l .
SOUTH TYNESIDE COLLEGE
FACULTY OF MARINE AND MECHANICAL ENGII\EERING
CLASS 4 EXAMINATION OUESTIONS
Explain what you know about 66M" Notices.
Merchant shipping notices, or "M" notices as they are commonly called, occupy a special position. are advisory notices which do not have a force in law, but those which give advice on safety matter regarded as authoritative documents by course of inquiry into shipping casualties and as such woulr considered extremely persuasive in a legal sense.
There are now three tlpes of notice issued by the MCA 1. MGN ( Marine Guidance Notes ) - Blue
Provide advice and guidance on safety and pollution matters. 2. MIN ( Marine Information Notices ) - Green
Provide information intended for a more limited audience or of short term duration. 3. MSN ( Marine Shipping Notice ) - White
Will contain mandatory information relating to the legal requirement set out in related statutory instruments.
There is no legal requirements to carry Marine Guidance Notes and Marine information Notes on UK registered vessels.
It is a legal requirement to carry Merchant Shipping Notices.
Explain what you know about " Code of Safe Working Practices".
Accidents are usually the result of carelessness, mistakes, lack of thought or care and often result in Consideration must be given on how to avoid accidents hence the " Code of Safe Working practice Examples include the wearing of working clothes chosen forthe job with its hazards in mind. They fit fairly closely with no loose flaps, straps or ragged pockets. Ciothing should cover as much as the as possible and a stout pair of shoes should be worn, with steel toecaps. Neck chains, finger rings ar wristwatches should not be worn, particularly in the vicinity of rotating machinery. Where particula hazards are present appropriate protection such as goggles or ear muffi, should be worn.
When overhauling machinery or equipment it must be effectively isolated from all sources of power may involve unplugging from an electrical circuit, the removal of fuses or the securing open of circu breakers. . Suction and discharge valves of pumps should be securely closed and the pump casing rel pressure. Special care should be taken with steam operated or steam using equipmetrt to "ngye no F build up occurs.
When lifting components during overhaul, screw in eyebolts should be used where possible. These : be fully entered up to the collar and the thread of the eyebolt should be in good condition. Lifting w should be in good condition without broken strands or sharp edges.
Before any work is done on the main engine, the turning gear should be engaged and a warning notic posted at the control position. Lubricating oil in the working area should be cleaned up and where necessary suitable staging erected. The turning gear should be made inoperative if nofrequired durir overhaul- Where it is used, care must be taken to ensure all personnel are clear before it is used. Overhead working, boiler operation. Entry into enclosed spaces are other examples where special car procedures have to be rigidly followed never taking short cuts.
3' What portable extinguishers would you expect to find in an engine room and what colo used?
The outer container contains sodium bicarbonate powder. A capsule of carbon dioxide gas is locatr beneath a plunger mechanism in the central cap. bn depressing the plunger the carbon dioxide gas the powder up a discharge tube and out if the discharg e-nozzle.
The dry powder extinguisher con be used on all classes offire but it has no cooling effecl It is t, located near electrical equipment in the mochinery tpori and elsewhere on the ship.
Foam - Red 5% Cream/Buff-- Chemical
The main container is filled with sodium bicarbonate solution and a long inner polyhene container with aluminium sulphate. The inner container is sealed by a cap held in place Uy r plunger. When plunger is unlocked by turning it , the cap is released. The extinguisher is then inverted-for the two to mix- Carbon dioxide is produced by the reaction which pressurises the container and forces out t foam.
Foam - Red 5% Cream/Buff-- Mechanical
The outer container in this case is filled with water. The central container holds a carbon dioxide ch a foam solution. A plunger mechanism with a safety guard is located above the central container. When the plunger is depressed the carbon dioxide is released and the foam solution and the water n: are then forced out through a special nozzle which creates the mechanical foam. This extinguisher I internal pipe and is operated in the upright position.
Foam extinguishers are used on class B fires and witl be located in the vicinity ofjtammabte tiqa C.O2 - Red 5% Black
A very strong container is used to store liquid carbon dioxide under pressure. A central tube providr outer passage for the carbon dioxide which is released either by a plunger bursting a disc or a valve operated by a trigger. The liquid changes to a gas as it leaves the ixtinguisher *d purses through th swivel pipe or hose to a discharge horn.
Carbon dioxide extinguishers are mainty used on Class B and Cfires and wig befound in the ma space, particularly near electrical equipmenl The carbon dioxitle extinguisher i not permitted it accommodation since, in a conJined space it is lethal.
CFC Extinguishers - Red 5%Green Soda - Acid Red
The container of this extinguisher holds a sodium bicarbonate solution. The screw-on cap contains r plunger mechanism covered by a safety guard. Below the plunger is a glass phial containing sulphur When the plunger is struck the glass phial is broken and the acid and sodium bicarbonate mix. The resulting chemical reaction produces carbon dioxide gas which pressurises the space above the liquir forcing it out through the internal pipe to the nozzle.
This extinguisher is usedfor class Afires and will befound in the accommodation ereas. what type of fire extinguisher would be used on a fire in:-?
(a) Galley (b) Accommodation (c) Control Room or Radio Room (d) Electrical Switchboard (e) Pump Room
(a) Galley - CO2 and Dry Powder
(b) Accommodation - Soda Acid Extinguisher ( see below for description ) (c) control Room or Radio Room - coz or Dry powder
(d) Electrical Switchboard - COZ or Dry powder (e) Pumproom - Foam, COz or Dry powder 4.
5. what are the main causes of serious engine room fires ? oil leaks. Fuel, hydraulic or lubricating oil onto hot surfaces. Smoking, burning or welding.
Rags and combustible debris allowed to build up in the bilge's
\ilhat immediate action must be taken if a fire becomes serious enough to have to evacuate all personnel from the engine room and what precautions must be taken before re-entering? Flood the machinery space with whatever fixed fire installation is fitted. Say CO2.
Before flooding get everybody out. - do a head count.
Where possible all personnel must be made aware of the decision to flood the machinery space with The space must then be completely sealed 4gainst the entry and exit of air and all oil suiplies isolatr tank valves.
When all these matters have been attended too the COz can be admitted and if the srurounding bulkl hold to contain the ftre , it will quickly go out. Cooling of the boundary bulkheads should continue outside the space while flooding is taking place. When the extinguished fir. has been left long enou cool down the space can be re-entered. This should be done from the tunnel, if there is one, oi fro-lowest point from the seat of the fire. Engineers wearing breathing apparatus may now enter, taki water spray hoses with them to cool down any hot surfaces. Coolingand smoke dispersal are the fir priorities, to provide an atmosphere in which others can operate andgradually bringthe machinery s back into service.
Where a machinery space fire involves electrical equipment then only dry powder or Co2extinguisl be used until the equipment is isolated.
What pumps on board ship can be used to supply water to the fire main ? Fire pump.- usually two or three fitted
Fire and bilge pump. General service pump. Emergency fire pump.
Is there an emergency fire pump ? If the answer is y€s, where is it fitted and how is it tested? External to the machinery space.- Run on a weekly basis.
Some pumps may be fitted in the steering compartrnent.
Define what you would consider to be an enclosed space where the internal atmosphere may br frequently hazardous to personnel who may enter.
Duct Keel, double bottom tanks, cofferdams, boilers, CO2 rooms, pumprooms. Bow thruster
compartments should be teated with caution if ventilation fans have not been running. Fore peak anr peak tanks should also be well ventilated and tested before entry.
Describe the procedure which should be adopted:-(a) Before anyone is allowed to enter an enclosed space. (b) While anyone is working inside a closed space. (i) Ventilation for at least 24 fus.
(ii) Test of atrnosphere by a chemist or Chief Officer for Oxygen and Hydrocarbon content. Zlyo o> (iii) Tank entry permit and tally board for personnel to enter tank.
(iv) Breathing apparatus at tank entrance, lifeline and portable lights(air), communication, ild tallier people entering along with ELSA sets.
(b) While anyone is working in the tank there must be a man at the entrance at all times with a mezu communication between him and the person(s) in the tank and the Bridge.
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13. l l . 12. 14. 15. 16. 17.
what types of pumps are suitable for use as bilge pumps? Positive displacement. - small volumes for use wifi ows centrifugal with priming pump - Large volume discharge.
Give reasons why a bilge pump may not be able to remove water from bilges. state typical suction and delivery pressures.
Blocked strum box. ( very high nuru.r* on the gauge)
Hole in suction line. ( zero or very low vacuum on the gauge )
Priming pump not functioning if working in series with centrifugal pump.
Explain what is the emergency bilge suction ( injection). Why is it necessarT and how is it bn into operation?
A bilge injection valve is fitted to the end of a branch line connecting with the main sea water suct The bilge injection valve is always of the screw down non-return type. This valve enables the larg seawater cooling pump to be used as a bilge pump in an emergency. To bring the bilge injection v use during an emergency , the bilge injection valve is openea rutyand the sea suctioi valve is full; After it is established that the sea watir pump is capable of lowering the water level in the engine sea water suction may be opened slowly. This should be done in stales so that the tank tops are no dry,as this would cause the sea water pump to lose suction. Care should be taken to ensue that the often situated on the outlet from the main condenser does not discharge near any electrical equipmr NB. Sea water pumps are not usually self priming, if of the centrifugiltype.
lhat is the purpose of the oily water separator?
To allow the bilges to pumped overboard with an oil content of not more than l5ppm. Read MARPOL regulations.
Explain in detait the procedure for testing the steering gear before leaving port. check for oil leaks and any loose linkages on th. steering gear.
check for correct oil level and test low level alarm.
Run one unit at a time, 30 degs- to 35 degs. in 28 secs at full power. where only one main unit is fi anx' unit, the auxiliaty unit must go from 20 degs. to 20 degs. In 60 secs. at g knots or half speed. Test the communication link between the Bridge and the Stee.irrg compartment.
What is the duty of the engine room crane?
To enable large and hearry engine components to be manoeuwed around the Engine
room in a safe manner.
Detail checks which should be carried out before using the crane and possible
hazards if not functioning correctly.
Check SWL is not exceeded.
Check that the direction indicators on the controls correspond to the actual movement of the crane. Check that the limit switches are working. ' ^^! v^
Check that the brake is operational.
Check that all personnel involved understand the signals to be used in any repair or overhaul. Give the correct procedure for starting an air compressor.
(a) Check the oil level (b) Check the cooling water.
(c) Ensure that the interstage drains are open.
(d) Check that all the correct valves *" ol"n fully to the air receiver and that there is sufficient ca1 available in the air receiver..
(e) If a manual unloader is fitted ensure that it is open. ( machine must be started in the unloaded position).
(D When the machine is up to speed, close the unloader and the interstage drains. 18.
19. What is the purpose of fitting a bursting disc into the air compressor casing?
A bursting disc' or sometimes a water jacket relief valve are fittedto prevent a build-up of pressur€ a cooler tube fail allo*ing high pressure air to enter the cooling *ut.i space.
Describe the procedure required to connect in parallel one diesel or steam driven alternator already on the switchboard with another alternator.
Three-phase alternators ilranged for parallel operation require a considerable amount of instrume This will include arnmeters, wattmeter, voltmeter, frequency meter and a synchronising device. M these instruments will use transformers to reduce the actual values taken to the instrument. This al enables switching, for instance, between phases or an incoming machine and the bus-bar, so that o: instnrment can display one of a number of values. The watfineter measures the power being used ir circuit' which' because of the power factor aspect of alternating current load. will be less thL the p: the volts and amps.
Reverse power protection is provided to alternators since reverse current protection cannot be used. Alternatively various trips may be provided in the event of the prime mover failure to ensure that th alternator does not act as a motor.
The operation of paralleling two alternators requires the voltage to be equal and in phase. The alter current output of any machine is always changing, so for two machines to operate together their vol must be changing at the same rate or frequency and be reaching their ma,rimum ( or Ly other value together
They are then said to be' in phase'. Use is nowadays made of a synchroscope when paralleling two machines. The synchroscope has two windings which are connected one to each side of th. p*utt"l switch.
A pointer is free to rotate and is moved by the magnetic effect of the two windings. When the two v supplies are in phase the pointer is stationary in the 12 o'clock position. If the pJinter is rotating tht frequency difference exists and the dial is marked for clockwise rotation FAST and anti-clockwise r sl-ow, the reference being to the incoming machine frequency.
To parallel an incoming machine to a running machine therefore, it is necessary to ensure firstly tha voltages are equal. Voltmeters are provided for this purpose. Secondly the frequencies must UL Uro into phase. In practice the synchroscope usually *orr.r slowty in the fast direction and the parallelir switch is closed as the pointer reaches the l1 o'clock position. This results in the incoming machinr immediately accepting a small amount of load.
A set of three lamps may also be provided to enable synchronising. The sequence method of lamp connection has a key latnp connected across one phase with the two other lamps connected over the two phases. If the frequencies of the machines are different. The lamps will brighten and darken in rotation, depending upon the incoming frequency being FAST or SLOW. The correct moment for synchronising is when the key larnp is dark and the other two are equally bright.
What is the purpose of having a synchroscope and why must it not be allowed to run continuo To ensure alternators to be connected to bus-bars are at th; correct frequency.
Not to be allowed to rtrrt continuously because they are not continuousiy rated and will burn out. Explain how an emergency alternator starts and supplies power in the event of a blackout. (a) Double pole switch trips on lose of power and on tripping makes contact with emergency switch
supplying power to emergency generator starter motor.
(b) A low voltage coil, typically 24v, is connected to the main switchboard. This coil is normally energised and corutected to a normally open contactor on the air start system for the alternator. r the main power fails the coil de-energises, thus completing the air start system and starting the alternator.
once the alternator has started the air will shut off.
When the machine is up to speed and has the correct cycles and volts, the auto synchroniser will the breaker and put it on the board, (emergency board) to supply the essential services.
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23. 24. 25. 26. 27. 28. 29. 30.
How can a blackout be simulated to test the operation of the emergency alternator?
Turn auto synch to offposition to prevent the emergency generator tying to put itself on the board starts. Shut power offto starting coil, this will de-energise coil and machine will start.
How often should an electric motor be cleaned?
Unless there are any specific problems every 5 years. Use of vibration monitors are helpful in high bearing problems and thermal trips in the windings can give prior warning of impending problems. How would you overhaul an electric motor that has been flooded with sea water?
Strip down and wash with distilled water, then dry out, if possible in an oven, then check meggar r Should be minimum of I megohm. Heating lamps can also be used. On completion coat with ,. gor quality electrical varnish.
Explain how to check the insulation resistance of the motor using a ..Meggerrr.
Corurect the Meggar between each phase in nrrn and the motor casing, after good contact has been : removing paint etc. Resistance should be I megohm.
Outline the dangers to pensonnel who may have to enter a battery room to check the conditio: batteries on charge.
Hydrogen fumes in poorly ventilated battery rooms which contain lead-acid batteries can be fatal. lr naked flames and danger from sulphuric acid burns. Safety gear must be worn including full face v No smoking as there could be danger of explosion.
What is the temperature inside low pressure evaporators and why is the water produced suitr drinking?
Drinking water can only be made from salt water in evaporators if it is boiled above 75 degs. C. Mr the low pressure plants operate at temps ranging from 4d degs C. to 60 degs C. and are therefore ur for making drinking water.
Other problems to look out for are additives used in diesel engine cooling systems and inhibitors u' water systems to prevent fouling by marine growth.The evaporator should not be used within 12 mi. land
what are the reasons for using the main engine turning gear?
(a) To ensure that the engine is warmed up evinly dissipalittg *y thermal stresses in materials ever therefore the engine can be loaded more quickty.
(b) For warming through with the indicator cocks open to ensure there is no water leakage in the cy (c) To be engaged if any major overhaul of the engine is taking place.
(d) For taking deflections.
Why is tappet clearance necessary and what effect would insufficient or excessive clearance h: engine operation?
Tappet clearances are necessary to allow for the thermal expansion of the valve spindle length at wo temperatures' and to ensure that positive closing of the valve continues as it wears or seats d*irrg ,r, Clearances should normally be set while the engine is cold and the czrm follower is offthe cam peak wear of the valve gear will tend to increase clearances.
Excessive tappet clearances will cause the valve to open late and close early in the cycle and will rec ma'ximum lift- It will also cause noise, and eventually damage, from the impact of working surfaces Insufficient clearance will cause the valve to open early and close late with increased marimum lift. extreme cases' it may prevent the valve from closing completely as it expands or beds in. This in tul cause hot gases to blow past valve faces, causing .ruln burning and low compression.
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Describe how to prepare the main engine from cold to ready to start to manoeuvring includi: that require to be carried out.
(1) Before a large diesel engine is started it must be warmed through bv circulating hot water thror jackets etc' This will enable the various engine parts to expand in relation to one another and a engine load to be increased sooner rather than later.
The lubricating oil should also be heated and circulated around the bearings etc., and the pisto: cooled.
The various return pipes on both the water and oil systems should be checked to ensure no blo and the return temperatues should be monitored.
(2) The various supply tanks, filters, valves and drains are all to be checked and opened or closed i required
(3) All control equipment, alarms etc. should be examined for correct operation.
(4) The indicator cocks should be open and the turning gear engaged and started to ensure that ther water present in the cylinders. If any water issues furth.r investigation can be ca:ried out to asc, l
Tne cause.
(5) All oil levels should be checked, i.e. sump, turbochargers, governors etc. (6) The fuel oil system can be lined up and circulated with hot fuel.
(7) Any scavenge blowers if manually operated, should be started. (8) Manually operate the cylinder lubri.utorr.
(9) The turning gear should be removed and the engine blown over on air before closing the indica cocks.
(10) The engine is now available for stand by.
Why should the cylinder indicator cocks be left open until the engine has first been turned ov, starting air?
To ensure that no water issues from the cocks which would indicate a leak from the liner, cylinder head, piston cooling, turbo brower or injector cooling.
Describe the routine inspection you would carry out before taking over the watch on a manne engine room arrangement..
Check the firnnel emissions. White smoke, black smoke, steam or sparks. Check steering gear and fridge flats.
Enter the engine room from the top. Do not use the lift. Check cooling water header tank.
check main engine cooling water returns and temperatures. check piston cooling water returns and temperatures. Listen for any unusual noises.
Check turbo charger oil levels
Check observation tank for signs of oil. Check mist detector.
Check condition of bilges.
Check purifier flat and condition of the fuel oil tanks. i.e. full, empty, temperature. Drain of water. Enter control .oop: check log book and note any irregularities.
Confirm the condition of the electrical supply equipmint. How many alternators on load, amount of on the board. Earth faults. Stand by machines. J --- )
Read any curent standing orders. The duty engineer should then
1nfo* the engineer taking over the watch of any abnormal operating conditions which have occured during the watch. Any oidrr, from the Bridge, recorded in the log br should be pointed out. Any repairs should be reported together with information on any machinery tt been dismantled' The presence of any other members oflhip's staff in the engine room e. g. Dayvor should be reported.
34. Give the various operating pressures and temperatures of an engine you are familiar wi
Scavenge air temperature - 40/45 degs. C F.O. Pressure - 5/6 Bar Scavenge air pressure
L.O. pressure L.O. temperafire Jacket C.W. pressure - 1.0 Bar - 2.0 Bar - 45 degs. C - 3.0 Bar
F.O. Temperahre - 125 Degs. C Cylinder oil pressure - 40 bar
Jacket C.W. temperatue - 65 degs. C
What factors must be present for an explosion to occur in the diesel engine crankcase? For a crankcase explosion to occur, oil mist must be present in the crankcase, and a hot spot must develop, perhaps from bearing wear or stuffing box rub etc. The hot spot then ignites the oil mist ca an explosion. ( See handout on crankcase explosions or Note 22 CLass 4 )
What device may be used to detect and warn of dangerous conditions within the crankcase? A Graviner oil mist detector is used to detect and warn of dangerous levels of oil mist in the crankca The detector consists of two tubes, fitted at one end of each is a photo electric cell, the other end is a lens to allow the passage of light through the tube of the P.E. cell. Light comes from a single bulb a reflected to each tube by a mirror. One tube is sealed and contains clean air and is termed the referer
tube. The other tube is called the measuring tube and is used to pass samples through it. Samples a drawn from the crankcase using a fan drawing through a rotary valve. If a large amount of mist is dr into the measuring tube, less light can penetrate the tube to the P.E. cell, so there will be a differencr output from each sample and depending on the amount of difference will activate an alarm. In the er an alarm, the load of the engine should be reduced immediately by slowing to Dead Slow Ahead and soon as possible the engine should be stopped and the turning gear engaged. Open the indicator coc turn the engine to prevent seizure. Allow engine to cool to normal operating conditions by observin return temperatures.When safe BUT NOT BEFORE 20 MINS the crankcase doors can be opened ar crankcase inspected. A visual inspection from outside the crankcase should be made for signs of wl metal or excessive oil leakage from bearings or anything which might indicate a problem. If nothing obvious the lubricating oil pump can be stopped and a more detailed inspection carried out.
What immediate action should be taken in the event of a warning being given?
Reduce power manually if crankcase mist detector does not do so automatically. Receive permission the bridge to stop the engine. Allow to cool down before inspecting the crankcase for signs of the hc (See note 23 Class 4 notes )
What factors must be present for a scavenge air manifold fire to start? Dirry scavenge air trunking.
lncorrect amount of cylinder lubricating oil. Defective fuel valve and bad combustion. lncorrect fuel valve timing.
Worn piston rings and liner. Choked exhaust.
Defective stuffing box. ( See class 4 notes page 20 )
How would you become aware that a scayenge fire had started? Erratic engine speed.
High exhaust temperatures. Smell of burning paint. Turbocharger surge. Smoke from funnel.
Rise in J.W. temperafire of affected unit.
35.
36.
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41.
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44.
How would you deal with a scavenge fire?
In the event of a scavenge fire the bridge must be informed, as should the C/E, that the engine has to reduced to D.S. Ahead immediately.
Increase cylinder lubrication to all units by increasing the mechanical lubricator flow to mar<imum. Take fuel offthe affected unit by lifting the fuel pump roller or suction valve offits seat ( depending type of fuel pump is fitted ). Shut off nozzle cooling(if nozzle is oil cooled ).
By increasing lubrication there is less chance of the engine seizing due to being overheated by the fir by taking the fuel offthe affected unit the heat developed due to combustion is reduced, which will 1 fire more chance of burning itself out.
The scavenge drains should be closed to prevent any sparks entering the engine room which c81 posr further risk to personnel in the vicinity.
Ifthe fire is of amore serious naflrre the engine will have to be stopped, the indicatorcocks opened r turning gear engaged and the engine turned. The scavenge space fixed fire fighting installation can t brought into use to extinguish the fire.
Scavenge spaces should be inspected to ascertain cause of fire before restarting the engine. Personnt should stay clear of relief/explosion doors where fitted.
What factors must be present for an explosion to occur within the starting air pipelines and wl limits the effect of an explosion?
Heat. Usually in the form of a leaking air start valve.
Fuel. In the form of lubricating oil coating the internal sr:rfaces of the air start lines.
Air. Devices for limiting the effects of explosion are.(l) Flame traps. (2) Bursting discs. (3) Reliel What is meant by the supercharging of a diesel engine and how is this achieved?
Supercharging is a means of supplying air to a cylinder at a greater pressure than atmospheric. This , done on earlier designs by means of scavenge pumps, roots blowers, under piston scavenge systems t Disadvantages with earlier systems were that they used up to 7% of engine power to drive the mecha to boost the airpressure. With the introduction of the turbochargerthe above components were phas out, although some installations combine both.
Describe the operating cycles of a two-stroke and four-stroke diesel engine.
4-stroke Air inlet valve opens - piston moves down cylinder drawing in air - air inlet valve closes a piston moves up cylinder compressing trapped air just before piston gets to TDC fuel is injected -expansion of gas forces piston back down cylinder where at BDC exhaust valve opens - piston rloVer up cylinder forcing out exhaust gases ready for the cycle to start over again. One complete cycle takr degs.
2 - stroke Air enters cylinder through scavenge ports, exhaust valve may still be open on turbocharl engines - trapped air is compressed - just before TDC fuel is injected - combustion takes place and expansion of the gas forces the piston down the cylinder where the exhaust valve opens to expel the exhaust geNes - the piston uncovers the scavenge ports to allow the fresh charge air into the cylinder . exhaust valve closes and the cycle starts over again. One complete cycle takes 360 degs.
Note. The higher the boost pressure the longer the exhaust valve overlap. Explain the function of a turbo-charger.
To boost scavenge air pressure to a pressure greater than atmospheric with no loss of engine power. Volutecasing-Filter-Inducer-Impeller-Difhrser-Rotor-TurbineWheel-NozzleRing--Labyrin Gland - Bearings - Oil Pumps/Thrower Rings.
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3:#hiil|]ilHll#Hve
a cvlinder
liner
rrom
a rarge
two-stroke
srow
speed
Remove alr connections from the cyrinder head.Remove the cylinder head. Remove the piston rod nut.
Disconnect stuffing box from diaphragm.
Grind off the carbg'l build up on the liner before lifting the piston. Tap out rhe piton lifting bolf holes.
Lift the piston from the cylinder
Remove the lubricator quilrs from the riner. Fit the liner lifting gear.
Remove the liner.
46' Explain how scale forms on the heating surfaces of boilers. If the feed water in high pressure boilers Is nora, pure as possible,
three main problems v encountered' These problems are serious and canlead to Lxtensive and ,*p..rri,ne damagr the ancillaty components and can sometimes
lead to injury of ttre engineroom staff, As th
il:'F::';ll?::'ffit3frl;Hgi*f
loo..tprocedure,*h,ndearingwiththis
(1) Scale build up on the inside of the tubes.
(2) corrosion of the feed system and the boiler tubes.
(3) carry over of soluble salts and suspended salts to the superheater
and t'rbine brades. The main cause of the problem is not carrying out proper tests on a regular basis (most
shc daily) to check for ph value, oxygen and co2 levels in the feed water, poor maintenance of
tr*lf.:#:t1"1ffiff"::chemicils
to ensure
limits
are
kepno,r,.
recommended
revels
as
Dissolved Solids are salts that dissolve in water, these sarts (chloride salts) are sometimes < boiler walls when there is an unusual concentration of heat.
susnended Solids are salts that do not dissolve in water but are carried aro'nd the boiler an water system in suspension, these particles *r rupf;;;il;;""*.r.
(Iron and copper o_x 47. Why is the scale undesirable?
(l) corrosion - takes several forms but the most severe cases
of oxygen pitting can lead to r failures' corrosion in the closed feed ,y*.* of high pressure water-tube boilers plants the transport of corrosion products
of coPPER *o lRoN into the boiler. Hard, iron ar
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giving
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i
(2) Impurities - ( soluble and suspended solids ) - trougt t in with the feed water concentrate ilHl"ntually reach a concentration where soluble salis una susfended salts are .. carried or This can result in deposits in thl superheater and on the turbine blades.
48'
why is the boiler water tested and what tests are made and how often?
To ensure the water pH is not acidic and that the chloride *d iDi readings are in the prescr
Dailv Boiler Tests.
100 ml sample of filtered boile, *ate,
Add l0 drops ofphenolphthalein indicator - sample
will turnpink if alkaliniry is > g.4 Add sulph'ric acid, strength 0. 02N from a me€rs'red b'rette until the sample goes clear.
ppm CaCo3:ml O.O2N x l0 Chlorides
Retain above sample
Add a few drops sulphtrric acid o.o2N to ensure solution is no longer alkaline. Add 10 drops potassium chromate.
Sample will turn yellow.
Add silver nitrate from a measured burette until sample just turns a brick red colot'. Ppm CaCo3 : ml silver nitrate x l0
IDS
100 ml sample
ldd l0 drops of phenolphthalein indicator. Neutralise with I drop of acetic acid
lT. a sample in pot & fitto conductivity meter. Take a reading of meter - temperature compensate
and read offscale. tLq!@ ( Vanadomolybdate Test )
Place 5 ml distilled water in r 0 ml left hana tube. Place 5 ml Boiler water in r 0 ml right hand tube. Top up to 10
$ with reagent- Stopler and shake and allow to stand for 3 mins. Place left hand tube in L.H. side of lovibond competitor
Place right hand tube in R.H. side of lovibond compactor
Hold up to light and find colour match - take reading of card in ppm.
@ (colourmetrictest)
Thoroughly rinse sample bottle with the water to be tested. Arrange tr;rro 50 ml nessler tubes side by side
Add 0'2 ml of thymol blue indicator soiution from a graduated glass dropper into the R.H. nessler tt Add 50 ml of sample to the R.H. nessler tube.
Add 50ml of sample to the other nessler tube. (This is the blank ) Place the sample
cylinder in the R.H- compartment of the Nessle riser and the blank cylinder in the compartment.
ilff,ffilii,fi:#,il;ffiffiTffi:'*.the
corours
in the
rwo
windows
using
a constant
right
s,
Hvdrazine Reselve.
Arrange two 50 ml nessler tubes side by side.
Agd 15 ml hydrochloric acid 0.5N ,t "rreilh to each cylinder
Add to the R'H' cylinder by pipette zs iitof sample and mix with a glass rod.
Add to the R'H' cylinder by pipette l0ml of dimethyl, amine amine berzaldehyde mix. solution and thoror Add to L.H. cylinder by pipene 35 ml of sample and thoroughly mix.
ftfiliifrT::H"ffi,*|"
"' cvlinder
in the
R-H.
comparnnent
of the
nessleriser
and
the
L.H.
cyri
Match the samples 4gainst the colo'rs of the disc.Disc readine : ppm hydrazine ml of sample
49.
50. Explain how the water level in the gauge glass can be verified as correct.
I E
52.
53.
54.
what is the purpose of adding chemicals to the boiler water? To increase the alkalinity or thJphosphate reserye
or to act as a Coagulant. In other words to mainti limits required by the manufacturer of the boiler and to minimise damage to the plant.
Close 2 &3 and 0pen I - If free flow from gauge then drain is clear. Open 2 - if free flow steam connection is clear. (No water level in glass) Close z---Open 3 - free flow from ar"i", water
connection is clear. Note gauge glass will be showing full. Finally close 3 and open 2leave io allow gauge glasslo retum to working level again then close I and open 3, level may be slightly high until water temperature returns to normal.
See blowing gauge glass notes 32,33.
If you find no visible water in the boiler gauge glass what immediate action should be takeni If there is no automatic shut-offof boiler nir to birners then shut-offthe fuel manually. sound tht Engineers alarm and call the Chief Engineer.
Blow the gauge glass to see if there is iven the slightest bit of water in the gauge glass. If no water Do Nor ADD WATER until the correct level oitt. boiler water has been established because tt shock of adding water to overheated boiler tubes could collapse the boiler tubes. It is better to let tl cool naturally to their working temperature.
Why is the presence of oil in the boiler water most undesirable?
(a) Cuts down the heat transfer when oil adheres to boiler tubes (internally)
(b) Causes priming resulting in water and oil carry over to the superheaters and turbines. (c) Combines with suspended solids in the boiler water to produce sticky deposits. why should oxygen content of boiler feed water be reduced to a minimum?
(A) Attacks on boiler metal resulting in pitting and deposition of iron oxide on the boiler tubes. (B) Corrosion of the condensate system to produce iron and copper** in the condensate. *:$ copper is attacked by ammonia in the presence of oxygen.
How can this be achieved when an open hotwell and feed system is used ?
(a) By keeping the hotwell temperature at approx. 90 degs. c. The oxygen content of water at 50 d is approx. FOUR times that of 90 degs C.
(b) Ensure deaerator is functioning conectly.
(c) Stop air leaks into condenser, condensate system and boiler feed system.
(d) Ensure the correct level of Hydrazine is being added to the deaerated feed water. (e) Introduce Amines into the low pressure/temperaftue part of the feed system. (f) BV floating polysryrene balls on top of the tank.
rf the plant is un-manned, what would be provided to raise the alam if the water level in the I too low or too high and how often are these tested? r' rsv vv "rr/r rrevrsr r'' rrr' I
Mowbray float alarms. Level transmitters. Tested weekly. Foxboro (Pneumatic) High /Low level trips. Tested *r.kly.
t
t
51.
56' what causes fires to start in boiler uptakes.
what are the hazards. How are they deter actions should be taken?
Build up of soot deposits are a cause of fires, possibly caused from faulty sootblowers. They are detected with temperafire sensors - thermometers or similar type devices. The hazards are that if left unchecked the fire may develop
into a hydrogen fire The action to be taken is:_
1. Shut down the boiler fires and close the air registers.
2' Shut down the F.D. fan and ensure vanes are closed. ( also stand by fans ) 3' Increase feed flow through economisers
(if fitted), blowing down the boiler drum as requ 57 ' on a steam ship, what are the main reasons
for using the main engine turning gear? To ensure that the heat is evenly distributed
while *u*rling through and that turbine rotors c to pressure in the main condenser (underslung varieties
). To aid in gearbox inspections, shaft bearings-etc. 58' Describe how to prepare and flash up a high pressure
water tube boiler. 1. open drum vents and economiser vents ( if fitted ).
2' Fill boiler to one inch in glass. ( enstue all drains
on water drum are closed ). 3. Open superheater vent. (Recirc ).
4. Open drains on superheater headers.
5' Set fuel oil rail up onHFO if steam available, otherwise flash up on DO. 6. Line up atomising steam.
7. Line up forced draught fan. 8. Ensure air heater is by-passed.
9 ' Flash up the boiler on small tip at lowest rate according to manufactures recommendatior steam gradually leaving drurn vent open until steam issues at approx. 2bar.Superheater vent until flow is guaranteed.( Boiler on line ).
10. Test all trips putting boiler on line.
59' Describe the warming through procedure required to prepare the main turbines from c to ready to start of manoeuvring including checks and tests.
1' Run main lubricatin-s oil purnps ensr:rinfall temperatures and pressures
are normal. 2. Start the main circulating pump.
3. Engage the turning gear.
4' open up the gland steam to maint?in u positive pressure above atmospheric at the turbine 5' Open the steam to the first stage air ejector. ( mar.vac 10 ins )
6' Start the main condensate pump ensuring the condensate re-circ valve is open. 7 ' open the auxiliaty exhaust from the auxiiary condenser to the main condenser. 8. Ensure all turbine drains are open.
9 ' Open warming through by pass valves on the main steam line. 10. Rotate turbines by means of the turning gear.
I l ' Gradually increase the main condenser vacuum
by slowly opening up steam to the air eject until fully open.
12' Adjust gland steam as necessary to keep pressure just above atmospheric. Check operation of various trips associated with main turbines.
i.e. overspeed, low lube oil, lr Depending on the installation there may be various other trips fitted.
61. 60. 62. 63. 64. 65.
How is the main turbine prevented from over speeding and what trips would need to be reset? The main n'bine has an overspeed trip ( normally . ,pJ"d hmiting u.n to, ) to prevent overspeed case of a coupling failure or the ship's propellet "I"-irrg the wavm o*ing rough seas. The trip ur fitted with three independent circuiis, which sense trre turuine speed by means of pick ups mo'nte, turbine pedestals, aod receive a speed signal from three pulses
iroauced by a tootled wheel. The shuts a number of control valveslo.ut"Jin the steam chlst, which is an internal part of the H.p. tu the overspeed trip operates, the boiler safety valves may lift, due to a sudden decrease in turbine lo when the trip operates, the mechanical movement alters the position of the trip switch which then energises
the upper coil of the relay and at the same instant dL- energises the lower coil, thus chanl position of the relay. The coil of the solenoid valve is thus de-energised and the spring moves dov the oil pressure keeping the manoeuwing valve open is lost. Simultaneously visual and audible alt activated and the particular trip is indicated. After the trip has been reset, (the fault being rectified) reset switch is made which energises the lower coil of thl relay, and the solenoid valve is repositio: protection system is thus reset. Any number of trips can be built into the system.
Explain how the final superheated steam temperature is controiled on a high pressure/high temperature water - tube boiler and why is it necessary.
Attemperators
are used to keep the final superheat t"mjeran r.s within the desired limits. It is necr control the temperafi[e to protect the superheater tube materials from overheating and to reduce tht deposits formed on the tubes.
Describe the routine inspection you would carry out before taking over a watch on a manned room of a steam ship.
See question 33 In addition :_
check deareator level, check F.D. fans, bearings etc.,. Check air heaters and economisers.
Inspect boiler water levels and automatic combustion controls including fuel oil temperatures and pressures.
check around turbine manoeuwing controls lookin g attemperatures and pressures and for signs of r lights etc. (Gagged valves ).
Check main condenser vacuum.
Check gravity tank overflow sight glass.
Give the various operating pressures and temperatures of a steam propulsion plant you may t familiar with.
\ilhy is there a vacuum in the main condenser?
There is a vacuum in the main condenser to improve the efficiency of the plant, i.e. to get more wor of the steam.
Give reasons why there may be some loss of main condenser vacuum and why is this undesiral l' If condensate temperature is below the saturation temperature of the condensri- ai, leakage into
condenser or incorrect operation of the air ejector.
2' If cooling water temperature difference is greater than normal - insufficient cooling water, or bloc tubes.
3' If cooling water temperature is less than normal - Dirty tubes, or in the extreme case, division plawashed away.
4' lngress of air at L.P. turbine gland due to insufficient gland steam pressure.
All the above toubles cause a loss of vacuum and raises the exhaust temperatue of the tubine. This loss of vacuum causes a loss of power and a loss in plant efficiency.
The efilect of a sudden loss in vacuum will be to lift the relief valves on the flrbines. over pressu The L'P' turbine and the condenser are undesirable hence a safety device shutting the steam to the flrbines is required.
66.
67.
which can cause the L.P. turbine to hog when fitted with an underslung condenser, thus produc thermal stesses. The limiting exhaust temperattrre is 77 degs C for cast iron and g2 degs C for casings.
Loss of Vacuum Trip
ln order to improve the efficiency of the turbine, the condenser and hence the ttrbine exhaust is rur very high vacuum (about 730 mm Hg ). This means that the saturation temperature of the steam 50 degsC. Ideally a turbine should be designed so that at the exhaust the steam i, dry saturated. SI condenserpressure suddenly rise i.e. the vacuum fails, then since the heat content of the steam is tl and the exhaust steam temperafltre has risen to the new saturation temperatrue, the steam will now I Thus the exhaust conditions have changed, since instead of dry saflrated steam at about 50 degs C
have wet steam at a temperafttre in excess of this. This change of condition will cause sudden ove of the last few rows of blades, the resulting expansion causing possible blade rubbing. Further to tl will also be very rapid erosion as the high speed L.P. blades strike the water particles.
To prevent this from occurring a vacuum trip is fitted which closes off the turbine steam supply sht vacuum fall below a preset level. ( usuaily about 50% )
Describe the procedure to start up a turbo-alternator from cold until it is ready to be connect switchboard including trips to be tested and reset.
Stan the TA condenser cooling water pump.
Circulate air ejector/gland steam condenser (if fitted ) bv means of condensate pump, ensuring recir is open.
with the use of the priming pump, pump oil round the bearings and the gearbox sprayers ensuring pressures are registering on the gauges.
Raise the condenser vacuum to 60Yoby means of the air ejectors and the gland steam and open up t exhaust to the atxiliary condenser.
Crack open the master steam valve having first made sure alt nrbine and line drains are fully open. Adjust steam to H.P. and L.P. glands as necessary until small amounts of steam issue from the glan, Check oil levels in the sump and ensure salt water cooling is lined up to the L.O. cooler.
overspeed trip should be tested every time the machine is started. one engineer should stand by tht master valve while another operates the throttle valve. The L.O. hand pump should be operated to e the steam confol valve to open and allow steam into the turbine once the throttle valve is cracked o Tubine drains can be eased in but not closed. By means of a special tool pressing on the governor I the machine can be oversped and the revs noted for the log book. Once the overspeed trip has work delay re-setting of the trips until machine is at approximatlly 40%of the normal speed. Check L.O. temperatures' Reset throttle/emergency valve and progressively open master steam valve until appn turn open' Bring machine up to full rated speed by means of the throttle valve and ensure master va fully opened' Raise vacuum to morimum. Close all drain valves. Machine is now ready to parallel on board s.w. valves to L.o. cooler etc. can be regulated to suit.
Trips fitted are;- overspeed - Low L.o. - Back p-rr*" trip. What are nodes and anti-nodes?.
Within a vibrating system certain points that do not move or have zeroamplitude are called NODES points where the amplitudes of vibratory movement are at a ma:<imum are referred to as ANTI-NOD Hence a bearing would be placed at or €ls near as possible to a NODE.
when coming into port, how do you change over from HFo to Do?
The method of changing over from HFo to Do will vary from vessel to vessel but a common metho use of a mixing chamber where-by the viscosity of the iuel is "sensed" by the viscometer and the he automatically removed from the heater as the DO filters through the system on its way to the fuel oil cool gradually and prevent thermal shock to the materials of the engine block etc.
Fuel supplied to motor vessels is usually of the high viscosiry rype.
This kind of fuel is a blend of low-viscosity distillate and high viscosity residual oils . The b'nker sr
69.
70.
has tables which give the proportional amounts of eachkinq of oil required to obtain some specif viscosity' After the proportions have been established the blend is produced by using rwo pumps aranged to discharge into a common pipe. The size of the pipe is such that turbuleni flow takes 1 the two tlpes of oil become will mixto.-th. speed of the two pumps is set so that the proportion r kind of oil passing into the common discharg; is maintained clnectly. Distillates from one crude do not always blend well with residuals from another. This occurs when the smaller part is not sc the larger part' If incompatible oils are used to produce a blended fuel, precipitation will occur. Tl itself in the operation of the centrifugal purifieis which quickly fill with asphaltic material and exr difficulty may be experienced in maintaining an adequatl throughput
of fuel through the purifier I requirements of the engine- This problem is well rcnown
1o n et oit suppliers and they take every ( blend compatible types of fuel. Normally fuels from different ro*.., should not be mixed aboar blend that is compatible in itself may not be compatible with a blend from another origin, and pre may occur.
what is cavitation and where would it appear?
Cavitation is the forming and bursting of vapotu-filled cavities or bubbles and it can occur as a res pressure variations' Found most commonlron ships propellers due to presswe variations on the b propeller blades the result being a loss of thrust, erosion of the blade suface, vibration in the afterl the ship and finally noise- It is usually limited to high speed heavily loaded propellers and is not a under normal operating conditions with a well designed propeller. Another component subjected t cavitation will be centrifugal pump impellerr, .rprJiuty condensate pumps used in dry-sump cond which bottom end bolt would you expect to fail first, a bolt fitted to a four stroke engine or a fifted to a two stroke engine?
Likelihood of bottom end bolt failing on 4-stroke engine first due to the various stresses affecting t (See attached notes)
Simple
stress:-Comes about from some static form of loading, and the value of the stress does not change. Fluctuatine
Stress:-Diesel engines when operating are not subject to static forms of loading . Due to cylinder pressure variations and dynamic effects of the -orrirrg parts the forces acting on *y part of an engine are a1 changing' As the forces change so the stresses in the various parts change. The changing values of experienced on parts of a machine are referred to as fluctuatirrg
,t .rr. et any instant in time the va stress can be related to a simple stress.
Alternatine
Stress:-Is said to occur when the value of a stress changes from some value of tensile stress to a similar valr compressive stress' The example is the overhung fly.rvheel where
a particle in the shaft surface will change from tensile loading at its uppermost position of rotation to .o*pr.rrive loading at its lowes The overhwtg flywheel may be considered as a cantilever with a concentrated load.
C)'clic
Stress:-when a certain pattern of stress change rTeats itself at equal time intervals (for example, each revt of an engine of shaft) the pattern of stress is refened to as cyclic stress.
Fluctuating' alternating' of cyclic stresses are of great importance as they are very closely associater a form of failure of machine parts known as fatigue failurl. Alternating of cyclic stresses are someti referred to as fluctuating stresses as a general t.trn to distinguish them rrorn simple stresses.
How is a fuel oil burner with steam atomisation, prevented from being removed from the boilt the fuel and steam are still flowing?
Mechanical interlock situated on tof of burner i.e. when fuel and steam valves are in the open positi burners are covered and cannot be removed.
what happens when a condenser loses its vacuum? (See question 65)
71.
73. why should you not run an astern turbin_e
on superheated steam for extended periods? Not designed to rur for periods longer than 30 minutes as higher t.*p, involved **ta affect ex1 the LP rotor with the added danger or uua. rub and subsequent dam4ge. (Materials & Tolerance why are intercoolers fitted onto air compressors?
i1'.'ff!,;1h:ffii:'*:"#ffif[:ff#ssed
ai,to
be
cooredafterthe
various
stages
thus
ir
Why is boiler furnace air heated?
Heating the air prior to entering the furnace increasing the thermal efficiency of the boiler by impr combustion process.
what safety measures are fitted to protect a steam turbine should a blackout occur?
Gear driven pumps on most modern pt*rtr (Stal-Laval) driven offthe main gearbox ( press,re /ga system) or gravity tanks situated at the top of the engine room provide adequate time to bring the t to rest in the event of a blackout.
Describe turbo-charger surging.
Turbochargers sluge when thty are uying to deliver more air than they can suck in. The causes afi usually blocked intake filter, failure to open cooling water valves for the charge air intercoolers. L bangs are heard from the scavenge tunking. (Not *tit. sonic bangs.)
What is a hi-jet valve?
Hi-Jet valve is a PV (pressure/vacuum
) breaker found on all cargo tanks and fitted to prevent vacu pressure conditions arising in cargo tanks with possible structural damage resulting to the tank. Flame screens prevent the ingress of sparks, ligirtening etc. into a flamniable atmosphere. The gast be cleared to 3 meters above the deck.
How do you test main engine trips and how often are these tests carried out?
when running up Main Engines various t ips can be tested by simulating the trip devices, i.e. over low lubricating oil pressure and high Jacket water Temperature.
Describe the process of tran-sferring heary fuel oil from a double bottom tank to a seftling tan ** Ullages of all the tanks before "oriro.rr.irrg ** ** Checklists ** ** Oil Record Book *:F * * communications ship to shore,if appropriate or Bridge and engine room senior watchkeeping of ** Don't rely on gauges for final ullages itopping off ; -,r*
Record all transfers in log book as well record book 'F* Regular checks ** *tspitt gearat the ready **
Take soundings /ullages of any tanks supplied from the common line. check all valves before conu the bnnker operation' If necessary lash ctosea any valves which could accidentally be opened. Line. correct transfer line' Inform duty engineer and Bridge that transfer is about to start. start pump and
:1l?',Y:Hi?tr::$j#s
to confirm
now
is conect.
Do
this
on
a regurar
basis.
Have
spnr
sear
If transfettittg to two tanks at the one time restrict flow to one so as only one tank to monitor when finishing.
YnI is the purpose of fuel oil settling tanks?
Settling tanks are used to allow any water which may have entered the tank accidentally with the oil leaked via a heating coil to "settle out " where it canbe drained to the oily bilge. They are fitted witl heating coils to allow the oil to be raised in temperature for ease of transfer to the daily service tank normally through a p'rifier. The temperature should be restricted to app;. 5l deg c ( 125 deg F temperahrre should be restricted to approx. 5l deg c (l2s deg F )
74. 75. 76. 77. 79. 79. 80. 81.
82. 83. 84. 85. 86. 87. 89. 89. 90. 91. 92. 93.
why are weighted cocks fitted to oil sounding pipes?
weighted cocks are fitted to oil sounding pipes on aouule bottom tanks ro ensure a positive shut-o In the unlikely event of the vessel touching bottom and the tank being holed, sea water at pressure enter the tank and displace the oil out via the sounding pipe.
Where and why are quick closing valves fitted in a fuel system and how can they fail to operr Quick closing valves are fiued to the suction lines of all fuel and lubricating oil tanks so that in the of a serious fire in the engine room, the tank can be isolated in the event of the pipeline melting in It would also allowthe engine to stop due to lack of fuel if the engine room had to be
lnv are oily-water separators necessary in an engine room? See question 14.
What pumps on board ship can be used to pump out engine room bilges? See question I 1.
Give possible reasons why an engine room bitge pump may not be able to empty bilges. See question 12.
What immediate action must be taken if a fire in the engine room is serious enough to have tr evacuated by all personnel?
See question 6.
Where would you expect to find the emergency fire pump and what is a very important valve make sure is closed if the pump has to be used?
Fire pump usually situated outside of machinery space normally in the Forecastle but sometimes in steering gear comparEnent. When running ensure anchor wash valves are closed to boost pressure. Describe the procedure, before the start of a voytge, to ensure that the steering gear is operatr satisfactorily.
Check for oil leaks - Check for loose linkages/pins
etc. - nrn pumps individually 30 - 35 degs in 2t seconds' Test means of communication betrveen bridge and Sieeti"g gear. If possible test alarms.. what gases may be found in empty bailast tanks?
Hydrogen gas may be present, withpossibly
C02. Lack of oxygen due to oxidation in the tank. What is the danger when using a spirit lamp to detect leakage of freon gas?
It decomposes in contact with flame io give products which are pungent and poisonous (Chlorine & Phosgene ).
what type of clutch is used on an electric windlass? Dogclutch or electrically operated magnetic clutch.
What means are taken to ensure that the lifeboat engine will start in any climatic conditions sr extreme cold?
Arctic fuel ( low pour point ) - space Heaters (intrinsically Safe)
Insulated engine housing - Electrical glow plugs - ether aerosol can- Anti - Freezein fresh water circ systems.
what means are provided to prevent overspeeding of the lifeboat when it is being lowered? Centrifugal Brake on Falls.
95.
96.
Describe how you would check a BA set.
(A) Check all straps on mask are O.K. & check condition of mask glass. @) Press demand valve (button/ lever ).
(C) Check boule connections. (D) Check opening of main valve. CE) Turn air on and offagain.
(F) Pressure should not drop more than l0 bar in two (2) minutes. (G) Test alarm, press demand valve or hold mask to face and breath. (H) Check tightness of face seal.
Having reassembled a pump you saw water slightly leaking from a gland packing-- would yor up to stop the leak?
No. On packed glands it is quite normal to have a slight leakage of water.
97 ' What temperature would you expect on a M.E. exhaust and what deviation would be a Under full load conditions. - 350 - 400 degs C Marimum of 50 degs differential.
98' What temperature would you expect for the M.E. lub oil in normal seruice? About 40 - 45 Degs c ( outlet 0 - 3s - 40 degs c. (inlet )
99' What temperature would you expect for the M.E. JCW ? What may happen if the teml low?
outlet - 65 degs C Inlet - 55 degs C. Too lowthermal shockingmayresult. Leakage of wa expansion pieces with the possibility of water leakage through tf,e sealing rings etc.
100. If the S-'lry'. cooling temp was too low what effect could it have on the M.E?
Cools down Lubricating oil, jacket water charge air and if cooled down too much will affect L . O .
(cold plugging in L.O. coolers) and cause thermal shocking and cold temperature corrosion. 101- How would you start an auxiliaty diesel engine (manuat)?
What would you suspect if the engine failed to start on air? What would you suspect if the engine failed to start on fuel? Take stand-by machine off..auto start',
Turn stating handle to stop and open indicator cocks. Check sump and governor oil levels.
Lubricate rocker gear with oil can.
operate had priming pump and open air start valve. Blow over engine.
Run up engine by turning handwheel to "Start" position. When engine is turning at speed tun to "Run" position.
Shut air start valves.
Check oil and water pressures.
Open sea water cooling valves on engine. Startpump if necessary. Check safe flow of fresh, water on flow sight glasses.
Switch on alarm/trip panel in control room. Machine is now ready to parallel.
102. What would you do in the event of a scavenge fire?
ln the event of a scavenge fire the bridge most be informed as should the Ch. Engineer that . to be reduced to D. S. Ahead immediately.
lncrease cylinder lubrication to all units by increasing the mechanical lubricator flow to max Take fuel offthe affected units by lifting the fuel pump rollers or suction valve offits seat ( r what type of pump is fitted). Shut off nozzle cooling (if nozz,le is oil cooled).
By increasing lubrication there is less chance of the engine seizing due to being overheated t by taking the fuel offthe affected units the heat developed due to combustion, is reduced wh the fue more chance of burning itself out.
The scavenge drains should be closed to prevent any sparks entering the engine room which further risk to personnel in the viscinity. If the fire is of a more serious nature the engine will stopped, the indicator cocks opened and the turning gear engaged and the engine turned. Thr space fixed fire fighting installation (C02, steam smothering etc) can be brought into use to e fire.
Scavenge space should be examined to ascertain cause of fire before restarting the engine. P should stand clear of relief / explosion devices where fitted.
103. How often would you inspect the scavenge drains?
What do you expect to see coming from the scavenge drains? What scavenge air temperature would you expect?
(a) Every watch (b) A little water with possibly a little lubricating oil. (c) Approx. 40 de1 104. How often do you blow gauge glasses on a package boiler?
How often do you blow down level transmitters?
Package boiler gauge glasses should be tested when put on line and at any time when there is least once a week to ascertain where the correct level is.
Level transmitters should be tested when the boiler is put on line and approx. Once per montJ 105. How often do you blow gauge glasses on a water-tube boiler?
How often do you blow down level transmitters?
Watertube gauge glasses should also be tested when put on line and in the case of very high t boilers with the bulls eye type of glass can usually be tested on aregular basis, but forthe nor pressure boiler gauge glass, great care has to be taken when blowing the glass in case the mic and the glass leaks.
Glasses should be tested once every two weeks and with twin boiler plants, one boiler every 1 Level transmitters should also be tested when the boiler is put on line and approx. every mon 106. Describe how you would start aTlAfrom cold condition
Why do you use gland steam? What trips do you have on a TIA?
How do you obtain a vacuum in the condenser? Why do you need a vacuum?
See question 66.
107. Passing the fridge unit you see bubbles in the sight glass, what do you suspect?
Large bubbles in the sight glass may indicate that the system is short of gas. When the syste: charged the sight glass should be clear and the discharge pressure normal, depending on the s temperature.
Small bubbles in the sight glass accompanied with a high discharge pressure would indicate a system.
108. How would you remove air from a fridge system?
Shut the outlet from the condenser/receiver and allow the refrigerant to be pumped down. Thr will cut out on high pressure when it is pumped down. The air can then be removed by openi the top of the condenser.
10e'
il" ili*::THJhi:l il
"" a svstem,
it has
a mi\ quariry
about
it (a)
wourd
yr
Ensue that the t'9' nTfier is opera:ing co:rectly and that the correct gravity disc is bein*iir";illT'ff]].Hhan8ed
the
oil should
ue it rieht to continue
iriuse
iithe source
r
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110. Bo'er water tests--what are you looking for?what tests do you carry out on a water tube boiler? why is it necessary. to reduce o{ygen in the feed water? How is the oxygen level ".Au..Jl
state the formurae for the chemicars used
To check that the Ph of the water is at the recommended value. That the TDS is not roo high.
That the chlorides in the boiler water are not too high.
fffr fr: ffn::l;:ff;';;i13:
llf:
;"#i;;*" recommended
rimit
( Hydrazine
readi:
Tests carried out are :_
*t$ilyir:Hfs'
TDs' Phosphates,
oxvgen
and Hvdrazine.
caustic
alkalinity
shourd
a
It is necessary to reduce oxygen to prevent
corrosion in the boiler fubes, corrosion in the fet copper is attacked by ammonia in the prescience
of oxygrrr. i i;; question 4g ). prevention - Ensure
that the deaerator is working efficiently.
stop air leaks into the condens.r, ,iniensate system and boiler feed system. Enstre the correct level of Hydrazirr. i, being added to the deaerated water. 111' why do we superheat steam
in the boiler and then desuperheat it before use?
;:ffi"::tf;lf:'*tlff
b"iil;; that
the
r,.u* "* store
more
enerry,
and
arso
the
stea
The p'rpose of a de-superheater
is to reduce the temperature of a quantity of superheated ste suitable for auxiliary services requiJrrg low temp";;r" or sat'ated steam.
ll2- why do you take power cards on a M.E.? How do you work out the poro." p.r cylinder?
Power cards are taken to enstue thai eactr cylinder is developing roughly the same amount o: engine is in a balances condition and the exhaust temperatures
should be within 50 degs c oI
,:ilT;il,:'#Hl,iiil*:#,';,';flH:il:#i:mx*ffi
::,ff
diagram,,hen
The formula for indicated pb*., is;_ -P = Mean Efifective power L = Length of Diagram A = Area of Diagram N = Number of Strokes
[13' why do you need to cool the air from the T/c before retuming it to the scavenge space? In order to alter its density and increurc irr mass no* to the cylinders. nge space? The greater the mass
of air supp[J;; rh..yrirra.rs; ,h" greater the amounr of fuel which can therefore the greater the power oboin.a.
14- If the steering system is overroaded wourd it trip out?
