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M.E.P ONLINE QUESTIONS
1. Which of the following v/v cannot be overhauled in place without removing valve from the piping?
1 Ball valve
2 Diaphragm valve 3 Globe valve 4 Butterfly valve
ANS D single D A multiple
NOTE: Ball valve cannot be opened at place if its union ended only except swing out type valve or valve having flange connection. But most of them could be overhauled in place. Butterfly valve cannot be overhauled in place without removing it from the position or removing the piping because if we want any maintenance in the valve disc or seat then it should be accessible at least; also we can’t remove the valve if it is stuck in open condition.
2. Copper tubing is used in refrigerant system because (single answer) 1 It has less internal resistance
2 It is cheaper compared to other materials
3 It is easier to check leaks in copper based system 4 None of the above
NOTE: Less resistance gives less pressure drop. Piping for the smaller halocarbon installations is usually of copper, because of the cleanliness and the ease of
fabrication and jointing. Copper and brass are not used with ammonia.
Refrigeration system pipes are sized to offer a low resistance to flow, since this reflects directly on compression ratio, commensurate with economy of pipe cost and minimum flow velocities to ensure oil return with the halocarbons. Copper
tube is widely used in air conditioning and refrigeration systems due to its high thermal conductivity which is about 8 times more than that from Aluminum tube. Copper, used for centuries, has gained new popularity in its modern form: light, strong, corrosion-resistance tube. It’s long lasting and maintenance free
characteristics make copper the leading choice for plumbing, heating, cooling and other mechanical systems. Copper tubing is most often used for supply of hot and cold tap water, and as refrigerant line in HVAC systems. There are two basic types of copper tubing, soft copper and rigid copper. Copper tubing is joined using flare connection, compression connection, or solder. Copper offers a high level of
resistance to corrosion, but is becoming very costly. The use of copper tubes for the transport of liquids in the condensers and evaporators, the main parts of a ACR system, is indispensable. The industry is exploring new applications and extensive uses of copper metal due to the special inherent properties and unique abilities of copper metal. Some of its special characteristics include high thermal conductivity (about 8 times more than Aluminum tube), light weight, strength, corrosion
resistance tube and durability. In air conditioning systems, you should look for parts and equipment that are small, quiet and efficient. You should look for
products with properties like, easily cold and warm bending, corrosion resistance, excellent heat conductivity, good welding and soldering qualities, which you can find in copper. Furthermore, some special requirements of air conditioning industry such as the reduction or elimination of harmful emissions have made copper, a metal of choice for product enhancement. You should also look for areas like, compatibility of copper parts, fabricating and joining requirements, heat transfer properties, effects of refrigerants and lubricants on copper system performance, predictive methods and safety-tests. The other things you should look for, while selecting products for Air Conditioning Systems are specially designed inner-grooved tubes for condensation and fin-tubes for evaporative cooling.
3. When pressure inside a system falls below that of the vapour pressure of the liquid, cavities are formed. Cavities travelling to high pressure region
collapses releasing considerable energy to damage the metal surface which is known as (single answer)
1 Cavitation 2 Erosion
3 Impingment corrosion 4 Cavitation erosion
ANS D
NOTE: The first sentence tells about the cavitation process. The second sentence tells about the cavitation damage or erosion.
4. Pump start out motor gets overloaded or trip on overload (multiple answer) 1 Alignment is wrong
2 Gland packing too tight
3 Worn out/damaged ball bearing 4 Cavitations exists
5 All of the above ANS A B C
NOTE: Over tightening of gland packing will only cause the damage to the
packing and it will wear out very fast. Cavitation will cause vibration only. Option (d) should not be there. Then option (e) is correct.
5. Why should only approved toilet cleaning chemicals be used in biological sewage treatment plant (single answer)
1 Unapproved chemicals can lead to corrosion in the system
2 Unapproved chemicals can lead to toxic conditions in the system leading to destruction of protective coatings
3 Unapproved chemicals can kill aerobic bacteria making the plant ineffective 4 Gases produced by use of unapproved chemicals can pose threat to the
operators ANS C
NOTE: Human safety first. However all the above can be correct. According to sewage manual if chemicals enter into the treatment device, operation may be hindered. Toxic chemicals going into the system chemicals like solvents, oils, paints, disinfectants, pesticides, household cleaning products and bleaches can kill
the helpful bacteria in your septic system. This may ‘kill’ the system and stop it digesting effluent. (http://wssproducts.wilhelmsen.com/marine-chemicals/cleaning-and-maintenance-1/bio-chemicals/gamazyme-btc-1/)
6. After overhauling reciprocal pump the motor connections were wrongly given. Determine outcome when pump is started (single answer)
1 The direction of flow will remain unaffected 2 The direction of flow will be reversed
3 The pump will get damaged because the suction valve will block the reverse flow causing overpressure leading to pump breakdown
4 The pump will lose suction and there will be no flow ANS A
NOTE: The direction of flow depends on the position of suction and discharge valve in the valve box.
7. Pump driven type clutch attached to vacuum pump are commonly used for priming of ballast pump and emergency fire pump. What is the factor which clutches the vacuum pump to the pump during starting of the pump? (single answer)
1 Low suction pressure acting against the spring loaded clutching piston 2 High suction pressure acting against the spring loaded clutching piston 3 Low discharge pressure acting against the spring loaded clutching piston 4 High discharge pressure acting against the spring loaded clutching piston
ANS C
8. The ballast valve of the forepeak tank is located in the duct keel and cannot be opened or shut by remote operation. The valves of other tanks can be operated without any trouble which of the following will be the best practice? (single answer)
1 Valve should be checked locally for trouble shooting without which it is difficult to find the exact problem
2 The actuator must be defective and should be replaced with a new one 3 The control circuit is defective and PCB should be replaced
4 Shore assistance will be required in such cases ANS A
9. You are responsible for daily transfers of engine room bilges. You follow the sequences aft –fwd (p)-fwd(s) bilge well and you have never experienced a problem but 5/e started the transfer and first transferred forward (s) bilge well without any problem and you join him later and you find that bilge pump is not taking suction from forward (p) and aft bilge well and then you have checked everything is normal. What is the cause? (single answer) 1 5th engineer made a mistake by 1st transferring the fwd (s) bilge well,
normal sequence of operation for engine room machineries should not b disturbed
2 Fwd (s) bilge well suction valve is leaking
3 Bilge pump suction filter cover gasket is leaking
4 Fwd (s) bilge well suction filter cover gasket is leaking ANS B
NOTE: Filter comes before valve so if say valve is okay then filter should not be a problem so option (d) is wrong. If pump suction filter is leaking then it will not be able to take suction from any well at all, so option (c) is also wrong.
10. The centrifugal pump are normally (single answer) 1 Positive displacement type
2 Rotodynamic 3 Screw type
4 Gear type ANS B
NOTE: According to REEDS rotodynamic pumps, in which a tangential
acceleration is imparted to the fluid. These include centrifugal, axial, mixed flow types.
11. Sludge pump suction pressure is going full vacuum when u start the pump taking water of double bottom tank suction you have checked the suction filter and found in clean condition. Taking suction from fuel oil sludge tank does not happen. Causes of the problem (single answer)
1 Pump is not working efficiently and required overhauling 2 F.O. sludge tank suction valve is leaking
3 W.O. Tank D.B. Tank suction pipeline has a blockage
4 Cannot say what is the problem but definitely the pump needs to be opened up for overhaul
ANS C
NOTE: As the pump is working okay when taking suction from F.O. sludge tank there is no problem with the pump. So options (a) and (d) are wrong. Option (c) seems to be the most appropriate one.
12. The difference between the discharges of a centrifugal pump and
reciprocating pump the discharge of centrifugal pump is ---while that if reciprocating is --- (single answer)
1 turbulent, laminar
2 intermittent, continuous 3 continuous, pulsating 4 pulsating, continuous
NOTE: Both options (a) & (c) are correct.
13. Which of the following is a true statement? (single answer)
1 Aluminum will be subject to preferential corrosion when in electrical continuity with stainless steel in presence of an electrolyte
2 Stainless steel will be subject to preferential corrosion when in electrical continuity with mild steel in presence of an electrolyte
3 Copper will be subject to preferential corrosion when in electrical continuity with stainless steel in presence of an electrolyte
4 Aluminum will be subject to preferential corrosion when in electrical continuity with zinc in presence of an electrolyte
ANS A
NOTE: Copper, stainless steel, mild steel, aluminum, zinc.
14. Ballast pump injection filter was cleaned and the pump was lined up it was found that there was some leakage in the suction filter suction. The pump started and the leakage started. During de ballasting it was found that the pump could not take suction from one of the double bottoms. The cause could be (single answer)
1 Pump was drawing air from
2 Pump was drawing air from suction filter
3 One of the pipelines on the suction side of the pump might be leaking 4 The filter was not cleaned properly
ANS B
NOTE: When ballasting the head is positive so water is coming out of the leaky filter. But when de ballasting, the head is negative. So air is drawn from the leaky filter.
1 The F.O. inlet and outlet valve should be kept shut, but steam heating valves should be kept crack open so as to keep the heater warm
2 F.O. inlet and outlet valve should be kept shut and heating valves also should be completely shut and should be drained of any remaining F.O. 3 F.O. inlet and outlet valve should be kept crack open so that the F.O.
recirculation through the heater can take place.
4 F.O. inlet and outlet valve should be kept shut while outlet valve should be left open so that heater can be put into use as fast as possible in case required
ANS B
NOTE: When the heater is not in use we don’t require heating and the first thing we do is stop heating if we keep on heating the oil it’s going to vaporize and safety valve may lift and if we cool it down the oil is going to be sticky so need to drain it.
16. Corrosion of mild steel can be effectively prevented by (multiple answer) 1 Cathodic protection
2 Protective coatings
3 Addition of suitable alloying elements 4 All of the above
NOTE: Here in the question it’s asked about method of prevention not protection. 17. You have to dismantle a F.O. heater for cleaning. You have closed both inlet
and outlet valves of the heater, both for F.O. and steam side. What will you do before you start opening the heater? (single answer)
1 There is nothing more to be done, if you know the valves are holding you can straight away start opening the heater without wasting time
2 Drain the heater till pressure gauge reads zero and then start opening the heater
3 Drain the heater till F.O. stops coming out of the drain and then start opening the heater
4 First open the vent valve and allow the heater to depressurize and then open the drain valve to drain the contents of the heater
ANS D
18. Sequence of metal in the increasing order of nobelity in galvanic series (single answer)
1 Stainless steel, mild steel, copper, zinc 2 Copper, stainless steel, mild steel, zinc 3 Zinc, mild steel, stainless steel, copper 4 Zinc, copper, stainless steel, mild steel
ANS C
NOTE: In corrosion pdf book its copper after stainless steel and in reeds its stainless steel after copper and in Wikipedia also.
19. During flooding of dry dock following items must be verified (single answer)
1 All sea valves are operational
2 All overboard discharge valves are operational 3 Stern tube seal are operational
4 All of the above ANS D
20. When M/E is running in emergency condition which of the alarms can't be bypassed
2 Jacket water high temp
3 Piston cooling water high temp 4 All of the above
ANS D
NOTE: Emergency maneuvering means that main engine cannot be started from remote location. When M/E is put in emergency, then just the governor is
bypassed, rest alarms will still come like lo low pressure, jacket high temperature etc... But we never bypass L.O. low pressure alarm because if there is no L.O. in the engine then the engine will cease.
21. Which of the following can be done to reduce the cold corrosion of main engine cylinder liners using high sulphur fuel oil (multiple answer)
1 Increasing cylinder oil feed rate 2 Using high TBN cylinder oil
3 Increasing scavenge air temperature 4 Decreasing cylinder oil feed rate
ANS B SINGLE,MULTI ABC
22. Vessel is at dry dock, who issue hot work permit? JUNE
1 C/E
2 2/E
3 Shipyard engineer 4 Ship superintendent
ANS C
23. Which of the following is not a method of applying metal coating on steel surfaces for corrosion protection? (single answer)
1 Hot dipping 2 Metal spraying 3 Electro plating 4 Explosion bonding
ANS D
24. Air compressor air cooler type? 1 Spring type
2 Floating type 3 Fixed tube 4 U- tube
ANS D MULTI B D
NOTE: Both (b) & (d) are correct In intercooler straight tube is used commonly which is otherwise known as floating tube because it is floating at one end. In after cooler U-tube is used commonly because for more heat transfer in small size, and also it’s free for expansion.
25. Cladding is the process used for
1 Protection of metal surfaces against corrosion 2 Protection of metal surfaces against erosion
3 Protection of metal surfaces against cavitation erosion 4 Protection of metal surfaces impingement corrosion
ANS A
NOTE: Cladding cannot give protection against erosion or impingement corrosion. 26. If 3 centrifugal pumps are running in parallel and the backpressure is
substantially increased, what effect will be observed on the pumps in use? 1 Flow rate will reduce
2 Increase alarms and trips (high casing temperature) will activate, if no corrective action in the pump casing temperature
4 None of the above 5 All of the above
ANS A B C
NOTE: Throttling of discharge valve will increase back pressure decrease flow rate also increase temperature of the fluid which in turn will increase the casing
temperature. If pumps are in tanker pump room then alarm can come due to high casing temperature.
27. Which of the following is a true statement? (choose more than one option if true, multiple choice)
1 Mild steel will be subject to preferential corrosion when in electrical continuity with stainless steel in presence of an electrolyte
2 Stainless steel will be subject to preferential corrosion when in electrical continuity with mild steel in presence of an electrolyte
3 Copper will be subject to preferential corrosion when in electrical continuity with mild steel in presence of an electrolyte
4 Zinc will be subject to preferential corrosion when in electrical continuity with aluminum in presence of an electrolyte
ANS A D
NOTE: Zinc, aluminum, steel, stainless steel, copper.
28. The steels with a carbon percentage close to 0.8% have 1 Poor strength but good weldability
2 High strength but poor weldability 3 Poor strength and poor weldability 4 High strength and good weldability
ANS B
NOTE: Up till 0.30 excellent weldability poor strength 0.30-0.45 very good weldability good strength
0.45-0.75 good weldability very good strength Till 1.5-2 poor weldability excellent strength
29. The lower half of main bearing of a very large diesel engine can be removed by
2 By hammering out with the help of a soft mallet
3 By slightly jacking the crankshaft and turning out the bearing half with a rope or similar tackle provided
4 By using a special tool in the oil hole and turning the shaft to turn out the lower half
ANS C
NOTE: According to DEVEN ARANHA to remove bottom half of the bearing, the engine is turned so that the respective crank web is parallel to the bedplate
separating face. Mount the support cross piece and jacks below the adjoining crank. Jack up the crank shaft by 0.1 to 0.15 mm (maximum 0.2 mm). Check the lift with dial gauge. The shims are removed and a rope support piece is fitted. A steel rope is passed around the lower shell and pulled out with a rope pulley. 30. A refrigerant compressor will run continuously when there is
1 Too heavy cooling load on the system 2 Air in the system
3 Insufficient refrigerant in the system 4 Any of the above
ANS A
NOTE: In case the load is too heavy then the refrigerant itself cannot cool the room to the set temperature. So the liquid shut off valve remains open and the cut out will never occur. In case insufficient refrigerant is there the same thing will happen and also sometimes the pressure at suction side can decrease to have LP cut out, but the liquid shut off valve is still open so when pressure increases it cuts in resulting short cycling. In case of air in the system the discharge pressure will be high enough for HP cut out.
31. The gland packing on centrifugal pump shaft should (single answer) 1 Not allow any leakage under positive suction pressure
2 Should only allow drop by drop continuous leakage under positive suction pressure
3 Should only allow drop by drop continual leakage under positive suction pressure
4 Should allow considerable leakage as gland packings are meant to allow considerable leakage
NOTE: Continuous means without any interruption but continual means with interruption. First option is correct and if cooling is required then packing is lubricated from pump delivery. If any leakage is there then there is a good chance of pump sucking air from the packing under negative suction pressure.
32. Which of the following cannot be used as sacrificial anode for the protection of mild steel structure against corrosion
1 Cadmium
2 Magnesium
3 Copper
4 Aluminum
ANS C
NOTE: Magnesium, aluminum, cadmium, mild steel, copper. 33. Excessive lubrication in compressors can lead to (multiple) 1 Sticking of valves
2 Carryover and deposit of oil particles in pipelines and reservoirs 3 Decompression
4 Detonation
ANS A B C
NOTE: Here detonation is nothing but starting air line explosion.
34. Corrosion protection of steel surfaces by zinc coating can be carried out only at temperatures below 65 deg. C. For higher temperatures (single answer) 1 Zinc reacts very fast and thus can only provide protection for a limited time 2 Zinc reacts with steel and protective layer vanishes due to chemical reaction 3 Steel may corrode preferentially to the zinc
4 Dezincification occurs leading to removal of zinc coating ANS C
NOTE: According to corrosion pdf file protection of steel by zinc is good at temperatures below 650C, but at higher temperatures it is possible for the steel to
corrode preferentially to the zinc.
35. The pumps performance depends upon
1 Clearance between the wear ring and the impeller 2 Clearance between the impeller and the casing 3 Clearance between impeller and shaft
4 Clearance between mechanical seal and shaft ANS A MULTI A D
NOTE: Mc GEORGE says the clearance between the wear ring and collar of the impeller is minimal to restrict the flow of liquid from the discharge side. A short circuit flow would reduce efficiency and pressurize the shaft seal.
36. The type of corrosion normally occurring in cooling fresh water systems of marine diesel engines is
1 Stress corrosion 2 Hot corrosion
3 Bimetallic corrosion 4 Selective phase corrosion
ANS D MULTI C D
NOTE: As the end covers and water boxes are commonly of cast iron or fabricated from mild steel, unprotected cast iron in contact with sea water, suffers from
graphitization, a form of selective phase corrosion. But again as two dissimilar materials are in an electrolyte bimetallic corrosion can also happen. Diesel engines invariably have a cast iron cylinder block sometimes with aluminum head and the heat exchanger and piping system is usually constructed of mixed copper alloy and steel components. Even with fresh water there are bimetallic corrosion problems with such mixed metal systems and depending on the climate in which the ship will operate it may be necessary to add antifreeze solution which is invariably inhibited ethylene glycol. The presence of copper ions in the fresh water which may be naturally present or result from corrosion of copper alloy components in the cooling system can cause pitting corrosion of aluminum, accelerate rusting of iron and steel, promote softening of rubber, and oxidation of ethylene glycol with the formation of formic and oxalic acids giving rise to further metallic corrosion. Wasim Hussain N reason given by Swapneil sir is: thats why we maintain
LiquiDewt treatment to form a nitrite level on cooling surfaces to avoid graphitisation of CI components. Ans D
37. The most important control measure to prevent boiler tube failure is (single answer)
1 Use of proper refractory material
2 Proper maintenance of fuel burning equipment 3 Proper maintenance of boiler water condition 4 All of the above
ANS C MULTI B C
can avoid corrosion, erosion, overheating. Direct impinge of flame cause tube failure (overheating and distortion).
38. It is given that engine room bilge pump has suction manifold on which 3 valves are located. One valve for the 3 engine room bilge wells suction, another one for bilge tank suction and the third one is for sea water suction. It is found that the bilge pump is unable to take suction from any of the bilge wells, but is able to take suction efficiently from bilge tank. What is the most probable cause?
1 Pump suction filter cover gasket leaking
2 Suction filter cover gasket of one of the bilge wells is leaking
3 Bilge well suction pipeline leaking between individual bilge well valves and suction manifold valve
4 Bilge pump suction pipeline leaking between the manifold and the pump NOTE: As the pump is taking suction from bilge tank there is nothing wrong with the pump or its suction line or its filter. So options (a) and (d) are wrong. Bilge suction filter come before the valve. If the valve is holding, then the pump should not have any problem in taking suction from that bilge well which is not having a leaky filter. But it cannot take suction from any bilge well. Option (b) can only be correct when location of filter is after the pump master valve.
39. Most steam traps respond well to cleaning. But when a thermodynamic trap fails to operate after cleaning, the next course of action should be (single answer)
1 Throttle the steam outlet valve 2 Renew the trap
3 Lap the disc and the seat of the trap 4 Throttle the steam inlet valve
ANS C
NOTE: in mc GEORGE it is said that if cleaning is not the solution then go for lapping the disc and seat.
40. When centrifugal pump is changed over for pumping a liquid of higher specific gravity which of the following is going to change? (single answer) 1 Discharge pressure
2 Discharge head 3 Power consumption 4 Pump speed
ANS C MULTI A C
NOTE: Head is independent of fluid density. Speed of the motor will always remain constant unless it is a variable speed drive, that’s why the pressure and the power consumption increase. A centrifugal pump will always develop the same head in feet regardless of a liquid’s specific gravity. Pressure will increase or decrease in direct proportion to a liquid’s specific gravity. Brake HP required will vary directly with a liquid’s specific gravity.
41. Auxiliary engine connecting rod bottom end bolts should be tightened 1 Only as per the prescribed torque using a torque wrench
2 As per prescribed torque as well as angular measurements as recommended by the manufacturer
3 By following previous match marks on bolt heads and connecting rod body 4 As per prescribed torque and another 10% increase during every subsequent
tightening ANS B
42. Why are large centrifugal pumps started with their discharge valves closed? 1 To ensure proper priming
2 To limit sudden rise in discharge rate 3 To limit motor starting current
4 To minimize starting torque on motor shaft
NOTE: Normally large centrifugal pumps are provided with independent priming system, but to ensure proper priming discharge valve is closed while priming the pump. But for priming attached priming pump or other priming methods are used. So priming is not the primary concern. Option (a) is not the answer. The main concern is to reduce starting torque which in turn will reduce the starting current as it is a huge pump.
43. Which of the following statements are true as far as painting of steel hull/structure is concerned? (multiple choice)
1 Painting can be done under any weather condition
2 Painting can only be done after proper surface preparation is carried out 3 Painting should only be done on top of appropriate primer coating
4 Several coats of paint can be applied one after the other without any time gap
44. Which of the following can lead to sudden stopping of a diesel engine? (multiple answer)
1 Air in fuel supply line 2 Water in fuel supply line 3 Obstruction in air filter 4 Water in the air filter
ANS A B C
NOTE: DEVEN ARANHA says air in fuel system or vapour due to water in the fuel system can cause clogging of fuel filter resulting irregular running, misfiring and stopping of the engine. And obstruction in air filter will cut the air supply to the engine which will stop the combustion resulting stopping of the engine. 45. A multistage centrifugal pump is normally used
1 High head
2 High discharge flow 3 High viscous fluids 4 Low viscous fluid
ANS A
NOTE: Generally multi staging is done to increase the head by having two stages or impellers in one shaft. It acts as if two pumps are running in series. Pumps can also be put on parallel operation for high discharge flow or to get variable flow, but generally it is done by having two separate pumps not by multi staging.
46. In a three phase electrical equipment, the immediate action in the event of a fuse blowing in one of the phases, would be (single answer)
1 To replace with a fuse of correct rating 2 To replace fuses on all three phases 3 To try to repair the fuse
4 To investigate the fault that led to the blowing of the fuse ANS D
NOTE: According to D.T. HALL the first step is to find the cause of the fault and repair before the fuse link is replaced. Second step is the replacement fuse link must be of the correct current rating, grade and type. Usually this means the
replacement fuse link is identical to the blown fuse link. The third step is to replace all three fuses in a 3-phase supply even if only one is found blown after a fault. The
others may be seriously weakened which makes them unreliable for future use. 47. A drain cooler is provided with S.W. cooling. What is the best way to
increase the temperature of condensate draining to the hot well? (single answer)
1 Throttle the S.W. inlet valve 2 Throttle the S.W. outlet valve
3 Open the condensate bypass to the cooler 4 Close the condensate bypass to the cooler
ANS C
NOTE: It is the best practice always to throttle the outlet valve of a heat exchanger to control the temperature of the medium to be cooled. But it will cause insufficient water to flow through the condenser and it will cause scaling of tubes. So to avoid salt deposition in condenser tubes bypass is to be opened for temperature control. 48. Which of the following option gives you the correct sequence of the metals
in decreasing order of preferential corrosion when all of them are bonded and immersed in an electrolyte? (single answer)
1 Titanium, mild steel , zinc , stainless steel 2 Titanium , stainless steel ,mild steel ,zinc 3 Zinc , mild steel , stainless steel , titanium 4 Zinc , titanium , mild steel , stainless steel
ANS C
IF INCREASING ORDER B
49. During auxiliary engine de-carbonization, which of the following checks need to be carried out?
1 Sounding of all double bottom tanks 2 Connecting rod big end ovality 3 Liner wear
4 Crack detection tests on connecting rod serrations ANS C MULTI B C D
NOTE: Taking sounding of all double bottom tanks is not even related to de-carbonization of auxiliary engine.
50. A reciprocating pump is used for engine room bilge service because 1 Reciprocating pumps are designed for smoother discharge
2 Only small capacity pumping capacity is required, while other pumps are of higher capacity
3 It doesn’t churn and mix the bilge water unlike other types of rotary and rotodynamic pumps
4 Shipbuilding industry is still going on old concept, future ships will have centrifugal pumps installed
ANS C
NOTE: Mc GEORGE says requirement is low capacity pump which encourages slow, smooth and laminar flow. Turbulence or agitation should be avoided since it causes mixing and re-entertainment of the oil. Laminar or streamlined flow is beneficial. The entrance area in oil/water separators is made large so that flow is slow and large slugs of oil can move to the surface quickly. So option (c) is the best one.
51. Increasing the rotational speed of a cargo pump the pump flow rate will 1 Increase in direct proportion to the increase in speed
2 Decrease in direct proportion to the increase in speed 3 Flow rate doesn’t depend upon speed
4 Flow
ANS A
NOTE: Mc GEORGE says capacity varies directly as the speed.
52. While re-floating the vessel after dry dock, which of the following checks should be carried out? (multi choice)
1 Sounding of all double bottom tanks
2 Checking leakages in the stern tube header tanks 3 Checking leakages at ship side valves
4 Checking levels of stern tube header tanks ANS A C
NOTE: Checking any leakages in the stern tube header tanks will not give any information about any leakage in stern tube.
53. The machinery which is usually tested first once the ship reaches a dry dock is
1 Engine room crane 2 Engine room lift
3 Gantry crane for engine room 4 All of the above
ANS C USCG
(single answer) 1 Millimeter cubed 2 Nano – millimeter 3 Microns 4 Micro millimeter ANS C
55. In a reciprocating pump the direction of flow depends upon 1 Direction of rotation of the pump
2 Position & fixing of suction and discharge valves 3 High pressure to low pressure
4 Whether pump is single acting or double acting ANS B
56. Fire side in boilers gets commonly corroded due to 1 Galvanic action
2 Formation of vanadium pentoxide and sulphuric acid 3 Stress corrosion
4 Crevice corrosion ANS B
NOTE: As the fuel contains vanadium and sulphur according to the temperature and other favorable condition it can form vanadium pentoxide and sulphuric acid respectively which are highly corrosive in nature.
57. Which of the following statements is false about hydraulic jacks/tensioning tools? (single answer)
1 The piston of the jack should be turned back by a certain degree after hand tightening to prevent easy removal after un tightening of the nut
2 The piston of the jack should not be turned back after hand tightening during un tightening of the nut
3 The piston of the jack need not be turned back during tightening of the nut 4 The hydraulic pressure need not be relieved during removal of the jack
ANS D
NOTE: If we don’t release the pressure then it is very unsafe and difficult to remove the jack.
58. In a shell and tube type M/E L.O. cooler, the temperature of L.O. is
controlled by an automatic temperature control valve. Out at sea with M/E running at normal sea load it is observed that the temperature control valve
opening to the cooler is increasing day by day until it becomes 100% open to the cooler. The L.O. outlet temperature _______________ after the above condition has reached
1 Starts decreasing immediately 2 Starts increasing immediately
3 Will be maintained at the set point of the temperature controller 4 Cannot be maintained at the set point and will increase slowly
ANS D
NOTE: If it is running at normal sea load then there should not be any problem as the L.O. temperature is maintained nearly constant, but here as the temperature control valve is opening gradually that means the S.W. temperature is increasing gradually. May be ship is moving toward hotter region. In order to maintain L.O. temperature now the control valve is fully open, but it cannot maintain the
temperature. So the temperature of L.O. will increase slowly. He is talking about TEMPERATURE CONTROL VALVE OPENING TO THE COOLER.
59. Which of the following is not a rotary motion valve? 1 Gate valve
2 Butterfly valve 3 Ball valve 4 Plug valve
ANS A
NOTE: Here all the valves turn to open or close, but gate valve slides to open or close.
60. Which of the following can lead to short cycling or frequent cutting in and cutting out of a fridge compressor? (single answer)
1 Dirty condenser
2 Air entrapped in refrigerant 3 High cooling water temperature 4 Grossly insufficient charge
ANS D
NOTE: If there is grossly insufficient charge then there will be low pressure at suction side which will lead to L.P. cut out. This will lead to short cycling or frequent cutting in and cutting out of a fridge compressor. But dirty condenser an air in the system will lead to high discharge pressure resulting H.P. cut out.
heavily for some time and then becomes normal until it finally comes to a stop. What is wrong with purifier?
1 The purifier design is faulty
2 The purifier bowl has a heavy sludge deposit and requires cleaning 3 The purifier bowl is not balanced properly
4 During shutting down most of the purifiers pass through the critical speed zone
ANS D
NOTE: It can be avoided by applying brake at the time of stopping so that it will pass the critical speed zone very fast.
62. Hot corrosion in exhaust valves and fire side of boiler mainly when 1 Fuels containing vanadium content with high sodium content are used 2 Fuels containing vanadium content with low sodium content are used 3 Fuels containing high vanadium and high sulphur content are used
4 Fuels containing high sulphur content is used and the exhaust temperatures are uncontrolled and exceed 600 deg. C
ANS A
NOTE: According to DEVEN ARANHA when both these impurities are present in a sodium and vanadium ratio of 1:3, vanadium pentoxide which is formed
combines with sodium to form a very hard compound whose melting point is around 630 deg. C. If the ratio is not proper then the reaction may not happen. So for the ratio to be matched vanadium with sufficient sodium should be present. 63. NPSH and the total suction head are two terms which are commonly used
for pumps. Which of the following is a true statement? 1 They are one and the same thing
2 Total suction head is greater than NPSH
3 NPSH is always greater than total suction head 4 Total suction head and NPSH have no relationship
ANS B
NOTE: Total suction head – vapor pressure head is NPSH.
64. You have overhauled a centrifugal pump and while assembling forgot to install the o-ring between the sleeve (provided in way of gland packing) and the shaft. What impact does this have? (single answer)
1 It will not affect the pump in any way
and will affect the pump performance
3 It will not affect the pump performance n any way but will corrode the shaft between the o-ring and shaft
4 It will cause dynamic imbalance of the shaft ANS B
NOTE: Pump shafts are usually protected from erosion, corrosion, and water at seal chambers, leakage joints, internal bearings, and in the waterways by
renewable sleeves. In designs with a metal to metal joint between the sleeve and the impeller hub or shaft nut, a sealing device is required between the sleeve and the shaft to prevent leakage. Pumped liquid can leak into the clearance between the shaft and the sleeve when operating under a positive suction head and air can leak into the pump when operating under a negative suction head.
65. You must have used reinforced rubber joints. The reinforcement is normally provided using non-asbestos fibers. The reinforcement is provided because (multiple answer)
1 Ordinary rubber gasket have a porous matrix, having capillaries which can allow liquid leakage when subjected to high pressure
2 To increase the load carrying capacity of joint so it can withstand higher pressures
3 To increase the temperature resistance of the joint
4 To protect the joints from fire or other accidental damage
NOTE: Ordinary rubber gasket is not made for high pressure application as they will leak. So we use reinforced rubber joints. It increases the load carrying capacity. To deal with the various forces on the joint they require fiber
reinforcement, which guarantees both flexibility and strength. Rubber expansion joints combine a rubber matrix and a reinforcing material, so high strength to weight ratios can be achieved. The reinforcing material, usually a kind of fiber, provides the strength and stiffness. The rubber matrix, with low strength and stiffness, provides air-fluid tightness and supports the reinforcing materials to maintain their relative positions. These important positions influence the resulting mechanical properties.
66. Metal cladding provides protection to the metal essentially for the life of ship because
1 During cladding the protective coating reacts chemically with the base metal and inhibits corrosion
2 This is the only method in which the completeness of the metal coating can assured, while other methods are liable to defects
3 The thickness of protective coating is greater compared to any other metal coating method used
4 The adherence of coating is best in case of metal cladding ANS C
NOTE: According to corrosion pdf file the metal coating thickness achieved by metal cladding is considerably greater than that obtained by the other techniques considered, and for this reason it is frequently used where a component is required to be essentially protected against corrosion for the life of the ship.
67. Which of the following can cause exhaust with black smoke in a diesel engine? (multi choice)
1 Choked air filter of turbocharger 2 Water mixed with fuel
3 Bad atomization of fuel 4 Overload
ANS A C D
NOTE: Water mixed with oil will give white smoke. 68. Net positive suction head is the
1 Difference of total suction head and total discharge head 2 Difference of static head and the frictional head
3 Difference of dynamic suction head and the vapour pressure of liquid 4 Difference of static suction head and the vapour pressure of liquid
ANS D
NOTE: In fluid dynamics, Total Dynamic Head (TDH) is the total equivalent height that a fluid is to be pumped, taking into account friction losses in the pipe.
Htotal = (P2 – P1) / ρg
TDH = Static Height + Static Lift + Friction Loss Where:
Static Lift is the height the water will raise before arriving at the pump (also known as the suction head).
pump (also known as the discharge head). Friction Loss is Head Loss.
This equation can be derived from Equation. For a relatively incompressible fluid such as water, TDH is simply the pressure head difference between the inlet and outlet of the pump, if
measured at the same elevation and with inlet and outlet of equal diameter.TDH is also the work done by the pump per unit weight, per unit volume of fluid.
69. The purpose of the wearing rings used in a centrifugal pump is to 1 Prevent internal explosion in the pump when it is overheated 2 Enable a visual inspection of the pump when it is running 3 Ensure a proper alignment of the pump coupling to the driver 4 To isolate suction and discharge side
ANS D
NOTE: Mc GEORGE says the clearance between the wear ring and collar of the impeller is minimal to restrict the flow of liquid from the discharge side.
70. The automatic/manual recirculation valve provided on the S.W. overboard line is provided so that
1 S.W. temperature can be regulated and coolers can maintain correct temperatures even with low S.W. temperatures
2 S.W. temperature can be regulated and coolers can maintain correct temperatures even with high S.W. temperatures
3 S.W. can be re-circulated when outside water is extremely muddy
4 S.W. can be re-circulated to conserve when sea chest suction filters become very dirty
ANS A
71. Before putting into operation a coalescer type oily water separator, it is important to
1 Fill it up with purge water 2 Drain it completely
3 Switch off the heater
4 Keep the three way valve manually open ANS A
with clean water.
72. For the S.W. side of a M/E L.O. cooler it is noticed that rise in S.W. temperature through the cooler has decreased from 12 deg. C to 7 deg. C over a period of time, while the drop in temperature of L.O. across the cooler has also decreased. All other coolers have been reported to be working normal & M/E is also running at a constant load in calm weather. What is the inference drawn by decrease in the temperature difference?
1 The cooling S.W. inlet temperature has reduced
2 The efficiency of the cooler has increased over a period of time 3 The cooler has become dirty on the S.W. side or L.O. side
4 S.W. side of the cooler may be partially blocked with mud and sea shells ANS C
NOTE: If the temperature differential of both the sides is decreasing then the cooling efficiency has decreased. This can happen when either S.W. side or L.O. side will become dirty.
73. Centrifugal pumps cannot handle air and require priming. But you are aware that centrifugal which on the same principal can handle air very well. Which two properties of air are responsible because of which the centrifugal pumps cannot handle air
1 Fluidity only 2 Density only
3 Both fluidity and density 4 Compressibility
74. Which of the following can lead to premature failure of roller bearings? 1 Misalignment
2 Contamination 3 Shrinkage
4 Over greasing ANS A B D
NOTE: In pdf file for bearing failure improper lubrication or less or no lubrication can cause damage to the bearing. Options (a) (b) (c) are correct. Option (c) can also be correct if it means too tight on the shaft.
75. Surface preparation of steel surfaces, prior carrying out painting is important because (choose the best alternative)
1 Any rust and contaminant inclusions may cause local paint film breakdown
2 Too much paint will be consumed if surface preparation is not carried out 3 Surface will be very rough if proper surface preparation is not carried out 4 Surface preparation deposits a chemical onto steel surface which reacts with
paint film and causes strong bonding ANS A
76. Vacuum priming pumps which work on the principle of fixed vane pumps require _____________ for___________ clearance between vane tips and casing
1 Lube oil, lubricating 2 Lube oil, sealing 3 Water, sealing
4 Gland packing, sealing ANS C
NOTE: Mc GEORGE says sealing water is drawn into the oval casing through a makeup supply pipe. The water, thrown out to the casing periphery by the turning rotor, whirls around and forms a moving layer against the oval casing. The water seals the rotor blades and also recedes from and re approaches the rotor boss twice
in each revolution. The effect is to produce a series of reciprocating water pistons between the blades.
77. The flow rate through a F.O. transfer pump will not be affected by which of the following factors?
1 Low F.O. temperature 2 Low sounding in F.O. tank
3 Internal leakage within the pump 4 Leaking discharge valve
ANS D
NOTE: Leaking discharge valve can not affect when the pump is running and the valve is in open condition if it is positive displacement pump.
78. The suction pressure gauge of the engine room bilge pump is broken and you don’t have a spare. Chief engineer has asked you to troubleshoot the problem with bilge pump not taking suction from fwd. (p) bilge well. You try taking suction from fwd. (s) & aft bilge well and find that pump is taking good suction. Thereafter you try suction from fwd. (p) bilge well for
sometime after priming with sea water but there is no change in level. You inspect the suction filter of the pump and find that it is very difficult to remove the same, you had to apply too much of force to lift the filter cover while normally it comes out easily. What does it indicate?
1 It does not indicate anything; sometimes the filter covers are difficult to remove
2 It indicates that the suction valve of the fwd. Bilge pump is leaking 3 It indicates that the suction filter of the fwd. (p) bilge well is clogged
completely
4 Pump suction filter might be clogged ANS C
NOTE: Here the pump suction filter is working completely fine because pump is taking good suction from other bilge wells. When we inspect the suction filter of the pump and find that it is very difficult to remove the same, and had to apply too much of force to lift the filter cover while normally it comes out easily. It indicates that when pump is taking suction from fwd. (p) bilge well too much of vacuum is getting produced. That means there is some blockage and here according to the options it is the bilge well filter.
79. Chromium is a nobler metal when compared to that of steel. In some marine applications chromium is electroplated to the steel surfaces. Why?
1 Chromium is a more noble metal so it will not get corroded and thus steel surfaces will remain protected
2 Chromium plating provides corrosion protection as well as high glossiness and high hardness for better wear resistance and reduced friction to the steel surfaces
3 Chromium plating is required for providing high glossiness and high
hardness for better wear resistance and reduced friction to the steel surfaces and not for corrosion protection
4 Chromium reacts with steel to form an alloy during electroplating which is corrosion resistant
ANS B
NOTE: According to corrosion pdf file chromium is also extensively used for electro-plating components that are subjected to mechanical deterioration as hard chrome plate surfaces can be obtained. Chromium is nobler than the steel and it is generally necessary to use a non-porous interfacial electro-plate such as nickel between steel and the outer chromium surface if the component is to be subjected to corrosive conditions.
80. Correct method of greasing a centrifugal pump bearing is
1 To pump the grease until you feel high back pressure on the grease pump 2 To pump the grease for 3-4 pumping strokes of grease pump for each
3 To pump the grease when the pump is stopped and drain any old grease at the same time by opening the drain plug, giving only 3-4 pumping strokes on grease pump for each bearing. The drain plug should then be replaced 4 To pump the grease when the pump is running and drain any old grease at
the same time by opening the drain plug, until all the old grease is removed and new grease starts coming out of the drain, repeating same for each bearing. The drain plug should then be replaced
ANS D
81. What is difference between pressure gauges of air compressor and fridge compressor? Is there difference between lube oil pressure of fridge
compressor and air compressor?
Yes the difference is ref pressure gauges are of compound type meant to measure vacuum as well as pressure along with corresponding saturation temp and some of pressure of and L.O. for fridge.
82. A ball valve was found leaking in service. Upon inspection it was found that the PTFE seat had worn out and was renewed. The valve stopped leaking in closed condition. How do you think a ball valve provides perfect sealing? (single answer)
1 The seat fitted is slightly smaller than the outer dimensions of the ball, thus providing interference fit when closed
2 Either a floating seat is pressed onto turnnion supported ball by liquid pressure or floating ball is pressed onto the seat
3 Ball is not exactly spherical and is shaped such that during closure the surface coming into contact with seat is of slightly bigger diameter providing sealing
4 Seat is not exactly spherical, but slightly tapered so that during closure the ball sits tightly on the seat
NOTE:
83. It has been reported that engine room bilge pump was unable to take suction from fwd. (p) bilge well while it is taking suction efficiently from fwd. (s) & aft bilge wells. What could be the most probable cause?
1 There is leakage in the bilge suction pipeline somewhere between the bilge wells and bilge pump
2 The fwd. (p) bilge well suction valve might be leaking
3 The fwd. (p) bilge well suction filter cover gasket might be leaking 4 The pump needs to be overhauled
ANS C
NOTE: According to Mc GEORGE the filter is situated just before the bilge well followed by the valve. So if the valve is leaking from the bonnet then pump will
face difficulty in suction from any of the bilge well or if it is leaking from the seat then why should the pump cannot take suction from port bilge well, but if the filter cover gasket is leaking then there is a good chance that the pump will suck air and cannot take suction from that particular well.
84. Which of the following is a correct point for sampling of system lube oil for on board or shore analysis?
1 Standpipes 2 Purifier outlets
3 Inlet or outlet of l. O. Coolers 4 Tank drains
ANS C
NOTE: My answer is none of the above. There is a fine filter after the cooler. Sampling should be just before lube oil in entering the main engine.
85. After maintaining correct discharge pressure, soon ceases to discharge water what are possible cause? (single answer)
1 Pressure gauge wrong 2 Pump sucking air
3 Discharge valve throttled 4 Casing wear ring is worn
ANS B
NOTE: After maintaining correct discharge pressure there is the only chance when pump will lose suction is when the pump is sucking air.
86. After removing all the bonnets and the securing nuts of a large globe valve it is found that the bonnet is coming out because of the strong adhesion of the gasket between the bonnet and the housing. What are you going to do in best
practice?
Screw in the valve onto the seat to lift up the valve and stem 87. Screw pump are normally
1 Slow speed pump 2 Medium speed pump 3 High speed pump
ANS C MULTI ABC
NOTE: Mc GEORGE says screw pumps are suitable for operation at high rotational speed.
88. During connection and disconnection of bunker hoses to discharge static electricity which of the following process is used?
1 Insulated flanges and hoses 2 Ship shore bonding cable
ANS A
89. In refrigeration circuit, the data logger will record what? 1 Room temperature
2 Recharge temperature 3 Liquid line temperature 4 Solenoid valve operation
NOTE: Parameters to be monitored for data logger in a refrigeration system are room temperature, discharge temperature, liquid line temperature, evaporating pressure, condensing pressure, suction pressure and discharge pressure, HP & LP pressure, pump/fan operation, S.W. temperature & pressure, differential oil
pressure, refrigerant leakage, defrost heating, solenoid valve operation. 90. Which of the following is a true statement?
1 Aluminum will be subject to preferential corrosion when in electrical continuity with stainless steel in presence of an electrolyte
2 Stainless steel will be subject to preferential corrosion when in electrical continuity with mild steel in presence of an electrolyte
3 Copper will be subject to preferential corrosion when in electrical continuity with stainless steel in presence of an electrolyte
4 Aluminum will be subject to preferential corrosion when in electrical continuity with zinc in presence of an electrolyte
ANS A
NOTE: According to previous question copper is nobler than stainless steel, if that is true then option (c) is wrong.
91. The corrosion protection for cooling fresh water systems of marine diesel engines is normally provided by
1 Sacrificial anodes
2 ICCP
3 Protective metal coatings of system components
4 Addition of corrosion inhibitors to the cooling fresh water ANS D MULTI CD
NOTE: For fresh water system corrosion protection is given by these two methods. In tubes we have cupro-nickel coating by skin cladding method. We also introduce corrosion inhibitors for fresh water system to protect it from corrosion due to dissolved oxygen or acids. These are nothing but chemicals which forms a protective film on metal surface to protect them from corrosion. But sea water system has sacrificial anodes as soft iron like zinc. We also use ICCP for sea water corrosion protection.
92. For shaft sealing of a main sea water pump for ship plying in coastal muddy waters, which is the best option?
1 Gland packing
2 Lip seal with garter spring 3 Mechanical seal
4 Cup seal ANS A
NOTE: Mc GEORGE says for sea water pumps playing in coastal muddy waters for shaft sealing gland packing is better than putting mechanical seal because any ingress of foreign matter can damage the sealing surface of a mechanical seal.
93. The seating material for perfectly sealing type ball valves is usually made up of
1 Rubber
2 PTFE or nylon
3 Rubber reinforced with steel wire 4 Stainless steel
ANS B
94. Bilge pump is not taking suction from any bilge well or holding tank what could be wrong inside the pump?
1 Bucket rings have worn out
2 Suction or discharge v/v have worn out and started leaking 3 Pump suction filter clogged
4 Suction or discharge v/v stuck in open and debris on the seat ANS A MULTI ABD if recently overhauled then only D
95. You have seen and operated several valves onboard ships. All the butterfly valve operation handles are operated by a locking arrangement because (single answer)
1 Butterfly valves do not used gland packings and thus spindle doesn’t have anything to keep it in position and can open by vibration
2 Butterfly valve does have a spindle packing but same cannot be excessively tightened to have good grip on the spindle to prevent it from opening against vibration
3 Butterfly valves can move by vibration but that is not the main
consideration, the main consideration being opening/closing against liquid pressure
4 All the butterfly valves do not have locking arrangement as there is no such requirement for the same
ANS C
NOTE: The valve can change its position due to vibration or due to the pressure of the liquid acting on it. So a locking arrangement is necessary to keep it in position.
96. Which of the group of method are used for priming of centrifugal pumps onboard ships? (single answer)
1 Gravity tank, attached vacuum pump
2 Attached vacuum pump, filling pump casing using a fresh water hose 3 Central priming system, attached vacuum pump, sea water priming 4 None of the above
ANS C MULTI A C
NOTE: Mc GEORGE says if the number of pumps to be primed is more than four, then central priming system is used. Attached vacuum pump is also used as
automatic priming system for a pump. Sometimes sea water priming from an independent supply can be given, for example opening sea suction of ballast pump. 97. Which one of the following is a type of corrosion (single answer)
1 Electroplating 2 Galvanization 3 Graphitization 4 De emulsification
ANS C
NOTE: It is selective phase corrosion where the matrix of the alloy is converted to iron oxides; the graphite flakes and the phosphorous rich compound are virtually not attacked which is not visible but causes loss of strength of that material. 98. Which of the following instruments measures propeller drop? (single
answer) 1 Poker gauge
2 Telescopic feeler gauge
3 Trammel
4 Propeller drop gauge ANS A
NOTE: Mc GEORGE says propeller drop or stern tube bearing wear down can be measured by poker gauge.
99. Your ship has an OWS and reciprocating bilge pump of capacity 2.0 m3 /hr. It takes about 12 hours to pump out the complete bilge tank through OWS. The ship is going to dry-dock and chief engineer is recommending company to install a centrifugal pump of 10 m3 capacity which will take the same space and can pump out the bilge tank only in 2.5 hrs. The company should (single answer)
1 Accept the proposal as a centrifugal pump has several advantages over a reciprocating pump
2 There is no question of accepting a centrifugal pump as a engine room bilge pump
3 Propose to fix a gear pump instead of a centrifugal pump
4 Pipelines and pumps once designed cannot be changed as they are class approved
ANS D
NOTE: Mc GEORGE says the pipeline diameter and the pump capacity for ship’s bilge system is formulated and approved by classification society. Centrifugal pump is not used for OWS as discharge flow is turbulent causing well mixing of oil & water. It is one of the reasons why the pumps are fitted at the OWS delivery side. Inlet of the OWS is laminar flow for efficient separation of oil from water. 100. Normally so called Single screw pumps are used as sludge pumps in engine
room. What is the correct technical name of these pumps? (single answer) 1 Snake pump
2 Screw pump
3 Progressive cavity pump 4 Gerotor pump
101. In a parallel-gate type valve the sealing between the valve and the disc is provided by (single answer)
1 Appropriate tightening torque of the valve spindle
2 Gate and valve seat have a taper and when tightened they will seal against each other
3 Either the seat or the disc gate are free-floating, allowing upstream pressure to seal the seat and disc against any unwanted leakage
4 For a gate type valve the sealing is never perfect and they always allow some leakage
NOTE: Mc GEORGE says valves and seats of the gate valve may be tapered or are parallel on their facing sides. When a Parallel Slide is opened or closed, the
positioning of two flat spring loaded discs will either seal or open the pipeline passage. Closure is achieved by positioning the discs between the seat faces in the valve body. The pressure differential across the disc forces the outlet disc against the outlet seat, creating a tight seal which is far superior to that of a wedge gate valve. The two separate spring loaded discs mounted in the belt eye/disc holder have sufficient loading and freedom of movement to allow accurate contact between the flat lapped faces over the range of expansion and contraction
regardless of the valve orientation. During valve closure the self wiping action of the discs ensures that debris is not trapped between the sealing faces. Stem travel is limited by the back seat in open position and the stem stop in the closed position. The stem stop prevents stem rotation and acts as a position indicator. Unlike a wedge gate valve it is line pressure and POSITION, not excessive mechanical force at the end of stroke that is required to make a seal. When the position
indicator is in the closed position the valve is fully isolated. DO NOT APPLY ANY ADDITIONAL FORCE. Because the discs are free to slide between the seat faces it is virtually impossible to create an overstressed condition under normal
operation. The advantages of this eyelet are. It produces a smoother flow between the seat faces by effectively eliminating the body cavity and the turbulence which it causes. It protects the seat faces from impingement of the line fluid or anything suspended in it. It prevents debris in the fluid being thrown out of suspension into the valve body. When the eyelet/conduit is positioned between the seats, the bottom of the disc faces are still in contact with seat faces. No, body guides are required. The gate is a split design using two discs spring loaded and held together by a gate holder with an inconel 750 springs toprovide initial energizing when
closed. The gate relies for seat tightness on the primary fluid pressure acting on the downstreamhalf. There is no wedging action or extra loading onthe seats resulting in considerably lower operating torque.When the valve is in the open position the gate is completelyclear of the seats. During closing there is a bevel on the bottom of the gate to guide it in between the seats and recompress the spring. Seating surfaces are hard faced with Stellite®6to provide high cycle capability in very high differential pressureservices.
102. The crank web deflection readings of a diesel engine would be erroneous in which of the following conditions? (multiple answer)
1 When the draught of the vessel has changed while readings were being taken 2 When cargo loading and discharging has been too rapid
3 When the crankcase temperature has changed substantially during the process of taking the readings
ANS A B C
NOTE: DEVEN ARANHA and RITENKER SEN say ambient temperature,
movements of ship as in rough weather, incorrect load condition resulting hogging or sagging are the factors affecting deflections. When comparing deflections this must be taken under similar draught conditions as the readings according to the way the ship is loaded or ballasted. So answer is all of the above.
103. The purpose of an evaporator in the domestic refrigeration system is to (single answer)
1 Transmit latent heat of evaporation 2 Absorb latent heat of fusion
3 Absorb latent heat of evaporation 4 Transmit latent heat of fusion
ANS C
NOTE: By absorbing latent heat of evaporation from the air the refrigerant cools the air.
104. If the direction of rotation of a gear pump is reversed due to change in-phase sequence, what happens when the pump is started? (single answer)
1 Direction of flow remains the same
2 The pump will get damaged due to overpressure on suction side 3 Pump relief valve will be lifted
4 The direction of flow will be reversed ANS D
NOTE: Mc GEORGE says the liquid being pumped by the gear pump is forced out after being carried around between gear teeth and housing, as the teeth mesh
together. So if you look at the diagram where direction of flow is given you can imagine that when you will change the direction of rotation of the gears, the direction of flow of liquid will also be changed.
105. Centrifugal pump will typically give you a low flow rate at a lower pressure, where a piston pump will give you more pressure at higher flow rate. Is the statement correct? (single answer)
1 True
2 False
3 First sentence is right. Second one is wrong 4 I don't know
ANS B
NOTE: According to the characteristics diagram of both the pumps given in Mc GEORGE centrifugal pump will typically give you a low flow rate at a higher pressure, where a piston pump will give you more pressure at lower flow rate. Piston pump delivers constant flow rate at any head. However in practice, when pressure increases, the internal leakages also increase, reduces the flow rate through system.
106. Which of the following is an important requirement for proper functioning of sacrificial anode system (multiple answer)
1 Good insulation between anodes and ship’s hull
2 Good electrical continuity between anodes and ship’s hull
3 Providing protection of anodes from being painted over during hull painting 4 Presence of an insulating material between anode and the cathode
ANS B C
NOTE: According to corrosion pdf file the most common reasons for failure of sacrificial anode systems are due to ineffective electrical contact between the anodes and the hull, or due to the anodes being painted while in dry dock.
107. The main disadvantages of a reciprocating pump over a gear pump is that (single answer)
2 Discharge of a gear pump is not affected by the direction of rotation while that of reciprocating pump is reversed
3 The discharge of reciprocating pump is pulsating and discharge rate is lesser 4 Reciprocating pumps are only available in high capacities and for smaller
capacities only gear pumps can be used ANS C
NOTE: Options (a), (b), (d) are wrong statements so left with only one option. 108. Which of the following types of damages is metal seating of a valve subject
to? Choose the correct alternative (single answer) 1 Corrosion, erosion, abrasion, deformation
2 Corrosion, fatigue failure, brittle fracture, caustic cracking 3 Erosion, caustic cracking, brittle fracture, clover leafing 4 None of the above
ANS A
NOTE: Classifications of Wear: Adhesive Wear – material loss due to sliding motion between metal surfaces, Abrasive Wear – material loss due to cutting action of hard particles, Erosive Wear – form of abrasive wear due to particles suspended in a fluid, Corrosive Wear – material loss due to chemical attack, Surface Fatigue Wear – material loss from repeated sliding or rolling motion, Cavitation Wear – bubbles form in liquids due to sudden pressure change and then collapse producing mechanical shock on the metal surface.
109. You are pumping out sludge to a shore facility using your sludge pump. You find that the discharge rate of pump is very slow and suction filter is getting clogged frequently. What is the best alternative to counteract the problem? (single answer)
1 Remove the pump suction filter and pump out the tank
2 Increase the tank temperature, keep an eye on the pump suction pressure and clean the filter as soon as it drops
3 As soon as the as the shore facility tells you that they are not receiving any sludge, you stop the pump and clean the filter
4 Filter so that frequency of filter blockage is reduced and you can get a better discharge rate
ANS B
110. When centrifugal pump is used to pump a liquid of higher specific gravity the pump power will (single answer)
1 Increase 2 Decrease
3 Will not be affected as the pump power depends only on the flow capacity 4 None of the above
ANS A
NOTE: A centrifugal pump will always develop the same head in feet regardless of a liquid’s specific gravity. Pressure will increase or decrease in direct proportion to a liquid’s specific gravity. Brake HP required will vary directly with a liquid’s specific gravity. Power = ρ g (N/m3) * h (m) * Q (m3/t)
111. The process of depositing zinc on steel surfaces by diffusion coating is known as (single answer)
1 Sherardising 2 Chromising 3 Calorising 4 Galvanizing
ANS A
NOTE: The process of depositing zinc on steel surfaces by diffusion coating is known as Sherardising. The process of depositing chromium on steel surfaces by
diffusion coating is known as Chromising. The process of depositing aluminum on steel surfaces by diffusion coating is known as Calorising.
112. By which of the following is the attached vacuum pump of a ballast pump is driven? (single answer)
1 Electrical motor 2 Hydraulic motor 3 Pump driven clutch 4 Pneumatically driven
ANS C
113. High tensile steels are (single answer)
1 High carbon steels with suitably added alloying elements 2 Medium carbon steels with suitably added alloying elements 3 Low carbon steels with suitably added alloying elements 4 None of the above
ANS B
NOTE: High tensile steel has 0.4% carbon and it comes under medium carbon steel.
114. After cleaning the sea chest filter you have placed the filter in the body and tightened the cover. Which one of the following is the best alternative? (single answer)
1 You can open the filter inlet and outlet valves & directly start using the filter 2 If you do not want to use the sea chest in question, you need not worry and
you can open the valves when required
3 Purged, any leakages and thereafter filter can be kept isolated or used as required
4 You will close the other side sea chest valves first and then open this side sea chest filter inlet and outlet valves
ANS C
115. Which of the following valves cannot prevent backflow of liquid in a pipeline? (single answer)
1 Gate valve
2 Globe check valve 3 Swing check valve 4 Angle check valve
ANS A
NOTE: Gate valve is not made to prevent back flow of liquid. 116. Bronze is an alloy typically consisting of (single answer) 1 Copper , lead & tin
2 Copper , zinc & lead 3 Copper , zinc & tin 4 Copper , tin & lead
ANS D
NOTE: Brass 70 Cu & 30 Zn, bronze 88 copper + 12 tin, gunmetal 88 cu + 10 tin + 2 Zn compositions. Aluminum bronze- copper, tin, aluminum. Aluminum brass- copper, zinc, aluminum.
117. In a positive displacement reciprocating pump, the use of the accumulator is to? (single answer)
1 Steady the flow in the discharge section of the pipe 2 Dampen the pressure surge on discharge side
3 To always maintain a discharge head on the pump 4 Both options a & b
ANS D
NOTE: According to INTRODUCTION TO MARINE ENGINEERING BY D.A. TAYLOR an air vessel is usually fitted in the discharge pipe work to dampen out the pressure variations during discharge. As the discharge pressure rises the air is compressed in the vessel, and as the pressure falls the air expands. The peak pressure energy is thus stored in the air and returned to the system when the pressure falls.
118. The process of depositing chromium on to steel surfaces by diffusion coating is known as (single answer)
1 Galvanizing 2 Chromising 3 Calorising 4 Coppering
ANS B
NOTE: The process of depositing zinc on steel surfaces by diffusion coating is known as Sherardising. The process of depositing chromium on steel surfaces by diffusion coating is known as Chromising. The process of depositing aluminum on steel surfaces by diffusion coating is known as Calorising.
119. When running two centrifugal pumps in parallel, flow rate is increased
1 True
2 False
3 May be
4 I don't know ANS A
