MARINERS VOICE

Battery maintenance

Cell tops must be kept clean and dry in order to reduce the risk of corrosion and electrical leakage.
Terminals should be kept tight, clean and free of any deposits. The connectors can be coated with petroleum jelly.
The cables should be examined from time to time for signs of corrosion.
Electrolyte level should be checked and topped up with distilled water to cover the electrodes.
Gas vent in the cells should be kept free from blockage by dirt or in case of alkaline batteries from crystallized electrolyte.
Pure distilled water should only be used for topping up.
Specific gravity should be measured and temperature correction should be applied.
A weekly log of critical parameters to be maintained.
Voltage reading of each cell should be taken while the current is actually flowing. [the voltage of battery on an open circuit is however rather misleading]
First aid treatment should be understood and first aid equipment must be available at all times.

Precaution of Batteries

Both batteries emit Hydrogen gas.So no naked lights allowed.
Battery is stored in well ventilated room.
Battery room should be clean and dry.
No smoking board to be displayed.
Paint work in room should be acid and alkaline resistance.
Acid cells should never be placed near Alkaline cells.
Never use Lead-acid batterymaintenance gear to Alkaline battery.
Use proper PPE. Insulated spanner should be used to prevent accidental short circuit and may cause spark.
First aid equipment should be kept near battery room.
Never use the thermometer to measure electrolyte temperature. Accidental damage of thermometer cause explosion.

Battery installation

Battery room should be well ventilated, clean and dry.
Both type batteries generate gas during charging. So, No smoking, Naked flames in the vicinity of batteries.
Steel work and decks adjacent to lead acid batteries should be covered with acid resisting paint and alkali resisting paint used near Ni-Cd cells.
Acid cells must never be placed near alkaline cells. Never use Lead-Acid battery maintenance gear to Alkaline battery installation or vice-versa.(e.g Hydrometer, topping up bottle,etc.,)

MEO CLASS4 ORAL 25/03/2021

MEO CLASS4 25/03/2021

QUESTIONS AND ANSWERS

Crank case explosion
Main engine one unit exhaust temperature is increased ,what PARAMETERS will you Check,what will be ur action, what can be the reason?
BOILER MOUNTINGS
AIR IN THE REFER COMPRESSOR,HOW WILL YOU FIND AND WHAT WILL BE THE ACTION.
MAIN BEARING AND BOTTOM END BEARING CLEARANCE

CRANK CASE EXPLOSION

HOW IT WILL HAPPEN?

TO MUCH CLEARANCE BETWEEN BEARINGS,
OIL FLIMS MAY BREAKDOWN
DIAPHRAGM IS NOT SEALING PROPELY
PISTON CROWN IS BROKEN, EXHAUST GAS MAY LEAK TO CRANK CASE,
CIRCULATING LUBRICATION OIL NOT PROPER.
ENGINE CHAIN DRIVE IS TOO TIGHT. WHICH MAY LEADS TO HOT SPOT.
GEARS DONT HAVE PROPER LUBRICATION.

PRIMARY EXPLOSION?

DUE TO ANY ABOVE REASON HOT SPOT WILL CREATE. WHEN LUBRICATION OIL CONTACT WITH HOTSPOT OIL BECOMES VAPOUR, AGAIN VAPOUR WILL COME AND CONTACT WITH THE HOTSPOT, PRIMARY EXPLOSION WILL HAPPENED.

SECONDARY EXPLOSION?

AFTER THE PRIMARY EXPLOSION, PRESSURE WILL INCREASED INSIDE THE CRANKCASE.
NOW CRANKCASE RELIEF VALVE WILL ACTIVATED RELEASE ALL PRESSURE .
AFTER THIS CRANK CASE BECOME VACCUM AGAIN. NOW IF FRESH AIR WILL COME INSIDE THE CRANKCASE SECONDARY EXPLOSION WILL TAKE PLACE.

TO AVOID THE SECONDARY EXPLOSION

ALL MAIN BEARINGS AND TRUST BEARINGS HAVE TEMPERATURE SENSORS. IT WILL GIVE ALARM ONCE TEMPERATURE INCREASED.
IN NEW TYPE OF ENGINES WE HAVE A SENSOR OF WEAR DOWN OF MAIN BEARINGS. (IF UNEQUAL WEAR DOWN MEANS OIL FLIMS WILL BREAKDOWN.)
AND WE HAVE NON RETURN VALVE TYPE RELIEF VALVE WHICH WILL RELEASE ALL PRESSURE WHEN PRIMARY EXPLOSION TAKE PLACE INSIDE THE CRANK CASE.

MAIN ENGINE ONE UNIT EXHAUST TEMPERATURE IS INCREASED- WHAT PARAMETERS YOU WILL CHECK,WHAT WILL BE YOUR ACTION AND WHAT CAN BE THE REASON?

REASON FOR ONE UNIT EXHAUST TEMPERATURE INCREASED?

THERMOMETER FAULT
BLOW PAST
SCAVENGE FIRE
EXHAUST VALVE LEAKING
FUEL PUMP MALFUNCTION
FUEL INJECTOR FAULT
LESS AIR IN FUEL
TAPPET CLEARANCE IS MORE.

WHAT ARE THE PARAMETERS SHOULD CHECK IF ONE UNIT EXHAUST TEMPERATURE IS INCREASED?

THERMOMETER SHOULD CHECK IF IT'S WORKING PROPELY OR NOT.
SCAVENGING MANIFOLD TEMPERATURE SHOULD CHECK
SHOULD CHECK TAPPET CLEARANCE

ACTION WHEN INCREASED EXHAUST TEMPERATURE IN SINGLE UNIT.

REDUCE ENGINE RPM
INCREASE CYLINDER LUBRICATION
TAPPET CLEARANCE CHANGE
OVERHAULING FUEL PUMP
OVERHAULING FUEL INJECTOR
ADJUST FUEL INJECTOR TIMING
SENSORS CHECK OR CHANGEOVER

BOILER MOUNTINGS

OGEE RINGS
DEMISTER
RING AND DISTRIBUTER
FUSIBLE PLUG
PRESSURE GAUGE
STEAM STOP VALVE
AUXILIARY STEAM STOP VALVE
BOTTOM BLOW DOWN VALVE
SCUM BLOW DOWN VALVE
SAFETY VALVE
SALINOMETER VALVE
FEED CHECKER VALVE
GAUGE GLASS
VENT

REFER AIR IN THE SYSTEM, HOW WILL YOU FIND AND WHAT WILL BE THE ACTION.

AIR IN THE REFER SYSTEM HOW WILL YOU FIND?

ABNORMAL HIGH DISCHARGE PRESSURE
JERKING OF COMPOUND PRESSURE GAUGE
VERY SMALL BUBBLES IN SIGHT GLASS
CONDENSER TEMPERATURE HIGH.

ACTION IF AIR IN THE REFER SYSTEM?

CHANGE THE COMPRESSOR TO MANUAL MODE
BYPASS THE LOW PRESSURE CUT OUT
CLOSE THE LIQUID STOP VALVE AFTER THE CONDENSER.
PUMPING ENTIRE REFRIGERATION INTO CONDENSER.
UNTIL SUCTION PRESSURE IS BECOME ZERO.
STOP THE COMPRESSOR AND CLOSE THE CONDENSER SUCTION VALVE
THEN GIVE SOME TIME TO COOL DOWN
THEN OPEN THE PURGE VALVE ON THE CONDENSER.
AIR WILL GO OUT. WAIT FOR REFRIGERANT COME OUT.
THEN CLOSE THE PURGE VALVE .
OPEN THE LIQUID STOP VALVE AND COMPRESSOR SUCTION VALVE START THE COMPRESSOR.
CHECK THE SIGHT GLASS.

MAIN BEARING AND BOTTOM END BEARING CLEARANCE?

MAIN BEARING (JOURNAL BEARING) CLEARANCE?

CLEARANCE MEASURES JOURNAL BEARING TO UPPER SHELL USING TELESCOPIC FEELER GAUGE

BOTTOM END BEARING (CRANK PIN)

PISTON - BDC

CLEARANCE BETWEEN BOTTOM END BEARING TO BOTTOM SHELL USING FEELER GAUGE.

Atomisation

Atomisation:

Break up of the liquid fuel into a minute vapour mist.

Factors affecting Atomisation:

small orifices of the injector.
pressure difference between fuel line and cylinder.
Temperature, mass flow rate and viscosity of the fuel.
Effect of too high atomisation - After burning
Very small fuel particles will not have enough kinetic energy to go through the whole combustion space. Fuel droplets gather near the fuel injector due to resistance from the dense compressed air.
Hence, they will be starved during combustion and after burning will take place.

Effect of too low atomisation - Poor combustion
Larger fuel droplets will possess more kinetic energy and get deposited on the liner wall. This causes after burning and poor combustion. Carbon deposits will be seen on the liner walls, side of the piston crown and piston rings.

Boiler Water Test

Boiler water tests:

Alkalinity test. [a.Phenopthelin (P) alkalinity test b.Total (T) alkalinity test ]
Chloride test
Excess phosphate test
pH test
Amerzine test (Hydrazine test)
Conductivity test (total dissolve solids test)
Hardness test

Purpose of Boiler water Test:

To ensure that proper chemical treatment are maintained at all time.
To detect the presence of contaminants in the water that may damage the boiler and feed system.

How to collect water sample for test?

Test sample must be cooled to 25°C with the help of sample cooler.
Allow sufficient water to flow through sample line before taking the sample, this will clear it from sedimentation.
Let the water overflow from sample bottle to prevent air being trapped.
Keep the bottle air tight for testing.
If sample is colored or turbid, filter paper should be used for testing.
Try to take sample from same point.
Try to avoid the sample to contact with air, this will change the dissolved Oxygen content.

Alkalinity test:

This is to ensure that the boiler water prevent corrosion by neutralization of acidic gases.

Phenopthelin test [P-Alkalinity test]

This test is for finding amount of hydroxides in boiler water.

Procedure:

Take 100 ml of boiler water sample.
Add 10 drops of Phenopthelin.
Colour will change to Pink.
Now add N/50 Sulphuric acid, till colour will varnish.
The quantity of Sulphuric acid will indicate Phenopthelin alkalinity of boiler water.

Result:

P-Alkalinity in PPM=Drops of Sulphuric acid ×10

Total Alkalinity test:

This test is to determine the amount of Hydroxide,Carbonate,Bi-Carbonate in boiler water.

Procedure:

With the above sample add 10 drops of Methyl Orange.
Colour will change to Orange.
Now add Sulphuric acid, till colour change to Pink.

Result:

T-Alkalinity in PPM=Drops of Sulphuric acid × 10

Hydroxides and Carbonates can co-exist together in a solution but Hydroxides and Bi-Carbonates cannot.

Chloride test:

This test is to know the amount of salt in boiler water.

To minimize the chloride level and to adjust the blow down.

Procedure:

Sample after P-Alkalinity to be used.
Add 10 drops of Potasium Chromate.
Colour changes to Yellow.
Add N/35.5 Silver Nitrate (Ag NO3), till colour changes to Brick Red.

Result:

Chloride content =No. of drops of AgNO3 ×10

Chloride content < 300 PPM

Phospate test:

To control the scale formation due to hardness.(presence of Phospate sample means no hardness salts)

A reserve of Phospate should be maintained in the boiler water ready to neutralize any hardness salts which may enter.

Procedure:

Take 25 ml of filtered boiler water sample.
Add 25 ml of reagent Molybdate.
Then add one small spoon of stannous Chloride.
Colour will change to Blue.

Result:

Use comparator to check the phospate.

40 - 60 PPM should be maintained.

pH test:

To control condensate pH value within limit.

To minimize corrosion in steam and condensate system.

Procedure:

It is checked by using pH paper.
Dip the pH paper.
Use the colour comparator to check the pH.

Result:

Should be 10-11

Hardness test:

To check for salt causing "hardness "

Hardness test of boiler is not necessary when the Phospate is above the lower limit of control range.

Procedure:

This test can be carried out by conductivity meter or by a standard soap solution.
Take boiler water in beaker.
Add soap solution and stir it for sometime.

Result:

more foam formed, less is the hardness in boiler water.

conductivity test:

To measure the total amount of dissolved solids (T.D.S) including treatment chemicals.

(Excessive density leads to priming and deposits)

To remove dissolved and suspended solid by blowing .

1.Higher conductivity, higher the hardness.

2.with the hardness test, have the general idea about conductivity.

3000 micro siemens/cm for high pr. boiler

400 micro Siemens/ cm for low pr. boiler

Amerzine test (Hydrazine test)

To test for dissolved Oxygen content.
To know reserve Hydrazine (N2H4) ppm to prevent corrosion and aeration.
To minimize Oxygen pitting and corrosion in boiler, steam and condensate system.

what do you do for preventing of Oxygen?

Oxygen scavenging chemical used for deaeration the water.

Usually Sodium sulphate (Na2O3) or Hydrazine (N2H4)

2Na2SO3 + O2 = 2Na2SO4

2N2H4 + O2 = 2H2O + 2NH3

Excess dosage of Hydrazine lead to steam and condensate line corrosion due to Ammonia being produced as the excess Hydrazine decomposed.

Fe3O4 --> Magnetite

{some Hydrazine carried away to steam line. It forms layer on pipe line & it will give corrosion protection}