U.S.C.G. Merchant Marine Exam DDE – Unlimited HP Q621 ... · o (A) properly treat the boiler...

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U.S.C.G. Merchant Marine Exam

DDE – Unlimited HP

Q621 Steam Plants

(Sample Examination)

of 20 Q621 Steam Plants

8/22/2019

Q621 Steam Plants U.S.C.G. Merchant Marine Exam DDE-Unlimited HP Illustrations: 4

Choose the best answer to the following Multiple Choice Questions.

1. The purpose of the boiler drum air cock is to __________.

o (A) permit escape of air when steam is forming in the drum after lighting off o (B) permit escape of air when the boiler is being filled o (C) admit air when the boiler is being emptied • (D) all of the above

If choice D is selected set score to 1.

2. The best conductor of heat in a marine boiler is __________.

o (A) steam o (B) brick • (C) steel o (D) water

If choice C is selected set score to 1.

3. Bottom blow valves are installed on water-tube boilers to __________.

o (A) completely drain the boiler in an emergency o (B) prevent sludge from forming in the steam drum o (C) remove floating impurities from the boiler water surface • (D) remove settled solids from the water drum


4. The purpose of the separating nozzle in the accumulator of a water-tube, coil-type, steam generator is to separate __________.

• (A) dry steam from the steam and water mixture o (B) condensate from feedwater o (C) superheated steam from saturated steam o (D) sludge accumulations from feedwater

If choice A is selected set score to 1.

5. Which of the following statements concerning fire-tube boilers is correct?

• (A) Combustion gases flow through the tubes. o (B) Flames impinge on the tubes. o (C) Combustion occurs in the tubes. o (D) Water flows through the tubes.



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Q621 Steam Plants U.S.C.G. Merchant Marine Exam DDE-Unlimited HP Illustrations: 4 6. Which of the following statements concerning fire-tube boilers is correct?

• (A) Combustion gases flow through the tubes. o (B) Flames impinge on the tubes. o (C) Combustion occurs in the tubes. o (D) Water flows through the tubes.


7. A boiler pressuretrol senses steam pressure changes and __________.

o (A) controls the flow of feedwater to the boiler o (B) monitors the boiler high water level o (C) secures the fires when a fusible plug burns out • (D) automatically regulates the quantity of oil and air flow to the burner


8. A photoelectric cell installed in a boiler burner management system __________.

• (A) opens the burner circuit upon sensing a flame failure o (B) detects a flame failure by monitoring radiant heat from glowing refractory o (C) requires mechanical linkage to secure the burner fuel supply o (D) must be bypassed at low firing rates


9. The purpose of the mica used in a boiler water gage glass assembly is to prevent __________.

o (A) overheating of the glass o (B) leakage from the glass o (C) light refraction in the glass • (D) etching of the glass


10. As shown on the illustrated boiler steam drum gauge glass, what do items "D" and "M" represent? Illustration SG-0020

• (A) mica sheets o (B) glass plate inserts o (C) cover plates o (D) asbestos gaskets



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11. On a boiler safety valve, the blowdown adjusting ring is locked in place by a __________.

o (A) locknut o (B) cotter pin o (C) wire seal • (D) set screw


12. The primary operational difference between a huddling chamber type safety valve and a nozzle reaction type safety valve is the __________.

• (A) principle by which blowdown is accomplished o (B) manner in which steam pressure causes initial valve opening o (C) manner in which lifting pressure is adjusted o (D) difference in valve relieving capacities


13. A secondary function of the refractory installed in a marine boiler is to __________.

o (A) support the burner distance piece • (B) direct the flow of combustion gases o (C) support the boiler casing o (D) maintain air flow through the burner diffuser

If choice B is selected set score to 1.

14. A corbel is used in a boiler furnace to __________.

o (A) contain the furnace heat o (B) reduce gas turbulence o (C) direct the flow of gases • (D) protect the expansion joints


15. As the percentage of CO2 in the stack gas decreases, you can assume that __________.

o (A) fuel is being burned with increasing economy o (B) the fuel to air ratio is increasing o (C) you are approaching secondary combustion • (D) excess air is increasing



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16. Why should the fuel oil be recirculated before lighting off a cold boiler on heavy fuel?

o (A) To allow the fuel strainers to thoroughly clean the fuel. o (B) To allow fuel pressure to buildup gradually. • (C) To heat the fuel enough for proper atomization. o (D) To ensure that all water is removed from the fuel.


17. When raising steam on a cold boiler under normal conditions, you should always __________.

o (A) use a large orifice burner sprayer plate to start o (B) take 24 hours to raise steam o (C) raise steam within one hour or less • (D) use a small orifice burner sprayer plate to start


18. Which of the following is the best reason for opening the air cock when draining a water-tube boiler?

o (A) Water flows out of the boiler too rapidly with the air cock closed. o (B) Air coming into the boiler will help dry out the boiler's surface. • (C) With the air cock open, the boiler drains without producing a vacuum. o (D) Air mixed with the water will create a cleansing effect in the tubes.


19. Before using a boiler compressed air soot blower system, you should __________.

o (A) lower the water level • (B) drain the soot blower pneumatic operating lines o (C) reduce the boiler pressure o (D) decrease the forced draft fan speed


20. When cleaning the inside surfaces of the boiler tubes of a water-tube boiler with a powered rotary brush, the brush should be kept in motion to __________.

• (A) avoid internal tube damage o (B) prevent it from seizing o (C) reduce tube pitting o (D) reduce wear to brush bristles



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Q621 Steam Plants U.S.C.G. Merchant Marine Exam DDE-Unlimited HP Illustrations: 4 21. A hole should be made in the sagged tube occurring in a water-tube boiler, prior to plugging the tube

to prevent a __________.

o (A) crack failure of the tube o (B) complete sagging failure of the tube • (C) pressure buildup in the tube o (D) quick burnout of the tube


22. To prevent a small plastic refractory wall patch repair from falling into the furnace of a boiler, you should __________.

• (A) undercut the existing brick around the area to be patched o (B) mix the plastic with concrete prior to using o (C) attach anchor bolts to the furnace casing o (D) reinforce the patch with fine mesh metal screen


23. Radial cracks have developed in the castable refractory of the burner cones after the first firing since the installation of new furnace front refractory. This is an indication of __________.

o (A) inadequate cone angle o (B) a need for castable refractory patchwork o (C) a need for plastic firebrick patchwork • (D) relieved stresses


24. When a boiler is removed from service for an extended period, why should the firesides be thoroughly dried after water washing?

o (A) Prevent flarebacks on lighting off. • (B) Reduce the probability of corrosion. o (C) Reduce the possibility of thermal spalling. o (D) Prevent cracking of the brickwork.


25. You are standing watch in the engine room of a steam vessel. You should blow down a gage glass periodically to __________.

o (A) provide water samples for the second assistant o (B) maintain the proper water level in the steam drum • (C) remove any sediment that has accumulated o (D) test the feedwater stop-check valve



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Q621 Steam Plants U.S.C.G. Merchant Marine Exam DDE-Unlimited HP Illustrations: 4 26. Water in the fuel supply to a steaming boiler can be detected by __________.

o (A) observation of the fuel oil heater drains o (B) panting of the casing o (C) dense white smoke being observed in the periscope • (D) sputtering of the fires


27. A higher than normal stack gas temperature could indicate __________.

o (A) defects in burner cone refractory • (B) dirty firesides or watersides o (C) inner or outer casing leakage o (D) eroded water screen tube walls


28. Oil accumulation in boiler water would __________.

o (A) increase the heat transfer rate • (B) cause foaming and carryover from the boiler o (C) practically eliminate boiler sludge formation o (D) prevent acid attack on the boiler tubes


29. Boiler tube failures can result from __________.

o (A) mechanical stress o (B) overheating o (C) corrosion • (D) all of the above


30. Treatment of boiler feedwater for the control of hardness is necessary to prevent __________.

o (A) carryover • (B) waterside scale deposits o (C) foaming o (D) excessive feedwater alkalinity



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31. Normally a boiler water sample should be taken __________.

• (A) before the boiler has been blown down or chemicals added o (B) after the boiler has been blown down o (C) when the boiler has been refilled with makeup o (D) from the highest point in the feed system


32. In the prevention of moisture carryover from a marine boiler, one important consideration is to __________.

o (A) properly treat the boiler water with hydrazine • (B) control the amount of boiler water solids o (C) maintain a high boiler water level o (D) add foaming agents to the boiler water


33. The property of a fuel oil which is a measurement of its available energy, is known as its __________.

• (A) heating value o (B) viscosity index o (C) cetane number o (D) cetane index


34. Which of the significant combustible elements of fuel oil is a major source of boiler corrosion?

o (A) Oxygen o (B) Hydrogen o (C) Carbon • (D) Sulfur


35. In a boiler furnace, incomplete combustion due to insufficient air yields an excess amount of __________.

o (A) sulfur dioxide o (B) carbon dioxide • (C) carbon monoxide o (D) nitrogen oxide



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Q621 Steam Plants U.S.C.G. Merchant Marine Exam DDE-Unlimited HP Illustrations: 4 36. Control of the fuel oil metering valve in an automatically fired boiler is accomplished by a

__________.

o (A) pressure magnifying device in the steam coil outlet • (B) steam pressure sensing device with linkage to the damper air vanes o (C) metering device in the air supply line o (D) signal from the feedwater electrode


37. The solenoid valves in the fuel oil supply line to a boiler are automatically closed by __________.

o (A) a decrease in feed temperature o (B) high furnace air pressure • (C) high steam pressure o (D) low steam pressure


38. Which of the following is the advantage of operating a typical closed feedwater system for a marine boiler when compared to an open feedwater system?

o (A) Allows for lower feed pump operating pressures. o (B) Reduced requirement for condensate purity. o (C) Reduced steam requirement for feedwater heating. • (D) Increased capability of removing and controlling dissolved oxygen.


39. A boiler main feed check valve functions to __________.

o (A) check pressure pulsations in the feed line o (B) provide feed pump positive discharge head • (C) prevent backflow of water from the boiler in the event of a feed pump failure o (D) reduce feed pump discharge pressure loading


40. Under normal conditions, the rate of heat transfer in a feed water heater is most greatly affected by the __________.

• (A) temperature differential between the steam and feed water o (B) density of the feed water o (C) pH of the feed water o (D) speed of the feed pump



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Q621 Steam Plants U.S.C.G. Merchant Marine Exam DDE-Unlimited HP Illustrations: 4 41. Large temperature and pressure drops which occur in the first stage of a combination impulse and

reaction turbine are caused by steam passing through __________.

o (A) a single row of blades more than once o (B) a nozzle diaphragm in the low-pressure end of the turbine o (C) a dummy piston and cylinder to offset axial thrust • (D) one or more velocity-compounded impulse stages at the high-pressure end of the turbine


42. A pressure-velocity compounded impulse turbine consists of __________.

o (A) velocity compounding with reaction pressure compounding • (B) two or more stages of velocity compounding o (C) several rows of moving blades attached to diaphragms o (D) two or more rows of nozzles in which no pressure drop exists


43. Why would superheated steam be used in a propulsion turbine instead of saturated steam?

o (A) Higher pressure available than saturated steam. • (B) Greater heat energy available per pound of steam. o (C) Less specific energy available per pound of steam. o (D) Lower required specific volume than saturated steam.


44. What statement concerning the operation of a propulsion steam turbine turning (jacking) gear is true?

• (A) The turning gear is used to prevent turbine rotor distortion while warming-through or while cooling, since distortion is an issue when warming-through or cooling.

o (B) The turning gear is used to rotate the turbines, gearing, and shaft periodically when the main engines are secured only. The turning gear is never used to prevent turbine rotor distortion.

o (C) The turning gear is used to prevent turbine rotor distortion while cooling only. The turning gear is never used while warming-through since rotor distortion is not an issue when warming-through.

o (D) The turning gear is used to prevent turbine rotor distortion while warming-through only. The turning gear is never used while cooling since distortion is not an issue when cooling.


45. Journal bearings used with turbine rotors are manufactured in two halves in order to __________.

o (A) provide for positive oil flow at all loads o (B) facilitate interchanging with other bearing halves o (C) maintain axial alignment and reduce thrust • (D) permit removal of the bearing without removing the rotor from the turbine



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Q621 Steam Plants U.S.C.G. Merchant Marine Exam DDE-Unlimited HP Illustrations: 4 46. Main steam turbine bearings are lined with __________.

• (A) Babbitt o (B) steel o (C) ferrous oxide o (D) cast-iron


47. Allowance for axial expansion of a steam turbine due to temperature changes is provided for by the use of __________.

o (A) pivoted-shoe type thrust bearings o (B) rotor position indicators o (C) casing flexible joints • (D) a deep flexible I beam support


48. The adjustable spherically seated self-aligning bearing housings used in turbines are provided with oil deflector rings. The function of these rings is to __________.

o (A) prevent the leakage of main steam into the oil o (B) direct the flow of oil through the bearing o (C) ensure efficient lubrication of the bearing • (D) prevent the external leakage of oil out of the bearing housing


49. Precautions to be observed prior to starting a turbine driven feed pump, should include __________.

o (A) assuring that the turbine casing drains are wired closed o (B) opening all governor oil relay drains o (C) observing the operation of the overspeed trip • (D) checking the manual trip device for proper operation


50. If contaminated lube oil were allowed to settle undisturbed in a tank, into which layers would the contaminants separate?

o (A) Sediment on the bottom, oil in the middle, and water on top. • (B) Sediment on the bottom, water in the middle, and oil on top. o (C) Water on the bottom, sediment in the middle, and oil on top. o (D) Water on the bottom, oil in the middle, and sediment on top.



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Q621 Steam Plants U.S.C.G. Merchant Marine Exam DDE-Unlimited HP Illustrations: 4 51. The gravity tank in a gravity lube oil system serves to __________.

o (A) settle lube oil prior to purifying o (B) supply the lube oil service pump with a positive suction head o (C) store heated lube oil • (D) maintain oil supply for several minutes to bearings should the lube oil service pump fail


52. In a pressure type main propulsion turbine lubrication system, the lube oil service pumps normally take suction from the main sump and discharge directly to the __________.

• (A) lube oil coolers o (B) gravity feed tank o (C) main thrust bearing o (D) lube oil header


53. During high-speed operation of the main turbine propulsion unit, the heat absorbed by the lubricating oil is removed by the __________.

o (A) distillate cooler o (B) lube oil purifier o (C) sump vents • (D) lube oil cooler


54. Which of the filters listed will deplete the additives in lubricating oil?

o (A) Extended area membrane filter o (B) Cloth bag extractor o (C) Absorbent filter • (D) Adsorbent filter


55. Of the many impurities commonly found in marine lubricating oil, which of the following CANNOT be removed by a centrifugal purifier at normal operating speeds and temperatures?

o (A) Carbon particles • (B) Diesel fuel oil o (C) Water o (D) Metal particles



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Q621 Steam Plants U.S.C.G. Merchant Marine Exam DDE-Unlimited HP Illustrations: 4 56. When monitoring steam propulsion plant lubricating oil temperatures while underway, what

represents the temperature rise across an individual bearing?

o (A) The temperature difference between the lube oil cooler oil inlet temperature and the lube oil cooler oil outlet temperature.

o (B) The temperature difference between the bearing lube oil outlet temperature and the lube oil cooler oil inlet temperature.

• (C) The temperature difference between the bearing lube oil outlet temperature and the lube oil cooler oil outlet temperature.

o (D) It is NOT possible to determine individual bearing temperature rises for lubricating oil.


57. The splits located in the halves of main reduction gear bearings are aligned at an angle to the horizontal in order to resist __________.

o (A) steam loss o (B) axial stress o (C) oil loss • (D) wiping


58. On main turbine propulsion units, gear-type flexible couplings are generally used between the __________.

o (A) rotor shaft and quill shaft • (B) rotor shaft and pinion shaft o (C) quill shaft and high-speed pinion o (D) second reduction and the shaft thrust bearing


59. The component shown in the illustration, labeled "I", is the __________. Illustration SE-0013

• (A) first reduction gear o (B) first reduction pinion o (C) second reduction gear o (D) second reduction pinion



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60. A Kingsbury, or pivot shoe type thrust bearing, can bear much greater loads per square inch of working surface than can parallel surface bearings because provisions are made in the Kingsbury bearing __________.

o (A) to allow the leveling plates to pivot on the collar when thrust loads are applied o (B) for adjusting the filler piece thickness behind the pivotal-shoes to give a more accurate fit • (C) for the shoes to tilt slightly, thereby allowing the formation of a wedge shaped oil film under a

thrust load o (D) for automatically adjusting clearances to the correct value when wear occurs


61. In the event of a failure of the pneumatic control system, a multi-element feed water regulator is designed to operate as a __________.

o (A) constant-pressure regulator o (B) thermo-hydraulic feedwater regulator • (C) manually controlled feedwater regulator o (D) constant-volume feedwater regulator


62. Where do fuel oil vapors tend to accumulate in an engine room?

• (A) In the lower engine room spaces, especially in the bilges. o (B) In the upper engine room spaces, especially in the fidley. o (C) Oil vapors tend to distribute throughout the engine room evenly. o (D) At the point in the engine room where the vapors were initially formed.


63. The part labeled "G", as shown in the illustration, is a __________. Illustration MO-0040

o (A) bearing shell o (B) piston bushing o (C) connecting rod cap • (D) connecting rod bushing


64. In the auxiliary diesel engine, shown in the illustration, the __________. Illustration MO-0006

• (A) governor is linked to the fuel injection pump by vertical linkage o (B) engine oil filter is outboard of the electric starter o (C) camshaft rotates at the same speed as the crankshaft o (D) explosion relief doors are clearly visible on both sides of the crankcase



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Q621 Steam Plants U.S.C.G. Merchant Marine Exam DDE-Unlimited HP Illustrations: 4 65. The intake and exhaust valves used in a diesel engine are returned to their seats by __________.

• (A) spring force o (B) exhaust pressure o (C) push rod pressure o (D) combustion pressure


66. A four-stroke cycle auxiliary diesel engine fuel cam has shifted from its original position during maintenance. To ensure correct timing of the fuel pump, the intake and exhaust valves should be in what position when approaching top dead center for injection?

o (A) Intake valve open, exhaust closed • (B) Intake and exhaust valves closed o (C) Exhaust valve open, intake valve closed o (D) Intake and exhaust valves open


67. Excessive vibration in an operating diesel generator may be caused by __________.

o (A) electrical overload • (B) loose engine mounting bolts o (C) surging at governed RPM o (D) coolant leaking into the cylinder


68. In a four-stroke cycle diesel engine, badly worn intake valve guides can cause excessive __________.

o (A) exhaust pressure o (B) exhaust temperatures • (C) lube oil consumption o (D) cooling water temperatures


69. One remedy for a high firing pressure, in addition to a high exhaust temperature in one cylinder of a diesel engine, is to __________.

o (A) retard fuel injector timing o (B) reduce fuel booster pump pressure o (C) increase scavenge air pressure • (D) adjust the fuel rack



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70. If an auxiliary diesel engine equipped with an electric starting system cranks very slowly afterrepeated attempts to start, the cause could be a/an __________.

o (A) low lube oil viscosityo (B) low compression pressure• (C) overheated motor windingso (D) ring gear with broken teeth



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National Maritime Center

Serving Our Nation’s Mariners

10/17/2018

MO-0006

Adapted for testing purposes only from WILBU R, Pounder's Marine Diesel Engines, Sixth edition

Copyright © 1986 by Butterworth's Publishers

Further reproduction prohibited without permission of 20 Q621 Steam Plants

National Maritime Center

Serving Our Nation’s Mariners

10/18/2018

Adapted for testing purposes only from Engineman 3

NAVEDTRA 14331

Further reproduction prohibited without permission

MO-0040



10/1/2018

SE-0013

Adapted for testing purposes only from HARRINGTON, Marine Engineering

Copyright © 1992 by the Society of Naval Architects and Marine Engineers

Further reproduction prohibited without permission of 20

Q621 Steam Plants


10/2/2018

SG-0020

Adapted for testing purposes only from POLSEN, Fundamentals of Steam Generators as

Applied to Marine Propulsion Power Plants

Copyright © 1969 by School of Marine Engineering & Navigation

Further reproduction prohibited without permission of 20

Q621 Steam Plants

U.S.C.G. Merchant Marine Exam DDE – Unlimited HP Q621 ... · o (A) properly treat the boiler...

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