Commissioning Engineer

20+ Commissioning Engineer Interview Questions and Answers

Updated 25 Feb 2025
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Q1. What is your expertise in water and waste water treatment plant

Ans.

I have extensive expertise in water and wastewater treatment plants.

  • I have a strong understanding of the processes involved in water and wastewater treatment, including coagulation, flocculation, sedimentation, filtration, and disinfection.

  • I am experienced in designing and commissioning various types of treatment systems, such as activated sludge, membrane filtration, and reverse osmosis.

  • I have knowledge of the equipment and instrumentation used in water and wastewater treatm...read more

Q2. How you manage a 10 or 15 people group at site?

Ans.

To manage a 10 or 15 people group at site, effective communication, delegation, and leadership skills are essential.

  • Establish clear goals and expectations for the team.

  • Communicate regularly and openly with the team members to ensure everyone is on the same page.

  • Delegate tasks based on individual strengths and skills.

  • Provide necessary resources and support to the team.

  • Encourage collaboration and teamwork among the group members.

  • Address conflicts or issues promptly and fairly.

  • L...read more

Commissioning Engineer Interview Questions and Answers for Freshers

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Q3. 1. What are the types of column, different types of stages/ plates, types of packing 2. troubleshooting in the column. 3. explain troubleshooting with particular example. for commissioning at entry level.

Ans.

The types of columns in commissioning engineering include packed columns and tray columns. Troubleshooting in columns involves identifying and resolving issues with pressure, temperature, flow, and separation efficiency.

  • Types of columns: packed columns and tray columns

  • Types of stages/plates: bubble cap trays, sieve trays, valve trays

  • Types of packing: structured packing, random packing

  • Troubleshooting in columns: pressure issues, temperature issues, flow issues, separation effi...read more

Q4. What's the best simulation of shrinkage in thermal expansion of casting ?

Ans.

The best simulation of shrinkage in thermal expansion of casting is achieved through finite element analysis (FEA).

  • Finite Element Analysis (FEA) is commonly used to simulate shrinkage in thermal expansion of casting.

  • FEA software allows for accurate prediction of shrinkage and deformation during the casting process.

  • By inputting material properties, boundary conditions, and thermal gradients, FEA can provide valuable insights into the casting process.

  • Examples of FEA software co...read more

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Q5. How to increase molten metal pressure in casting area?

Ans.

To increase molten metal pressure in casting area, adjust the pouring rate, increase the height of the pouring basin, and use a pressurized system.

  • Adjust the pouring rate to control the flow of molten metal into the casting area.

  • Increase the height of the pouring basin to create more pressure when the metal is poured.

  • Use a pressurized system such as a vacuum or pressure casting method to increase the pressure of the molten metal.

Q6. What are the types of boilers and and process of its installation?

Ans.

Types of boilers include fire tube, water tube, and electric boilers. Installation process involves site preparation, assembly, piping, and testing.

  • Types of boilers: fire tube, water tube, electric

  • Installation process: site preparation, assembly, piping, testing

  • Examples: Fire tube boiler - used in small industrial plants, Water tube boiler - used in power stations

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Q7. What is Thermax product portfolio where you had heard about Thermax?

Ans.

Thermax offers a wide range of products including boilers, heaters, chillers, water treatment solutions, and waste heat recovery systems.

  • Boilers

  • Heaters

  • Chillers

  • Water treatment solutions

  • Waste heat recovery systems

Q8. Thermal expansion and Young's modulus and mfg process of PDC and press tool?

Ans.

Thermal expansion affects PDC and press tool manufacturing due to Young's modulus.

  • Thermal expansion can cause dimensional changes in materials during manufacturing processes.

  • Young's modulus is a measure of a material's stiffness and resistance to deformation.

  • PDC (Polycrystalline Diamond Compact) is a material commonly used in cutting tools due to its hardness and wear resistance.

  • Press tools are used in metal forming processes and must be designed to account for thermal expans...read more

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Q9. What is the maintenance protocol of switchgear and transformer .

Ans.

The maintenance protocol of switchgear and transformer involves regular inspections, testing, cleaning, and preventive maintenance.

  • Regular inspections are conducted to identify any signs of wear, damage, or malfunction.

  • Testing is performed to ensure the equipment is functioning properly and within specified parameters.

  • Cleaning is necessary to remove dust, dirt, and debris that can affect performance.

  • Preventive maintenance includes tasks like lubrication, tightening connection...read more

Q10. How to correction casting thickness within model?

Ans.

To correct casting thickness within a model, adjust the design parameters and re-run simulations.

  • Modify the CAD model to adjust the thickness of the casting.

  • Update the material properties and casting parameters in the simulation software.

  • Run simulations to analyze the effects of the changes on the casting quality.

  • Iterate the process until the desired casting thickness is achieved.

  • Consult with design engineers and casting experts for guidance.

Q11. Where is VFD use in power plant and why?

Ans.

VFDs are used in power plants to control the speed of motors and pumps, resulting in energy savings and improved process control.

  • VFDs are used in boiler feed pumps to control the flow of water to the boiler, resulting in improved efficiency and reduced wear and tear on the equipment.

  • VFDs are used in cooling tower fans to adjust the speed of the fan based on the cooling demand, resulting in energy savings.

  • VFDs are used in air handling units to control the speed of the fan base...read more

Q12. How to change trim line within process?

Ans.

To change trim line within a process, you need to adjust the setpoint of the control system.

  • Access the control system interface

  • Locate the trim line parameter

  • Adjust the setpoint to change the trim line

  • Monitor the process to ensure the trim line is functioning correctly

Q13. What is the outlet temperature of coal mill.

Ans.

The outlet temperature of coal mill depends on various factors such as coal type, mill capacity, and air flow rate.

  • Outlet temperature is typically measured in degrees Celsius or Fahrenheit.

  • The temperature can range from 60 to 120 degrees Celsius depending on the above factors.

  • The temperature needs to be carefully controlled to prevent overheating and potential fires.

  • Regular monitoring and maintenance of the coal mill is necessary to ensure safe and efficient operation.

Q14. What checks are done while starting the pump?

Ans.

Checks done while starting the pump include verifying power supply, checking for leaks, ensuring proper alignment, and monitoring vibration levels.

  • Verify power supply to the pump

  • Check for any leaks in the pump system

  • Ensure proper alignment of the pump with the motor or drive shaft

  • Monitor vibration levels to ensure smooth operation

Q15. What is working principle of wind turbine

Ans.

Wind turbines convert kinetic energy from the wind into mechanical power.

  • Wind turns the blades of the turbine

  • Blades are connected to a drive shaft

  • Drive shaft spins a generator to produce electricity

  • Electricity is then fed into the grid or stored in batteries

  • Turbines can have horizontal or vertical axis

Q16. How to calculate flow rate ?

Ans.

Flow rate can be calculated by dividing the volume of fluid passing through a pipe or channel by the time it takes to pass.

  • Flow rate = Volume / Time

  • Units of flow rate are typically liters per minute (L/min) or cubic meters per second (m^3/s)

  • Flow rate can be measured using flow meters or calculated based on known parameters such as pipe diameter and fluid velocity

Q17. Have you a transferable iqama?

Ans.

Yes, I have a transferable iqama.

  • I have a transferable iqama.

  • I can provide the necessary documentation to prove it.

  • Having a transferable iqama allows me to work in different locations without any restrictions.

  • It demonstrates my flexibility and adaptability to new environments.

Q18. What is the coal mill tripping on.

Ans.

The coal mill can trip on various reasons such as coal hang-up, mill overload, flame detector failure, etc.

  • Coal hang-up: when coal sticks to mill internals due to high moisture content or poor coal quality

  • Mill overload: when the mill motor is overloaded due to high coal flow or low grindability

  • Flame detector failure: when the flame detector fails to detect the flame in the furnace

  • Other reasons: such as feeder blockage, coal pipe blockage, etc.

Q19. What are the commissioning activities?

Ans.

Commissioning activities are the set of procedures and tests performed to ensure that a system or equipment is ready for operation.

  • Inspection and verification of equipment installation

  • Functional testing of individual components

  • Integration testing of the entire system

  • Performance testing to ensure the system meets specifications

  • Documentation of test results and procedures

  • Training of operators and maintenance personnel

Q20. Different between Cold and Hot commissioning?

Ans.

Cold commissioning is done without the presence of heat sources, while hot commissioning involves testing with heat sources.

  • Cold commissioning is done at ambient temperature, while hot commissioning involves operating equipment at design temperature.

  • Cold commissioning focuses on mechanical and electrical systems, while hot commissioning tests the performance of the system under normal operating conditions.

  • Cold commissioning is typically done before hot commissioning to identi...read more

Q21. What is Dfig in wind turbine

Ans.

Dfig stands for Doubly Fed Induction Generator, a type of generator used in wind turbines.

  • Dfig is a type of generator that allows variable speed operation in wind turbines.

  • It has two sets of windings - one connected to the grid and the other to a converter.

  • The converter controls the power flow between the grid and the generator, allowing for better efficiency.

  • Dfig is commonly used in modern wind turbines for its ability to adjust to changing wind conditions.

  • It is more cost-ef...read more

Q22. How many unit 1 MW.

Ans.

The question is unclear. 1 MW is a unit of power, not a unit of measurement.

  • 1 MW is a unit of power, not a unit of measurement

  • It is like asking how many pounds are in a mile

  • The question needs to be rephrased or clarified

Q23. Mold temperature depend upon?

Ans.

Mold temperature depends on various factors such as material type, cooling system, injection speed, and mold design.

  • Material type: Different materials require different mold temperatures for optimal results.

  • Cooling system: The efficiency of the cooling system affects the mold temperature.

  • Injection speed: Faster injection speeds may require higher mold temperatures to prevent defects.

  • Mold design: The design of the mold can impact how heat is distributed and controlled.

Q24. Logic behind the operation of an AHU

Ans.

AHU operates based on setpoint temperature, fan speed, and air flow requirements.

  • AHU receives signals from temperature sensors to maintain setpoint temperature.

  • Fan speed is adjusted based on cooling or heating demand.

  • Air flow is controlled to meet ventilation requirements.

  • AHU may have filters to remove contaminants from the air.

  • Variable Air Volume (VAV) systems adjust air flow based on zone requirements.

Q25. What is the confined space?

Ans.

A confined space is an area that is not designed for continuous occupancy, has limited entry and exit points, and may have poor ventilation.

  • Confined spaces are typically small and enclosed, such as tanks, silos, tunnels, and crawl spaces.

  • These spaces may contain hazardous substances, lack oxygen, or have other dangerous conditions.

  • Workers entering confined spaces must follow strict safety protocols, including proper training, equipment, and monitoring.

  • Examples of confined spa...read more

Q26. Flue gas outlet temperature?

Ans.

Flue gas outlet temperature is the temperature of the gas leaving the combustion chamber.

  • Flue gas outlet temperature is an important parameter to monitor the efficiency of a combustion process.

  • It is usually measured using a thermocouple or infrared thermometer.

  • The temperature should be within the design limits to avoid any damage to the equipment.

  • For example, in a gas turbine, the flue gas outlet temperature should not exceed 650°C.

  • The flue gas outlet temperature can also be ...read more

Q27. What is Loto?

Ans.

Loto stands for Lockout Tagout, a safety procedure used to ensure that dangerous machines are properly shut off and not started up again prior to the completion of maintenance or servicing work.

  • Loto involves locking the energy isolating device with an assigned individual lock and tag.

  • Only the person who applied the lock and tag can remove them after the work is completed.

  • Loto helps prevent accidents caused by the unexpected startup of machinery during maintenance.

  • Examples of ...read more

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