• Gearboxes are used for power transmission in conveyors.

• Conveyor gearboxes can be worm gearboxes, helical gearboxes, etc.

Bearings and gears are mechanical components used in various machines and mechanisms.

• Bearings are used to support and reduce friction between moving parts.

• Gears are toothed wheels that transmit power and motion between rotating shafts.

• Bearings can be classified into various types such as ball bearings, roller bearings, and plain bearings.

• Gears can be classified into different types including spur gears, helical gears, and bevel gears.

• Bearings are commonly used in applications...read more

Types of compressors include reciprocating, rotary, centrifugal, and axial compressors.

• Reciprocating compressors use pistons to compress air or gas.

• Rotary compressors use rotating mechanisms such as screws or vanes.

• Centrifugal compressors use a rotating impeller to create centrifugal force.

• Axial compressors use rotating blades to compress air in a straight line.

• Examples include reciprocating air compressors, rotary screw compressors, centrifugal compressors, and axial compres...read more

Standard oxygen transfer efficiency for fine bubble diffusers is typically around 30-40%.

• Fine bubble diffusers are commonly used in wastewater treatment plants to transfer oxygen to the water.

• Factors that can affect oxygen transfer efficiency include bubble size, diffuser design, and water temperature.

• Efficiency can be improved by optimizing these factors and ensuring proper maintenance of the diffusers.

• Typical oxygen transfer rates for fine bubble diffusers range from 1.5 to...read more

Centrifuge pump power and capacity calculations involve understanding the pump's efficiency, flow rate, and head.

• Calculate the pump's power using the formula: Power (kW) = (Q x H x SG) / (3.6 x η)

• Determine the pump's capacity by calculating the flow rate (Q) in m^3/s

• Consider the pump's head (H) in meters and specific gravity (SG) of the fluid being pumped

• Efficiency (η) of the pump is crucial for accurate power calculations

• Example: If a centrifuge pump has a flow rate of 0.05 ...read more

Spiral casings turbines are a type of hydraulic turbine used for generating electricity from water flow.

• Spiral casings turbines are commonly used in hydroelectric power plants.

• They are designed to efficiently convert the kinetic energy of water into mechanical energy.

• The spiral casing is a spiral-shaped structure that houses the turbine runner.

• Water enters the spiral casing tangentially, creating a spiral flow pattern.

• This spiral flow helps to increase the efficiency of the t...read more

To start erection after civil clearance, follow these steps:

• Ensure all civil work is completed and cleared by the relevant authorities

• Review the civil clearance documentation to understand the scope and requirements

• Prepare the necessary equipment and materials for erection

• Coordinate with the civil team to ensure a smooth transition from clearance to erection

• Follow safety protocols and guidelines during the erection process

• Monitor and inspect the erection progress to ensure qu...read more

The type of electrode used in structure welding depends on the specific requirements of the project.

• Common types of electrodes used in structure welding include E6010, E7018, and E7014.

• E6010 electrodes are used for deep penetration and are often used in pipeline welding.

• E7018 electrodes are known for their high tensile strength and are commonly used in structural steel welding.

• E7014 electrodes are versatile and can be used for both vertical and overhead welding.

• The choice of ...read more

M cube in pump refers to the specific speed of the pump. Pump head is the height to which a pump can raise water.

• M cube in pump is a dimensionless number that represents the specific speed of the pump

• It is calculated using the formula: Ns = N * sqrt(Q) / H^(3/4), where N is the pump speed, Q is the flow rate, and H is the pump head

• Pump head is the height (in meters or feet) to which a pump can raise water

• It is an important parameter in determining the performance of a pump

Reverse a string without using string or inbuilt function

• Create an array of characters to store the string

• Use two pointers, one at the beginning and one at the end, swap characters until they meet

• Repeat until all characters are swapped

Installation of glass lined and hydrogenation reactors requires careful planning and execution.

• Ensure proper site preparation and foundation design

• Follow manufacturer's instructions for assembly and installation

• Use appropriate lifting equipment and safety measures

• Ensure proper sealing and insulation

• Test for leaks and pressure before use

Stresses in a thin cylinder are caused by internal pressure and can lead to hoop stress and longitudinal stress.

• Stresses in a thin cylinder are primarily caused by internal pressure exerted on the walls of the cylinder.

• Hoop stress is the stress in the circumferential direction of the cylinder, while longitudinal stress is along the length of the cylinder.

• The formula for hoop stress in a thin-walled cylinder is given by: σ = PD/2t, where σ is the hoop stress, P is the internal...read more

The pneumatic cylinder operating pressure varies depending on the specific application and design.

• The operating pressure of a pneumatic cylinder can range from 20 to 150 psi (pounds per square inch).

• Higher pressure is typically used for heavy-duty applications, while lower pressure may be sufficient for lighter tasks.

• The operating pressure should be within the recommended range specified by the manufacturer to ensure optimal performance.

• Factors such as cylinder size, load req...read more

The rpm and discharge of a pump are key parameters that determine its performance.

• RPM (revolutions per minute) is the rotational speed of the pump's shaft.

• Discharge refers to the volume of fluid that the pump can move in a given time.

• The rpm and discharge of a pump are typically provided by the manufacturer in the pump's specifications.

• For example, a centrifugal pump may have an rpm of 1750 and a discharge of 500 gallons per minute.

Condition monitoring is the process of monitoring the condition of machinery or equipment to identify any potential issues or failures before they occur.

• It involves using various techniques such as vibration analysis, thermography, oil analysis, and ultrasonic testing.

• By regularly monitoring the condition of equipment, maintenance can be scheduled proactively to prevent unexpected breakdowns.

• Condition monitoring helps in reducing downtime, increasing equipment reliability, an...read more

A four wheeler runs by converting fuel into mechanical energy through a series of processes involving the engine, transmission, and wheels.

• Fuel is burned in the engine to create combustion, which generates power

• The power is transferred to the wheels through the transmission system

• The wheels rotate and propel the vehicle forward

• Brakes are used to slow down or stop the vehicle

Preventive maintenance of water seal involves regular inspection, cleaning, and replacement of worn-out parts.

• Inspect water seal regularly for signs of wear and tear

• Clean water seal and surrounding area to prevent buildup of debris

• Replace worn-out parts such as gaskets and O-rings

• Ensure proper lubrication of moving parts

• Monitor water levels and pressure to prevent leaks

• Train operators on proper use and maintenance of water seal

SI and CI engines are types of internal combustion engines used in vehicles and machinery.

• SI engine stands for Spark Ignition engine, also known as gasoline engine.

• CI engine stands for Compression Ignition engine, also known as diesel engine.

• SI engines use a spark plug to ignite the fuel-air mixture, while CI engines use compression to ignite the fuel.

• SI engines are commonly used in cars, motorcycles, and small machinery, while CI engines are used in larger vehicles and machi...read more

tph refers to tons per hour and AQC and PH boilers are used in power plants.

• tph stands for tons per hour and is a unit of measurement for the flow rate of material

• AQC (Air Quenching Cooler) and PH (Pre-Heater) boilers are commonly used in power plants

• The tph of AQC and PH boilers depends on various factors such as the size of the boiler and the type of fuel used

• The tph of AQC and PH boilers can range from a few tons per hour to several hundred tons per hour