Marine engineering practice

! 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 innergrooved 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/cleaningand-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 ANS C MULTI C A

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. 15.

When one of the M/E F.O. heater is not in use then (single answer)

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

1

L.O. low pressure

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. 1 2 3 4

Cladding is the process used for Protection of metal surfaces against corrosion Protection of metal surfaces against erosion Protection of metal surfaces against cavitation erosion 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 3 Safety taken

4 5

None of the above 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. 1

The lower half of main bearing of a very large diesel engine can be removed by Pulling out with a chain block

2 3

By hammering out with the help of a soft mallet 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 ANS B

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 NOTE: According to GTH FLANAGAN by maintaining boiler water condition we

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 ANS B C

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 decarbonization 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 54. The size of solid particle contaminants in hydraulic systems is measured in

(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. 61. During shutting down the purifier you find that purifier always vibrates

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 2 It will cause leakage of fluid (air/water) in between the shaft and the sleeve

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). Static Height is the maximum height reached by the pipe after the

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. 1 2 3 4

The purpose of the wearing rings used in a centrifugal pump is to Prevent internal explosion in the pump when it is overheated Enable a visual inspection of the pump when it is running Ensure a proper alignment of the pump coupling to the driver 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 NOTE: Mc GEORGE says before initial operation, the separator must be filled

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 bearing

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 ANS B

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. 1 2 3 4 94. 1 2 3 4 95.

The seating material for perfectly sealing type ball valves is usually made up of Rubber PTFE or nylon Rubber reinforced with steel wire Stainless steel ANS B Bilge pump is not taking suction from any bilge well or holding tank what could be wrong inside the pump? Bucket rings have worn out Suction or discharge v/v have worn out and started leaking Pump suction filter clogged Suction or discharge v/v stuck in open and debris on the seat ANS A MULTI ABD if recently overhauled then only D 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. 1 2 3 4

Which one of the following is a type of corrosion (single answer) Electroplating Galvanization Graphitization 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 ANS C

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 to provide initial energizing when

closed. The gate relies for seat tightness on the primary fluid pressure acting on the downstream half. There is no wedging action or extra loading on the seats resulting in considerably lower operating torque. When the valve is in the open position the gate is completely clear 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®6 to provide high cycle capability in very high differential pressure services.

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

4

None of the above

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) 1

A gear pump is self priming while a reciprocating pump is not

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 brasscopper, 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

NOTE: Pumps are put on parallel operation for high discharge flow or to get variable flow. 120. You have started pumping out a fore peak tank. The ballast pump is running showing a low discharge pressure but a positive suction pressure, chief engineer asks you to throttle the discharge valve to increase the back pressure on the pump. Why do you require doing the same? 1

The pump’s discharge rate needs to be controlled as it is pumping at a higher than rated capacity

2

Chief engineer wants you to slow down as the de ballasting is going on too fast and will finish sooner than expected

3

It is a misconception that pumps operate smoothly at increased back pressure and throttling of the discharge valve is a wrong practice

4

Centrifugal pumps cannot operate at greater than rated capacity, so throttling the discharge valve is only going to decrease the discharge rate below rated capacity ANS D

121. Which of the following types of boiler burners have maximum turn down ratio? (single answer) 1

Pressure jet type

2

Spinning cup burner

3

Spill type burner

4

Y-jet type burner ANS D

NOTE: According to GTH FLANAGAN the turn down ratio of pressure jet type burner is limited to a value of about 3.5. Spinning cup burner has values of over 10:1. Y-jet type burner has a turn down ratio up to 20:1.

122. F.O. transfer pump was working efficiently, but it stopped taking suction suddenly. There is a sounding of 6.0 m in the F.O. deep tank. The suction pressure gauge was renewed recently and is showing a positive pressure when pump is running, but pump is not transferring any F.O. what is the most probable cause? (single answer) 1

Pump is damaged and needs overhaul

2

Suction filter cover gasket might leaking

3

Pump relief valve might be leaking

4

The pump suction pipeline is blocked ANS C

NOTE: As in the question it is said that the pump was working efficiently, but it stopped taking suction suddenly, so there is nothing wrong with the pump. If the pump filter cover gasket would have been leaking then the pressure gauge would have been showing zero pressure that is the atmospheric pressure or negative. If the pump suction pipe would have been blocked then the pressure gauge would have been showing negative pressure. But it is showing positive pressure and it was renewed recently so the relief valve is leaking due to which discharge side is connected to suction side. So it is not transferring any oil. 123. Motor stator winding badly contaminated by dirt, oil and grease should be cleaned by (single answer) 1

High pressure compressed air

2

Suction or vacuum cleaning

3

Brushing, spraying or immersion in an approved cleaning solvent

4

Immersion in fresh water followed by drying ANS C

NOTE: If it is badly contaminated then vacuum cleaning is inefficient. We have to use cleaning solvent to clean it.

124. Aluminum being lower than zinc in galvanic series provides lesser protection to steel compared to the zinc coating. Which one of the following is a true statement (single answer) 1

Aluminum coating provides good corrosion protection compared that of zinc at elevated temperatures

2

Zinc is always preferred over aluminum coating irrespective of the temperature of metal surface

3

Aluminum is never used as coating material

4

Aluminum reacts with steel, so cannot be used for coating steel ANS A

NOTE: Aluminum can withstand high temperature when protecting steel from corrosion. 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. 125. Which of the following is not a true statement? (single answer) 1

Butterfly valves are used for modulating flow and can be throttled

2

Globe valves can be straight flow or angle flow type

3

Swing check valve will provide lesser resistance than same bore diameter globe type check valve

4

In a globe type valves, mechanical seals are used for providing sealing between the valve bonnet and the spindle ANS D

NOTE: According to Mc GEORGE leakage along the valve spindle is prevented by a stuffing box, packed with a suitable material and a gland. 126.

Impingement corrosion is an

1

Physical action

2

Chemical action

3

Physical and chemical action

4

None of the above ANS C

NOTE: Corrosion is a chemical process in which metal reacts with its environment. Although cavitation erosion is regarded as a mechanical deterioration process, when considering sea water as the working fluid the influence of corrosion must be acknowledged in any situation where damage to a metallic surface is experienced. Conditions which lead to cavitation erosion in piping systems are also capable of inducing impingement corrosion particularly of the comparatively thin wall copper alloy piping downstream of components of interest. In fact, the latter mechanism is more insidious in some respects since a lower order of hydrodynamic forces is sufficient to promote attack and at least the presence of cavitation may be detected by the characteristic noise emitted by the collapsing cavities. So significant is the influence of corrosion, particularly impingement corrosion, and those failures by hydrodynamic deterioration processes are sometimes termed "corrosion/erosion". Design considerations for the avoidance of impingement corrosion will be discussed in the following section. However, the fact that cavitation may be detected makes somewhat easier the task of defining conditions for its avoidance. 127. In which of the following types of refractory failure, softening of the refractory bricks takes place due to presence of sodium/vanadium in fuel? 1

Spalling

2

Cracking

3

Shrinkage cracking

4

Slagging ANS D

NOTE: According to GTH FLANAGAN due to reaction of vanadium and sodium salts with the refractory material molten slag is formed, which then runs down to the furnace floor. This reduces the wall thickness and leads to build up in the level

of furnace floor which can eventually interface with the shape of the flame. Cold air impinging upon the hot refractory causes a surface flaking known as Spalling. 128. A thin layer of electrolyte trapped in a small pits on a metal surface and remaining stagnant over a period of time may cause 1

Erosion

2

Bimetallic corrosion

3

Crevice corrosion

4

Corrosion fatigue ANS C

NOTE: According to corrosion pdf file this is a form of attack which may occur when a thin film of electrolyte is trapped in a crevice and becomes stagnant. Such crevices may be formed between closely fitting components or even under mounds of corrosion product. In this condition, corrosion occurs due to concentration cells created by either limited oxygen availability or a difference in metal ion concentration. 129. In case of tankers, the speed of cargo pumps is reduced while stripping, why? 1

To avoid cavitation of the pump as the NPSHA may fall below NPSHR if speed is not reduced

2

To avoid cavitation of pump as the NPSHA may rise above NPSHR if speed is not reduced

3

To prevent the pump from over speeding if it loses suction

4

Decreasing the speed increases the discharge head of the pump which is required to pump out the remaining cargo ANS A

NOTE: NPSH increases when velocity of flow reduces (NPSH = Suction Head – losses – vapour pressure), Losses α vel. of flow2.

130. Which of the following statements is false about cleanliness of electric motors? 1

External motor body cleanliness of totally enclosed is important since the body helps to dissipate heat generated

2

Dirt, oil, grease and moisture are primary culprits in deterioration of insulation of stator windings of a motor

3

High-pressure dry compressed air cleaning is preferred over suction cleaning for stator windings

4

Dry compressed air at a high pressure can drive in dirt inside windings instead of removing them ANS C

NOTE: We never use high pressure air for cleaning as it may damage the winding by inserting dirt inside it. 131. The attached vacuum pump of a ballast pump operates on the principle of a 1

Centrifugal pump

2

Reciprocating pump

3

Gear Pump

4

Vane Pump ANS D

NOTE: Attached vacuum pump works on water ring principle of reciprocating water piston like a positive displacement pump for example reciprocating pump. Vane pump is also used sometimes but vanes wear and they sometimes jam in the rotor slots. So this is not so good. Ejectors are effective is sized correctly but their efficiency is low. 132. Super chlorinating of fresh water tanks in dry dock is done by 1

Washing the tanks with 100ppm chlorine solution

2

Washing the tanks with 50ppm chlorine solution

3

Leaving a 50ppm chlorine solution in the tank for 4 hours before flushing with clean water

4

Leaving a 50ppm chlorine solution in the tank for 24 hours before flushing with clean water ANS C

NOTE: According to Mc GEORGE super chlorinating when the vessel is dry docked, consists of leaving a 50 ppm chlorine solution in the tank over a four hour period, followed by flushing with clean water. 133. An auxiliary engine turbo-charged makes strange noises when the load changes. The engine parameters however are absolutely fine. An external examination of turbocharger parameters as stated in the manual also reveals nothing. Would you 1

Continue to run the engine and wait for some time

2

Stop the engine for a while and make some checks

3

Reduce the load of the engine

4

Run it on steady load to make some checks ANS B

NOTE: It is a symptom of turbocharger surging. So the first step is to reduce the engine speed which in turn reduces scavenge air pressure and there is less tendency of reverse flow from scavenge air manifold to the turbocharger diffuser. But turbocharger should not surge within designed load. Engine should be stopped & turbocharger checked for fouling. Here the engine itself is making noise. 134. During prolonged astern maneuvering of the relative expansion between any of the turbine its casing is likely to increase for an alarming level you should (multi choice) 1

Inform the bridge that no further maneuvering is possible as the turbine are likely to be damaged

2

Reduce the vacuum further to control the relative expansion

3

Keep maneuvering irrespective of damage to the turbines

4

Request the bridge to try to reduce number of astern movements ANS B D

135. Refer cooling tubes act as self-cooling & expansion by 1

Straight tube

2

U tube

3

Spring tube

4

Fixed tube ANS A IF MULTI A D

NOTE: According to REEDS temperature difference is not so high and the little expansion can be taken up by metal resilience. So we use straight tube. 136. The direction of centrifugal pump depends upon what 1

Vane curvature from eye to impeller

2

Vane curvature from impeller to eye

3

Direction of volute casing ANS C MULTI B C

NOTE:

DIRECTION OF VOLUTE CASING

The Volute casing and Discharge tube are designed and located according to “the Direction of Rotation of the Pump" which is pre determined for a particular design. The correct direction of rotation can be often deduced from the pumps shape. Focusing on the discharge volute, in which direction do the areas increase? Then that is the direction of rotation. There is a particular hazard with the double suction. Here it is quite possible in many cases to install the impeller wrong way round. The shaft may rotate in the correct direction, but the impeller does not. As a rule, the impeller vanes should always curve away from the direction of rotation. 137. Purifier not rotating with desired rpm reason 1

Frequency low

2

Bus bar voltage low

3

Friction pads worn out ANS A B C

NOTE: According to ALFA LAVAL purifier manual, Speed too low, possible cause action:

Bowl not closed or leaking - Dismantle and check Friction elements worn or oily - Fit new friction elements or clean the old ones if they are oily Belt tension too loose - Tighten the belt Motor failure/motor bearings - Repair the motor Bearing overheated/damaged or worn - Fit new bearings Incorrect transmission (60 Hz pulley running on 50 Hz power supply) - Make sure that the pulley is intended for 50 Hz power supply. If there is an option for all of the above then go for that option. 138. Purifier leaking bowl opened, cleaned and seal ring changed and put back but still leaking, what might be wrong 1

high temp

2

high density

3

disc size not proper

4

rpm low ANS C MULTI C D

NOTE: According to ALFA LAVAL purifier manual, Outgoing water contains oil, possible cause action: Gravity disc hole too small - Use a gravity disc with a larger hole Incorrect separating temperature - Adjust temperature Throughput too high - Reduce throughput Sludge space in bowl is filled with sludge - Clean the bowl and shorten time between discharges Disc stack clogged - Clean the bowl discs Inlet clogged - Clean Bowl speed too low – See previous question for possible cause action Gravity disc hole too large - Use a gravity disc with a smaller hole Seal ring under the gravity disc defective - Fit a new seal ring The supply of operating water is not sufficient due to clogged strainer, kinked hose or low water pressure - Straighten the hose, clean the strainer, check the water pressure Oil discharge through water outlet = broken water seal, possible cause action Gravity disc too large - Use a gravity disc with a smaller hole Separation temperature too low - Increase temperature

Throughput too high - Reduce throughput The supply of operating water is not sufficient due to clogged strainer, kinked hose or low water pressure - Straighten the hose, clean the strainer, check the water pressure Valve(s) in oil outlet line closed - Open the valve(s) and adjust the back pressure to normal value Sealing water volume too small - Check water supply Disc stack clogged - Clean the bowl discs Seal ring on gravity disc/clarifier disc defective - Fit a new seal ring Seal ring in sliding bowl bottom or upper or lower distribution ring defective Install a new seal ring Bowl hood seal ring defective or sealing surface of sliding bowl bottom damaged Install a new seal ring, polish the surface on sliding bowl bottom or install a new one Valve plugs defective - Install new valve plugs on operating slide Bowl speed too low - Bowl incorrectly assembled - Examine and make correct, assuming leakage through water outlet. This is taken from MITSUBHISHI PURIFIER MANUAL

139. Sherardising, Chromising, and Calorising are methods of protection from corrosion by which method 1

Electroplating

2

Galvanization

3

Metal diffusion

4

Cladding ANS C

NOTE: In diffusion coating method the most commonly used coating materials are zinc, chromium and aluminum and the respective processes are known as Sherardising, Chromising and Calorising. 140. In Impressed Current Cathodic protection system, the current for cathodic protection is supplied by 1

Use of sacrificial anodes

2

A low voltage D.C. supply

3

A low voltage A.C. supply

4

110 V A.C. supply ANS B

NOTE: In ICCP the supply current and the voltage are also low and D.C. 141. Which of the following instruments is used to measure rudder carrier bearing wear down? (single answer) 1

Poker gauge

2

Telescopic feeler gauge

3

Depth gauge

4

Trammel ANS D

NOTE: Trammel gauge is used to measure rudder drop.

142. In a Sea Water cooled J.C.W. cooler, the most common cause for loss in cooling efficiency of the heater is 1

Scale formation on J.C.W. side

2

Mud/silt deposits on J.C.W. side

3

Scale formation on S.W. side

4

None of the above ANS C

NOTE: In sea water cooled J.C.W. cooler the main problem is with the S.W. side because as F.W. side is closed we put chemicals for treatment, but in S.W. side there is always chance for scale formation which will affect the cooler efficiency. 143. Cadmium coatings provide corrosion protection. Cadmium coatings are commercially carried out using which of the following methods 1

Metal Spraying

2

Electro-plating

3

Hot-dipping

4

Metal diffusion ANS B

NOTE: According to corrosion pdf file cadmium coatings have good resistance to marine corrosion, but the only commercially practical form is electro plating. Consequently its application is for small components, such as fastening materials used for atmospheric exposure conditions. 144. The common term used for failure of metal and alloys in a corrosive environment , when subject to high stresses is known as 1

Fatigue failure

2

Corrosion fatigue

3

Stress corrosion cracking

4

Fretting Corrosion ANS C

NOTE: According to corrosion pdf file stress corrosion cracking is a process caused by the joint action of stress and a corrodent. 145. Wheel operated butterfly valves are operated through a reduction gearbox. The Gear arrangement inside of gear box is of _________ type 1

Bevel Gear

2

Rack & Pinion Gear

3

Planetary Gear

4

Worm & Worm Wheel ANS D

NOTE: M Series hand wheel gear actuators are totally enclosed, weatherproof, worm gear actuators for reliable manual operation with Type A11, A31A and A41 High Performance Butterfly Valves. The M Series actuator consists of a body housing, cover, worm gear, input shaft, and hand wheel. The housing is greasepacked. Gear Operators: DEMCO Weatherproof Gear Operators are offered with a choice of hand wheel, chain-wheel, or square nut. The worm gearing has selflocking set screws to control open and closed positioning or an optional adjustable memory stop for “balance return” to a preset open position after closing. 146. Use of synthetic polymer treatment limited to low pressure boiler why 1

Does not prevention of scale formation

2

Does not help in corrosion prevention

3

Does not form phosphate to tackle caustic

4

All of the above

NOTE: Polymer is a giant molecular built up by stringing together simple molecules, E.G.

1

Poly-electrolytes-Formed from natural or synthetic ionic monomers

2

Polyacrylates- Polymers of acrylic acid

3

Polyamides- Polymers of amides

Polymer treatment prevents scale formation and minimizes sludge formation. It can also loosen scale so established boilers introduced to this form of treatment may develop leaks where previously plugged with scale, especially in way of expanded joints. Also can absorb trace oil. Use limited to LP boiler as no PO4 present to prevent caustic alkalinity for auxiliary boiler. This is a superior form of treatment to the old alkaline and phosphate treatment. The correct level of alkalinity must be maintained as too low a level neutralizes the electric charge of the poly-electrolyte. Too high causes caustic alkalinity. 147. Resistance to corrosion of Aluminum alloys is due to 1

Aluminum being a very noble metal when compared to other metals in electrochemical series

2

Formation of aluminum oxide (Alumina) passive film on surface

3

The rate of corrosion is very low due to very high corrosion potential

4

All of the above ANS B

NOTE: Aluminum forms alumina on alloys exposed to air which gives a very good corrosion resistance. It is also very noble metal as compared to others in galvanic series. Breaks in the film do not normally lead to accelerated attack at such positions unlike stainless steels and the film remains stable except when exposed to alkaline waters or hot sea water. 148. Graphitization is the term used to describe (single answer) 1

Bimetallic corrosion of brass and bronze alloys leading to deposition of graphite

2

Selective phase corrosion of grey cast iron leading to corrosion of graphite flakes and leading to loss of strength

3

Electroplating process in which graphite is deposited on the mild steel components to protect them against corrosion

4

Chemical reaction between pure graphite and iron so as to increase the graphite content of iron ANS B

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. Under graphitization C I iron will be corroded leaving behind a soft graphite and loose its strength and it will crack. 149. Accelerated corrosion due to removal of protective surface films (e.g.) oxide layers on metal/alloy surfaces due to turbulence of working fluid is known as (single answer) 1

Bimetallic corrosion

2

Impingement corrosion

3

Cavitation erosion

4

Selective phase corrosion ANS B

NOTE: Impingement attack is accelerated corrosion due to the removal of protective corrosion product films by turbulent water flow, thereby continually exposing a clean metal surface which forms the anode site. 150. Cold and viscous lubricating oil of an auxiliary engine is most likely to cause ___________ (single answer) 1

Sudden stopping of the engine

2

Difficulty in starting the engine

3

Rhythmic knocking sound from inside the engine

4

Drop in RPM of the engine ANS B

NOTE: According to MAN B&W OPERATION MANUAL DIFFICULTY: Engine turns on starting air, but no fuel injection occurs due to too low fuel pump index. ONE OF THE CAUSES: Too high viscosity of fuel oil. According to DIHATSU AUXILIARY ENGINE MANUAL troubleshooting: when starting is difficult/engine does not start, because: too high lubricating oil viscosity. 151. A sea chest filter has to be cleaned. Which one of the following best practice should be followed prior opening the filter? 1

Close inlet & outlet valves of the filter before opening the filter

2

Close inlet & outlet valves of the filter, then open the vent to release pressure before opening the filter

3

Close inlet & outlet valves of the filter before opening the filter

4

Put the other sea chest into use, isolate the filter by closing inlet & outlet valves, purge the filter body to depressurize it and then open up slowly ANS D

152. What is the correct procedure in tightening a torque spanner? (multiple answer) 1

Tightening beyond the cracking sound

2

By using a addition length rod

3

Fluctuating load

4

None of the above ANS D

153. The delivery rate of an axial piston hydraulic pump is controlled by varying the position of the _____________ 1

Tilting box

2

Slide block

3

Pintle

4

Reaction ring ANS A

NOTE: Mc GEORGE says tilting box is used in axial piston pump to control the stroke by changing the tilting angle. 154. Freight paid by charterers on a quantity of cargo short-shipped, i.e. quantity agreed upon but not loaded by the charterer is called 1

Pro-rata freight

2

Back Freight

3

Dead freight

4

None of the above ANS C

NOTE: According to EDWARD F STEVENS AND C.S.J. BUTTERFIELD (SHIPPING PRACTICE) the ship owner is not entitled to claim pro rata freight for the part of the voyage he has carried the goods, but if the ship does not complete the voyage, the master may make arrangements to transship the cargo to final port of discharge and thus earn his freight, all charges for such transshipment or forwarding being for his account. There is no exception to this rule, however: if the consignee is notified that the ship has stopped short of its destination, and voluntarily agrees with the ship owner to take delivery at the intermediate port, then pro rata freight would become chargeable. Dead freight: payment for space booked but not used. When by contract or charter party space is booked for a definite quantity, and shippers fail to provide cargo, or do not provide the full amount agreed, then the owner is entitled to claim dead freight for unoccupied space. The ship owner, however, is not entitled to place him in a better financial position by receiving dead freight in excess of the actual freight he would have earned by the carriage of the goods. Dead freight is therefore calculated by the amount of cargo which should have been carried, but which in fact was not, at the

agreed rate of freight, less all charges which would have been incurred by the owner in the carriage of the goods, that is, loading and discharging expenses. Dead freight is rarely demanded in cases in a berth shipment and fails to supply them. Back freight: freight charged for the return of goods which have not been accepted at port of delivery. Should a shipper forward goods to a consignee who refuses to take delivery, the owner may either exercise his lien-if freight has not been paidand sell goods, or return them to the shipper. The shipper is then charged with an additional amount of freight for their return, which is known as back freight. Another form of back freight is when goods have been over stowed or over carried, through a wrong mark appearing on the case. For example, goods intended for Montevideo, and port marked Buenos Aires would not be accessible at Montevideo, and would, therefore, have to be over carried to Buenos Aires. There again back freight would be chargeable for the return of the goods from Buenos Aires to Montevideo, and if wrongly marked would be chargeable to the shipper. 155. Which of the following will be required to be done in order to reduce sulphur corrosion of Main Engine components 1

Increasing the atomization pressure of fuel injectors

2

Fitting exhaust valves with valve rotators

3

Running engine at or near normal sea load

4

Decreasing the F.O. purifier feed rate, running two purifier in series one acting as purifier and other as clarifier ANS C

NOTE: Running at normal sea load will maintain the cylinder temperature above dew point, by which chances of sulphur corrosion will be less. 156. A ball valve is found leaking in service and needs to be overhauled. What type of repairs can be carried out? 1

The ball and seat can be lap together

2

The ball can be machined while the seat can be replaced

3

Normally both the non-metallic seats get worn out and have to be replaced

4

Normally ball gets damaged and has to be replaced ANS C

NOTE: Normally the seat material is softer and it worn out first. When it’s leaking the seat has to be replaced. 157. When A/E stand by F.O. heater in use of main engine 1

Sudden opening F.O. inlet valve pressurized and damage the heater

2

F.O. in vapour lock inside heater allow steam

3

F.O. inlet valve causes pressure drop M/E F.O. pressure standby water is not pressurized may cause sudden change in engine /per load/rpm

4

heater leaking ANS C

158. Not preventing cold corrosion in M/E component 1

Running engine at high load

2

J/W cooling temperature high

3

High TBN cylinder oil

4

Cooling charge air in air cooler below dew point ANS D

NOTE: Cooling charge air below dew point will increase the risk of water condensation inside the cylinder which can mix with sulphur to produce sulphuric acid and cause corrosion. 159. The function of an accumulator on the discharge side of a reciprocating bilge pump is to 1

Supply liquid even when the pump is not running

2

Dampen out the pressure pulses and smoothen the flow

3

Increase the discharge pressure by storing liquid under pressure

4

No such device is required to be fitted to modern bilge pumps ANS B

NOTE: The function of an accumulator in reciprocating pump is to steady the flow in the discharge section of the pipe and dampen the pressure surge on discharge side. 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. 160. Which of the listed operations will cause an automatically controlled refrigeration compressor to restart? 1

Closing of the solenoid valve

2

Closing of the expansion valve

3

An increase in the suction pressure

4

Decreasing the suction pressure ANS C

NOTE: Automatic operation of refrigeration compressor depends on LP cut out. LP cut out automatically starts the compressor when there is an increase in suction pressure above set pressure. 161. The discharge head of a centrifugal pump will vary directly with the 1

Change in impeller diameter

2

Square of the impeller diameter

3

Cube of the impeller diameter

4

Impeller efficiency for large changes in the size of the impeller ANS B

NOTE: According to Mc GEORGE in case of a constant speed pump the head varies as the square of the diameter, the capacity varies as the diameter and the power varies as the cube of the diameter. 162. The gland of main sea water pump was leaking badly. You have renewed all the packings using packings of correct size and specification. After starting the pump, you see that the pump gland is still leaking badly and doesn’t stop even after tightening of gland. What is the most probable cause? 1

The packings used are duplicate and should be replaced with the original

2

The cooling water supply to lantern ring is clogged

3

There is some scale formation on the shaft in way of gland packings

4

The shaft sleeve is scored and needs replacement ANS D

NOTE: As the packing is good sleeve might not be properly finished to give perfect sealing. 163. What is the purpose of the Bypass valve (Automatic or Manual operated) on the positive displacement pump? 1

Control the Discharge Pressure

2

Another valve provided for Discharging

3

Not required

4

I don't know ANS A

NOTE: According to Mc GEORGE bypass or relief valves are often fitted with automatic volume control valves which control the output of the pump in order to maintain either a constant pressure or a vacuum at a specific point in the system, as

in diesel engine lubricating oil supply to ensure constant pressure at engine inlet irrespective of oil viscosity. 164. You have a two stage centrifugal pump, with both stages in parallel configuration. After dismantling the pump you realize that you forgot to the marking and both impellers are identical. Both the impellers are single entry type and the eye of both the impellers will come in opposite direction what are you going to do? 1

Since marking was forgotten, so we need not worry, any impeller can come in any place as they are identical

2

Any impeller can come in any place, but the phase sequence of the electrical motor driving the pump may have to be reversed, if impellers have exchanged places

3

You have to find out the right placement of the right impeller with respect to the direction of rotation or by looking at the volute casing

4

Hit n trial method can be utilized for fitting the impellers ANS C

NOTE: If we don’t fit the impellers in correct position as per their direction of rotation then they are not going to serve the purpose. 165. Boiler corrosion is prevented above 100 deg by formation of a protective layer inside of 1

Ferrous hydroxide

2

Magnetite

3

Hematite

4

Iron sulphate ANS B

NOTE: According to REEDS BOILER hydrazine reserve is essential for maintaining the black magnetite (Fe3O4) layer, removing oxygen and keeping the

water in a reducing condition. According to REEDS GENERAL caustic corrosion results in the destruction of the protective magnetic oxide of iron film (Fe3O4) and the base metal is then attacked by the concentrated sodium hydroxide. 166. Removable sleeves on centrifugal pump shaft 1

Make easier to replace pump shaft packing

2

They can be economically replaced as they wear out

3

To lighten weight of pump

4

Increase strength of shaft ANS B

NOTE: Basically to protect shaft from erosion, corrosion and wear sleeves are provided so that in case of more damage we can replace the sleeve no need to replace the whole shaft. 167. Boiler pump operate at an elevated temperature and pressure. The ideal materials for the pump casing and impeller should be 1

Gunmetal casing, al bronze impeller

2

High grade CI casing, bronze impeller

3

Cast steel casing, SS impeller

4

Cast steel casing, al bronze impeller ANS C

NOTE: According to Mc GEORGE boiler feed pump casing is of cast steel, shaft and impeller are of stainless steel. 168. Direction of rotation of centrifugal pump is reversed by changing the motor connections 1

Pump will deliver the liquid in reverse direction

2

Pump discharge and capacity will be affected

3

Efficiency will decrease

4

Casing get overheated ANS B C D

NOTE: If the direction of rotation is reversed then the impeller will do nothing but churn the liquid inside it. So the discharge and capacity will affect. Temperature of the liquid can go up due to churning action. Casing temperature can also increase. Overall efficiency will be affected. There is a big difference between the terms "Reverse Rotation" and "Reverse Flow" related to the Centrifugal Pump. Reverse Rotation means that the direction of the rotation of the Impeller is reversed. This may be caused by the reversal of the direction of the driving motor by the reversing of the wiring connections. In this case there will be no difference in the Operation of the Pump principally. That means the Pump would still continue to deliver the fluid from the low pressure suction side to the Higher Pressure Delivery side in the positive direction of flow. But the fact is that the flow would not be generating the flow characteristics and parameters according to the original design. The flow would certainly be forward directed but there will be jamming in the flow and pressure heads would drastically change affecting the discharge. This is actually happening because of the original design of the Involutes Casing of the pump and the location of the Discharge tube. The Volute casing and Discharge tube are designed and located according to “the Direction of Rotation of the Pump" which is pre determined for a particular design. The Impeller type used (open flow, closed, mixed type) and the Volute Casing designed as per the original pump specifications will be responsible for the actual type of discrepancy in the pressure head and the flow characteristic observed and will vary from pump to pump. But certainly the changed flow pattern (though forward directed) will reduce the efficiency and cause bubbling etc. in the flow chamber eventually affecting the efficiency of the pump and reducing the discharge. There may be cavitation observed in the larger sections of the volute chamber and the pressure head will be affected accordingly. But as far as the Basic Pumping action is considered the Pump would still continue to pump the fluid in the Positive Discharge Direction. 169. Main engine is running but viscosity of fuel cannot be maintained. Fuel oil heater has a maximum rating of 4 bar steam pressure. Steam through a pressure reducing valve is provided to the heater at 4 bars but still viscosity of fuel cannot be brought down below 20cst. As a good marine engineering practice what will you do?

1

Let the engine run at same rpm n wait for the port to come to carry out the cleaning of heater

2

Reduce the rpm till next port arrives n then clean the heaters

3

Increase the steam pressure by adjusting the setting of steam reducing valve

4

Stop the engine and clean the heaters ANS D

NOTE: With high viscosity engine will have difficulty in firing and cause irregular running. So we cannot continue to run the engine at high viscosity. We also cannot increase steam pressure more than the maximum rating. So we have to stop the engine and clean the filters. 170. Fuels as produced in a refinery are generally sterile, however contamination can occur as fuels are 1

Stored at the refinery

2

Stored on the vessel

3

Transported to the distribution sites

4

All of the above are correct ANS D

171. Which of the following statements concerning antifriction bearings installed on pumps is true? 1

The inner race should be free to turn on the shaft

2

The outer race should be free to turn its housing

3

Alignment is not a critical factor in their installation

4

They are usually pressed on to their shafts ANS D

NOTE: Antifriction bearings are nothing but the ball or roller bearings. The inner race is fixed to the shaft and the outer race is fixed to the bearing housing. The only thing which free to rotate is balls or rollers. If alignment is not proper then load distribution among the balls will be unequal resulting damage to the bearing. Here last option is the best one. 172. The water from discharge side of the a centrifugal pump is supplied as sealing water to the stuffing box for the pump shaft at 1

Sealing ring

2

Shaft sleeve

3

Lantern ring

4

Neck bush ANS C

NOTE: The pumped liquid is supplied as sealing water sometime act as cooling water also to the stuffing box for the pump shaft at lantern ring. 173. After overhauling pumps, pumps cannot be turned freely by hand. The possible cause could be 1

Uneven tightness of the casing Nuts

2

Gasket between the casing too thin

3

Big clearance between the wear Ring

4

Only A

5

Both A and B ANS E

174. Resistance testing should be ideally done on electrical equipment when the equipment is 1

Cold

2

Hot or at working temperature

3

In operation

4

At part load ANS B

NOTE: When measuring resistance the equipment must be dead. At working temperature readings are better. 175. Auxiliary engine crankpin bearings are normally renewed 1

At each de-carbonization

2

At alternate de-carbonization

3

At 10000 hours interval

4

After checking the bearings wear down ANS D

NOTE: In DAIHATSU engine manual its 20000 hours. 176. It is a known fact that centrifugal pumps require priming for pumping liquids, as they can’t handle air and will lose suction due to air entry. But on the other hand turbochargers use centrifugal compressors for supercharging. Which of the following do you think makes a centrifugal compressor to pump air and behave differently than the centrifugal pumps? 1

Presence of air cooler

2

Presence of labyrinth seal

3

High speed of rotation, very fine internal clearance and large impeller diameters

4

Difference in the principle of operation ANS C

NOTE: According to REEDS motor the air from the inducer enters into the eye of the impeller and flung radially outward at increasing velocity due to the centrifugal effect at high rotational speed. At discharge from the impeller it passes to the diffuser where its velocity is reduced in the divergent passages thus converting its kinetic energy into pressure energy. 177. Which of the following cannot be removed from fuel oil by centrifugal force in the purifier and micro filtration? 1

Sodium

2

Aluminum and silicon

3

Vanadium

4

Ash ANS C

178. Sudden opening or closing of sea water pipe can cause 1

Cavitation

2

Water hammering

3

Steam hammering

4

No problem ANS B

NOTE: High initial velocity of water will cause severely water hammering in the pipelines. 179. Steam stop valve is eased off its seat during boiler start up for? 1

To allow thermal expansion of parts

2

To allow steam flow during start up

3

To prevent water hammer

4

All of the above ANS A

NOTE: To prevent water hammer we open the drain of main steam line. To warm up main steam line and parts we normally crack open the steam stop valve. 180. Which of the following is the material is used to manufacture tube plates of a shell and tube type heat exchanger? 1

Cupro nickel

2

Aluminum brass

3

Admiralty brass

4

Gunmetal ANS C

NOTE: Cupro nickel and aluminum brass are used for tubes. Naval brass (60% Cu 40% Zn 1% Sn) and admiralty brass (69%-Cu 30%-Zn 1%-Sn 0.02-0.06% As) are used for tube plates. 181. Throttling of suction valve of screw pump? 1

Alter discharge capacity

2

No alter discharge capacity

3

Alter fluid density

4

Alter fluid pressure & density ANS A

NOTE: Throttling of suction valve of screw pump will only affect the discharge quantity and the suction pressure. If we close the valve more less liquid will get sucked into the pump and less liquid will also discharge. 182. Reciprocating compressors lines are fitted with a _______ to keep the discharge free of pulses

1

Accumulator

2

Unloader

3

Safety valve

4

Pressure reducing valve ANS A

183. Boiler not starting in 2-3 time, what do we do? 1

Check fuel ignition system

2

Check fuel burning system

3

Check furnace

4

All above ANS D

184. Sea chest is to be cleaned and you found that the filter is stainless steel bucket type filter, inside which there is a zinc anode. The purpose of the anode is to __________ and should be electrically _________ with filter body. 1

Stainless steel filter, isolated

2

Mild steel body, continuous

3

Protect adjacent pipelines, continuous

4

Sea chest, isolated ANS C MULTI B C

NOTE: The body or pipelines are made of mild steel and the filter is made of stainless steel. Mild steel can corrode preferentially to stainless steel. If we put zinc as anode then being less noble it will corrode first saving them. 185. Sewage air compressor frequency of starting

1

Every 18 hour

2

Every 24 hour

3

Continuously

4

Once in two week ANS C

NOTE: According to Mc GEORGE in order to exist, the bacteria need a continuing supply of oxygen from the air and sewage wastes. If plant is shut down or bypassed or if the air supply fails, the bacteria die and the plant cannot function correctly until a new bacteria colony is generated. So in order to fulfill this requirement the air compressor has to run continuously. 186. After removing all the bonnet securing nuts of a large size globe valve it is found that the bonnet is not coming out because of strong adhesion of the gasket between the bonnet and the body. What are you going to do in line with the best practices? (choose the best alternative) (single answer) 1

A chain block can be hooked onto the hand wheel and bonnet should be (freed out of gasket adhesion) lifted clear of the valve body

2

Hammer the valve bonnet and the bridge from all sides using a big hammer until the bonnet is free

3

Use a hammer and chisel and try to force the chisel in, at the joint of bonnet and body equally from all the sides until the bonnet is clear

4

Try to close the valve disc further onto the seat by turning the hand wheel in closing direction so as to jack-up the bonnet ANS D

NOTE: Usually it is combination of all depending on the strength of adhesion. 187. Double entry impeller of centrifugal pump 1

Increases axial thrust

2

Increases motor load

3

Reduces Load on pump bearings

4

Increases load on pump ANS C

NOTE: In case of double entry impeller theoretically the hydraulic forces are balanced but practically it is not possible due to the construction of pipelines and the motion at which the fluid is entering into the impeller. But eventually the load and the thrust are lesser as compared to other types. 188. Corrosion resistance of stainless steel in presence of oxygen in aerated water? 1

Oxygen inhibits chemical reaction

2

Oxygen combines with stainless steel to form passive oxide layer

3

Oxygen gets absorbed into stainless steel ANS B

NOTE: Stainless steel forms an oxide film spontaneously on exposure to oxygen in air or aerated water. Without this oxide film their corrosion resistance is only slightly better than normal engineering steels but with it they act as noble alloys. The corrosion resistance of stainless steel in sea water is dominated by the ability to maintain and repair the passive oxide film. 189. Before starting either a centrifugal pump or a priming pump, it should be ensured that _____ is at the correct level 1

Lube oil

2

Sealing water

3

Fuel oil

4

Sealing oil ANS B

NOTE: During starting of a centrifugal pump the most important thing is priming. So sealing water is important factor. 190. The amt of current required for ICCP depends upon 1

Wetted surface area

2

Quality and condition of protective paint coatings

3

Speed of the ship

4

Sea water temperature ANS A MULTI ALL

NOTE: According to D.T. HALL changes in underwater hull area, speed, water temperature, salinity and paint condition will all cause the anode currents to vary in ICCP system. 191. Which of the following anodes of ICCP can be used for comparatively higher current densities? 1

Zinc

2

High silicon iron

3

Lead silver

4

Platinized titanium ANS D

192. What could be the reason if feed pump can hardly pump in water to the auxiliary boiler causing cascade level to rise and temp too high? 1

High ambient temp

2

Clogged condense water tubes

3

Filter dirty

4

Low cascade water level

ANS B NOTE: High temperature of feed water reduces NPSH, pump looses suction. 193. #1 cargo tank has a cargo A with specific gravity of 0.7 and #2 cargo tank having cargo B with specific gravity of 1.05. #1 cargo pump is taking suction from #1 cargo tank while #2 from #2 and both is pumping shore to two identical tanks. #1 and #2 cargo tanks both are identical and both had same sounding during starting. Pumps are also identical and placed in pump room. Discharge manifold and shore pipelines for both the cargoes are identical and discharge valve for both are fully open. What will be the discharge pressure reading of both the pumps? 1

#1 discharge pressure will be higher than 2nd one

2

#2 discharge pressure will be higher than 1st one

3

Both will be same as pipelines are identical

4

Can’t say anything as discharge pressure will be affected by various other parameters ANS B

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. 194. Which is biggest? 1

NPSH

2

NPSHA

3

NPSHR

4

Total suction head ANS D

NOTE: Total suction head – vapor pressure head is NPSH. 195. Carbon content in steel? 1

Less than 1%

2

Less than 2 %

3

Less than 3 %

4

Any carbon content ANS B

NOTE: 0.05-2.0% 196. Screw pump normally used for 1

Fluid with high viscosity

2

For better performance at variable temp

3

Fluid mixed with solids

4

All above ANS A

NOTE: According to Mc GEORGE screw pumps are used at sea especially for pumping high viscosity liquids such as oil and some liquid cargoes. 197. Centrifugal pump required priming because they are unable to handle 1

Volatile liquid

2

High temp liquid

3

Lighter liquid

4

Air & gas ANS D MULTI A D

198. A centrifugal pump may fail to deliver water when first started if the _________ 1

Water seal pipe is plugged

2

Pump is not primed

3

Seal ring is improperly located

4

Impeller is flooded

ANS B 199. In a centrifugal pump sealing between gland packing and bearing housing is provided by_____ 1

Shaft seal

2

Water flinger

3

O-ring

4

Lantern ring ANS B

200. Two compressors should not run in parallel because 1

It’s not efficient

2

It will give overcapacity in the system

3

There is possibility of losing oil from one compressor to other

4

Both a and b ANS C

201. Less vacuum in centrifugal pump 1

Leaky discharge valve

2

Loss of gland packing

3

Loss of fluid from suction tank

4

Long suction pipe ANS B MULTI B D

NOTE: There is a chance of sucking air from the gland packing area. So vacuum will be less. 202. Sewage plant blower is off, what is the ideal alarm 1

Blower suction pressure low

2

Blower disc pressure low

3

Blower motor fail

4

None of the above ANS D

NOTE: Sewage treatment plant abnormal. 203. Which of the following will cause cavitation 1

Low discharge pressure

2

Throttling the suction valve

3

Low water level in the wet well

4

High discharge pressure ANS B MULTI B C

NOTE: Throttling of suction valve may cause the pressure to fall below vapour pressure which will cause cavitation. Low suction head causes low NPSH.

204. With reference to centrifugal pump characteristics what will be the effect when pump is started with suction valve closed or discharge valve closed (single answer) 1

Suction valve shut head & flow rate will be 0; discharge valve shut flow rate will be 0 and head will be maximum height

2

Suction valve shut head will be 0 & flow rate will be minimum, discharge valve shut flow rate will be 0 head will be minimum height

3

Suction valve shut head and flow rate will be 0; discharge valve shut flow rate will be minimum and head will be at min height

4

None of the above ANS A

NOTE: According to the characteristic diagram if suction valve is shut then flow and head both will be zero. If discharge valve shut then flow will be zero and head will be at maximum. 205. The overheating of fuel oil in the fuel oil heaters may result in 1

Excessive atomization

2

Clogged fuel oil heaters

3

Ineffective straining of fuel oil

4

Low fuel service pump discharge pressure ANS B

NOTE: According to DEVEN ARANHA atomization depends on fuel temperature and viscosity. If we overheat the fuel excessive atomization can occur. High temperature will cause lower in density so the pressure developed by the service pump will also be low. USCG BOOK 13 QUES 1348 ANS IS B 206. In refrigeration system vegetable room and meat room are maintained at different temperature by 1

Different expansion

2

By putting solenoid valves

3

By boiling refrigerant at different pressures

4

By using smaller evaporator ANS B

NOTE: According to Mc GEORGE the temperature of the refrigerated spaces with a direct expansion system is controlled between limits through a thermostatic switch and a solenoid valve which is either fully open to permit flow of refrigerant to the room evaporator or closed to shut off flow. 207. The best way to clean compressor impeller of an auxiliary engine turbocharger would be 1

By soaking it overnight in a strong chemical solution like carbon remover or air cooler cleaning chemical

2

By chipping the dirt off the impeller blades

3

By using a pneumatic wire brush

4

By soaking in warm water and then cleaning it gently by rags ANS D

208. For any pump maximum theoretical lift is 1

10.5 feet

2

10.2 meter

3

10.5 meter

4

12.0 meter

5

None ANS E

NOTE: According to Mc GEORGE the theoretical suction lift of a pump at sea level with water at 150C is 1.013 x 10.2 = 10.3 meter where the barometric pressure is 1.013 bar (1 atm) and 10.2 meter is the head of water equivalent to 1 bar. 209. De sludging sequence for purifier? 1

Stop feed- give sealing water- close sealing water- shut operating wateropen and close de sludging water quickly

2

Stop feed-shut operating water- open and close de sludging water quickly

3

Shut operating water- stop feed- open seal water for short time- close open and close de sludging water

4

Shut operating water- stop feed- open and close de sludging water quickly ANS A

210. Globe valve is in operation. It is seen that the gland packing is leaking, when valve is in throttled condition, tightening of gland packing doesn’t stop the leakage. What is the reason? 1

Valve spindle was badly scored in a way gland packing while throttled. While movement of the spindle cause smooth portion of valve spindle to come in the way of packing thus stop leak

2

Valve spindle was bent and eccentric of spindle in way of gland packing decreased while valve was opened completely thus provide better seal in good position

3

Almost all globe valve are designed with back seat and spindle seat itself on the back seat when fully open thus packing stopped leakage

4

Leakage sometimes just stops and it has nothing to do with any of the above ANS A

NOTE: If the spindle itself is badly scored then the gland packing is not going to provide perfect sealing. 211. In A/C room people complained of being too cool the problem might be

1

Relative humidity high

2

Air velocity low

3

Heater failure to cut out at proper temperature

4

Relative humidity low ANS D

NOTE: USCG 4464 D BOMBE 4 212. Purpose of balancing hole on single entry enclosed type impeller of centrifugal pump 1

Static balancing of impeller

2

Dynamic balancing of impeller

3

Balance out axial thrust on the impeller & hence the shaft

4

To reduce weight of impeller at the same time of dynamic balancing the complete rotating assembly ANS C

NOTE: To eliminate the axial thrust of a single suction impeller, a pump can be provided with both front and back wear rings. To equalize the thrust areas, the inner diameter of both rings is made the same. Pressure approximately equal to the suction pressure is maintained in a chamber located on the impeller side of the back wearing ring by drilling balancing holes through the impeller. Leakage past the back wearing ring is returned to the suction area through these holes. However, with large single stage single suction pumps, balancing holes are considered undesirable because leakage back to the impeller suction opposes the main flow, creating disturbances. In such pumps, a pipe connection to the pump suction replaces the balancing holes. 213. Primary advantage of central cooling system is 1

More simplified cooling circuit

2

Most part of the cooling system being fresh water based, corrosion is minimized

3

It allows better control of temperature by using fewer controllers

4

All of the above ANS B

NOTE: According to Mc GEORGE the corrosion and other problems associated with salt water circulation systems can be minimized by using it for cooling central coolers through which fresh water from a closed circuit is passed. 214. Which of the following is false statement about galvanic corrosion? 1

Metals close to anodic end of the series corrode in preferentially to those near cathodic end

2

When single metal exist in the system galvanic corrosion doesn’t take place

3

Zinc is anodic to steel and used as a protective coating

4

Corrosion rate is affected by temperature ANS B

NOTE: Alloys can corrode on their own in presence of favorable condition. 215. Double entry impellers have advantage over single entry impeller. What is it? 1

They balance out axial thrust

2

It gives a higher pumping efficiency

3

It is cheaper and easier to manufacture

4

The need of installing line bearing onto the pump shaft is eliminated ANS A B

NOTE: For the general service single stage axially split design, a double suction impeller is favored because it is theoretically in an axial hydraulic balance and because the grater suction area of a double suction impeller permits the pump to operate with less net absolute suction head. 216. HSS are 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 A

NOTE: Normally high speed steels are used for cutting tools. So they are alloyed with different metals like chromium, tungsten, vanadium, cobalt, molybdenum and given with high carbon percentage, more than 0.7% to make them strong enough for this use. 217. Non return valve of main sea water pump is leaking in closed position. You have a return type of valve onboard of same dimension. What will you do? 1

Do nothing and run same pump order for a new one

2

Replace and run the same pump keeping the other standby until new valve arrives

3

Put blank on the valve and run other pump

4

ANS B 218. In a electro- hydraulic steering gear, the movement of actuator is created by _______________________ 1

Starting the motors on both power units

2

Operating the isolating valves

3

Starting at least one power unit and actuating the direction valves

4

Starting both power units and actuating the direction valves ANS C

NOTE: To get hydraulic pressure for the movement of actuator we need to start at least one power unit. Direction valve if actuated will allow the flow of pressurized oil into the system. 219. A retarded fuel injection timing can be due to 1

Worn timing chain

2

Incorrect VIT setting

3

Worn fuel pumps

4

All of the above ANS D

220. The side thrust due to the oscillatory movement of the con-rod in a 2-stroke trunk type engine will be taken by 1

Crosshead guide and shoe

2

Piston and liner

3

Crosshead and piston rod

4

Crank pin and the crosshead pin ANS A

221. Scaling of boiler tubes from within will lead to overheating of the tubes. How does it affect the boiler operation? 1

It doesn’t affect the boiler as the boilers are designed to run with scaling of tubes

2

Excessive overheating may lead to tube material oxidation as well as loss in strength at elevated temperature leading to tube failure

3

If tubes are overheated, it will lead to greater steam generation

4

The natural circulation of water will be effected ANS B

NOTE: According to GTH FLANAGAN overheating is caused due to loss of cooling effect caused by loss of circulation and scaling. Due to overheating metal loses its strength and distorts. This can result in expanded tubes pulling out of tube plates, local bulging of tube surfaces with eventual rupture, the sagging of super heater tubes between their supports. 222. In modern 2-stroke marine diesel engines, the combustion chamber is designed to have a _____________ shape to suit 3 fuel injector used 1

Cylindrical

2

Toroidal

3

Cycloidal

4

Spherical

223. One function of the fuel pump delivery check valve is to 1

Prevent carbon deposits from forming on the injector nozzle

2

Help the injector needle reseat without dribbling at the nozzle holes

3

Provide a prolonged pressure drop in the high pressure steel piping to the injector

4

Ensure a fuel leak off between the plunger and barrel which provides lubrication for relative movement ANS B

224. A control action which produces a corrective signal relative to the length of time the controlled variable has been away from the set point, is known as 1

Integral action

2

Proportional action

3

Rate action

4

Derivative action

225. Which of the following is one of the major advantages of resin chocking over cast iron chocking, in holding down arrangements of modern diesel engines? 1

Better vibration damping properties

2

Better compressive strength

3

100% contact, no need for surface preparation

4

None of the above ANS C

NOTE: According to DEVEN ARANHA resin chocks gives 100% contact on uneven surfaces. 226. The over speeding of the diesel engine driving an electric generator could cause 1

Low voltage trip to trip

2

Reverse power trip to trip

3

Damage to windings

4

Excessive exhaust temperatures ANS C

227. How do you know that a ballast pump is taking suction or not? If a ballast pump is taking good suction it will depend on the available suction head and a positive discharge pressure. To confirm if the pump is still pumping, throttling of suction valve will lead to a fall in suction& discharge pressure, while throttling of discharge valve will to a rise in suction and discharge pressure show (single answer) 1

Positive suction pressure and positive discharge pressure

2

Negative suction pressure and positive discharge pressure

3

Negative or positive suction pressure depending on the available suction head and a positive discharge pressure

4

Negative or positive suction pressure depending on the available suction head and a positive discharge pressure ANS A

228. Viscosity of fuel oil used for M/E was 14.5 cst. New fuel comes whose viscosity is more than earlier. What should you do? 1

Increase temp setting

2

Change setting of viscotherm

3

Do nothing

4

Open steam valve manually more ANS C

NOTE: Viscosity of fuel to the engine is maintained at set point by viscotherm by opening the steam valve automatically. If the new oil is having different viscosity then in order to maintain the viscosity at correct value the viscotherm will open the steam valve accordingly. We don’t need to do anything manually. Assuming the viscotherm is working absolutely fine. 229. Pump driven clutch type attached vacuum pumps are commonly used for priming ballast pumps and emergency fire pump. What is the factor which de-clutches the vacuum pump from the pump clutch?

1

Low suction pressure acting against the spring loaded declutching piston

2

High suction pressure acting against the spring loaded declutching piston

3

Low discharge pressure acting against the spring loaded declutching piston

4

High discharge pressure acting against the spring loaded declutching piston ANS D

230. How many power strokes per crank shaft revolution are there in an eight cylinder two stroke diesel engine? 1

One

2

Two

3

Four

4

Three ANS A

NOTE: In a two stroke engine power stroke is achieved in one revolution of crank shaft. 231. By using which of the tank we can change the draft but not changing trim of the ship 1

peak tank

2

DB tank

3

Deep tank

4

Top side tank ANS C

NOTE: None of these are correct. Tank cg should be at centre of floatation for no change in trim. But assuming DB tank is in the center option (b) can be correct.

232. How much is fresh water allowance? 1

5 TPC

2

10 TPC

3

20 TPC

4

40 TPC ANS D

NOTE: All wrong. Correct answer is Δ/40 TPC. According to H.J. PURSEY fresh water allowance is equal to Δ/40 TPC. 233. Which of the following option gives you the correct sequence of the metals/alloys in decreasing order of preferential corrosion when all of them are bonded and immersed in an electrolyte? (multiple question) 1

Stainless Steel, Naval Brass, Aluminum bronze, Copper

2

Aluminum Bronze, Cupro-Nickel, Monel metal, Titanium

3

Stainless Steel, Cupro-Nickel, Naval Brass, Monel Metal

4

Stainless Steel, Copper, Naval Brass, Aluminum bronze ANS A B

234. The main disadvantage of a centrifugal pump is that 1

They are only available in high capacities

2

They are difficult to maintain

3

They are not self priming in nature

4

They are extremely expensive pumps ANS C

235. The advantage of a reciprocating bilge pump over centrifugal pumps is that

1

They do not have any advantage over a centrifugal pump

2

They have greater capacity to weight ratio

3

They give a smoother discharge if used in conjunction with an accumulator

4

They are self priming in nature ANS D

NOTE: According to INTRODUCTION TO MARINE ENGINEERING BY D.A. TAYLOR reciprocating displacement pumps are self priming, will accept high suction lifts. 236. Refer compressor oil should have the following properties 1

Chemically inert with respect to refrigerant

2

Should be able to perform at lower temp (viscosity and cloud point)

3

Should have a certain emulsification properties with water

4

Should absorb water but still perform the lubrication ANS A B

NOTE: According to A. R. TROTT AND T. WELCH (REFRIGERATION AND AIR CONDITIONING) it must be compatible with the refrigerant, i.e. not form any compounds or promote chemical activity. The mixture with the refrigerant in the lubrication circuit must provide adequate lubrication of the working parts. It must not solidify or throw out any solids such as waxes, within the working range, or clog strainers or driers. It must be free of water or other contaminants which will affect the system. It must not be prone to foaming. It must be resistant to oxidation (high flash-point).It must have a low vapour pressure. For hermetic and semihermetic compressors, it must have a high dielectric strength. According to REEDS the first essential for such oil is that it should have a low pour point, i.e. must remain fluid with good lubrication properties at low temperatures. Oils which are miscible with the refrigerant can be carried round the circuit and could congeal on the evaporator coils so drastically reducing heat transfer rates. The oil should be free from moisture under all conditions to prevent plant corrosion and freezing at

the expansion valve. The viscosity should not be seriously affected at low temperature. 237. Where boiler point temp is high? 1

Riser

2

Super heater

3

Primary steam drum

4

Secondary steam drum ANS B

238. IR testing of 3 phase induction motor is done across 1

Phase to phase

2

Earth to body

3

Phase to earth

4

Both a and b ANS A C

NOTE: Actually it is measured across phase to earth but in case of normal motor we check ohmic value of winding across phase to phase. In case of star delta starter used motor we may check IR across phase to phase but only after disconnecting the terminals from the starter and completely isolating the motor from the circuit because in this case the windings are not connected with each other, they are connected outside the motor in the starter panel when the motor is starting or running. According to D.T HALL for insulation resistance test on a three phase machine, measure and log the phase to phase insulation resistance values. Three readings should be measured as U-V, V-W, and W-U. Measure and log the phase to earth insulation resistance values. Three readings should be measured as U-E, V-E, and W-E. 239. Which of the following valves are designed to have valve seat in pairs - one facing the inlet side and the other facing the outlet side within the valve body?

1

Butterfly valve

2

Ball valve

3

Globe valve

4

Gate valve ANS D MULTI B D

240. Which of the following is NOT 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 A B D

NOTE: Option (c) is also not correct but best option to take sample 241. All other conditions remaining constant, when centrifugal pump is changed over for pumping a liquid of higher specific gravity, the discharge head of the pump at the rated capacity will 1

Increase

2

Decrease

3

Remain same

4

Can’t say, depends on other factors too ANS C

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. 242. Static suction head of the pump is 1

Distance of the suction liquid level above the centre line of the pump

2

Distance of the suction liquid level below the centre line of the pump

3

Force necessary to overcome frictional losses in the pump and piping

4

Amount in inches of mercury the total suction head is below atmospheric pressure ANS A

NOTE: Meaningless. 243. Which of these not self actuating valves? 1

Check valve

2

Relief valve

3

Ball valve

4

Safety valve ANS C

244. When two dissimilar metal having electrical continuity are placed in an electrolyte, the type of corrosion is (single answer) 1

Selective phase corrosion

2

Cavitation erosion

3

Bimetal corrosion

4

Corrosion fatigue ANS C

NOTE: According to corrosion pdf file when two metals of different electric potential are in contact with an electrolyte then bimetallic corrosion can occur. 245. Cavitation of centrifugal pump 1

NPSHR > NPSHA

2

NPSHA > NPSHR

3

Total suction head < NPSHR

4

Total suction head > NPSHR ANS A

NOTE: According to Mc GEORGE in actual practice always NPSHA > NPSHR. A lesser cavitation problem occurs when NPSHR by the pump is only just matched by the NPSHA from the system, because centrifugal pumps have features which promote localized cavitation. So when NPSHR > NPSHA cavitation problem will be more. 246. Cavitation erosion occurs due to 1

Chemical action

2

Physical action

3

Chemical or physical action

4

Combination of chemical or physical action ANS B

NOTE: When pressure inside a system falls below that of the vapour pressure of the liquid, cavities are formed. Cavities travelling to high pressure region collapse releasing considerable energy to damage the metal surface. It is completely a physical action. 247. Best sealing is which? 1

Globe valve

2

Butterfly valve

3

Gate valve

4

Ball valve ANS C D

248. Protection by zinc protective coating is good at 1

500C

2

650C

3

900C

4

1150c ANS B

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. 249. If oil ingresses in the boiler feed water, what will be the effects? 1

Increase in tube temperature

2

Corrosion of tubes

3

Low water density

4

All the above ANS D

NOTE: According to REEDS oil can get in to feed system sue to over lubrication of machinery and inefficient filtering of the feed. Oils such as animal and vegetable oils can decompose in the boiler liberating their fatty acids, these acids can cause corrosion. Hence it is advisable to use pure mineral oil for lubrication of

machine parts where contamination of feed can result, but oil of any description should never be allowed to enter the boiler as it can adhere to the heating surfaces causing overheating. It can also cause priming due to excessive ebullition. As oil density is less than water it will lower feed water density also. 250. Centrifugal pump dismantled, without marking how to reassemble, there are three questions but options are not available 1

If pump is single stage Answer - Look at the direction of running of motor and the curvature of impeller. Construction of volute casing also gives an idea about the running direction of the pump.

2

If pump is multistage with opposite eye

5

Answer – Impellers should be opposite to each other. You have to find out the right placement of the right impeller with respect to the direction of rotation or by looking at the volute casing.

3

If pump is double entry impeller Answer - Look at the direction of running of motor and the curvature of impeller. Construction of volute casing also gives an idea about the running direction of the pump.

251. What to check if engine is not taking load? 1

Water tightness to be checked

2

Air to be removed from jacket water outlet line

3

Priming lube oil pump to run before starting the engine

4

Check the lube oil level

5

Check the flow of lube oil

6

Blow through the engine before starting

NOTE: All the above things should be checked 252. Shaft tunnel requires 1

Drain

2

Escape trunk

3

Water tight door

4

All the above ANS D

NOTE: According to D A TAYLOR the forward end of the tunnel is fitted with a sliding water tight door to seal off the tunnel if necessary. The tunnel is made of sufficient proportions to enable access for maintenance to the shafting, and an escape route is provided from the after end. According to H J PURSEY a water tight door must be fitted at the engine room bulkhead, to enable the tunnel to be sealed off in emergency, whilst an escape shaft must be provided at the after end. Drainage from the tunnel is provided for by a ‘tunnel well’. This usually formed by stopping the inner bottom plating four or five floor spaces short of the after peak bulkhead and fitting a suction in the space thus formed. 253. When securing a centrifugal distillate pump, which of the listed steps should be carried out first? 1

Stop the pump

2

Close the pressure gage valves

3

Trip the three-way solenoid valve

4

Close the sealing line valves to the pump

ANS A NOTE: According to fresh water generator manual we stop the pump first and then turn off the salinity alarm. 254. Which are self expansion condenser 1

Straight tube

2

Spring type

3

U tube

4

Open type ANS C

NOTE: U tubes are free to expand at one end. 255. Liquid ring primer used for priming main and emergency fire pumps onboard 1

Is to be filled with water in the water tank to maintain water level

2

Is to be capable of automatic engagement and disengagement with drive shaft

3

Is to have sufficient capacity to exhaust air out from pump in all sea conditions

4

All of the above ANS D

NOTE: According to Mc GEORGE the continuous supply of sealing water is circulated from the primer reservoir to the whirlpool casing and discharged with the air back to the reservoir. Automatic means of engagement is provided by a clutch or float. It should be of sufficient capacity also.

256. In case of failure of control air supply, some valves continue locked in the position they were at the time of failure. They are said to be 1

Fail safe

2

Fail proof

3

Fail set

4

Fail blocked ANS C

257. If the superheat value of a thermostatic expansion valve is set too low________ 1

The suction line of the compressor will be too hot

2

The suction line of the compressor will be too cold

3

The discharge line of the compressor will be too hot

4

The discharge line of the compressor will be too cold ANS B

NOTE: Lower the superheat value lesser the temperature at suction side of the compressor. There is also chance of liquid going to the suction side of the compressor. 258. Water carryover from boiler onboard through the steam causes(DOUBT) 1

Erosion of the steam plant machinery

2

Low water level inside the boiler

3

Build up of deposits on the steam plant machinery

4

None of the above ANS C MULTI C A

NOTE: According to GTH FLANAGAN priming and carry over must be avoided, as impurities passing over with the water will result in a buildup of deposits in the super heater tubes, again causing eventual overheating. 259. A major controlling factor in the location of the condensate return piping from a heating system is/are 1

The requirement for a gravity return

2

The requirement for short laterals run

3

The requirement to minimize conflict with headroom and other services

4

All of the above ANS D

260. How is the water circulated between water and steam drums in a water tube D type boiler? 1

By the boiler feed water pump

2

By a circulating pump outside the boiler

3

Due to difference in densities of water and steam

4

None of the above ANS C

NOTE: According to GTH FLANAGAN in Foster Wheeler D- type boiler feed water entering the steam drum flows through the down comers to the water drum to replace the water rising up through the water wall and generating tubes, as its density decreases upon receiving heat from the hot gases, thus providing the positive circulation of water required in all types of water tube boilers.

261. Water leaking from a pump packing gland is kept away from the bearing housing by the use of 1

Shaft sleeves

2

Lantern rings

3

Water flingers

4

Water seals ANS C

262. To prevent main engine stoppage during periods of bad weather 1

Ensure lube oil level is topped up

2

Ensure over speed trip override switch set up to rough sea setting

3

Ensure reduced speed setting to prevent overload

4

All of the above ANS D

263. Supercharging an existing medium speed naturally aspirated engine will 1

Reduce weight of the engine

2

Reduce bulk of the engine

3

Increase existing power

4

Increase piston speed

5

Reduce fuel consumption ANS C

NOTE: According to RITENKER SEN and DEVEN ARANHA by supercharging the engine power will increase for same engine dimension and piston speed. Thermal efficiency will be higher lowering the fuel consumption for the same power. For the same power the engine can be made of more compact design, smaller size, space and weight of engine. However according to RITENKER SEN chapter 4 question 4 page 165 for existing engine supercharging will only increase the existing power. 264. The muffling of exhaust gas noise in 4 stroke auxiliary engines in achieved by 1

Allowing the gas to expand

2

Change the direction of their flow

3

Cool the gas with injected water

4

Cool the gas with scavenge air ANS A B C

NOTE: RITENKER SEN page 15 questions 12. 265. To avoid the engine running too long on critical speed during start up it is necessary to 1

Start at speeds above critical speed

2

Start at speeds just below critical speed and quickly move across the critical speed

3

Start at maximum speed and quickly bring down to just above critical speed

4

Eliminate totally the hazards of critical speed by ignoring it ANS B

266. Both power units of a steering gear system need to be switched on ____________

1

When the ship is within 12 nautical miles from shore

2

When pilot is on board

3

When navigational circumstances demand caution

4

All of the above ANS D

267. Dezincification of brasses may be prevented by introducing which of the following additives during manufacturing brass? 1

0.04% Nickel

2

0.04% Cobalt

3

0.04%Arsenic

4

0.04%Tungste ANS C

NOTE: According to corrosion pdf file the only plain brass of interest is the alloy containing 70% copper, 30% zinc and inhibited by 0.02-0.05 % arsenic against dezincification. 268. Back pressure valve in a refrigeration system with multiple chambers is fitted_____________ 1

At the refrigerant exit end of evaporator of each chamber

2

At the refrigerant exit end of evaporators of chambers with higher temperature settings

3

At the refrigerant exit end of evaporators of chambers with lower temperature settings

4

None of the above ANS B

NOTE: Back pressure regulation valves can be used in the suction line, and their function is to prevent the evaporator pressure falling below a predetermined or controlled value, although the compressor suction pressure may be lower. It permits two or more evaporators, working at different load temperatures, to work with the same temperatures, to work with the same compressor. 269. Frequent cutting- in & cutting -out of a fresh water pump on a hydrophore system indicates which of the following? 1

Nothing abnormal

2

Excessive air charge

3

Insufficient air charge

4

The differential setting between cut-in and cut out is too low ANS C MULTI C D

NOTE: If the differential setting is too low then it is the obvious reason for cutting in cutting out of the pump. If there is insufficient air charge then the run time of the pump will increase. 270. Which of the following will result in automatic stopping of IG blower 1

Low water level in deck water seal

2

Oxygen content above 8%

3

Scrubber tower low water level

4

Scrubber tower high water level ANS A

NOTE: According to IGS pdf file for inert gas systems of the flue, gas type and the inert gas generator type, audible and visual alarms shall be provided to indicate low water pressure or low water flow rate to the flue gas scrubber, high water level in the flue gas scrubber, high gas temperature, failure of inert gas blowers, oxygen content in excess of 5% by volume, failure of the power supply to the automatic

control system for the gas regulating valve and to the indicating devices, low water level in water seal, gas pressure less than 100 mm water gauge. The alarm arrangement shall be such as to ensure that the pressure in slop tanks in combination carriers can be monitored at all times; and high gas pressure forward of the non-return devices. High oxygen content of gas in IGS main; alarms activated at an 8% concentration. A low level water alarm, high level water alarm, or low flow pressure alarm fitted to the deck water seal to shut down the IGS blowers automatically. 271. Engaging the turning gear and turning the engine until working temperatures are reduced 1

Blank starting air to the affected cylinder

2

Shut cylinder oil to the affected cylinder

3

Shut all cylinder liner ports of affected cylinder

4

Open relief valve of affected cylinder ANS A

272. The coating on a electrode used for electric arc welding _________________ 1

Creates a gas shield to prevent oxidation of the weld material

2

Helps the weld formation by shaping the metal transfer

3

Provides an electrical insulation for the user

4

All of the above ANS A

NOTE: According to HAJRA CHOUDHURY WORKSHOP TECHNOLOGY AND REEDS it helps to protect the molten metal from the oxygen and nitrogen of the air by producing a shield of gas around the arc and weld pool.

273. A diffuser is provided at the end of a mechanical atomizer in boiler onboard (multiple answer) 1

To prevent blow back of the flame

2

To mix the air and fuel properly

3

To prevent blow out of the flame

4

To eject the excess fumes from the atomizer ANS A B

274. Duty of standby person at the entrance of the enclosed compartment during enclosed space entry is 1

To alert others in case of untoward emergency

2

To provide first aid to injured person

3

To assist for the work carried out in the enclosed compartment

4

All of the above ANS D

275. Which of the following statements about the design of D- type boilers is false? 1

The heavier water in top drum flows back to the bottom drum through the down- comers outside the furnace

2

Inside the furnace the water is heated up in the risers

3

The upper drum is the steam/water drum and the lower one is the water drum

4

The feed water is pumped into the lower drum ANS D

NOTE: According to GTH FLANAGAN the feed water is fed directly to the steam drum. So, option (d) is false. Risers are the generating tubes in D-type boiler. Other options are correct. 276. If the watch keeping engineer encounters a main engine slow down alarm he should____________________ 1

Immediately cancel the slowdown in the control panel

2

If navigation circumstances permit, after consulting chief engineer he should tell bridge to stop engine, investigate the fault, rectify it in consultation with senior engineers and then prepare for restarting the engine

3

He should raise engineer's alarm and wait for all engineers to reach the engine room

4

He need not take any action and wait for the alarm to resolve on its own and then cancel the slowdown ANS B

277. Which of the following types of coatings used in tanks of a chemical carrier provides a comprehensive protection against most solvents? 1

Epoxy coatings

2

Polyurethane coatings

3

Zinc silicate

4

Phenolic resins ANS D

NOTE: According to Mc GEORGE all of the above coatings are used in tankers of a chemical tanker. Phenolic resins have good resistance to strong solvents and most of the substances acceptable to the other coatings. 278. Presence of catalytic fines in fuel oil is significant to engineers on board because_____________ 1

Catalytic fines tend to impair proper operation of purifiers

2

Catalytic fines lead to abrasive wear in liners , piston rings and fuel injection equipment

3

Catalytic fines necessitate increase in injection temperature

4

Catalytic fines necessitate increase in storage temperature ANS B

279. A partial opening of which of the following kinds of valves can lead to wire -drawing of its seat? 1

Globe Valve

2

Butterfly valve

3

Gate Valve

4

Full bore angle valve ANS C

NOTE: According to Mc GEORGE gate valve is not suitable to partially open operation since wire-drawing of the seat will occur. 280. Which of the following types of steam traps uses the pressure energy of the steam to close the outlet? 1

Thermostatic trap

2

Thermodynamic trap

3

Mechanical trap

4

Vacuum trap ANS B

NOTE: According to Mc GEORGE thermodynamic type of trap uses the pressure energy of the steam to close the valve which consists of a simple metal disc.

281. Sequential starting of machineries after black out in engine room is necessary 1

To prevent overload of Generators

2

To quickly restore the failed power supply in order

3

To prevent damage to machinery which has been switched off

4

All of the above ANS A

282. Positive displacement, helical gear pumps are well suited for pumping oil because 1

Stuffing boxes eliminate the leakage problems usually associated with other gear pumps

2

It is not necessary to closely maintain design clearances this pump

3

They are essentially self-priming and produce a high suction lift

4

These pumps are designed with extreme tooth angles ANS C

NOTE: According to Mc GEORGE these pumps are used at sea specially for pumping high viscosity liquids such as oil and some liquid cargoes. Being self priming and able to pump liquid and vapour without loss of suction they are particularly useful when draining tanks of high vapour pressure liquids. 283. Scale formation in a fresh water generator evaporator can lead to ____________________ 1

Impaired heat transfer

2

Reduced capacity

3

Increased shell temperature

4

All of the above

ANS D 284. Salinity of distilled water produced from fresh water generator onboard depends on 1

Amount of feed set in fresh water production

2

Amount of salt water leaking from condenser if any

3

Temperature of the sea water used

4

Efficiency of brine ejector from the evaporator shell ANS A B D

285. Prior to major overhaul of main engine onboard, the engine room crane is tested by 1

Operating the crane through the normal range

2

Testing of the crane with two sample ???abnormal??? conditions

3

Inspection of the crane hook and other safety arrangements

4

Stress testing of crane wire with peak loads ANS C MULTI A C

286. A high pressure differential in a main engine fuel oil filter onboard can be best reduced by 1

Back flushing the filter manually

2

Stopping the main engine to change the filter element

3

Changing over to stand by filter if provided

4

None of the Above ANS C MULTI A C

287. When there is excessive ingress of water in the engine room onboard causing dangerous levels of bilge water 1

Start oily water separator and pump overboard

2

Start General service pump and pump bilges overboard

3

Use bilge injection valve and pump bilges overboard

4

None of the above ANS C MULTI B C

288. The by-products of oxidation, as a result of water contamination of hydraulic oil, are generally 1

Removed by cellulose type filters

2

Gums, varnishes, and acids

3

Always neutralized by oil additives

4

Harmless and have no effect on system components ANS B

NOTE: USCG book 11 question 6 289. Short cycling of a fridge compressor can occur in which of the following cases? 1

Air ingress into the system

2

A leaking solenoid valve

3

High cooling water temperature going to the condenser

4

Excessive refrigerant charge ANS B

290. A ballast pump is use to de ballast a fore peak tank which is full. It is seen that suction pressure is positive and discharge pressure is very low compared to rated discharge head. It indicates that (single answer) 1

Pump is not operating satisfactorily and pumping capacity is too low

2

Pump is not operating satisfactorily and pumping capacity is higher than rated, throttling of discharge valve is required

3

Pumping capacity is not affected by suction and discharge pressures

4

Pump is operating normally ANS A

291. Which of the following valves is liable to open or close under influence of fluid pressure if not locked in position (single answer) 1

Gate valve

2

Globe valve

3

Plug valve

4

Butterfly valve ANS D

292. An engine room should be _________ for better performance of turbochargers (single answer) 1

Slightly under pressurized

2

Slightly over pressurized

3

Substantially under pressurized

4

None of the above

ANS B 293. Impingement corrosion can be best avoided during pipeline system design by (single answer) 1

Keeping flow velocity to a minimum

2

Keeping fluid temperatures low

3

Avoiding conditions leading to cavitation and turbulence

4

Keeping working pressures in the system high ANS C

NOTE: According to Mc GEORGE to avoid the impingement attack, care must be taken with the water velocity through tubes. For aluminum brass, the upper limit is about 2.5 m/s. 294. On centrifugal pump the impeller is generally (single answer) 1

Shrunk fit on the shaft

2

Welded on to the shaft

3

Key fit on the shaft

4

Held with a shaft with a holding nut ANS C

295. Last month you found one globe valve with a stuck spindle, the valve was stuck in crack open position. You had removed the valve and replaced it with a spare one. Today you have found that spindle of one butterfly valve is stuck with valve about half open position. What are you likely to do? (Choose the best alternative) 1

Remove the butterfly valve from flanges in the pipeline and replace the entire valve

2

It is not possible to remove a butterfly valve stuck in open position. Either the spindle has to be freed somehow or the pipe section on one side has to be removed to create a gap to remove the open valve

3

There is no need to remove the valve from pipeline and it can be overhauled in place

4

You will hammer the valve body and the spindle using a hammer to free the spindle before trying to remove the valve from pipeline ANS B

296. An inverted gate valve (stem pointing downward) may be subject to wear sooner than a similar valve installed in the upright position because ______________ 1

The gate's full weight is upon the stem

2

The gland stud nuts are under more pressure

3

Sediment collects in the bonnet

4

The packing will not properly adhere to the stem ANS C

297. The gasket and the broken studs have been replaced on a tank manhole cover. Which of the following methods is satisfactory for testing the repair? 1 Pressurize the tank with 10 psig air, soap the repaired area, watch for visible signs of leakage or bubbles 2 Fill the tank with water via the ballast pump until the reading corresponds to the maximum depth of the tank 3 Hose test the repaired area with a minimum of 100 psig water pressure 4 Fill the tank via the ballast pump until water flows from the vent line opening on deck ANS C NOTE: USCG book 11 question 130

298. 1 2 3 4

Pipe threads are cut with a taper to Prevent over tightening the joint Provide a leak proof fit Permit easy joint disassembly Produce a fine even thread ANS B NOTE: USCG book 11 question 102 299. Exhaust gas boiler fire suitable measures 1 Frequent soot blowing 2 Increase engine speed to blow soot 3 Stop cooling water circulation to avoid leakages 4 None of the above ANS D 300. Which of the crankshaft is lighter, if same power required 1 Welded type 2 Forged type 3 Semi built 4 Fully built ANS A NOTE: According to DEVEN ARANHA welded type crank shaft is the lighter one. 301. Evaporator pressure testing in (multiple answer) 1 Pressure testing in shell 2 Leak test in vacuum pump n fittings 3 Leak test in distillate pump 4 Vacuum testing in shell ANS A B C NOTE: According to fresh water generator manual for any leakage or plant not maintain vacuum pressure testing is carried out by keeping the shell pressure of about 0.05 MPa and applying soap solution to packing and joints. 302. During the vessel’s stay in a dry dock the following machinery may be still kept in operation 1 Air conditioning system 2 Refrigeration system 3 Sewage treatment plant 4 All of the above

ANS D 303. Which of the following instruments can be used without interrupting a live electrical circuit? 1 Megger tester 2 Continuity tester 3 Current clamp meter 4 None of the above ANS C NOTE: According to D.T. HALL power currents (A.C.) can be measured simply by means of a clamp meter which acts as a current transformer. The instrument tongs are dipped round a single insulated conductor and the circuit is not interrupted. 304. When specified Discharge pressure is not achieved, the possible cause could be 1 Discharge pressure too high 2 Pump speed too low 3 Casing ring is worn out 4 Cavitations exists 5 All of the above ANS B C D NOTE: According to pumps manual for insufficient discharge the causes could be air leakage, speed too low, discharge head too high, suction lift too high, suction pipe end not sufficiently submerged, suction strainer and suction line clogged, impeller clogged, wrong direction of rotation, clearance between impeller and mouth ring, due to wear down, cavitation due to high liquid temperature. 305. You must have worked with mooring winch and windlass hydraulic systems. The cooling of hydraulic oil for the above system on large merchant ships is provided by 1

There is no cooling arrangement as the system doesn’t require cooling

2

Air cooled hydraulic reservoir

3

Water cooled plate or shell type heat exchangers

4

Radiator and fan arrangement ANS C

NOTE: According to Mc GEORGE oil cooling is provided by conventional sea water circulated tube type heat exchangers. 306. The dipping of aluminum on metal by electroplating is known as 1

Sheradising

2

Aluminizing

3

Graphitization

4

Calorising ANS B

307. Turbocharger running, what washing not to be done? 1

Dry washing on blower side

2

Wet washing on blower side

3

Dry washing on turbine side

4

Wet washing on turbine side ANS A

308. Which washing we cannot do on turbochargers? 1

Wet washing during full load condition on turbine

2

Wet washing during full load condition on impeller

3

Dry washing during full load condition on turbine

4

Dry washing during full load condition on impeller ANS D

309. Which one of the following is not a type of corrosion 1

Dezincification

2

Coppering

3

Graphitization

4

Galvanization ANS D

310. When steel components electroplated with chromium are used in a corrosive environment then 1

Chromium plating provides corrosion protection to the steel components

2

Chromium plating cannot provide corrosion protection as steel will be preferentially corroded

3

Zinc plating is to be used on top of chromium plating for corrosion protection

4

Thickness of chromium plating is required to be increased for corrosion protection ANS A D

311. Which of the following can provide galvanic protection to cupro-nickel tubes of sea water coolers (single answer) 1

Steel

2

Zinc

3

Aluminum

4

All of the above ANS D

312. How do you know that a ballast pump is taking suction or not? If a ballast pump is taking good suction it will show 1

Positive suction pressure and positive discharge pressure

2

Negative suction pressure and positive discharge pressure

3

Negative or positive suction pressure depending on the available suction head and a positive discharge pressure

4

Negative or positive suction pressure depending on the available suction head and a positive discharge pressure. To confirm if the pump is still pumping, throttling of suction valve will lead to a fall in suction& discharge pressure, while throttling of discharge valve will to a rise in suction and discharge pressure ANS D

313. You have to clean a sea chest filter. You have closed both the inlet and outlet valves of the filter. Upon opening the vent valve on the filter body, you find that there is no water coming out of the vent valve. Which of the following is a true statement? 1

It is perfectly safe to open the filter cover

2

Vent valve is for purging the air out of the casing before putting the filter into use, and should not be used while opening the filter

3

No water is coming out of the vent doesn’t mean that it is safe to open the filter cover. It should be confirmed that vent valve is not choked, by crack opening the filter inlet valve

4

The sea chest valves are valves with high level of reliability and hence there is no need to check by vent valves ANS C

314. In old ships we used to carry ballast water in same tank as for carrying cargo. If the water is having same density as of the cargo oil then the current for motor of ballast pump will 1

Increase

2

Decrease

3

Same

4

Motor current does not depends upon the density of the fluid to pump

ANS C 315. While overhauling double impeller how will you assemble? 1

Hit and trial method

2

It does not effect because impeller of same

3

Assemble the pump than see the pressure if it is not coming than change it

4

Impeller should be assemble by checking the direction of rotation and volute casing ANS D

316. How the discharge rate of oil to shore is calculated? 1

Pump characteristics

2

Shore line characteristics

3

Pump characteristics and shore line characteristics

4

Port inspector tells the discharge rate ANS D

317. Pump is not discharging what is the most possible cause? 1

Water seal pipe is plugged

2

Pump is not primed

3

Casing ring is improper

4

Any of the above ANS B

318. You are transferring oil from forward deep well. Sounding is 5m and heating is set to 45 deg. Pump is put on auto-stop. Last time oil was transferred without any problem. But this time pump is running double the time but still running. What could be possible cause?

1

Pump filter clogged

2

Viscosity is high, so temperature need to be increased

3

Suction head is very less ANS A

319. Which valves is not bi directional flow? 1

Gate v/v

2

Globe v/v

3

Butterfly v/v

4

Ball v/v ANS B

320. Process of enrichment of surface of steel and steel alloys by zinc using electroplating is known as 1

Cathodisation

2

Galvanization

3

Neutralization

4

Dezincification ANS B

321. Corrosion of mild steel can be effectively prevented by 1

Cathodic protection

2

Protective coatings

3

Addition of suitable alloying elements

4

Using some adhesives ANS A B C

322. Which of these are not self actuating valves? 1

Check valve

2

Relief valve

3

Ball valve

4

Safety valve ANS C

323. 1 2 3 4

Which of the following can leads to degradation of foam? Exposure to excess of heat Mixing of different grade of foam Exposure to air None of the above ANS A B C 324. When removing the cap from a sounding tube on a MODU, the sound of air escaping indicates _______________ 1 The tank is full 2 The tank may be partially flooded 3 The tank level has dropped 4 The tank is completely flooded ANS B 325. During shutting down the purifier you find that purifier always vibrates heavily for some time and then becomes normal until it finally comes to a stop. What should be done to avoid this situation? 1

The purifier bowl should be cleaned before next startup

2

The brake should be applied so that the critical speed doesn’t last long

3

Complete overhaul of the purifier should be carried out and the bearings need to be renewed

4

The bowl should be sent for balancing ANS B

326. Dezincification is the term used to describe 1

Loss of zinc an alloy due to formation of internal bimetallic cells due to different alloying elements

2

Loss of zinc due to external bimetallic cells between zinc alloy and another dissimilar metal or alloy

3

Removal of zinc from an alloy by precipitation from Eutectic solution

4

Removal of zinc from an alloy by dissolving the alloy in a zinc dissolving chemical ANS A

327. When centrifugal pump is overhauled it was found that shaft had developed grooves on it and no spare is available onboard what action can be taken 1

Order a new spare

2

Assemble the pump without doing anything and wait for the spare to arrive

3

Machine the shaft sleeve on lathe and put back with new packing

4

Leave the pump as it is ANS C

328. Dirty air filter on a centrifugal blower cause 1

Overheating

2

Cavitation

3

Vibration

4

All ANS A

329. ____ Provide protection against mild steel in galvanic corrosion 1

Copper

2

Aluminum

3

Stainless steel

4

None ANS B

330. Fire pump 1, water to deck discharge pressure is 5 bars, but deck hydrant is not getting water. Fire pump 2 discharge pressure is 2.5 bars and gives water. Fire pump 1 unable to send water to hydrant. What is the reason? 1

Pump pressure gauge defective

2

Overboard discharge valve fully opened, so water is not going to deck

3

Pump suction filter choke

4

Pump discharge valve may be stuck ANS D

331. Corrosion resistance of stainless steel in presence of O2 in aerated water? 1

O2 inhibits chemical reaction

2

O2 combines with stainless steel to form passive oxide layer

3

O2 gets absorbed into stainless steel ANS B

332. After cleaning the M/E F.O. heater you have assembled the heater and want to try out the heater before putting into use. Which is the correct sequence of operation of the valves? 1

Vent valve open (2) F.O. inlet valve crack open (3) When F.O. starts coming out of vent line close vent (4) F.O. inlet valve full open (5) F.O. outlet valve full open (6) Steam return and inlet valves slowly opened up

2

(1) Vent valve open (2) F.O. outlet valve crack open (3) When F.O. starts coming out of vent line close vent (4) F.O. outlet valve full open (5) F.O. inlet valve full open (6) Steam valves slowly return and inlet opened up

3

(1) F.O. outlet valve crack open (2) F.O. inlet valve crack open (3) As the pressure gauge shows pressure open steam heating valves slowly (4) Fully open F.O. inlet and outlet valves

4

(1) Open steam return ANS A

333. A submerged type centrifugal pump is sometimes used as the Main L.O. pump. Why is this? 1

Flow rate required for Main L.O. systems are very high

2

The pressure required for Main L.O. system is high

3

It is a wrong design and such systems normally give problem

4

Both the pumps can be run together when the bearing temperatures are increasing ANS A

334. Refer compressor working continuously. Reason could be 1

Insufficient condenser cooling

2

Air in the system

3

Leakage from solenoid valve

4

Excessive refrigerant ANS C

335. You have valves of same bore diameter but of different types. Which of the following is arranged in the decreasing order closing torque required for giving a perfect seal?

1

Globe valve, Ball valve, Butterfly valve(rubber seat)

2

Ball valve, Globe valve, Butterfly valve(rubber seat)

3

Butterfly valve(rubber seat), Globe valve, Ball valve

4

Globe valve, Butterfly valve(rubber seat), Ball Valve ANS C DOUBT

336. Which of the following conditions can cause above normal air temperature to develop in the intake manifold of a four stroke cycle, turbocharged, diesel engine? 1

Clogged air intake filters

2

Piston blow by

3

A defective after cooler

4

Faulty exhaust valves ANS C

337. Which of the following is an important factor in hydrodynamic lubrication? 1

Viscosity of the lubricating oil

2

Relative speed between lubricated surfaces

3

Bearing clearance

4

All of the above ANS D

338. The purpose of down comers in a water tube boiler is 1

To allow the steam to rise to the steam drum

2

To allow cold water to sink to the bottom

3

To protect the fire wall tubes

4

They are one type of generating tubes ANS B

339. Which of the following reduce fatigue endurance limit in engine components? 1

Surface flaws

2

Stress raisers like oil holes, change in sections etc

3

Corrosive environment

4

All of the above ANS D

340. High pressure cut out in refrigeration system is activated when 1

Low cooling in condenser

2

Air in the system

3

Over charge

4

None of the above ANS A B C

341. Ship is in dry dock, stern tube seal renewal has been carried out, how will you check for leak? 1

Fill the system with oil to maximum level in header tank

2

Fill the system with oil to just fill stern tube

3

Fill the aft seal and forward seal tank to the deepest draught

4

Refloat vessel to check for any leak ANS A MULTI A C

342. When G.S. centrifugal pump shows zero discharge and negative suction 1

Discharge valve closed

2

Suction strainer clogged

3

Clearance in impeller

4 ANS B 343. Why centrifugal pump is not provided with safety valve while positive displacement pump is provided with?JUNE 1

Centrifugal pump shut down head is 0

2

Centrifugal pump shut down head is infinity

3

Centrifugal pump is so designed that it can withstand high pressure

4 ANS C 344. Butterfly valve stuck in half open position. How to repair? (multiple answer) 1

Can’t be taken out in open position from line, so try to close valve any how

2

Apply hammer to shut it

3

Remove pipeline and do overhaul

4

Cannot be repaired onboard ANS C

345. Which of the following statements about pipe repairs is true? 1

A very small hole in a pipe does not necessitate permanent repair by way of renewal of section

2

Welded doublers are acceptable as permanent repairs

3

Permanent repairs can only be done by using classification society approved material

4

None of the above ANS C

346. M/E F.O. heater steam control valve set on viscosity control mode, when you start using F.O. with different viscosity 1

Change setting viscosity index

2

Temperature controller

3

No change in viscosity and viscosity will automatically controlled

4

We have to change the mode manually ANS C

347. SDNR valve is the term used for which of the following type of valves? 1

Standard Dimension Non-Rusting Valve

2

Screw Down Non-Return Valve

3

Small Diameter Negative-Range Valve

4

Stainless Disc Non-Rusting Valve ANS B

348. Which of the following valve types is available with non-return arrangement? 1

Gate Valve

2

Globe Valve

3

Ball Valve

4

Butterfly Valve ANS B

349. In a centrifugal pump discharge must be in the direction as that of 1

Direction of vane curvature from eye to impeller

2

Direction of vane curvature from impeller to eye

3

Depends on shape of volute casing

4

None of the above ANS C MULTI B C

350. A simultaneous rise in stern tube forward seal tank and drop in level of header tank indicates_________________ 1

Aft seal ring of forward seal assembly damaged or sealing disturbed by foreign object

2

Forward seal ring of forward seal assembly damaged or sealing disturbed by foreign object

3

Either of the above

4

None of the above ANS A

351. Throttling the discharge valve of a centrifugal pump the NPSHR 1

Increases

2

Decreases

3

NPSHR remains constant depending on pump design and only NPSHA changes

4

Both the NPSHR & NPSHA will remain unaffected by throttling of discharge valve ANS C

NOTE: NPSH increases when velocity of flow reduces (NPSH = Suction Head – losses – vapour pressure), Losses α vel. of flow2. NPSHA will increase.

352. Centrifugal pump recently overhauled, connections were wrongly given by interchanging the terminals. Now the pump is rotating in opposite direction. What will happen? (single answer) 1

Suction pressure will be above the normal

2

No effect

3

Flow will be reversed

4

Pump suction and discharge pressure/head will be affected ANS D

353. When de ballasting ballast pump suction filter was clogged. The pump will show (single answer) 1

Positive suction pressure

2

Nothing

3

High negative suction pressure

4

Positive suction pressure and positive discharge pressure ANS C

354. Diffusion coating on metal surface is done to prevent them against corrosion. What is the best advantage over other metal coating method? (single answer) ANS: The essential difference between diffusion coatings and the other metal coatings are that this coating consists essentially of an alloy of the coating metal and the base metal which has been coated. The great advantage of the process is that the diffusion coating results in little dimensional change on the base component size and, consequently, it can be applied to components subjected to fairly tight tolerances. 355. What is the metal composition of gunmetal? (single answer) 1 Copper and zinc 2 Copper and tin 3 Copper, tin and zinc with a little lead 4 Copper, zinc and antimony/arsenic

ANS C 356. F.O. heater to be open, before opening it you will _____ the heater by opening _______ to _______ it (single answer) ANS: purge, vent valve, depressurize 357. Which valve is use to moderate/regulate flow (single answer) 1 Globe valve 2 Gate valve 3 Swing check valve 4 Relief valve ANS A 358. Moisture in refrigeration system will cause (single answer) 1 Faulty thermostatic expansion valve 2 Discharge temperature high/low 3 Suction temperature high/low 4 Evaporator pressure low/high ANS A 359. F.O. heater to be opened up. You opened the vent valve two or three drops of oil came out, but the pressure gauge is showing 8 bars. Then you open drain valve still no oil is coming out and the pressure is not falling down. What will you do to open the heater? (single answer) 1 Don’t open, clear the vent/drain valve first then depressurize and check the valves are holding 2 You don’t care because you have done everything. You will open the heater no matter what happened 3 Leave it to cool down and then open because the chances of fire hazard with cold oil is less when you open it 4 Leave it for sometime then the pressure will automatically come down ANS A 360. Which valve doesn’t turn quarterly to open? (single answer) 1 Gate valve 2 Ball valve 3 Butterfly valve 4 Plug valve ANS A 361. Why flinger ring is provided? (single answer) 1 To prevent leakage of grease from the bearings 2 To prevent leakage from the gland 3 To prevent leakage of water from the pump packing gland to the bearing housing 4

362. 1 2 3 4 363. 1 2 3 4 364. 1 2 3 4 365.

ANS C Purifier is rotating slower than rated rpm. What is the most probable cause? (single answer) Frequency low Bus bar voltage low Friction pads worn out High temperature ANS C To know weldability of steels what is the best criteria? (single answer) Carbon percentage Carbon equivalent Welding type Welding electrode type ANS B You know carbon equivalent is the best way to determine weldability of steels. It is denoted by CE. Excellent weldability comes under which CE? (single answer) < = 0.3 0.4 - 0.6 0.6 – 0.7 0.7 – 2 ANS A Use of polymers is limited to LP boilers. What is the most probable reason? (single answer)

1

Does not help in prevention of scale formation

2

Does not help in corrosion prevention

3

Use limited to LP boiler as no PO4 present to prevent caustic alkalinity

4

All of the above ANS C

NOTE: Polymer is a giant molecular built up by stringing together simple molecules, E.G. 4

Poly-electrolytes-Formed from natural or synthetic ionic monomers

5

Polyacrylates- Polymers of acrylic acid

6

Polyamides- Polymers of amides

Polymer treatment prevents scale formation and minimizes sludge formation. It can also loosen scale so established boilers introduced to this form of treatment may develop leaks where previously plugged with scale, especially in way of expanded joints. Also can absorb trace oil. Use limited to LP boiler as no PO4 present to prevent caustic alkalinity for auxiliary boiler. This is a superior form of treatment to the old alkaline and phosphate treatment. The correct level of alkalinity must be maintained as too low a level neutralizes the electric charge of the poly-electrolyte. Too high causes caustic alkalinity. 366. Which of the refrigerants listed is considered safe and ideal for most marine applications? 1

R-21

2

Ammonia

3

R-12

4

Sulfur dioxide ANS A

367. In reference to air conditioning, when air attains the maximum amount of moisture it can hold at a specific temperature, it is said to be 1

Superheated

2

Saturated

3

Condensed

4

Convected ANS B

368. Which of the following terms represents the form of heat removed from the refrigerant in the condenser of a refrigeration system? 1

Latent heat of vaporization

2

Heat of compression

3

Superheat

4

All of the above ANS B

369. The temperature at which water vapor in the atmosphere begins to condense is called the 1

Dew point temperature

2

Condensation temperature

3

Psychometric temperature

4

Absolute humidity temperature ANS A

NOTE: The dew point is the temperature below which the water vapor in a volume of humid air at a given constant barometric pressure will condense into liquid water at the same rate at which it evaporates. Condensed water is called dew when it forms on a solid surface. 370. In a refrigeration system, the refrigerant absorbs the latent heat of vaporization in the 1

Compressor

2

Condenser

3

Receiver

4

Evaporator ANS D

371. The only means of removing the latent heat of condensation from a refrigerant in the normal refrigeration cycle is by 1

Passing it through the expansion valve

2

Condensing refrigerant in the system condenser

3

Passing the gaseous refrigerant through the heat interchanger on the suction side of the compressor

4

Maintaining a high pressure on the system's receiver ANS B

372. The heat required to change a substance from a solid to a liquid while at its freezing temperature, is known as the latent heat of 1

Fusion

2

Vaporization

3

Condensation

4

Sublimation ANS A

373. The heat required to change a substance from a liquid to a gas without experiencing a temperature change, is defined as the latent heat of 1

Fusion

2

Vaporization

3

Sublimation

4

Condensation ANS B

374. Heat which brings about a change in the physical state of a substance without a change in temperature, is called 1

Specific heat

2

Sensible heat

3

Latent heat

4

Ambient heat ANS C

375. Latent heat can be defined as the heat which must be added to a substance in order to change it from a 1

Solid to liquid

2

Liquid to vapor

3

Solid to vapor

4

All of the above ANS D

376. Personnel working with refrigeration systems, and subject to the exposure of refrigerants should wear 1

face shield

2

a respirator

3

rubber gloves

4

an all purpose gas mask ANS A C D

377. The amount of moisture in a given sample of air, when compared with the amount of moisture the air could hold if totally saturated at the existing temperature of the sample, is called 1

Absolute humidity

2

Specific humidity

3

Effective humidity

4

Relative humidity ANS D

378. The ratio of the weight of moisture contained in a given volume of air, to the weight of moisture that the same sample would hold if saturated, is called the 1

Absolute humidity

2

Relative humidity

3

Specific humidity

4

Total humidity ANS B

379. The moisture sensitive element of a humidistat can be made of 1

Hair

2

Copper

3

Plastic

4

Steel ANS A

380. When handling contaminated oil from a hermetically sealed refrigeration compressor unit that has burned out its motor, you should 1

Store the oil in a clean refrigerant drum

2

Use rubber gloves

3

Circulate the oil through a filter drier

4

Remove the oil with a portable charging cylinder

381. When replacing ball bearings on an electric motor shaft, you should 1

Tap the outer race with a mallet

2

Apply even pressure to the outer race

3

Apply even force to the inner race

4

Apply pressure evenly to both the inner and outer races ANS C

382. People familiar with ammonia refrigeration systems become accustomed to its odor and may forget that the vapors 1

In a low concentration can cause death

2

Will dissolve in perspiration and cause caustic burns

3

Will burn or explode

4

All of the above ANS D

383. Ammonia when used as a refrigerant is valuable because of its high efficiency, it is however 1

Toxic

2

Flammable

3

Explosive

4

All of the above ANS D

384. When subjected to high heat from an open flame, or an electric heating element, which of the listed refrigerants will break down and produce phosgene gas? 1

CO2

2

Methyl chloride

3

R-22

4

Sulfur dioxide

ANS C 385. When the relief valve opens it discharges high pressure refrigerant vapor to the 1

Liquid strainer

2

Refrigerant inlet of the condenser

3

Inlet side of the evaporator

4

Suction side of the compressor ANS D

386. In the presence of an open flame or hot surfaces, chlorinated fluorocarbon refrigerants decomposes and form 1

Petroleum crystals

2

Phosgene gas

3

Water vapor

4

Carbon monoxide ANS B

387. R-12 is generally considered to be a safe, nontoxic, nonflammable, and no explosive refrigerant. It can, however, become highly toxic when 1

Superheated outside the system

2

In contact with an open flame

3

Heated to the boiling point

4

All of the above ANS B

388. A refrigeration system contaminated with moisture can be affected by 1

Acid formation

2

Sludge formation

3

Ice in the expansion valve

4

All of the above ANS D

389. Some chlorinated fluorocarbon refrigerants may decompose into a toxic irritating gas if it is 1

Stored at temperatures below 100 C

2

Charged into a system having copper fittings

3

Allowed to mix with compressor oil

4

Exposed to an open flame or hot surfaces ANS D

390. For the proper control of the air temperature in an air conditioning system using chilled water circulation, which of the listed conditions should remain constant regardless of load changes? 1

Chilled water system supply temperature

2

Chilled water system return temperature

3

Compressor discharge temperature

4

Compressor suction pressure

391. In a direct expansion type multi-box refrigeration system, the compressor is set up to cycle on and off by the 1

Pressure stat

2

High pressure cut out

3

Solenoid valve

4

Low pressure cut out switch

ANS D 392. Saltwater is typically provided to a refrigeration system to 1

Cool the expansion valve

2

Prevent refrigerant superheating

3

Condense the refrigerant gas

4

Prevent motor overheating ANS C

393. In a direct expansion type cargo refrigeration system, a box is normally changed from chill to freeze by adjusting the 1

Hand expansion valve

2

Compressor suction valve

3

Solenoid bypass

4

Back pressure regulating valve ANS A

394. A pressure drop in the liquid line of a refrigeration system may cause 1

The solenoid valve to seize

2

The compressor to hunt

3

Flash gas to form in the liquid line

4

The expansion valve to freeze open

395. Moisture is removed from a refrigeration system by 1

Bleeding refrigerant from the condenser

2

Opening a drain petcock on the oil separator

3

Condensing the water in the heat exchanger

4

Using a dehydrator cartridge ANS D

396. Moisture in the refrigerant may 1

Freeze on the expansion valve seat and reduce the flow of liquid refrigerant

2

Emulsify the oil in the condenser

3

Freeze in the king valve

4

Clog the oil trap ANS A

397. Moisture entering a typical refrigeration system will most likely 1

Boil in the condenser

2

Be removed by the liquid line strainers

3

Cause sweating and frost on the evaporator coils

4

Freeze in the expansion valve ANS D

398. Moisture in a refrigeration system can cause 1

Freezing the expansion valve closed

2

Corrosion of system piping

3

Improper temperature regulation

4

All of the above ANS D

399. Which of the problems listed could be indicated if a sight glass in the refrigerant liquid line is full of bubbles? 1

Proper refrigerant charge

2

Faulty expansion valve

3

Insufficient refrigerant

4

Solenoid valve stuck open ANS C

400. Some refrigeration systems have chemical moisture indicators installed in conjunction with the sight glass in the liquid line. If excess moisture is present in the system, the indicator will 1

Activate the driers

2

Change color

3

Secure the compressor

4

Add the predetermined amount of liquid drier

401. A liquid indicator sight glass is useful in determining whether or not a refrigeration system is sufficiently charged. It is generally located in the 1

High pressure liquid line

2

Low pressure liquid line

3

High pressure vapor line

4

Low pressure vapor line ANS A

402. If a liquid sight flow indicator in a refrigeration system shows gas bubbles in motion passing inside of the glass, there is 1

Too much refrigerant in the system

2

Oil entrained in the refrigerant

3

Less than a full charge of refrigerant in the system

4

Ice crystals forming in the refrigerants

ANS C 403. A sight glass is installed in the liquid line to indicate the condition of the refrigerant charge and may also indicate the 1

Condition of the expansion valve

2

Moisture in the system

3

Condition of the compressor suction valves

4

Condenser temperature

404. In an operating refrigeration system low on refrigerant, a liquid line sight glass will 1

Be clear

2

Be blue

3

Be light green

4

Show bubbles ANS D

405. If the refrigeration compressor crankcase is sweating, the cause may be due to 1

A shortage of refrigerant

2

The compressor running continuously

3

Liquid refrigerant returning to the compressor

4

The compressor short cycling on the high pressure cutout ANS C

406. If the suction line between the evaporator and compressor is frosting up, the cause may be due to the thermal expansion valve 1

Thermal bulb coming loose from the suction line

2

Needle valve is stuck closed

3

Thermal bulb is in a cold air stream

4

All of the above ANS D

407. If a refrigerating compressor crankcase is sweating, the trouble could be caused by 1

Excessive superheat

2

A minor amount of air in the system

3

Normal oil circulation with the refrigerant

4

The expansion valve being stuck in the open position ANS D

408. Frosting or sweating of the suction line of a reciprocating refrigeration compressor indicates a condition which could result in severe damage due to 1

Minor amount of oil in the refrigerant

2

Liquid slugging

3

Insufficient refrigerant

4

A failed heat interchanger ANS B

409. A refrigeration system compressor crankcase is sweating or unusually cold. This is an indication of 1

A shortage of refrigerant in the system

2

Air in the system

3

An accumulation of liquid refrigerant in the crankcase

4

A shortage of oil in the crankcase ANS C

410. Refrigeration system compressor crankcase sweating is an indication of 1

Insufficient lube oil circulating through the system

2

Excessive circulation of lube oil through the system

3

Insufficient refrigerant in the system

4

An overworked compressor

411. Sweating of the refrigeration system compressor crankcase is caused by 1

Too much superheat

2

Insufficient superheat

3

Suction pressure too low

4

Excessive refrigerant returning to the compressor ANS D

412. Crankcase sweating in a refrigeration system is caused by 1

A stuck solenoid valve

2

A shortage of refrigerant

3

Too much oil in circulation

4

Too much superheat ANS A

413. Properties of good refrigeration oil include 1

Low wax content

2

High pour point

3

High viscosity

4

All of the above ANS A

414. Oil separators installed in refrigeration systems serve to 1

Remove excess oil from the system

2

Remove oil entrained in high pressure liquid line

3

Return oil entrained in refrigerant vapor back to the compressor crankcase

4

All of the above ANS D

415. An oil separator is a device used to remove oil from the 1

Liquid refrigerant

2

Receiver

3

Gaseous refrigerant

4

Expansion valve ANS C

416. The oil separator (trap) used in a shipboard refrigeration system is located between the 1

Compressor discharge valve and the condenser

2

Condenser and the receiver

3

Receiver and the king valve

4

Receiver and the expansion valve ANS A

417. The purpose of the refrigeration system low pressure cutout switch is to 1

Protect the compressor from liquid flood back

2

Protect the compressor from low discharge pressure

3

Start and stop the compressor upon system demand

4

Start the compressor after a drop in the evaporator pressure ANS C

418. The purpose of the low pressure cutout switch is to 1

Maintain liquid refrigerant at the suction of the compressor

2

Maintain a preset suction pressure to the compressor

3

Start and stop the compressor at preset operating pressures

4

Operate at minimum efficiency ANS C

419. The sensing line for the low pressure cutout switch to a refrigeration system is located 1

In the chill box

2

Before the receiver

3

On the suction side of the compressor

4

On the discharge side of the compressor ANS C

420. The refrigeration system low pressure cutout switch is actuated by 1

An electric system manager

2

A sensing bulb at the tail coil of the evaporator

3

Pressure changes in the suction line

4

Failure of the king solenoid valve ANS C

421. When you adjust thermostatic expansion valve 1

Refrigerant must be bled off the sensing line before adjustments are made

2

All refrigerant must be pumped into the receiver before adjustments are made

3

Time must be allowed for conditions to stabilize in the evaporator before further adjustments are made

4

All refrigerant must be routed through the dehydrator while changing the superheat setting ANS C

422. The cylinder unloading mechanism used on low pressure air compressors is an example of which mode control? 1

Two positions

2

Derivative

3

Integral

4

Single speed floating

423. Which of the following is the primary operational difference between a huddling chamber safety valve and a nozzle reaction safety valve? 1

Adjustment of lifting pressure

2

Valve relieving capacities

3

Principle in accomplishing blow down

4

Initial valve opening cause by steam pressurejj