1. overboard valve inspection in drydock. 2. diff bet overboard valve and shipside valve3. During propeller mounting on the shaft, why is it required to position M/E unit #1

at TDC .4. Types of nr valves in engine room.5. How expansion of quills in lubricator takes place6. lifeboat engine fuel oil timing how do u check7. ME bottom end bearing survey8. How do u take measure rudder drop. How do u rectify if the rudder drop back in

position9. bunker overflow precautions before taking bunker10. Name types of files?11. How to order grinder wheel?12. What do you mean by 1-diamond cut, 2-diamond cut, 3-diamond cut? What

are methods for surface finishing?13. What is Molybdenum Di-Sulphide?

1.Assembly of various machines and equipment.2.Smooth initial running.

3.Prevents wear and scuffing.4. Lubrication under extreme pressure at low-speed and high-load.

5.Lubricates and prevents seizure of threaded connections14. Your ship is maneuvering at harbor and propeller got entangled with rope. The

engine got stuck up and couldn't be started or turned by turning gear. The rope was removed successfully. On starting the engine, you find that engine was firing abruptly, reasons and remedy?

15. What are Resilient chocks?

16. Purpose of jack bolts.TO prevent excessive bending movements of the transverse girders, the tie bolts are positioned as close to the centre of the c/shaft as possible. Bcoz the tie bolts are so close to the c/shast, some engines(sulzer) employ jack bolts to hold the c/shaft main brg cap in position instead of conventional studs nd nuts/ wasted bolts.17. What checks will u make on tie rods- Fretting, vibration, tensioning of bolt, 18. Stern tube aft seals.19. Refrigerant charging.20. How will u weld a crack on SW line21. Mechanical seals.22. Propeller drop.- by poker gauge 1mm/160mm dia shaft

23. On what basis will u discard piston rings—jammes/sticking, scuffing,liner wear24. while running,m/e fuel injector leaking..what steps u will take..rough weather

can't stop engine..25. how will u go about making 100mm dia hole on 10mm thick plate with oxy-

acetylene flame..26. how purifier nowadays claim to purify oil above density 1.27. while boxing up life boat engine all markings are missing..how will u time

engine..open the head nd put some water on the top of piston nd turn the engine, as water flowing out initially nd afterwards stop is the tdc position

28. hydraulic hose handling crane suddenly struck in between. How will u trouble shoot?

29. jackbolts n not wastd studs why30. reverse osmosis plant where is conc hcl added n why31. blr Alarms n trip...why high level alrm is dere32. .refr comp head has one addtnal safety featur that mac doesnt ve ..wht is it n why33. axial vibration damper torsional vibration damper,, detuners34. .p-alkalinity,,t alkalinity35. rudder clearances,propeller clearances,how to check and values36. aft-seal leaking what action u will take?37. main bearing dismantling and checks after dismantling on bearing38. deadship to normal running condition procedure

39. .how to check bedding of main bearing40. how Cr protecting stainless steel(tanacious film of oxide adhere to surface)41. how to simulate FD fan low air cut out(by changing the setting of air controller

setting which give signal to main controller to allow metered oil to burner)42. dismantling of cyl. head starting v/v..what all checks to b carried out.how

lubrication of brass sliding piston done(self lubricated).43. what is shrouding of valve.(hyper lapping of valve tending to early opening)44. difference btw lapping & grinding45. .accumulation test procedure.y it is done.y it is not caried out on air bottle.if more

than 110% pr accumated, what wud be reasons.

Biswas nd bndas46. sluggish operation of steering gear,causes&remeady.47. how you purges air frm.steering gear?48. after co2 flooding when you enter co2 room.49. enclosed space entry procedure&checks.50. rudder&propp.drop procedure&value.

Mr biswas and Mr chakraborty51. what is ovality? what happens when ovality occurs?how do you repair ovality?

how much machining is it allowed? what are the limitations?52. what is toughness?

53. air is there in refrigerant plant,, what are the indications? why pressure at compressor outlet pressure is high? how is the air removed?

54. Wt is hydrodynamic n hydrostatic lubrication with eg. Main n bottom end brg clearances

55. All types of pumps used onboard n detail of services fr wch they r used.56. Air comp safeties. Why bursting is used why not relief vv.57. Steering gr motor safeties apart fm mechanical. 58. Wt to do if blr g.glass is not showing water level.59. Why back pr vv is used in ref. Plant. Wl u use bk pr vv if vl is doind small

voyages.60. Hw purifier vibrations r prevented. N types of brgs used in pfr.61. e/r crane maintenance62. gas cutting63. how to arrest crack in e/r floor plate64. what is the problem with rough hull?what ll u recommend to minimize this

problem at dry dock? t/c casing crack,how u repair during voyage?65. wt checks to be carried out on anchor chain in dry dock?66. in t/charger wt arrangement is provided for shaft expansion?67. changing of piston crown & how do u test for usage?68. maintaining of diff temps in refer rooms? details69. after taking out exhaust v/v, exp detailed process for grinding exh v/v & making it

suitable for use?70. check trueness of shaft?71. what is the name for modern type of supercharging?72. l.o. cooler leaking ?73. hole in ballast line in e/r?74. jkt water p/p casing is worn out, too thin, what repairs?75. types, advs/ disadvs of heat exchanges?

Biswas and Bhowmik76. Poker gauge how, where n why77. All rudder clearances, how n where78. What is electric arc welding79. All welding instrument required before welding 2 steel plates.80. Centrifugal pump survey – prepare n checks before surveyor comes.81. After grounding – what all to check as 2nd eng.82. main engine C/case inspection to carry out quickly after a heavy weather voyage

only list important points?83. After the vessel has entered the drydock a preliminary report is to be sent in 1hour

what all only important checks are to be carried out?84. As a 2/E what checks you will carry out on gas welding torch & gas cutting torch?

How to identify between gas cutting torch and gas welding torch by looking at them?

85. How sacrificial anodes are connected to ship's hull......86. In A/E ,decarb all the checks.87. Dry dock inspection of Sea water chest?

88. Normal Crank case inspection whn U engine in running?(didnt want hear Book stuff)

89. Double eye pump ? Compare wth multistage pump?90. Dry dock inspection of Propeller and Tailend shaft?91. Workshop welding machine specimen plate full details and wat other thngs

needed for electric arc welding?92. anchor chain calibration?93. in dry dock in 1 hr wat will u check & make a report by seeing ship?94. in dry dock repairs carried out in DB tank & have to carry ourt hydraulic pressure

testing, how 2 do?95. how to weld two pipes as per class?96. what all checks in puttig keyed propellor?97. generator, alternator , how dey r connected, name of the coupling?98. wat u wil check in drydocking99. bedding of main bearing100. use of sacrificial anode101. .wat 2/E wil check in engine room tools.102. definition of drydock and wat is docking plan.103. difference between interference fit bolt nd fitted bolts, where used in

engine room, 104. clearances in rudder and stern-tube...values...procedure to take...and questions about pintles....105. things u will check in lifting equipment's such as tackles,slings,etc...when

taking over from signing off 2nd engr...time is very limited...106. what specific instructions u will give j/e during ums round...he told don't

tell which is connected alarm systems which will give alarm...107. key less propeller removal procedure...108. piston overhaul....109. reefer compressor unloading mechanism...

Biswas and B k roy chaudhary110. .Conatmination of lub oil?possibilities?Effect?Action to be taken?111. Osmosis and reverse osmosis?principle?112. type of memebrane?material of memrane?113. pre and post treatment?114. What r the cat fine?Purpose of putting cat fines?115. How they come in FO?cause of cat fines?list the compnents get affected by cat fines?116. effective measures to reduce cat fines on board?117. Ex v/v knocking?why it happens?what are the effect of knocking?how to reduce it?118. LO tests?purpose of carring LO test?signifince of each test?what all properties are119. listed in test report?

120. purpose of boiler water test?differnt chemicals added and purpose?whats added to reduce o2?

121. cylinder liner how u take out and new liner to put122. condensor how to take out one of the tube, and put new one.123. botton end bearing survey.124. 4-s jacket water leaking, u already come 2 know, u have taken out, by

which process u will come to know where is the crack.125. .metal stitching asked by biswas126. interpretation of crank web deflections127. grinding and lapping differences128. ref leak tracing... He asked me for a system with out charge ti check ait

thghtness.. Halide torches for charged systems... Also he asked me for a charged system if halide torch colour has changed as soon as i enterd ref room hw to find the exact leal position..

129. weldind plates of different thickness

Sinha nd paul130. How to fabricate a ruptured pipe131. When leaving drydock, after flooding of the dock , what all things to

check in engine room.132. Acetylene bottles , oxygene bottles cylinder storage pressures , their

working pressures and how you can identify by looking at them.133. How the crankcase oil of an a.c compressor can get frosted, explain the

reasons in detail.134. Crosshead guide and shoe, how lubricating oil is passing through them.135. What is the purpose of cooling engine various components, explain.136. In A/E, if a cam has turned for any one unit how you will correct it back

and in which direction you will correct it.137. Why economiser water circulating pump is started 1 hour before starting

main engine and why it is stopped 1 hour after stopping main engine.138. In a.c compressor, how load is getting controlled(25%, 50%, 100%).....139. .How to dismantle vertically mounted centrifugal pump.140. (Cross questons: how to remove bottom bush?, how impeller nut is

attached and where it is attached?)141. you are lifting main engine piston and suddenly load is slipping(the e/r

crane is not able to lift load) what will be your action?

Sinha nd bhattacharya142. Bottom end brg chks nd removal,bolts chk143. Meat room temp rising,causes+soelnoid nt wrkng hw wl u maintain temp144. Removing cyl head,if one of the hydralic bolt leaks,hw wl u open ?145. stud removal146. crankshaft deflection curve,wt do u interpret,action

fun#6:

1.zero setting of fuel p/p

2.key propeller fitting nd spcl checks b4 installing

3.how wl u order hydralic pipe,...all point wise to b put in indent

4.stellite in exhaust valve...composition nd how wl u put on the seat

5.Dry dock, rudder survey as a second engineer. The clearances measured and values.

6. How u measure prop drop? where to measure it?

7. exhaust valve, state composition percentage wise and what properties each of the material is providing

the exhaust valve.

8. what is critical temperature? what is numeric value of critical temperature of CO2?

9. CO2 used as a refrigerant and for fire fighting differences. state critical temperature of any refrigerant.

10. difference between single stage and multi stage air compressor. what does intercooling do

For a vertical 2-stage centrifugal fire pump.

11. list of all spares required before starting overhaul

12. bearings used

13. how shaft supported.

14. name of the part dividing the two stages

15..windlass and anchor chain inspection in drydock. wot type of drive for windlass. wot type of pump?

draw it. hw much pressure?

16. stern tube .hw is it fitted . hw is it connected and to wot is it connected? tell stern tube length, clearance

type of bearing?type of lubrication.? sealsand chrome liner why fitted? draw the arrangement.

17.wot is metal locking?hw s cylinder block constructed? if a crack, wot to do?

18.where all do you find non return v/v onboard? show arrangement of attachment of spindle n v/v in a

normal globe v/v.

19 .aluminium welding?

20 .crank pin crack., wot to do?

21 .axial vibration damper. draw it s attachment. when surveyed.n wot surveyed?

22..name all bearings in a generator. why thrust bearing? hw much clearance?

23. how is synthetic L.O FORMED

24.if one cylinder head cracks...what will u do,in case u have to reach port .

25.what is ovality,in case need to run what will u do.

26-crankshaft deflection procedure,sample readings,check to confirm accuracy.

27-what clearances checked for rudder in drydock

28.-how magnetic particle test done for keyless propellor

29-after having dismantled blr safety v/v,what u check,how u measure lips clearance,what other checks.

.in drydock inspection of sea chest??how grating is attached to hull??material of ship side valve??

30..resilient chocks??details??how side wise movement is taken(holding down bolts complete tight??

31.crack shaft deflection data interpretation after getting values of deflection??

32.safety valve survey??lip clearance singnificance??what checks between between spindle nd valve??

importance??

33.me cyl liner wear affects??

34.drilling tool damaged??have to grind correct value of tip

angle???

35. grinder size how it is decided??

36.What spare parts will u require for overhaul of cargo oil pump ? How many bearings and what kind

How many seals? What are the parts of a mechanical seal?

37 ) define boundary and elasohydrodynamic lubrication and examples of each

38.. 4 factors that govern the lubrication in a journal bearing( you have only 1 shot for this...if any one

answer is wrong .....he would take the answer as wrong)

39) How would you change the peak pressure of a unit in an A/E.

40) you have been told by ur cheif engineer to fit a pressure gauge at a distance of 5m from a pipe .....what

are the things you will order and how will you fit it

41..Compression Ratio,Significance of C/R ,,Do the Life Boat Engine and E/M gen. engine and main

engine has got the same ratio?

42..How will you knw that the Ref. system has got air in it?

43..How to purge it and when do u knw that the system is free from air?

44..Reasons for tie rode braking

45..how to remove a broken tie rode

46..Low Hydrogen Welding

47..how to take bottom end bearing clearance of a/e

48..refer compressor sweating..give reasons

49..diff. between pipe threads & normal stud threads

50..temperature diff. b/w exh. gas & steam in boiler..its terminology

51..cross hd brg survey

52..tail shaft survey

53..engine not moving on air why

54.. why jack bolts in sulzer not in b&w,advantages & disadvantages of jack bolts.

55. what is the difference in main bearing of generator & main engine of your last ship.

56. why & where ribs are provided in liners.

57. liner removal procedure,checks on liner before disassembly and after disassembly,where cracks appear

on liners.

58. 4 important properties of refrigerent.

59...survey of scrubber tower

60...what is leadscrew n its function?

61...how is pressure adjusted in man b&w fuel valve?

62...pressure testing of man b&w fuel valve?how is the injector fitted on the stand?

63...how is the cam position adjusted on the camshaft?how do u come 2 know that u have applied sufficient pr. to float

the cam.

How to Prepare Metal for WeldingPreparing metal for welding is a very important step in the welding process. If your metal is not prepared properly, you can compromise on the integrity of the welds themselves. It pays to take time with the preparation of the metal to ensure you have the best welds possible.Instructions• Check the metal before welding it. If the metal has a coating, which could possibly be a thin layer of metal, you must remove it. You can use a grinder to prepare the surface of the metal for welding.• Clean the metal of any rust when you are preparing metal for welding. Metal on a car can be rusty, and before welding anything onto it, you'll need to take off any rust spots with a grinder or steel wool.• Try different techniques for cleaning metal as you prepare it for welding. Straight or flat grinders work well, but for metal of different shapes, you might want to use an angle grinder.• Take off any bad welds with a grinder when you are preparing metal fir welding. Removing a bad weld and starting over is often better than trying to make a bad weld better. Starting fresh means that you can now create a fresh, clean weld that will be nice and strong.

• Use a grinder to clean the edges of the metal when you are preparing to weld metal together. By having clean edges, you can ensure that the weld will be solid and hold well.• Wear your safety glasses when you are preparing metal for welding

Tie rod tightening procedureTensioning:Preparation.1. Clamping bolts to be tightened.2. The lower tie rod nut is screwed on and secured with looking screw.3. The contact surface of intermediate ring and upper tie rod nut are to be cleaned and coated with ‘molykote’ paste.4. Screw eye bolt into the tie rod and carefully lift until the lower tie rod nut rests tightly against bearing girder. (It is best to use block and tackle between crane hook and tie rod. The tie rod can thus be lifted by hand until the lower nut lands on the girder. With a crane, it may not be possible to feel when the lower nut lands).5. In this Position, the upper tie rod nut is tightened with a tommy bar until it rests firmly on the intermediate ring and the tie rod is removed from the lifting device. (There must be no clearance between the bearing girder and the lower nut).

Procedure of Tensioning.

1. Once all the preparations mentioned above have been made the engine manufacturers’ instruction for tensioning has to be followed.2. Mount pre-tensioning jacks on the two tie rods 1/1 in the middle as shown in the sketch and the lower part of the cylinder has to rest on the intermediate ring.3. Connect pre-tensioning jacks to high-pressure oil pump and vent the system.4. Operate pump until a pressure of about 350 bar. (1st stage, Half value) is reached. Maintain this pressure while thetw o upper nuts are tightened by tommy bar and a snug fit is obtained.5. After the operation and tensioning of tie rods 1/1, go over to 2/2, 3/3, 4/4 till out ward end of the engine.6. Repeat the same for full pressure from 1/1 to out ward end.7. For a third time do the same for full pressure once again to eliminate any residual stresses on the cylinder jackets.8. After completion of pre-tensioning procedure, coat the protruding thread with non-acidic grease and fit the protective hoods.

Degree of superheat calculationTo measure evaporator superheat, record the actual line temperature at the outlet of the evaporator. Hopefully, there is a pressure tap there to record the evaporator outlet pressure.

Take the pressure reading and use a pressure-temperature chart for the refrigerant you are using in the system. Look up the pressure in the chart, then cross-reference that pressure to the corresponding temperature for the refrigerant. This is the saturation temperature for the refrigerant at that pressure.

Subtract the saturation temperature from the actual temperature (from the evaporator outlet). This is the evaporator superheat. You should check the evaporator rating to see what is the correct superheat.

The evaporator manufacturer should have designed the evaporator to provide the required cooling capacity at a specific superheat. That is the number you want.

What is a thermal boiler? Water and steam are typically used as heat carriers in process heating systems. But at high temperatures, water and steam requires a corresponding high operating pressure.

In industrial heating systems this high temperature level is often a great advantage in order to get a high output of the process. Thus establishing this with water and steam, you must deal with systems and components of high pressure. This means large dimensions, weights, more safety issues and thus extra costs. In thermal oil boilers (thermal oil heaters), a special oil-based thermal fluid is used as the heat carrier, instead of water or steam. This oil operates at atmospheric pressure up to 300°C. Comparing to water and steam, it would require a corresponding pressure of 85 bar to obtain this temperature. This system is used in ships which carry cargo like bitumin n coaltar. Procedure for CWT test

1. Fill the sample cup to the 25 mL mark with sample (fig 1).2. Slide the open end of the valve assembly over the tapered tip of the Titret1 so that it fits snugly to the reference line (fig 2).3. Snap the tip of the Titret at the score mark (fig 3).4. Lift the control bar and insert the Titret assembly into the body of the Titrettor2 (fig 4).5. With the tip of the valve assembly immersed in the sample, press the control bar firmly, but briefly, to pull in a small amount of sample (fig 5). The contents will turn a green color.CAUTION: Do not press the control bar unless the tip of the valve assembly is immersed below the surface of the liquid.6.Press the control bar again briefly to allow another small amount of sample to be drawn into the ampoule (fig 5).7. After each addition, rock the entire assembly to mix the contents of the ampoule. Watch for a color change FROM GREEN TO BRIGHT ORANGE.NOTE: Immediately before the contents turn bright orange, they will briefly turn blue. Make further additions with care.8. Repeat steps 6 and 7 until a permanent color change occurs.9. When the color of the liquid in the ampoule changes to BRIGHT ORANGE, remove the ampoule from the Titrettor. Hold the ampoule in a vertical position and carefully read the test result on the scale opposite the liquid level (fig 6). See the following chart to obtain results in ppm product.Satisfactory Ranges ScaleFigure eProduct Scale ppm productLIQUIDEWT 1.2-1.8 3 10,0000 -15000^ MAXIGARD1 1.6-3.0 19,000-36,000' DEWT® NC .5-5.0 3,000-4,300. why jack bolts are provided in sulzer engine?main purpose?To hold the bedplate,frames and entablature firmly together in compression and to transmit the firing forces back to the bedplate long tie bolts are fitted in through this 3 components and then tighten hydraulically. To prevent this excessive bending moment in transverse girder the tie bolts are positioned as centre of the crankshaft as possible. Because of the tie bolts so close to the crankshaft sulzer employs jack bolts to hold the crankshaft main bearing cap in position instead of conventional studs and bolts.

61. How you will purge air from refrigerant compressor? Close condenser liquid outlet valve

Keep cooling water to condenser on till s.w.outlet temp = inlet temp

Check condenser sw outlet temp

Check correct condenser pr for the corresponding temp

Release air ( using purge v/v on top of the condenser) till the pressure in the condenser comes correct.

. Induction hardeningInduction hardening is a form of heat treatment in which a metal part is heated by induction heating and then quenched. The quenched metal undergoes a martensitic transformation, increasing the hardness and brittleness of the part. Induction hardening is used to selectively harden areas of a part or assembly without affecting the properties of the part as a whole.Induction heating is a non contact heating process which utilises the principle of electromagnetic induction to produce heat inside the surface layer of a work-piece. By placing a conductive material into a strong alternating magnetic field electrical current can be made to flow in the steel thereby creating heat due to the I2R losses in the material. In magnetic materials, further heat is generated below the curie point due to hysteresis losses. The current generated flows predominantly in the surface layer, the depth of this layer being dictated by the frequency of the alternating field, the surface power density, the permeability of the material, the heat time and the diameter of the bar or material thickness. By quenching this heated layer in water, oil or a polymer based quench the surface layer is altered to form a martensitic structure which is harder than the base metal.[2]

63. Volumetric efficiency.This is the ratio of the volume of air drawn into the cylinder(at normal temp and pressure) to swept volume . In naturally aspirated four stroke engines the volumetric efficiency will be from 0.85 to 0.95.

64. How to order greese?NLGI Grades 000 to 1 are used in application requirings low viscous friction. Examples include enclosed gear drives operating at low speeds and open gearing. Grades 0, 1 and 2 are used in highly loaded gearing. Grades 1 through 4 are often used in rolling contact bearings where grade 2 is the most common.

65. Compression ratio,Stoichiometric ratio values of your last shipcompression ratio min req for combustion of diesel is arnd 16 but is maintained arnd 22 in most of the engines stoichiometric ratio is 14~15. Stoichiometric ratio is around 14 to 15 :1 that is 14 parts of air per part of fuel. It does not depend upon whether the engine is 2 stroke or 4 stroke. It is just the value of right quantity of air required for complete

combustion of fuel so it a function of fuel quality and depend upon the chemical composition of fuel.Why piston rings are positioned in a down place in a marine engines as compared piston rings are down in IC engines as the temperature above will be higher and may cause LO particles to break down and hence loss of lubrication while in case of AC compressors temp is not so high as no combustion of fuel is there and hence less temp are experienced so the only criterion is to increase the volumteric efficeincy of the engine.

66.How to measure T/C rpm.Turbocharger rpm s measured on the same principle of induction motor. A magnet is there at the end of the turbocharger shaft and it is rotating in a coil now the emf generated in the coil will be a function of rpm of the turbochager shaft and hence the emf can be calibrated as a function of rpm of turbocharger

66.Bore cooling,why in angular directionbore cooling is in angular direction as it increases the effective heat transfer area and also does not compromise on the strenghth too much\

67.Bumping clearance =so so; but still piston hitting,what are the reasons.if the bumping clearance is ok and piston is still hitting the crown this means ur bottom end bearing has worn out and clearance has increased and when the piston is moving up its hitting the cyl head due to inertia.

68. Change fuel oil from HFO to DO at same fuel rack,whether speed increase or decrease,Why.The calorific value of diesel oil is higher than that of heavy oil so the speed in diesel should increase but the calaorific value is measured per unit mass and not volume and all ur fuel pumps that is the metering devices of fuel controls the volume of fuel oil injected. now the effective mass of heavy oil is much more than the diesel oil for same volumes of both oils. taking both into accountthe effective result is that the speed is DECREASED when u changeover from heavy to diesel oil.

69. Hydrodynamic lubrication and boundary lubrication.

Diesel engine bearings are lubricated by fluid films. The journal is always smaller than its surrounding bearing. When the shaft is static it will make contact with the bearing and this contact will be a line. On each side of this line the normal distance betweens the shaft and the bearing will increase gradually and will in effect be a curved wedge. When the shaft revolves in the presence of an adequate liquid supply (lub oil) the oil is pulled into the wedge and pressure is set up. The pressure of liquid in the wedge shaped space sets the shaft over to one side and lifts the shaft away from the bearing so it is supported by an oil film. The position where the oil film thickness is least will be a small distance away from the static contact line in the direction of shaft rotation. For pressures to build up to a

value high enough to separate shaft from the bearing, the oil must have sufficient viscosity and the speed of the shaft muct be above a certain value. This form of lubrication is known as fluid film or hydrodynamic.

Boundary lubrication occurs when the rotational shaft speed falls and oil wedge is lost. Metal to metal contact then occurs. To prevent metallic contact under boundary conditions grease may be used or additives may be added to the oils. The bearing of the diesel engine do not work under boundary conditions. Very highly loaded crosshead bearing in 2 stroke engine may approach boundary conditions.

In diesel engine bearings are supplied with large quantity of oil to maintain the oil film and remove the heat generated.

70.Advantages and disadvantages of single and double volute casing.Yes, single volutes have more radial load on the shaft but the advantage is that the load is very predictable. We may not like radial loads but hey, bearing technology is very well developed.A dual volute is basically two pumps in one casing. At one point or another depending on the design and on the machining quality and precision one of these pumps will shut off the other and radial loads will become unpredictable.

However, if your operation point is well known you will be able to stay out of troublesome operation area's regardless of the type of design.*A double volute scroll pump has almost no radial thrust at any point on the curve, from zero flow all the way out to well beyond the BEP. In other words, the double volute pump has little or no radial thrust reaction to operation above or below BEP.But a single volute pump has a very pronounced radial thrust reaction when operated off BEP. If the bearings and shaft are insufficient to withstand the thrust, bearing and shaft life are shortened.*The single volute pump impeller will deflect either 60° or 240° from the cut water depending upon which side of the pump's best efficiency point (BEP) you are operating.*The double volute design is actually two single volute designs combined together.Although this drawing does not show it clearly, the total throat area of the two volutes is the same as the single volute design.Double volute pumps were created to eliminate most of the radial thrust caused by operating off the pump's best efficiency point (BEP).*Testing has shown that the double volute does not entirely eliminate the radial forces, but they are reduced greatly. Although the volute is symmetrical around its centerline, the two passages directing the liquid to the discharge nozzle are not. This means that the radial forces do not exactly cancel and a slight radial force does exist. Testing has further shown that a double volute pump will be 1% to 2% less efficient at its best efficiency point (BEP), but 2% or more efficient on either side of the best efficiency point (BEP). This means that the double volute will have an overall higher efficiency than its single volute cousin. Unfortunately many pumps are purchased with the efficiency given at the best efficiency point not the actual operating point used to make the purchasing decision. 

Double volute pumps should never be specified for low flow (less than 400 gpm or 90 m3/hr.) operations especially if there are solids in the product. The narrow passages behind the dividing rib can easily clog with solids. They should, however, always be specified for larger volume applications. The rib can cause some production problems with the castings especially in small sizes. Testing has shown the minimal radial thrust was experienced when the dividing rib did not extend all the way to the volute discharge flange. On large pumps there has been some problems with the rib cracking at the center when the pump is subjected to high hydro test pressures. The reason for this is not really understood. Some manufacturers ignore this because in operation they know that the pressure will be the same on both sides of the rib. Other manufacturers leave a gap of 2-3 millimeters in the center to prevent the cracking. Triple volute casings have been tried, but haven't proved to be effective enough to justify their high manufacturing cost. If you have an occasion to repair the double volute cutwaters (and you can with some of the newer metal repair compounds), be sure the cutwaters are located physically 180 degrees apart. Many large double ended pumps have atrocious L3/D4 shaft numbers and are therefore supplied with a double volute as a standard.

71.Advantages of plate type cooler

Plate cooler are smaller and lighter than tube type cooler giving the same performance.

No extra space is required for dismantling

Higher efficiency is shown by the smaller size

Plates can be added in pairs to increase the capacity and similarly damaged plates can be easily removed if necessary without replacement.

Cleaning and maintenance is simple

Turbulent flow helps to reduce the deposits which would interfere with heat flow.

Flow velocity is not limited as is in the case of al br tube.

Mixing of fluids not possible unless plate cracks.

Disadvantages of plate type cooler

Plates cant be tested for leakage easily hence crack plates are difficult to locate.

Deteriorated joint are difficult to remove and hence remove on the site.

Expensive due to large number of plates and cost of titanium and joint required.

Plates are easily damaged due to over tightening.

Operating temp limit (200 deg c)

Operating pressure limit (20 bar).

72. High lift and improved high lift safety valve.High lift :- winged valve , waste steam piston and no floating ring.Improved high lift safety valve:- wingless valve , waste steam piston, floating ring.Formula for calculating :-C X A X P = 9.81 X H X EWhere c – discharge coefficient which depends upon the type of valve.c- for high lift 7.6c- improved h.l. 9.2A – aggregate area through seating of v/v in mm2P- working pressure of safety v/v in Mn/mm2H- total heating surface in m2E- evaporative rate in kg of steam /m2 of heating surface per hr. Deriving we get D2C=constant D is diameter of seating of one valve.

For super heated steamAs –A(1+Ts/555)As- aggregated area thorugh the seating of the valves in mm2 for superheated steam.aggregate area through seating of v/v in mm2Ts- degree of superheat in degree celcius.

73.Laminar and turbulent flow Reynolds number.Reynolds number = velocity of fluid x pipe diameter/ kinematic viscosity. If the number is less than 2000 the flow is stram lineIf the number is more then 2500 then flow is turbulent.

The laminar stream line flow of a fluid whose velocity variation is approximately parabolic . being a max in center and zero where the fluid is in contact with the pipe or plate surface.

74. Centrifugal pump cannot handle air but turbocharger can?Both cent pp nd t/c does one thing in common ... it addes kinetic energy to the medium by inducing centrifugal force to medium ... due to this cent force , the medium moves out from impellar eye nd this creates a vaccum behind it which causes low press and so the new medium is pushed in to the eye...... so the amount of cent force determines the medium being moved out from eye to the periphery.... but this cent force = mv^2/r=mw^2r as (v=wr) ....... so the cent force depends on mass and velocity ...... in cent pp , the medium being liquid mass is more so the velocity can be less to push the liq

out ... but in T/c , the medium being air , the mass is less so since the velocity is high , it can pump out the air..

75. How feed is adjusted in boiler corresponding to demand in auto A drum level is only measured parameter, this type of control scheme is usually referred to as single element feedwater control.An electronic D/P cell monitors the drum level over a span of 2-3m, and provides a measurement signal to the level controller(LIC)The usual feedwater Cv is an to open (A/O) style which will fall closed upon loss of instrument air,An increase in pneumatic signal applied to this actuator will increase with feedwater flow.

76.Two –element feed water control.If the true steam flow was measured then a predictive control decision could be made regarding the drum level. Elbow taps could be installed on the steam line to provide a differential measuremtn input to an electronic D/P cell. This differential signal is routed to a square root extractor to provide a linear – flow signal. A two element feed water control scheme can be designed .

. liner bending stress? where and how?liner bending moment is maximum at the liner flange....its bcz the line of action of forces by the cylinder head and reaction force from the entabulature don't pass thru the same line and hence a bending moment is setup in the liner flange..

79. Engine vibrationsAxial vibration – when the crank throw is loaded by the gas pressure thru the con rod mechanism the arms of the crank throw deflect in the axial direction of the c/s exciting axial vibrations. These vibration may be transferred to the ships hull thru the thrust bearing.Remedy Axial vibration damper.Torsional vibration – the varying gas pressure in the cylinders during the working and the c/s conrod mechanism create a varying torque in the c/s. it is these vibration of the shaft system. Tortional excitation also comes from the propeller thru its interaction with the non uniform wake field.Remedy modify c/s natural frequency by adjusting its dia.Use a torsion damper.Choke – The engine is supported on a series of chocks fitted around the underside of the periphery of the base of the bedplate. The chocks sit on the foundation plate which forms part of the inner bottom platting of the hull structure. The holding down bolts pass through holes in the bed plate. Chocks and foundation plate. When all the holding down bolts are tightened the bed plate is held fast to the hull structure. The choks are fitted in place after the engine has been aligned to the intermediate shafting. The spacing between the choks is approx 250-400mm and they are closely spaced in the ;location of cross girder so that good support is given to the area of the bed plate which is supporting the main bearing and engine A frame. This prevents any localized distortion or sag in the bed plate and so makes the support from the chocks a continuous effect.

83. Light spring diagram :- it is also known as scavenge efficiency diagram. This dig is taken with a light spring. The variation of pressure in the cylinder during exhausting and scavenging is magnified in a separate dig. The pressure during this part of the cycle is low so a light spring is utilized. For most of the time cylinder pressure is outside the range of the spring. The drop in pressure is a measure of clearances of exhaust passages . this dig also shows the pressure of scavenge at cylinder intake.

84. Why governor spring is conical.It seen that variation of spring force is having non linear relation with the variation of speed. The desired linear relation is achieved by designing the spring conical or combination of springs of varying diameter and stiffness. 85. How signal is carried to ecr from rpm indiactor.Magnetic pick up sends signal to transducers, o/p coming from the transducer is filtered signal conditioned and chopped. Finally it is converted into square waves. The square wave is passed through phase lock loop multipliers. The o/p is gated by a precise time base generated through piezo crystal and then counted. This counts are displayed in bright LED. Its nothing but RPM with accuracy of +/- 1 .

86. What are the safeties provided on the A/C or fridge compressor.

L.P. cut out

H.P. cut out.

Relief valve

Check valve at the discharge of comp to prevent reverse rotation when stopped.

High temp sensor at discharge

Oil diff pressure trip

Master solenoid valve at condenser discharge to prevent flooding of evaporator in case of comp stop or abnormal stop.

87. Steering gear safeties Hydraulic tank low level

Overload

Power failure

Relief valve

Bypass valve

Auto change over

35 deg- telemotor change over switch

36 deg- telmotor limit switch

36.2 deg- ruddr angle limit switch

37deg – rudder stopper

39 deg – mechanical stopper

88. Windlass safety- electrical – electromagnetic brake, motor overload, short ckt protection, restart delay timer, remote stop.Mechanical – manual mechanical brake, cable stopper, slipping clutch, relief valve. 89. Zero setting what is the significance of its name?

At zero position of the governor the load indicator and cut out servomotor should coincide for zero fuel injection.At zero setting shield position the suction and spill valves must never be closed at the same time i.e. one is open other is closed.

90.Creep:- creep is the tendency of a solid material to slowly move or deform permanently under the influence of stresses. It occurs as a result of long term exposure to high level stresses that one below the yield strength of the material . creep is more severe in materials that are subjected to heat for long periods.

91. In life boat engine if all the flywheel marking have been erased/removed how to check TDC or BDC position of piston.Take out the injector now u can see access or see the piston put the dial gauge with the pin touching the piston take the piston to almost TDC set the gauge to any value say 0.2mm and make a mark on the flywheel rotate the flywheel. Piston will move up will reach TDC and then will move down just as it comes to 0.2mm make another make on flywheel the midpoint of the 2 marks will be TDC.

There r how many stern tube bearing n how they r connected with stern  stern tube bearings generally consists of two ( fwd & aft ) bearings which r pressed in and secured to the stern tube the bearing sleeves r made of high strength ductile iron and centrifugallylined with high tin base babbitt. the bearing bore is normally finish machined to fit the propeller shaft and outside diameter is semi finished for final machining in shipyard Two procedures are commonly used for fitting stern tubes 1.the stern frame is finish machined.the stren tube is pressed in and secured by bolting or welding .the stern tube is bored and bearings are then pressed into stern tube 2.In the second procedure, the stern tube is bored in the shop and fitted with its bearings then the entire assembly is pressed into the stern frame at shipyard. Boring of stern tube to provide an interference fit

96. ECU- engine control unit – engine control system has several integrated units , engine control unit cylinder control unit engine interface control unit and auxiliary unit.ECU- the engine speed reference to the set reference Governor control and functionsEngine protection system and faultsOptimum condition requirement running for that running conditionControl of the function for start stop and reversingControl of the function of auxiliary blower and turbo charger.

CCU- the control of the fuel injection pump the injector , exhaust valve , start air valve and cylinder lubrication for each cylinder.

97. What is RVK in piston ring what it means?It is for surface roughness of the piston rings , RVK means depth of the valleys and RPK means peak height. Rz is the mean highest peak to valley measurement taken from 5 samples. RK is the average core roughness depth.

Bearing faults and defects Abrasive wear due to fine scoring by hard particles and impurities in the lub oil.

Corrosive wear due to acidic lub oil

Erosive wear due to erosion

Adhesive wear due to galling scoring or scuffing

Fatigue failure cracks at areas of stress concentration

Overheating due to poor lubrication supply or contaminated oil , misalignment, increase clearance ,uneven load distribution poor surface finish and overloading

Misalignment of the bearing due to distorted bed plate adjacent bearing failure or imbalanced cylinder pressure.

Incorrect clearance or incorrect tensioning of bolts.

Housing dimension not suitable for bearing shell especially during replacement.

102. Puncture valve It is device to positively stop engine irrespective of its rack position.

It reduces the high pressure of the fuel by connecting high pressure side to the pump body thereby stopping the injection of the fuel.

Engine stops and shutdown is carried out by the use of puncture valve.

It allows the fuel oil recirculation even when the engine is stopped as the oil pressure is not totally bypassed

It is operated by pneumatic air pressure

Its used in MAN B&W

103. Under which condition spring of the stuffing box is changed When oil from the tel tel hole of individual unit of stuffing box lot of oil coming

and lub oil loss is there and u don’t have sealing ring or lamellae so for time being spring can be changed

While completely o’hauling the stuffing box

When spring elongation is exceeded as per manual. Usually checked by hanging one kg wt at end and new length original – original length gives the elongation . check with manual for limit and replace it with new one.

104. Whats the time period to discard the chain and renew with new one in B&W engines . tell % elongation max .Max allowable limit of elongation is 1-2% and chain should be renewed once in 8 yrs or 50000 hrs

105. Distance of the lubricating quills from top of liner in terms of the length .At 20% stroke from TDC . in this case lubrication is most effective especially for single level of quills. Continuous groove row of quills at 30% stroke from TDC.Usually quills are 250mm apart from each other around the liner bore. Grooves are angled downward. The combustion gas pressure differential across the rings assist in pushing the oil downwards in the groove. The disadvantage of grooves is that they increase the area of oil flow. Hence velocity and pressure of the oil decreases there by reducing spreadibility.

R.O. plant treatment?Sea water feed for reverse osmosis plant is pretreated before being passed through. the chemical sodium heat meta phosphate is added to assist wash through the salt deposits on the filter elements and sea water is sterilized to remove bacteria which could otherwise become resident in the filter. Chlorine is reduced by the compressed carbon filter while solids are removed by the other filter.Post treatment of produced water is same as low temp evaporators.

108. Lantern ringA latern ring is perforated hollow ring located near the center of packing box that receives relatively cool clean liquid either from the discharge of the pump or from the external source and distributes the liquid uniformly around the shaft to provide lubrication and cooling. The fluid entering the lantern ring can seal the joint between the shaft and packing against leakage of air into the pump in the event pump suction pressure is less than that of atmosphere.

109. Parts of electric governor Load sensing unit

Speed sensing unit

Setting control unit

Setting for droop or isochronous mode

Speed setting signal

Ramp generator

The comparator/ampifiler control unit which compares the i/p signal with the reference setting and sends o/p signal to the actuator to change the rack position of the engine fuel pump.

110.Wear ringWear ring can be defined as a device used to seal the pressure leakage of the liquid between i/l of the impeller and pump casing. Wear rings are typically found on pumps with closed impeller. A similar device that serves the same purpose called a wear plate can be found on some pump with semi open impeller. The typical reason for using a wear ring is to decrease the amount of leakage loss around the impeller. Due to more work available to push the pumped liquid out of the discharge there is slight improvement in the pump efficiency.

What is the name of the instrument that measures vibration? How thus it work and part that measure it? Accelerometer, and working on piezo crystals i.e. piezo electric effect

113. what is the crank pin oil hole position? when the piston is at TDC the crank pin oil hole position is horizontal, this done to reduce the stresses which could have generated if otherwise, this position is the only position allowed.

114.why shims fitted on the bottom end bolts have to be of exact thickness?This will lead to uneven tightening of palm nuts and they will bend.

What 4 criteria s r to be fulfilled for satisfactory working of a journal bearing? Viscosity of oil, clearance, load on the engine, rpm.

116. Sweating of refer compressor crankcaseWhen there is liquid flood back to the compressor the effect can be detrimental. After creating a host of other problem the liquid eventually boils off in that hot crankcase. Boling is possible by taking latent heat of evaporation from the surrounding oil in the crankcase.This leads to a cold crankcase if the temp of the crankcase reaches temp below that of dew point the air outside. moisture on the oil precipitates in the crankcase. This is commonly referred to as sweating of crankcase.

117. What is first order moment. These moments acts in both vertical and horizontal direction.

For engines with 5 cyl and more the 1st order moment is rarely any importance to the ship but it can be of disturbing magnitude ti the ship with 4 cyl.

Resonance with 1st order moment may occur for hull vibrations with 2-3 nodes.

Ist order compensator can be introduced in chain tightener wheel . it comprises of 2 counter rotating masses rotating at the same speed as the crank shaft.

118. What is 2nd order moment The 2nd order moments acts only in the vertical direction and precaution need

only to considered for 4,5 and 6 cyl units.

Resonance with the 2nd order moment can occur at hull vibration more then 3 nodes.

A second order moment compensator comprises of 2 counter rotating masses running at twice the engine speed.

Remedies Compensator mounted on the aft end of the engine. Driven by the main chain

drive .

Compensator mounted on the fore end of the engine. Driven by the crank shaft with a separate chain drive.

Compensator on both aft and fore completely eliminating 2nd order moment.

119. Electric compensatorIt is electrically driven compensator normally located at the steering gear compartment,Where deflection are largest and the effect of compensator with be therefore greatest. Such a compensator is synchronized to the correct phase relative to the external force or moment and can be neutralize the excitation. The compensator required an extra seating be fitted.

Guide force momentGuide force moment are caused by the transverse reaction forces acting on the crosshead due to con rod/ crankshaft mechanism.These moment may excite engine vibration moving the engine top athwart ship and causing a rocking or twisting moment of the engine.Guide force moment are harmless except when resonance vibration occur in the engine. As a precaution top bracing is installed between the engines upper platform brackets and the casing side for all its 2s models.

. Oros pistonWith the view omitting the safety valve on the exhaust valve actuator the oros P version of the oros design was chosen for the updated K engines. The reason was the oros piston

leaves less room for fitting the exh valve spindle than with the traditional piston design . to prevent contact between piston and spindle therefore a mechanical stop is built into the exh valve air spring thus limiting the max spindle lift. Using oros p version with a slightly lower piston dome creates enough space to allow longer exh valve spindle lift. This makes it possible to exploit the well proven relief bore design of the exh valve oil cylinder and safety valve on the actuator is no longer necessary.

121. Fare line curve , procedure of drawing and what is base line? Where it comes from?Here it is based on the assumption that initially the bearings are in a straight line and then load on each brg are found out and these are called influence number. Using computer application data bank of influence numbers are generated using different lifting condition. Of each bearing and their effect on others and finally taking in to consideration of other external factors a compromise of fair curve for the bearing is found out and shaft alignment is done.

122. Wick boiling:-It’s a boiling process where boiler water enters the deposit though fine pores drawn through the capillary action. Evaporation takes place at this surface the steam escapes through the larger pores. The evaporation causes concentration of boiler salts and may reach a level of many thousands times the concentration in the bulk fluid as there is no flow at the metal surface to flush the salts away. The concentrated boiler solution rapidly attacks the boiler steel. The deposits has an insulating effect and temp rise accelerates the rate of attack. The tube thins down over the considerable length and eventually fails.

123. Hoop stressThe internal gas pressure within the cylinder liner causes a tensile stress, referred as hoop tensile stress. the cooling water pressure on the outside of the liner causes a hoop compressive stress, which is negligible....but the hoop tensile stress due to internal gas pressure is prominent 124. Cascade systemCascade system is useful when there are more then one variable that influence the single parameter which is to be controlled.The system consists of a pump drawing lubricating oil from the main engine sump and pumping it through the cooler where the oil is cooled by circulating sea water thorugh the cooler tubes . the outlet oil from the cooler is led to the main engine bearing oil and piston cooling oil system.For proper functioning of the system, it is desired to maintain a constant oil temp of 45 deg celcius at the engine inlet. The control is by means of a 3 way valve that allows a certain amount of oil to by pass the cooler . if the engine inlet temp is too high more oil will be passed through the cooler and if too low more oil will bypass the cooler.There are 2main variables in this case that influence the oil inlet temp – then engine load and the sea water inlet temp forming 2 loops

An outer loop that measures the engine oil inlet temperature and passes the information for the further processing to a controller which is called the master or primary controller.

An inner loop that measures the sea water inlet temp and passes the information to a secondary controller . the second controller is called the slave or secondary controller. The secondary controller process the signals from the primary controller and the second sensor and sends an appropriate signal to the 3 way valve to control the oil temp at inlet to the engine.

The main advantage of the cascade system is that it provided a quicker response and better management of the controlled parameter. When the sea water temp changes an immediate signal will be sent to the slave controller for adjustment of the 3 way valve even before the actual oil inlet temp begins to change. The response is therefore faster.

125. Draw back pressure v/v of ref. wat all considerations are taken wen converting an meat room into veg When 2-3 evaporator are used from same compressor temp of rooms are different. Veg room is kept at positive and meat room and fish room are kept at negative. So pressure of gas after evaporation also differs. As veg room temp is maintained at positive saturation temp will also be high. There is a chance of reverse flow of gas from veg room to the other rooms evaporator. So back pressure valve is provided at outlet of veg room evaporator. It is a spring loaded non return valve . It throttles the ref from high pr to low pressure.Back pressure valve regulates pressure in the low pressure section and thes evaporating temp of refrigerant is adjusted. That’s how different temp in different room.

126. Material of fusible plug?fusible plug 50% bismuth, 30%lead and 20% tin

127. Sn(tin) has a major disadvantage in white metal, what is that?tin forms tin oxide,sno2

128. Function of inducer in centrifugal pump? An Inducer is an axial flow impeller with blades that wrap in a helix around a central hub. An Inducer serves as a small booster pump for the main impeller. Usually inducers have between 2 and 4 vanes, although there may be more. The inducer imparts sufficient head to the liquid so that the NPSH requirement of the adjacent main impeller is satisfied. Although the inducer usually has a lower NPSH requirement than the main impeller, it can, and often does, cavitate during normal operation. The key is that there is so little horsepower involved with an inducer that there is virtually no noise, vibration, or resulting mechanical problems. Meanwhile, the higher horsepower main impeller sees sufficient head to operate without cavitation.

131. what are the Advantages of using Wasted studs for securing main bearing top keep in MAN B&W.Why not jacking bolts?The main bearing keeps were held down by Jacking bolts (eg. Sulzer RND ). The reason behind that was the the kind of construction of the bed plate itself. When a cylinder fires, the pressure not only forces the main journals down but there is also a component of force which pushes the cylinder head up. Now the Cylinder Head, entablature and the bed plate is tied and precompressed by the TIE RODS. Now when the firing forces come, then there is a couple formed- a) One component of force tries to push the journal down and b) the other component tries to Push the Tie Rods up. Now at the bottom, the tie rods are bolted to the bed plate so a couple thus formed will try to rock the bed plate and thus the engine. To counter attack this problem, the tie rods were kept as close to the centerline of the engine as possible and due to space restrictions, the jack bolts were used to keep the bearing top covers tight(reaction force through the entablature). Note that there was only one cover for the main bearing having two jack bolts. Now recent development has waisted studs on the main bearing cap but the are OFFSET FROM the transverse centerline of the engine. Waisted studs give more comression as they have more elasticity and resilience. As a matter of fact, from the foundation bolts to the con rod bolts, the x-head bolts etc are all waisted studs. So care has to be taken while working as the necked region should not be marked, scored or cracked as due to reversal os stresses, fatigue will cause a crack initiation and finally fracture.

The use of studs as opposed to bolts provides a more accurate and uniform clamping load pattern..Waisted studs give more comression as they have more elasticity and resilience...Studs also offer component installation advantages over bolts. Studs act as guide pins during alignment.Studs are available with "bullet" noses, where a slightly diminished-diameter bare tip is featured. This greatly eases nut installation, allowing the nut to be dropped into position before thread engagement beginssince wasted studs doesnt require any material to be removed from the bed plate ... thus the position of the tie rod is made flexible

Difference between mc and mc-c engine? Shorter cylinder distance

Shorter chain drive

Shorter connecting rod

Longer stroke

Reinforced structure

Improved bearing material

Narrow shells = shorter engine

Increased journal diameter

Improved axial stiffness

Reduced edge pressure on main bearing

Easy mounting of second order moment for 4,5,and 6 cylinders engines

Straight forward and more rigid housing design

Shorter stay bolts

Higher natural frequency no bracing required

Low postion of mating surface cylinder cover/ cylinder liner

Slim cylinder liner

Straight forward cooling jacket

Cylinder frames smaller and lighter

Uncooled and straight forward design

Combustion chamber

high top land

lower mating surface

lower heat load of upper piston ring

better cooling of piston rings

cylinder frame straight forward casting

no cooling water chamber

no cut tube for cooling water for telescopic cooling pipe

improved drain from scavenge space

telescopic mounting on wide guide shoes no need of dismantling pipe for o’hauling piston.

Crosshead straight forward design and reduced mass

Camshaft arrangement

Bearing located between roller guide Camshaft on shrunk on cams

Reversing of fuel pumps only

Hydraulic activated exhaust valve

With indicator valve

. Where does the liner experience the maximum bending moment?The liner is supported by the lower face of the flange over a small width at the outermost radius. The joint face between the cylinder cover and the top surface of the liner is usually at or near the bore of the liner. When the cylinder cover is hardened down a downward force is exerted on the joint face and an upward reaction is given on the outer landing face of the flange. As the forece and reaction are not given on the same line , a bending moment is created on the liner upper flange and the cylindrical part of the liner adjacent to the flange.

136. How do u take bottom end bearing clearance in a 4 stroke engine? Take the unit to tdc push the conrod up by a crowbar......take the clearance at top half of the bottom end brg.

. How will u find the exact TDC of Main Engine, Auxilary Engine and Air Compressor......He wanted 'EXACT' TDC??? In case of aux engine, access the piston top either by removing head or fuel valve.....then take the unit to some angle before the approx tdc and measure the depth by putting a depth gauge on top of piston and make a mark on flywheel..............turnthe engine, the unit will cum to tdc and start moving down............when it reaches the same depth as measured earlier make another mark on flywheel............mid point of both the marks will be the tdc.......... in ME three things shud match.......the markings on camshaft and housing, crankcase markings and flywheel markings...

CREEP MAY BE DEFINED AS THE PROCESS WHEN PLASTIC FLOW OCCURS IN A METAL WHEN CONSTANT STRESSES ARE APPLIED OVER A PROLONGED PERIOD OF TIME. CREEP CAN BE PREVENTED BY CREEP RETARDANT WHICH IS" NEUMONIC STEEL WITH ALUMINIUM" WHICH IS CAPABLE OF SUSTAINING TEMPERATURES UPTO 800 DEGREES CENTIGRADE.

IMPROVEMENTS WHICH HAVE BEEN MADE IN EXHAUST VALVE TECHNOLOGY ARE: 1) HYDRAULIC CLOSING 2) SPRING AIR OPENING 3) VALVE ROTATION DURING ENGINE RUNNING PERIOD 4) COOLING ARRANGEMENTS PROVIDED AROUND THE EXHAUST VALVE SEAT IN ORDER TO MINIMIZE & TO ENSURE THAT THE EXHAUST TEMPERATURES DOES NOT EXCEED THE LIMITS SPECIFIED BY THE MANUFACTURER.

MIN. LIFT OF BOILER SAFETY VALVE IS D/4 AND ITS PURPOSE IS TO ENSURE THAT THE ESCAPE AREA AROUND THE VALVE DISC EQUALS THE SAFETY VALVE BORE AREA.

IF A TIMING CHAIN BECOMES SLACK THEN THE INDICATIONS ARE: 1)CAMSHAFT TIMING WILL GET DISTURBED (RETARDED WHEN THE ENGINE IS RUNNING AHEAD) AND AS A RESULT FUEL PUMP TIMING, EXHAUST VALVE OPENING TIMING, STARTING AIR DISTRIBUTOR TIMING ALL WILL GET DISTURBED & TOGETHER THEY AFFECT THE PERFORMANCE OF THE ENGINE & COMBUSTION DROP. TO TAKE UP THE SLACKNESS THERE IS CHAIN TIGHTENER DAMPER WHICH IS EITHER PNEUMATICALLY OR HYDRAULICALLY TIGHTENED.2) THE PROCEDURE FOR TIGHTENING THE SLACK CHAIN IS AS FOLLOWS:1)TURN THE ENGINE SO THAT THE SLACK PART OF THE CHAIN IS ON THE SAME SIDE OF THE TIGHTENER UNIT. 2) IF THE CHAIN DRIVE IS EQUIPPED WITH FLYWEIGHTS TURN THE ENGINE UNTIL THE FLYWEIGHTS ARE HANGING VERTICALLY DOWNWARDS. 3) LOOSEN THE NUTS A,B,C & D ON THE CHAIN TIGHTENING BOLT( FOR DIAGRAM REFER PG.65 ARANHA) 4) WITH THE FLYWEIGHTS IN THIS POSITION TIGHTEN THE NUT B ON THE CHAIN TIGHTENER BOLT UNTIL THERE IS A CLEARANCE OF 10 mm BETWEEN THE SHAFT AND THE NUT B. 5) TIGHTEN THE BOTTOM NUT 'C' AGAINST THE CONTACT FACE OF THE PISTON ROD & ENSURE THAT THERE IS CONTACT BETWEEN PISTON ROD & TOP NUT 'B'. 6) NOW TIGHTEN THE BOTTOM SELF LOCKING NUT 'D' AND LOCK BOTTOM NUTS 'C' & 'D' WITH TAB WASHER. 7) NOW LOCK THE TOP NUTS 'A' & 'B' WITH TAB WASHER. 8) FINALLY ADJUST THE INDICATOR TO THE ZERO POINT ON THE SCALE.

CASCADE CONTROL IS MOSTLY USED IN MAIN ENGINE L.O TEMP. CONTROL SYSTEM. IN THIS THERE ARE TWO CONTROLLERS, ONE IS MASTER CONTROLLER & OTHER IS SLAVE CONTROLLER. IN THIS THE MASTER CONTROLLER SENSES THE L.O OUTLET TEMPERATURE THROUGH SENSOR AND GIVES SIGNAL TO THE SLAVE CONTROLLER. IN SLAVE CONTROLLER THERE IS A SET TEMPERATURE READING VALUE FIXED IN THE SLAVE CONTROLLER WHICH ON RECEIVING THE MEASURED TEMP. READING VALUE FROM THE MASTER CONTROLLER, IT GENERATES THE DIFFERENCE BETWEEN THE 2 READINGS(i.e measured value-set value) & DEPENDING ON THE TEMP. DIFFERENCE IT SENDS A PNEUMATIC SIGNAL OF (4-20 MICRONS) TO OPERATE THE 3-WAY VALVE WHICH ACTS ON THE DIAPHRAGM OF 3-WAY VALVE & CONTROLS THE VALVE. THAT MEANS IF THE TEMP. DIFFERENCE IS LOW THE 3-WAY VALVE BYPASSES THE L.O FROM PASSING THROUGH THE L.O COOLER & IF THE TEMP. DIFFERENCE IS HIGH THE 3-WAY VALVE ALLOWS THE MAJORITY OF L.O TO PASS THROUGH THE L.O COOLER UNTIL SET DESIRED TEMPERATURE IS OBTAINED.

DEGREE OF SUPER-HEAT IS MEASURED BY THE EXPANSION & CONTRACTION OF HEAT SENSITIVE FLUID IN THE CAPILLARY BULB (WHICH IS SAME AS THE SATURATION TEMPERATURE OF THE REFRIGERANT IN THE SYSTEM) CORRESPONDING TO THE TEMPERATURE CHANGES IN THE GAS LEAVING THE EVAPORATOR SECTION & ALSO TO ENSURE THAT LIQUID REFRIGERANT DOES NOT RETURN BACK INTO THE SUCTION LINE. IT IS FOR THIS REASON A CONSTANT DEGREE OF SUPER-HEAT IS ALWAYS MAINTAINED AT THE EVAPORATOR OUTLET & NORMALLY A DEGREE OF SUPER-HEAT OF 5-6 DEGREES CENTIGRADE IS ALWAYS MAINTAINED. IT IS DECIDED BY HOW BIG THE EVAPORATOR SECTION IS TO COUNTER FOR THE EXCESSIVE PRESSURE DROP.

PURIFIER BOWL NOT CLOSING AFTER MANUAL DE-SLUDGE & THE REASONS ARE: 1) BOWL IS OVERLOADED WITH SLUDGE (i.e sludge is unevenly deposited in the purifier bowl) WHICH CAUSES CAKING OF SLUDGE AT HIGH TEMP. THAT CAUSES THE BOWL NOT TO CLOSE EVEN AFTER MANUAL DE-SLUDGE. 2) OPERATING WATER (i.e bowl closing water) PRESSURE IS NOT SUFFICIENT. 3) THE TEFLON SEALING RING BETWEEN THE BOWL HOOD & SLIDING BOWL BOTTOM HARDENED UP THAT CAUSES IMPROPER SEALING OF SLIDING BOWL EVEN AFTER MANUAL DE-SLUDGE & HENCE THE BOWL DOES NOT CLOSE PROPERLY.

CHECKS TO BE DONE BEFORE PUTTING NEW LINER IS:1) YOU HAVE TO CLEAN THE NEW LINER OF ANTI RUST CORROSION COATING. 2) YOU HAVE TO GAUGE THE LINER BORE OF NEW LINER FOR OVALITY AND COMPARE WITH ORIGINAL LINER TO MAKE SURE THAT IT IS WITHIN MANUFACTURERS RECOMMENDATIONS. 3) TO ENSURE THAT THE LINER MATERIAL & THICKNESS ARE OF APPROVED QUALITY BY CHECKING THE STAMP MARKING FROM THE CLASSIFICATION SOCIETY ON THE LINER WHEN IT IS DELIVERED. 4) THEN YOU HAVE TO CAREFULLY INSPECT THE LINER SURFACE FOR ANY VISIBLE SIGNS OF CRACKS FOR THE NEW LINER.5)ALSO CLEAN THE JACKET WATER SPACE THOROUGHLY WHERE THE LINER IS GOING TO BE SEATED.6) ALL THE COOLING WATER SPACES TO BE BLOWN THROUGH WITH COMPRESSED AIR THOROUGHLY.7) NOW YOU HAVE TO LOWER THE LINER WITH THE HELP OF WIRE SUSPENSION STRAP INTO THE LINER JACKET WITHOUT O-RINGS IN THE O-RING GROOVES TO MAKE SURE THAT LINER IS GOING FREELY INTO THE JACKET AND THEN YOU HAVE TO PULL THE LINER OUT AGAIN AND FIT O-RINGS INTO THE O-RING GROOVES AND SMEAR IT WITH A THIN FILM OF LUBRICATING OIL AND ANY TWIST IN THE O-RINGS TO BE REMOVED. 8) BLOW THROUGH THE TELL- TALE HOLES. 9) AND FINALLY YOU HAVE TO APPLY SILICONE SEALING COMPOUND AT THE SEALING FACE OF THE GUIDE RING AND COLLAR OF THE LINER WALL. 10) NOTE THAT THE LINER HAS REFERENCE MARKING ON THE LINER TOP FLANGE AND MAKE SURE THAT DURING THE LOWERING PROCESS THIS REFERENCE MARKING ON THE LINER SHOULD COINCIDE WITH THE

REFERENCE MARKING ON THE JACKET AT ALL TIMES DURING THE LOWERING PROCESS. 11) IN SULZER ENGINES THERE IS IS A DOWEL PIN & THIS MUST GO INTO POSITION TO ENSURE THAT LINER IS PROPERLY SEATED & IN OTHER ENGINES THE POSITION OF LUBRICATING QUILLS TO BE CHECKED TO ENSURE THAT LINER IS PROPERLY SEATED. ( II) CHECKS TO BE MADE AFTER FITTING THE LINER ARE: 1) MAKE SURE THAT LUBRICATING QUILLS GO INTO THE POSITION PROPERLY THIS MEANS THAT LINER IS PROPERLY SEATED.2) AFTER FITTING THE NEW LINER AGAIN YOU HAVE TO GAUZE THE LINER BORE IN BOTH FORWARD & AFT( ATHWARTHSHIPS DIRECTION), PORT& STARBOARD.3) AFTER FITTING THE LINER YOU HAVE TO FILL THE JACKET WATER SPACE WITH WATER & CHECK FOR ANY LEAKAGES. 4) THEN YOU HAVE TO MAKE SURE THAT LUBRICATING OIL IS COMING FROM THE LUBRICATING QUILLS PROPERLY. 5) AFTER FITTING THE PISTON & CYLINDER HEAD MAKE SURE THAT THERE IS NO LEAKAGES FROM THE TELL-TALE HOLES

VIT(VARIABLE INJECTION TIMING) WAS USED IN SULZER RTA ENGINES WHERE THE BEGINNING OF THE THE INJECTION CAN BE ADJUSTED & CONTROLLABLE BUT THE TERMINATION OF THE INJECTION IS FIXED. IN VIT THE FUEL INDEX OF ALL THE INDIVIDUAL FUEL PUMPS & FUEL INJECTION TIMING IS FIXED, SO IT IS NOT POSSIBLE TO ALTER THE FUEL INJECTION TIMING WITHOUT ADJUSTING THE FUEL INDEX OF INDIVIDUAL FUEL PUMPS. FOR THIS REASON MAN B&W CAME UP WITH SUPER VIT WHERE FUEL INDEX OF INDIVIDUAL FUEL PUMPS & FUEL INJECTION TIMING CAN BE SEPARATELY & INDEPENDENTLY ADJUSTED BY RAISING OR LOWERING THE PLUNGER & BARREL. NOTE THAT THE FUEL INDEX IS THE EFFECTIVE STROKE OF THE FUEL PUMP.

FQS (FUEL QUALITY SETTING): MODERN ENGINES ARE FITTED WITH FQS SYSTEM ESPECIALLY IN SULZER. IT IS A FORM OF CONTROL TO ADJUST THE FUEL PUMP TIMING MANUALLY FROM CONTROL ROOM IF THE QUALITY OF FUEL IS BAD. IT IS ELECTRONICALLY CONTROLLED BUT MANUALLY ADJUSTED & IS CONNECTED TO THE VIT SYSTEM. VIT IS LOAD DEPENDENT. IT IS ONLY POSSIBLE IF WE HAVE SUPER VIT, AS WE HAVE VIT RACK IN SUPER VIT. THAT MEANS IF THE QUALITY OF FUEL IS GOOD, THEN WE HAVE TO RETARD THE FUEL INJECTION TIMING, OTHERWISE EARLY INJECTION TAKES PLACE & PEAK PRESSURE DEVELOPED WILL BE TOO HIGH. SIMILARLY IF THE QUALITY OF FUEL IS BAD THEN WE HAVE TO ADVANCE THE FUEL INJECTION TIMING, OTHERWISE AFTER-BURNING TAKES PLACE DUE TO LATE INJECTION & ALSO PEAK PRESSURE DEVELOPED WILL BE LOW. THIS CAN BE MANUALLY ADJUSTED FROM CONTROL ROOM BY CHIEF-ENGINEER DEPENDING ON THE QUALITY OF FUEL & FQS SETTING IS NORMALLY ADJUSTED BETWEEN +2 TO -2.

AXIAL VIBRATIONS ARE CAUSED DUE TO VARYING GAS FORCES INSIDE THE ENGINE CYLINDER WHICH CAUSES VARYING TORQUE THEREBY RESULTING IN THE OPENING OUT & CLOSING IN OF THE CRANK-WEBS DUE TO GAS FORCES, FURTHER RESULTING IN THE LENTHENING & SHORTENING OF THE CRANK-PINS & JOURNALS. TO PREVENT AXIAL VIBRATIONS THERE ARE AXIAL VIBRATION DAMPERS FITTED ON THE CRANKSHAFT OF THE ENGINE TO DAMPEN THE SHAFT GENERATED AXIAL VIBRATIONS (i.e OSCILLATION OF THE SHAFT IN FWD & AFT DIRECTIONS, PARALLEL TO THE SHAFT HORIZONTAL LINE).

TORSIONAL VIBRATIONS : THE ELASTIC SHAFT SYSTEM OF A MULTI- CYLINDER DIESEL ENGINE IS ACTED UPON BY A PERIODICALLY VARYING TORQUE WHICH CAUSES HARMONIC DISPLACEMENT OF MASSES IN THE PLANE OF ROTATION WHICH IS TERMED AS TORSIONAL VIBRATIONS.THE SYSTEM WILL HAVE FORCED AS WELL AS FREE NATURAL TORSIONAL VIBRATIONS. THE FORCED TORSIONAL VIBRATIONS ARE CAUSED BY THE VARYING TORQUE IMPOSED BY THE GAS FORCES & THE INERTIA FORCES OF RECIPROCATING MASSES. THE TORSIONAL VIBRATIONS ARE MADE UP OF A LARGE NUMBER OF HARMONICS OF VARYING AMPLITUDE & FREQUENCY. TO PREVENT TORSIONAL VIBRATIONS WE HAVE TO IMPROVE THE NATURAL FREQUENCY OF THE SHAFT BY USING BIGGER DIAMETER SHAFT & CAN ALSO BE PREVENTED BY FITTING TOP BRACINGS CONNECTING AT THE SIDE OF THE ENGINE STRUCTURE ON BOTH SIDES OF THE ENGINE BOTH PORT & STBD.