Capítulo 3. Los Requisitos de ISO/IEC 17020
3.4 Requisitos relativos a los recursos
Keep clear of spaces below loaded cranes.
The opening of cocks may cause discharge of hot liquids or gases.
The dismantling of parts may cause the release of springs.
The removal of fuel valves or other valves in the cylinder cover may cause oil to run onto the piston crown. If the piston is hot an explosion may blow out the valve.
When testing fuel valves do not touch the spray holes as the jets may pierce the skin.
Beware of high pressure oil leaks when using hydraulic equipment, wear protective clothing.
Arrange indicator cocks with pressure relief holes directed away from personnel. Wear goggles when taking indicator cards.
Do not weld in the engine room if the crankcase is opened before fully cooled.
Turning gear must be engaged before working on or inside the engine as the wake from other ships in port or waves at sea may cause the propeller to turn. Also isolate the starting air supply.
Use gloves when removing O-rings and other rubber/plastic based sealing materials which have been subjected to abnormally high working temper-atures as they may have a caustic effect.
Fire in Scavenge Air Box Cause
If flakes of burning or glowing carbon deposits drop into the oil sludge at the bottom of the scavenge air box, this sludge can be ignited and, if very combustible material is found here, serious damage can be done to the piston rod and the scavenge air box walls. The latter could possibly cause a reduction in the tension of the stay bolts.
Ignition of carbon deposits in the scavenge air box can be caused by:
Prolonged blow-by
‘Slow combustion’ in the cylinder, owing to incorrect atomisation, incorrect type of fuel valve nozzle, or ‘misaligned’
fuel jets
‘Blow-back’ through the scavenge air ports, owing to an incorrectly adjusted exhaust cam disc or a large resistance in the exhaust system (back pressure)
To keep the exhaust resistance low, heavy deposits must not be allowed to collect on protective gratings, nozzle rings and turbine blades. The back pressure after the turbocharger must not exceed 350mm w.g.
Warnings of Fire
A fire in the scavenge box is indicated by:
1. An increase in the exhaust temperature of the affected cylinder 2. The scavenge air box being noticeably hotter
If the fire is violent, smoky exhaust and decreasing engine revolutions will occur.
Violent blow-by will cause smoke, sparks, and even flames, to be blown out when the respective scavenge box drain cock is opened, therefore keep clear of the line of ejection.
Monitoring devices, in the scavenge air space will give an alarm and operate the main engine slow-down function at an abnormal temperature increase.
Measures to be taken
Due to the possible risk of a crankcase explosion, do not stand near the relief valves, flames can suddenly be violently emitted.
a) Reduce speed to SLOW, if not already carried out automatically, (see above) and ask bridge for permission to stop.
b) When the engine STOP order is received, stop the engine and switch off the auxiliary blower.
c) Stop the fuel oil supply.
d) Stop the lubricating oil supply.
e) Apply boundary cooling.
f) Engage the turning gear and turn the engine into a position where the affected unit exhaust valve is closed and the scavenge ports are shut off. This will assist in allowing the fire to burn itself out.
g) If the fire is serious, put the scavenge air box fire extinguishing equipment into operation.
(Note! Be aware of possible thermal shock and loss of extinguishing medium through the exhaust. Do not open the scavenge air box or crankcase before the site of the fire has cooled down to under 100°C. When opening, keep clear of possible fresh spurts of flame.)
h) Remove dry deposits and sludge from all the scavenge air boxes.
i) Clean the respective piston rods and cylinder liners. Inspect their surface condition, alignment and whether they are distorted. If in order, coat with oil.
j) Repeat the checking procedure and concentrate on piston crown and skirt, while the engine is being turned (cooling oil and water on).
k) Inspect the stuffing box and bottom of scavenge box for possible cracks.
If a piston caused the fire, and this piston cannot be overhauled at once, follow the precautions referred to in the Maker’s Manual.
If heating of the scavenge air box walls has been considerable, the stay bolts should be checked and re-tightened at the first opportunity.
Before tightening, normal temperature of all engine parts must be re-established.
To ensure proper draining of oil sludge from the scavenge air boxes, (thereby reducing the risk of fire in the scavenge air boxes), it is recommended to check (on a daily basis) that the drain lines from the scavenge spaces are clear.
Ignition in the Crank Case Cause
When the engine is running, the atmosphere in the crankcase contains the same types of gas (N2 - O2 - CO2 ) in the same proportions as the ambient air, however, there is also a heavy shower of coarse oil droplets present.
If abnormal friction occurs between the sliding surfaces, or heat is otherwise transmitted to the crankcase (for instance from a scavenge air fire via the piston rod/stuffing box) or, for some engine types, through the hot uncooled interme-diate bottom, 'hot spots' on the heated surfaces can occur. The 'hot spots' will cause the oil falling on them to evaporate. When the oil vapour condenses again, countless minute droplets are formed which are suspended in the air.
This appears as milky-white oil mist, which is able to feed and propagate a flame if ignition occurs.
The ignition can be caused by the same 'hot spot' which caused the oil mist. If a large amount of oil mist has developed before ignition, the burning can cause a tremendous rise of pressure in the crankcase (explosion), which forces a momentary opening of the crankcase relief valves.
In isolated cases, when the entire crankcase has presumably been full of oil mist, the consequential explosion has blown off the crankcase doors and set fire to the engine room.
(Note ! Similar explosions can also occur in the chain casing and scavenge air box.)
Every precaution should therefore be taken to:
1. Avoid ‘hot spots’
2. Detect the oil mist in time
‘Hot Spots’ in Crankcase
Well-maintained bearings only overheat if the oil supply fails, or if the bearing journal surfaces become too rough (due to the lubricating oil becoming corrosive, or being polluted by abrasive particles).
For these reasons, it is very important to:
1. Purify the lubricating oil correctly 2. Make frequent control analysis
3. Ensure that the filter gauze is always intact
Due to the high frictional speed of the thrust bearing, special care has been taken to ensure the oil supply to this bearing.
Monitoring equipment is arranged to give an alarm in cases of low circulating oil pressure and/or high temperature of thrust bearing segments. Keep this equipment in tiptop condition.
Feel over moving parts (by hand or with a ‘thermo-feel’) at suitable intervals (15-30 minutes) after starting and again at full load.
If in doubt, stop and feel over.
Oil Mist in the Crankcase
In order to ensure a reliable, and quick warning of oil mist formation in the crankcase, constant monitoring is obtained with an ‘Oil Mist Detector’, which successively samples air from each crankcase compartment.
The detector will give alarm and slow-down command at a mist concentration which is only a fraction of the lower explosion limit (LEL), in order to gain time to stop the engine before ignition of the oil mist can take place.
Measures to be taken when oil mist has occurred:
a) Do not stand near crankcase doors, or relief valves, corridors or near doors to the engine room casing.
b) Reduce speed to slow-down level, if not already carried out auto-matically (see above.)
c) Ask the bridge for permission to stop.
d) When the engine STOP order is received, stop the engine and close the fuel oil supply.
e) Switch-off the auxiliary blowers.
f) Open the skylight(s) and/or 'stores hatch'.
g) Leave the engine room.
h) Lock the casing doors and keep away from them.
i) Prepare the fire-fighting equipment.
j) Do not open the crankcase until at least 20 minutes after stopping the engine.
k) When opening up the crankcase, keep clear of possible spurts of flame. Do not use naked lights and do not smoke.
l) Stop the lubricating oil pump.
m) Take off/open all the lowest doors on one side of the crankcase.
n) Shut off the starting air, and engage the turning gear.
o) Locate the ‘hot spot’.
p) Feel over, by hand or with a ‘thermo-feel’, all the sliding surfaces (bearings thrust bearing, piston rods, stuffing boxes, crossheads, telescopic pipes, chains, vibration dampers, moment compen-sators, etc.).
Look for squeezed-out bearing metal, and discolouration caused by heat (blistered paint, burnt oil, oxidised steel).
Keep any bearing metal found at bottom of oil tray for later analysing.
q) Prevent further ‘hot spots’ by preferably making a permanent repair.
r) Ensure that the respective sliding surfaces are in good condition.
Take special care to check that the circulating oil supply is in order.
s) Start the circulating oil pump and turn the engine by means of the turning gear.
t) Check the oil flow from all bearings, spray pipes and spray nozzles in the crankcase, chaincase and thrust bearing.
u) Check for possible leakages from pistons or piston rods.
Start the engine. After: 5 minutes, 30 minutes, one hour and then when full load is reached carry out the following:
1. Stop and feel over 2. Look for oil mist
Especially feel over (by hand or with a ‘thermo-feel’) the sliding surfaces, which caused the overheating.
There is a possibility that the oil mist is due to 'atomisation' of the circulating oil, caused by a jet of air/gas, e.g. by combination of the following:
1. Stuffing box leakages (not air tight).
2. Blow-by through a cracked piston crown or piston rod (with direct connection to crankcase via the cooling oil outlet pipe).
An oil mist can also develop as a result of heat from a scavenge fire being transmitted down the piston rod or via the stuffing box.
Hot air jets or flames could also have passed through the stuffing box into the crankcase.
Alarms and Trips
Automatic Shut Down Functions
L.O. to Bearings and Thrust Bearing Pressure Low/low Thrust Bearing Temperature High/high
L.O. to Camshaft Pressure Low/low Engine Over-speed Trip
Manual Shutdown
Emergency Stop Button Slow Down Functions
Piston Cooling Oil Outlet/Cylinder Temperature High Piston Cooling Oil Outlet/Cylinder No Flow
Jacket Cooling Water Inlet Pressure Low
Jacket Cooling Water Outlet/Cylinder Temperature High Scavenge Air Box/Cylinder Temperature High
Exhaust Gas Outlet/Cylinder Temperature High Oil Mist in Crankcase
Cylinder L.O. No Flow
Stern Tube Bearing Temp High
Alarms
Leakage From High Pressure Fuel Pipes Fuel Oil Temperature High
Fuel Oil Temperature Low Fuel Oil Viscosity High Fuel Oil Viscosity Low Fuel Oil Inlet Pressure Low L.O. Inlet Temperature High
Piston Cooling Oil Outlet/Cylinder Temperature High Piston Cooling Oil Outlet/Cylinder No Flow
Piston Cooling Oil Inlet Pressure Low
L.O. to Bearings and Thrust Bearing Pressure Low Thrust Bearing Temperature High
L.O. to Camshaft Inlet Temperature High L.O. Inlet to Camshaft Pressure Low Turbo Charger L.O. Inlet Pressure Low Turbo Charger L.O. Inlet Temperature High Turbo Charger L.O. Outlet Temperature High Cylinder Lubricators No Flow
Jacket Cooling Water Inlet Pressure Low
Jacket Cooling Water Outlet/Cylinder Temperature High Starting Air Pressure Low
Control Air Pressure Low Safety Air Pressure Low
Air Supply to Exhaust Valve Air Cylinder Pressure Low Scavenge Air Manifold Temperature High
Scavenge Air Inlet Pressure Low
Scavenge Air Box/Cylinder Temperature High Air Cooler Cooling F.W. Inlet Pressure Low Exhaust Gas/Cylinder Temperature High Exhaust Gas After Turbocharger High Oil Mist in Crankcase
20 0
1 2 3 4 5 6 708 91
40 80 60 100
PERCENTAGE OF ALARM LEVEL
SAMPLE NUMBER
SELECT
TEST
RESET SYSTEM
ON
SIMULATION MODE
TEST MODE
AVERAGE ALARM DEVIATION ALARM FLOW FAULT
OPTIC FAULT
Oil Mist Detector Mark 5 Made in England
Enlarged View of Oil Mist Detector Panel
Illustration 2.1.1b Oil Mist Detector
Oil Mist Detector
Introduction
Oil mist detection is now widely accepted as a means of providing early warning of incipient bearing failure in diesel engines. The Graviner Mark 5 Oil Mist Detector embodies electronic and electrical means of carrying out fast and accurate sampling of the crankcase oil mist, without the use of rotational mechanical parts.
Principle of Operation
At high temperatures the oil used for lubricating engines generates vapours.
When these come into contact with the colder atmosphere in the crankcase at temperatures around 700°C, they condense into an oil mist. This situation represents the condition associated with the excess temperatures, such as those caused by main crankshaft, big end or connecting rod small end bearing defects.
The ‘Oil Mist Detector’ works on the principle that oil mist density is propor-tional to optical obscurity. It samples the oil mist in the crankcase at a regular repetitive sequence.
The sample is measured by passing it through a measuring chamber which has a light source at one end and a photo cell at the opposite end.
The output signal from the photo-cell represents oil mist and is compared with threshold levels set during commissioning.
If the thresholds are exceeded an alarm indicates the need for an engine slow-down and an immediate investigation of engine condition.
Preparation for the Operation of the Oil Mist Detector a) Supply power to the oil mist detector.
The detector will now begin scanning.
After each crankcase has been sampled the first scan is completed.
No alarms will be given during the first scan, as the system is forming the microprocessor memory stores.
Test Functions
The test switch may be pressed at any time after the first complete cycle. This initiates the microprocessor programme for testing the oil mist detector and is indicated by the test mode lamp being lit.
The programme will commence by the deviation alarm indicator being lit, and will continue by simulating a gradually increasing average oil mist density, resulting in the display building up to 100 per cent of the alarm level, at this point, the average alarm indicator will light and the main alarm relay contacts will change state.
The programme now simulates a ‘flow fault’ which lights the flow fault indicator.
The microprocessor memory circuit is then checked and a test is conducted on the engine slow down relay coil without actually operating it.
Satisfactory completion of all tests results in the 'optical fault' indicator being lit and the fault alarm relay contacts will change state.
Should the tests not be completed correctly the fault relay will not operate.
If the facility to operate the test from a remote position is used, the test programme remains the same, but should it not be completed correctly it is not possible to reset from this remote position. This ensures that the oil mist detector is examined to define the fault condition. Therefore, at the end of a satisfactory test of the oil mist detector the following should be seen:
Deviation alarm indicator lit Average alarm indicator lit Flow fault indicator lit Optical fault indicator lit
Main alarm relay contacts change state Fault alarm Relay contacts change state
Test Routines
The oil mist detector incorporates self-checking routines, which operate whenever the detector is switched on.
The only necessary routine maintenance consists of running a brief additional self-test prior to engine starting, and at least at four-weekly intervals.
Provided the detector is switched on, the test is commenced by first operating the local test switch and then operating the reset switch on the detector.
a) Inspect/clean air line filter at least at a minimum of four-weekly intervals.
Remote testing and indications
A test of the oil mist detector from the remote position should be carried out daily as follows:
a) Pressing the remote test switch for a minimum of 20 seconds initiates the same test programme as the test switch on the oil mist detector.
Passing of the test is indicated at the remote position by the remote main alarm and fault alarm enunciator being lit.
b) The remote reset button is pressed on completion.
DMS 2100 BRIDGE MANOEUVRING SYSTEM
Lyngso Marine
ALARM FAULT
ALARM LIST
STOP HORN
ALARM ACKN.
STATUS LIST
MAINTE-NANCE EDIT MENU S1 S2 S3 S4 DIMMER
BRIDGE CTRL.
ECR CTRL.
EMERG CTRL.
ORDER ADJUST
SLOWD.
ACTIVE
SLOWD.
CANCEL
SLOWD.
RESET
ESC ENT
SEA MODE
STAND
BY F.W.E. CANCEL
LIMITS SHUTD.
ACTIVE
SHUTD.
CANCEL
1 ABC 2 DEF 3 GHI 4 JKL 5 MNO 6 PQR
7 STU 8 VWX 9 YZ 0 space . +/- #
AUTO BRIDGE START AIR 29.8 BAR
ORD: 0.0 SET: 40.0 ACT: 35.0
Illustration 2.1.2.a Main Engine Manoeuvring Control Panel
2.1.2 Main Engine Manoeuvring Control Maker: Lyngso Marine
Type: 2100
The main engine manoeuvring control system can be divided into two parts:
1. The DMS 2100 Bridge Manoeuvring System 2. The DPS 2100 Engine Safety System DMS 2100 Bridge Manoeuvring System
The DMS system is designed to control the ship’s engine directly from the bridge. Automatic operation is also possible from the ECR. The normal operating condition of the DMS is with the lever of the bridge telegraph unit but the ECR position may be used for additional monitoring/control etc. DMS controls the following functions:
Starting, stopping and reversing the propulsion plant Acceleration and deceleration of main engine speed Engine speed sensing
Quick progress through critical speed ranges Monitoring manoeuvring sequences
Self monitoring
Control of auxiliary systems
Selection of control and operation modes Automatic limitations
The DMS system is serial connected to both the DPS engine safety system and the UMS/UCS alarm, monitoring and control system. The requested orders from the telegraph system are internally processed and routed as a set speed value to the electronic governor (EGS 2000).
The hardware consists of 4 main groups:
Bridge and ECR operating panels ECR Indication Panel
Propulsion control cabinet (PCC) Electronic governor (EGS 2000)
Bridge and ECR DMS Operating Panels
The operating panels enable communication with the the DMS system. The display is able to show operating state information. All nominal and actual values, operating data and list contents can be read and adjustments made to the operating state. Any faults or alarms within the system are shown and accompanied by a warning buzzer.
The following table shows the facilities and operations available from the bridge and ECR operating panels.
Button Action
Bridge Control: Indication or request/acknowledgement of Automatic bridge control
ECR Control: Indication or request/acknowledgement of ECR control (manual or automatic) Emergency control: Indication or acknowledgement of
emergency (local) control Sea mode:
If not in manoeuvre mode then the button is for indication only.
This order indicates, by LED illumination: ‘No need to man the engine room’.
If in manoeuvre mode:
Sea mode active if LED on, speed set value released to SEA FULL AHEAD.
Pressing the key again extinguishes the LED, manoeuvre mode is activated and
Pressing the key again extinguishes the LED, manoeuvre mode is activated and