Skip to main content

Chain conveyor troubleshoot guide

  Problem Identification & Corrective Action Sl No. Problem Potential Cause Solution 1 Chain rises off from sprocket 1.Excess chain slack. 2.Excess wear at the bases of sprocket teeth. 3.Excess chain extension. 4.Foreign material stuck to the bases of sprocket teeth. 5.Reverse rotation of conveyor 6.Uneven chain tightening of chain 1.Adjust the amount of slack equally at both sides. 2.Carryout hard facing of the sprockets 3.Replace the elongated chain parts. 4.Remove the foreign material from the bases of the teeth. 5.Avoid reverse rotation of the conveyor when chain tightened is uneven 2 Chain separates poorly from the sprocket. 1.Sprocket misalignment. 2.Excess chain slack. 3.Excess wear at the bases of sprocket teeth. 4.Uneven chain tightening of chain 1-Adjust alignment. 2-Adjust the amount of slack.

Why do Bearings fail?

 Following are the 16- top listed reasons for bearing failure or damages


Following are the 7 major reasons for bearing failures related to lubrication

1-Lack of lubrication

2-Less lubrication

3-Over lubrication

4-Contaminants in lubricants

5-Wrong method of lubrication

6-Poor quality of lubricants

7-Selection of wrong lubrication

8-Lubricant failure

2-Bearing clearance:

Bearings may fail if the clearance between rolling elements & race is too less & too more. Lesser bearings clearance than desired creates friction & temperature rise.

More bearing clearance creates vibrations

3-Operating the bearings at higher vibrations for long time:

Bearings can operate satisfactory at the vibrations range up to 5 mm/sec, vibrations more than this reduces the bearing life & eventually failure.

Operation range: 0.5 to 3 mm/sec

Alarm Range: 3 to 5mm/sec

Trip range: > 5mm/sec

High vibrations in machine or bearings are due to;

1-Axial vibrations due to misalignment

2-Horizontal vibrations due to imbalance in machine

3-Vertical vibrations are due to looseness in foundation bolts

4-Shaft run out

4-Operating the bearing at excessive loads:

Excessive load on bearings leads to premature fatigue, over loading creates other side problems like bearing overheating, damage to rolling elements.

Brinelling occurs when loads exceed the elastic limit of the ring material. Brinell marks show as indentations in the raceways which increase bearing vibration (noise]. Severe brinell marks can cause premature fatigue failure.



Overheating & damage of the bearings is due to;

1-Lack of lubrication

2-Over lubrication

3-Improper cooling of bearings

4-Excessive loads

6-Smaller clearance between rolling elements & race

Operating the boilers at higher temperature (>90 deg C for ball bearings & sump cooling) will lead to annealing the races & rolling elements that, eventually fails the bearings.

7-Miss alignment

Running the equipments at misaligned condition creates vibrations & excessive loads on bearings in axial, vertical & horizontal directions that causes bearing failures.

Misalignment also leads into failure of couplings & equipments parts like seals, impellers, pulley etc

8-Frequent start & stops of machine

Leads to jerk load on bearings & leading to reduction of its life

9-Not following of equipment/machine SOP:

If machine SOP (standard operating procedure) is being not followed, then it could cause not only bearing failure but also machine other elements.

For example if pump is not started with discharge valve closed or not stopped without closing discharge valves, it could cause jerk loads on bearings & impellers. After some cycle it will reflect it effect on misalignment, vibrations etc

10-Reverse rotation of machine or reverse loading of bearing element:

Some machines & bearings are not recommended for reverse rotation.

For example: Boiler feed pumps & screw compressors are meant to rotate in only one direction

Also Angular contact ball bearings are meant to take load only in one direction

11-Corrosion in Bearings:

Red brown areas on balls, raceways, cages, or bands of ball bearings are symptoms of corrosion. This condition results from exposing the bearings to corrosive fluids or a corrosive atmosphere. The usual result is increased vibration followed by wear, with subsequent increase in radial clearance or loss of preload. In extreme cases. Corrosion can initiate early fatigue failures.

12-Loose & tight fittings of bearings:

Fitting of bearings loose on shaft or loose in housing leads to rotation of bearings outer race in housing, this causes rubbing & bearing damage.

As like loose fitting, very tight fit can also cause excessive load on rolling elements which eventually creates overheating & vibrations

13-Entry of water in bearings grease

14-Material or manufacturing defects in bearings cause bearing failure as soon as it is been installed.

15-Leakage current in VFD motor bearings lead to bearing failure

16-Carrying out welding near bearings or Plummer blocks without proper earthing can lead to flow of currents through bearings, which ultimately causes bearing failure



Questions & answers on bearings


Frequently visited posts

Boiler feed pumps (BFP) questions & answers for interview

Boiler feed pumps (BFP) questions & answers for interview: 1-What is the function of Boiler feed pumps (BFP) in power plant? Functions: To supply the feed water to boilers To conduct the Boiler hydraulic tests To supply the desuperheating & attemperator water required for process steam lines & boilers respectively TOP-6 BEST POWER PLANT O&M BOOKS Boiler calculations for Boiler operation engineer (BOE) exam Viva Questions & answers for preparation of BOE exam & interview  2- What are the type of prime movers (drives) used for BFPs? Prime movers: LT drive (415 V) HT drive (11 KV) Turbo drive (Steam driven) 3-What are the auxiliaries associated with BFP? BFP auxiliaries Cooling water pump & lines Lube oil system ARC valve Mechanical seal flushing system Balance leak off line & its PRV 4-What are the various pipe lines connected to BFP? Questions & Answers on AFBC Boilers Suction pipe line D

Basic things you must know about nut bolts & spanners

A Bolt is a mechanical device which has head on one end of a body and a thread on the other end designed for fastening of two parts. Bolt is inserted into holes in assembly parts, it is mated with a tapped nut. Tension is normally induced in the bolt to compress the assembly by rotating the nut. This may also be done by rotation of the bolt head. A Screw is a headed and threaded bolt used without a nut. It is inserted into an internally tapped hole and tension is induced by rotation of the screw head. A Stud is a fastener with no head but it has threads at both ends of the shank. It, like a screw, has one end those screws into a tapped hole. A nut is used on the other end to create tension. Major diameter – largest diameter of thread (D) Minor diameter – smallest diameter of thread Pitch – distance between adjacent threads.       Boiler calculations for Boiler operation engineer (BOE) exam TOP-6 BEST POWER PLANT O&M BOOKS Types of nut bolts & Washer

Calculation of heat rate & efficiency of the power plant

Heat rate  is the amount of energy used by an electrical generator/power plant to generate one kilo Watt-hour (kWh) of electricity Heat rate (HR) = Heat input / Power generation =Kcal / Kwh Boiler calculations for Boiler operation engineer (BOE) exam Viva Questions & answers for preparation of BOE exam & interview Total heat input: The chemical energy available in the fuel (coal, biomass, oil, gas etc) is converted into heat energy in Boilers, this process is called as oxidation. The heat available in the fuel is measured in terms of Kcal/kg, KJ/kg or BTU units. The part of this fuel is used as useful heat and rest is lost as dry flue gas loss, moisture loss, un  burnt loss, radiation/convection losses etc.Based on Boiler efficiency this heat energy from the fuel is utilised, generally fuel heat utilisation is in the range of 60 to 90%. This heat generated in the boilers due to oxidation of fuel is used to generate high pressure & temperature steam. Thus genera


A steam condenser is device or an appliance in which steam condenses and heat released by steam is absorbed by water. Heat is basically shell & tube type heat exchanger, where cooling water passes through tubes & steam condenses in shell. The functions of the condensers are: It condenses the steam exhausted from Turbine last stage Increase the thermal efficiency of the plant reducing the exhaust pressure and thereby reducing the exhaust temperature It maintains a very low back pressure on the exhaust side of the Turbine Supplies feed water to Boiler through deaerator TOP-6 BEST POWER PLANT O&M BOOKS Condenser related components: Hot well Cooling water inlet & outlet system Cooling tower Support springs or expansion neck Air Ejector system Condensate extraction system Cooling water tubes & tube sheet Vacuum breaker valve Safety valve or rapture disc Water box Air & water vent lines Types of steam condensers: Surface Co

22-Most likely Question Answer Guide for Boilers troubleshooting

TOP-6 BEST POWER PLANT O&M BOOKS 1.What are the emergencies that are expected to happen in boiler operation? Emergencies that can happen in boilers operation are: Boilers tubes leakage Failure of feed water control station Unbalanced draft in furnace Furnace explosion Blow down valve failure Feed water pumps failure Secondary combustion in super heaters and ESP Also read 16-Perfect reasons for increasing the fuel consumption of Boilers 2.List out the potential reasons for boiler tubes failure. Reasons for boiler tubes failure: Failure due to overheating Failure due to internal scales Failure due to aging Failure due to uneven expansion Failure due to ash and flue gas erosion Failure due to material defects Failure due to internal and external tube corrosion Improper or effected circulation due to opening/passing of low point drains 3.List down the sequential action taken after boiler tube leakage to restore the boiler. Following activities ar

Questions answers & calculation on Boiler draught & Chimney

1-What do you mean by the term draught? It is the pressure difference, which causes flow of gases to take places. 2-What is the function of draught in Boiler? To supply the combustion air required for proper combustion To evacuate the combustion products from the furnace or combustion chamber To evacuate the combustion products to the atmosphere So draught is the pressure difference between the inside the boiler and outside air. Inside the boiler pressure is due to combustion products (Flue gas) & outside pressure is due to fresh atmospheric air. 3-What are the different types of draughts used in power plant boilers? There are mainly two types of draughts. Natural draught & artificial draught Natural draught is generally obtained by Chimney Artificial draughts have main two types Steam jet: It is again classified into Induced & forced draught Mechanical draught: This is classified into Induced draught, forced draught & Natural draught

Boiler calculations for Boiler operation Engineer Exam (BOE)

  1-Oxygen percentage in Boiler outlet flue gas is 4.9%, then what will be the percentage of excess air? We have excess air EA = O2 X 100 / (21-O2)                                    EA = 4.7 X 100 / (20-4.7)                                    EA = 30.71% 2-Calculate the Oxygen level (O2) in flue gas, if excess air is 25% We have Excess air EA = O2 X 100 / (21-O2)                                    25 = O2 X 100 / (21-O2)                                    O2 = 4.2% 3-A Boiler’s combustion system requires 5.5 kg of air for burning 1 kg of fuel, then calculate the total air required for complete combustion if its flue gas has 4.1% of O2 We have, Total air = (1 + EA/100) X Theoretical air EA = O2 X 100 / (21-O2) EA = 4.1 X 100 / (20-4.1) = 25.78% Therefore Total air = (1 + 25.78/100) X 5.5 = 6.92 kg of air per kg of fuel burnt 4-A Coal fired boiler having total heating surface area 5200 M2 produces 18 kg of steam per square meter per hour of heating surface, then calculate the Boiler cap