Saturday, May 30, 2020

condition-based-maintenance (CBM)

Condition-based maintenance (CBM)

Condition-based maintenance is also called (predictive, proactive) in which perform the activity depends on the condition of the equipment. To achieve the maximum production goal and avoid the unexpected equipment failed.



Condition-based maintenance has two parts

  1. condition monitoring maintenance 
  1.  reliability-centered maintenance 

When Condition-based maintenance (CBM) should be needed and when it to be applied?

1. Mostly Condition-based maintenance applies to expensive and critical equipment used.
2. Equipment overhauling is expensive and required highly trained people to overhaul.
3. Required when it works with high speed and high-pressure temperature equipment,
        catastrophic failure could occur.
4. Is this case equipment is operated mostly by remote-based?

What is maintenance strategy?

There are mainly three types of maintenance strategy

1. Run to failure (breakdown maintenance)
2. Schedule base (preventive maintenance)
3. Condition-based maintenance (CBM)

Above maintained strategy on one is superior or advance to each other. Every strategy has its own value. later we discuss in detail go bottom of the page for follow and subscribe for the latest update.

What is the goal of condition-based maintenance?

The main goal of the condition monitoring is the online monitor of the equipment running conditions and given the information, any malfunction could occur before it's happened and will take appropriate action to correct it.

The main goal of condition-based maintenance is 

  1. Optimize the maintenance resources and increase the reliability of the plant.
  2. increase production prevents catastrophic failure from equipment.
  3. Increase the efficiency of the equipment.
  4. to improve equipment Safty and integrity.
  5. Increase the knowledge and awareness of equipment.
  6. Increase the availability of equipment.
  7. Reduce the maintenance cost
  8. It is also part of predictive maintenance.

what type of technics use in the condition-based maintenance system?

There are many techniques used to perform the condition-based maintenance of equipment, piping systems other types of equipment.

  1. Vibration analysis
  2. Condition monitoring
  3. Lube oil and debris analysis
  4. Ultrasound analysis
  5. Acoustic emission analysis
  6. motor current signature analysis, and etc

Difference between preventive maintenance and condition-based maintenance?

Condition-based maintenance (CBM) systems monitor online systems and give live reports of running equipment. Whereas preventive maintenance is used as a calendar-based maintenance system. Preventive maintenance is schedule-based maintenance perform at regular interval time.
Whereas the condition-based maintenance (CBM) works at the on-time when any malfunction is going happen it inform. 
The cost of the preventive maintenance is medium to high whereas the condition monitoring system is medium too high and higher as used.

Predictive maintenance to predict the equipment malfunction in advance improves the maintenance task of equipment. Where is the condition monitoring system is done only on running equipment?  Preventive maintenance system mostly cheap and other equipment’s used but the condition monitoring system is highly constable but by the help of Condition-based maintenance (CBM) system we can analyze what is going to wrong with the equipment and where and which parts are going to malfunction or wear out by the deep analysis of condition monitoring parts of the vibration analysis.

Friday, May 29, 2020

What is role of maintenance engineer

What is the role of a maintenance engineer? 

The main role of a maintenance engineer is

  1. To maintain the equipment.
  2. Reduce maintenance costs.
  3. To keep the plants in running with reliability and with full capacity.
  4. Reduces the resources like human effort and assets. 
  5. Inspection of the equipment on a routine base.
  6. Analysis of the criticality of equipment on the base of RPN number after we will discuss it.
  7. Troubleshooting of malfunction of equipment. 
  8. Manpower management use in plants to minimize the maintenance cost.
  9. Overhauling of equipment and its maintenance.
  10. Take the decision about what type of maintenance to do on equipment either overhauling or inspection and cleaning only. this is a very important and decision making role.
  11. Accept the safety and follow the safety rules and guidelines.
  12. Aware of the risk and hazards could happen during the maintenance of the equipment.

There are two types of overhauling maintenance 

  1. Partially overhauling
  2. Complete overhauling

Partially overhauling

In the partially overhauling equipment, some parts change only like as, seal replacement, bearing replacement, lube oil change, seal ring change, greasing the equipment, in it less time to required to maintenances 

Complete overhauling

Complete overhauling in time taking maintenance in this type of maintenance measure part to be changed like impeller change, rotor change, casing change, or completely internal part to change. It is costly, but sometimes very important to this type of maintenance for capacities increase of particular equipment or plant or equipment to change due to some catastrophic failure happen.

What qualifications required to be a maintenance engineer?

Who can apply for a maintenance engineer? 

  1. Btech in mechanical engineering
  2. Btech in electrical engineering
  3. B tech in instrument engineering 
  4. Btech in civil engineering
  5. Btech in automobile engineering 

   Junior maintenance engineer

  1. Diploma in mechanical engineering
  2. Diploma in electrical engineering
  3. Diploma in automobile engineering
  4. Diploma in civil engineering 

 Responsibility of maintenance engineers 

  1. Maintenanceaintenance engineer should have good communication skills.
  2. Should be time punctual 
  3. Availability when required ability to work on big equipment as well as small equipment.
  4. Good knowledge for reading and understanding of drawing reading like ISO drawings, general drawings (GA), cross-sectional drawing, etc.
  5. Awareness for a soft skills like excel, PowerPoint, MS word, SAP pm, Microsoft project. 
  6. Is working in a plant? Itself to ensure that he is aware of all equipment maintenance and safety hazard.
  7. Maintenance engineers should have good knowledge about the inspection of plant machinery equipment parts.

There are many types of maintenance needed.

     Types of maintenance are breakdown maintenance, corrective maintenance, 
     preventive maintenance, productive maintenance, and condition-based maintenance.

Skills required for a maintenance engineer. 

  1. Inventory control and spare planning.
  2. Prepare permits, planning to schedule.
  3. Maintain a recorded history of equipment 
  4. Analysis of equipment criticality RPN numbers.
  5. Every department has it’s own maintenance engineer and each maintenance engineer has a different role, responsibility, and skill required.

Instrument engineers will be done the only instrument-related, like a probe, control valve, thermowell, etc.  
Maintenance mechanical engineer will be done only equipment related maintenance like a pump, compressor, vessel, column, turbines, etc.
Electrical engineer will be done only electrical equipment maintenance only like motor, solenoid valve, etc

Wednesday, May 27, 2020

What is preventive maintenance

Preventive maintenance

Preventive maintenance is a proactive type of maintenance in its action is taken before breakdown maintenance and prevents failure of machines and also saves from equipment downtimes. 
Preventive maintenance could be done like as weekly, monthly, quarterly, half-yearly, yearly some time also use a quote (prevention is better than cure) for preventive maintenance many types of action to be taken to save unexpected machines failure. That is mention below.

  • Periodically lubrication to change
  • Daily LLF (look listen to feel) activity and fill up checklists
  • Periodically inspection of the machine and its accessories
  • Overhauling and parts replacement if needed
  • Condition monitoring of equipment
  • Maintains equipment history record of all type of maintenance has done  

Type of preventive maintenance

There are two types of preventive maintenance

1.       Time-based maintenance

2.       Uses biased maintenance

preventive maintenance

Time-based maintenance

It is period maintenance like lube oil change, bearing change, grease change, wearing change and etc. it is totally based on the life of the equipment part has been gone or wear out as expected time as per designer. everything existed in the world has some life on the based of this we decided to maintenance.

Advantages and disadvantages of preventive maintenance

Advantages of preventive maintenance

1.       Save from catastrophic failure.
2.       Reduce the downtime of equipment.
3.       Planned maintenance (available all resources).
4.       Improve the quality and reliability of equipment.
5.       Breakdown happens at the expected time.
6.       Increase production rate.

            Disadvantages of preventive maintenance

  1.         Loss of resources.
  2.        Maintenance Cost goes up.
  3.        Unneeded maintenance of equipment.
  4.        Labour intensive.

What is the difference between preventive and breakdown maintenance?

The main difference between is breakdown maintenance is upland maintenance sometimes the catastrophic failure occurs, spare unavailability whereas preventive maintenance is planed every resource is available and reduce downtime of equipment, increase production.

Breakdown maintenance

Breakdown maintenance

breakdown maintenance is also called unscheduled maintenance, in breakdown maintenance, the equipment has completely failed and immediate action to be taken, breakdown maintenance causes for production loss. Sometimes breakdown maintenance used as optimization for preventive maintenances.
Learn more for mechanical maintenance

type of breakdown maintenances
Type of breakdown maintenance

How many types of breakdown maintenance?

There are two types of breakdown maintenance.

  1. Planned breakdown maintenance
  2. Unplanned breakdown maintenance

Planned breakdown maintenance

In the planned breakdown maintenance machine is in operation until its failure, the maintenance team is aware of the failure and well prepared for repair.

Unplanned breakdown maintenance

In this maintenance equipment failed unexpectedly, Unplanned breakdown maintenance

It is more costly than other maintenance.

There are to the type of Unplanned breakdown maintenance

  1. Corrective type

  1. Reactive type

What is the goal of breakdown maintenance?

The goal of breakdown maintenance is repairing the machine's urgent basis.

what are the causes of breakdown maintenance?

there are many causes of breakdown maintenances listed below.

  1. Improper maintenance
  2. Planed inspection not to be done on time.
  3. Not proper operation
  4. Design problem

How to minimize breakdown maintenance?

  1. Operate equipment within the designer limit
  2. To do regular preventive maintenance
  3. Follow the checklist during preventive maintenances.
  4. Overhauling and parts change on regular time
  5. To do regular inspection
  6. To do LLF (look listen feel) daily

Why breakdown maintenance could occur in plants.

  1. A pump is running overload and failed due to the wrong operation,
  2. The incurrent part has been installed.
  3. Could be lubrication issue or wrong lubricants used.

What are the advantages and disadvantages of breakdown maintenance?


  1. Very few staff need it.
  2. Take time to repair
  3. Easy to understood what is failed and how to repair
  4. Less time for repaired


  1. Downtime of plant increase
  2. Production loss
  3. Some difficult to find out the reason for failed
  4. Catastrophic failure could happen.

what is the difference between breakdown and preventive maintenance?

In the breakdown maintenance unscheduled and high-cost maintenance.

In preventive maintenance is scheduled, low cost and regular time-based maintenance.

Saturday, May 23, 2020

Types of maintenance

Types of maintenance

What is maintenance?

The work that is done according to the schedule to operate any equipment safely, to keep its condition better or to take its output with full efficiency, is called maintenance.

The maintenance department of industries has competent personnel for equipment maintenance.

Who maintains equipment regularly?

Mechanical, instrument, and electrical departments do the type of maintenance. Where mechanical maintain equipment like as pumps, blowers, compressor, gearbox, fan, turbine, valve, and other rotating and static equipment, and instruments department maintain solenoids, PG, TG, XV, PV, PRV, Thermowells, proves, sensors, etc. electrical department maintains only electrical related equipment like as transformers, motors, generators in electricals, and valves in
The main objective of maintenance is to increase the UP time (availability) of equipment.

Types of maintenance in industries

1.     preventive maintenance 
2.     predictive maintenance (condition-based maintenance)
3.     corrective maintenance
4.     breakdown maintenance

Preventive maintenance

Maintenance is done to correct the possible defects of equipment before its breakdown is called preventive maintenance. It is also known as scheduled maintenance. The checklist to follow of each equipment during preventive maintenance is different.

Predictive maintenance (condition-based maintenance)

The malfunction observation in the equipment could damage our equipment, and action taken to correct the malfunctions before the breakdown of equipment is called predictive maintenance. By use of condition-based maintenance increase the life and efficiency of the equipment.

Corrective Maintenance 

The malformations which are observed in the equipment and equipment have a breakdown or go after some time, action taken to correct the malfunctions before or after the breakdown of equipment is called corrective maintenance.

 Breakdown Maintenance

Fix it when it is a complete failure.

Efficient equipment is tied to any problem and the work that is done in trying to make it functional again is called break down maintenance.

Which is considered to be the worst among all types of maintenance.

This type of scenario occurs when equipment and its part wear out.

Or some mishappening happened with equipment. In this production, the loss goes up, to prevent this type of maintenance we do all above Maintenon maintenance models.

Friday, May 22, 2020

Type of fan


Fan is a mechanical device which is used to transfer air from one place to another place.
Fans create pressure against duct and piping.The rotating impellers increase velocity, and
then air speed Convert in to pressure.Mostly fan are used for ventilation system.

As per American Association of Mechanical Engineering (ASME) specific ratio the

ratio of discharge air to section air is defined to the blower and fan.

API standard of fan (API STD 673)

Type of fan

  1. Centrifugal fan 

  2. axial fan

Classification of centrifugal fan

On the base of impeller blade design fan classified in 3 type

  • backward curve vane
  • Forward curve vane
  • Radial curve vane

Type of axial fan

     In the axial fan flow is came parallel to the rotating shaft and discharged in also same.
  • Propeller fan

  • Vane axial fan

  • Tube axial fan

Thursday, May 21, 2020

Common Interview questions for mechanical engineer

Interview questions for mechanical engineer

  1. How many types of pumps?
  2. How many types of compressors?
  3. How many types of valves used in industries?
  4. How many types of blowers?
  5. How many types of fans?
  6. How many types of columns?
  7. How many types of internal materials used in columns?
  8. What is heat exchanger?
  9. How many types of heat exchanger?
  10. How many types of gaskets used in piping and equipments?

Wednesday, May 20, 2020

Type of agitator


  Agitator and mixer are mechanical device which is used for mixing, blending the process fluid  like liquids, gases and Solids. Agitator use in tanks, reactors Vessels for 
  • To produce static or dynamic uniformity in multi component multi phase systems. E.g. Blending of liquids.
  • To facilitate mass or energy transfer between parts of a system not in equilibrium.
  • To promote phase change in a multi component system with or without change in composition. E.g. Homogenization, gas dispersion and crystallization.

Impeller of agitators


An impeller converts the input energy to fluid flow and head (velocity or shear).Based on the predominant flow pattern, impellers are classified as follows.

Radial Flow Impeller generates flow in a direction away from the blades towards the tank wall.

Axial Flow Impeller creates flow parallel to the axis of the impeller.

Tangential Flow Impeller generates flow tangential to the impeller periphery and, in the pure case, no fluid discharge

Types of agitator

Mechanical agitators are divided into six basic groups depending upon their design and application.
  • Paddle agitator
  • Propeller agitator
  • Radial propeller agitator
  • Turbine agitator
  • Helical agitator
  • Anchor agitator

Paddle agitator

This type of agitator use for where uniform laminar flow of services required. These types of agitator simply push the inside liquid cause that create laminar flow but not any radial flow. And the circulation and mixing are poor as compare to other type. The RPM of this type of agitator is very less approx. 80 to 150 RPM. interview question

Propeller agitator

Propeller type agitator uses for simple application in reactor for mixing, blending, suspending, and dispersing application. It is uses with tapering type blade due to the tapering blade reduce the buildup of centrifugal force and increase the axial flow. The propeller blades diameter is around 15 to 35% of the tank or vessel diameter and the RPM is approx. 300 to 500 RPM. It is some time close couple with electrical motors. Practically it is very expensive for simple mixing process in small tanks.

Radial propeller agitator

In the radial type agitator blades are fixed at bottom of the agitator and these blades are create the shear and turbulence flow but the turbulence and shear are controlled by varying the its height, width and angle of blade pitch. The blades are pitched to the direction of rotation.

Turbine agitator

Turbine agitator is use in reactors for effective mixing, blending and suspending applications.  Turbine type of agitator creates turbulence flow of the fluid because of the centrifugal and rotary motion. There are many types of blades are use in the turbine type of agitator these are mentioned below flat blade, disk flat blade, curved type blades, pitched type blades. It is use for homogeneous mixing, good heat transfer, and high blending capacity. Radial type blade agitator gives high discharge velocity but consume more power. Pitched blades give radial and axial flow of the liquids but radial flow is more than axial flow.  The diameter of the blade is kept between 1/3 to 1/6 of the tank’s diameters. For the general rule for higher viscosity fluid take higher blade angles.

Helical screw type

In the helical screw type agitator instead of the blade, screw is use. The screw is fixed in shaft from bottom of the tank to liquid surface. Baffles are use in tanks for create turbulence flow. Use for very high viscous fluids. The main function of this type of agitator is that to increase the contact between reactive product and increase the heat transfer coefficient.

Anchor type

This type of agitator has very close clearance between blade and shaft. The diameter of the blade is between 90 to 95 % of the tank diameter. It is use for very less viscous fluid between 5000 to 50000 cp. This is mostly use in crystallization reactor where cooling jacket is necessary along with good mixing.

What is blower


Blower are used for moving process gases with moderate pressure. It also increases the velocity of process gases. Blower or fan are uses for low pressure requirements whereas compressor are uses for high pressure requirements. When the resistance to flow is at the downstream of the machine, is known as fan or blower.
Whereas the resistance to flow is upstream of the machine, they are known as exhausters.
There many types of bearing uses in blower

Application of Fan or blowers

Fan are used for generally delivery pressure requirement is less than .5 psi but for blower delivery pressure requirement is .5 to 1.5 psi. The axial fan has higher capacity but lower discharge pressures as compare to centrifugal blower (fan).
The uses capacity is mentioned below.
  • Circulating air in rooms or any other close confines area.
  • For cooling and heating purposes
  • Cooling motors, materials and products.
  • For exhausting toxic, hazardous gases or exhausting dust
  • For conveying very light materials
  • Heat removal purposes by forced draft or by induced draft

Type of blower

Blower is also use for transfer gases or air like fans and compressor, but blower use for transfer non-pressurize air or gases.

Type of blower
  • Centrifugal blower
  • Positive displacement blower
  • Helical screw blower
  • High speed blower


Centrifugal blower

Centrifugal blower uses for transfer constant volume of air or other gases, the operating speed of centrifugal blower is around 15000 RPM. Centrifugal type blower use in single or multistage impellers arrangement. The single stage centrifugal blower is uses for uniform airflow but whereas multi stage centrifugal blower uses for varying air flow at fixed volume required. In centrifugal blower uses high speed impeller to impact velocity to air or gases. In the impeller three types of blade are used like backward curved, forward curved and straight. Centrifugal blower is driven by an electrical motor, and that can be closed couple or coupled by a spacer and coupling to electrical motors. Affinity law (Fan) use for modification or any changes (speed, pressure, power) in centrifugal blower. Centrifugal blower are also use for transfer combustion air, for cooling or drying system. Sometime also use for fluid bed aerators with air conveyor system for dust control. In this type of blower air enter axially and exit radially. Relatively high efficiency almost 70 to 90 %. Forward curved blade impeller use for high volume and clean services. And efficiency range is almost 72 to 76%. Backward curved vane impeller has lowest efficiency and the range almost 77 to 91%. Radial vane impellers have efficiency almost 70% but it has stable operation.

Positive displacement blower

Positive displacement blower is uses for push the relatively constant volume of gases to outlet .it is uses for 30 to 65000 m3/h, and services like air, natural gases but it is oil free.

Axial blower

The axial flow blower is uses for transfer or move air or gases in parallel direction to shaft. Whereas centrifugal blower use for transfer air at 90 degree. As compare to centrifugal blower it has more capacity to transfer air. Based on the design axial fan are divided in three categories.
  • Propeller fan the application are wall or ceiling mounted exhausts fan, cooling tower and air-cooled heat exchanger.
  • Van axial fan- in this type of fan vans installed on the stator housing before or after the rote to direct and streamline the gaze for better fan action.
  • Tube axial fans in this type of fan uses guide vane, but it is less efficient than other type of fans.

What are fan lows?

Fan laws the fan lows are basic proportional relationship between power, speed, diameter, and flow.
  • The flow change in fan is directly proportional to speed.
Q2 / Q1 α N2 / N1
  • The pressure change in fan is directly square proportional to speed.
H2 / H1 α (N2 / N1 )2
  • The power change of fan is directly cube proportional to speed.
  • P2 / P1 α (N2 / N1 )3

Saturday, May 16, 2020

Types of compressor

Compressors are used for transferring gas or air from one place to another place with increase pressure.

general compressor

Friday, May 15, 2020

mechanical equipment used in industries

Mechanical equipment

Any human mead machine which reduces human efforts and time. There are two types of mechanical equipment. these are listed below.

  1. Rotating equipment
  2. Static equipment 

Rotating equipment 

Any Equipment which internal or external part rotate by human effort electric motors it is
called rotating equipment. There are many types of rotating equipment on the base of working
and body construction.


The Pump is a mechanical device that is used to transfer the processes fluid.

  1. Centrifugal pump
  2. reciprocating pump


A compressor is a mechanical device that is used to transfer the processes gases or air with increased pressures and reduce volume.
 The turbine is used for power generation or as a driver of rotating equipment like a pump, compressor, blower, fans, etc.

  1. Steam turbine
  2. Gas turbine
  3. Hydraulic turbine

An agitator is a device or mechanics which is used for mixing, blending, or to put in motion to process fluid.
fin fan is a mechanical device that is used to cool the process fluid. In the fin fan, tow parts are there induced draft, force draft, and the second part is fins tube bundles.


Blowers are used to increasing the velocity of gas or air, but not compress.


A fan is a mechanical device used for move air or gas without more increases in velocity.


It is a type of turbine which is used for power generation. It is also called an expansion turbine. It is generating power with the help of dynamo.


The gearbox is a mechanical device that is used for transition the rotary motion from driver to drive equipment. It works as a mediator.

Diesel engines


Mills are used to crush the processed material. There or many types of mills a few list of then mentioned below. Ball mill, rod mill, and rolling mills, etc.
Mechanical equipment used in industries like (industries, oil & gas refinery, Steel plants, pharm, power generation, power plants, etc.

What is the type of mechanical equipment? 

On the base of working there are three types of equipment.

Static equipment
Rotating equipment

Static equipment

  1. Vessel
  2. Column
  3. Reactors
  4. Heat exchanger
  5. Steam generator
  6. Heaters
  7. Boilers
  8. Tanks Valves
  9. Piping’s