In spite of taking all the precautions and safety measures while handling engine room machinery systems, accidents are bound of take place in the ship’s engine room.
Many of these accidents are extremely dangerous not only for the ship’s property but also for the lives of seafarers. Mentioned below are such types of engine room accidents which watchkeeping offices must be aware of.
Crankcase Explosion of Ship’s Engine
Explosion of ship’s crankcase is one of the most dangerous accidents in the ship’s engine room which has led to devastating consequences, including loss of lives in the past.
In case of crankcase explosion, follow the below mentioned points:
- Inform officer on bridge about the condition
- Inform the chief engineer immediately
- Inform bridge and find out about traffic condition
- Change over controls to ECR & reduce engine speed at once and prepare for stoppage. Reduction of RPM will minimize further creation of oil mist. However the ship’s forward momentum will cause the propeller to turn the crank shaft.
- Increase the cooling of bearings by increasing MECC oil circulation
- If the problem is due to blow past, cut out the fuel pump of the affected ME unit, if stopping has to be delayed
- Stop the main engine and engage the turning gear. Keep FFA ready
- Open sky light, ventilate engine room and stay away from the ME crankcase doors and more importantly, crankcase relief valves / flame arrestor
- Continue with lubrication for at least 30 minutes. Do not open crankcase doors for at least 30 minutes after stopping, to avoid closing the fire triangle with oxygen
- Continue with lubrication for at least 30 minutes. Do not open crankcase doors for at least 30 minutes after stopping, to avoid closing the fire triangle with oxygen. Stop the lube oil pump
- Open all lower most doors , and try to locate the hot spot. Look for discoloration at the surface, squeezed out white babbitt metal. Find out the hot spot by looking for excessive flow of lube oil, high temperature at sliding surfaces
- After repairing defect, start lube oil pump and check oil flow through each bearing, while turning the engine on turning gear
- Clean the detector and check the `ZERO’ setting and sensitivity test of the mist detector
- Start the engine and gradually increase the speed
- Stop the engine again after about 15 minutes of running and do a serious recheck
Blackout
Blackout condition is a scenario on a ship, wherein the main propulsion plant and associate machinery such as boiler, purifier and other auxiliaries stop operating due to failure of power generation system of the ship – generator and alternator.
With technologies and automation, measures are provided to avoid such blackout situation by means of auto load sharing system and auto standby system in which the generator set that is running in parallel or standby comes on load automatically if the running diesel generator fails.
In case of blackout following precautions and actions should be taken:
- Never panic in such situation, be calm and composed. Emergency generator will restore the power
- Call for man power and inform the chief engineer
- If the main propulsion plant is running, bring the fuel lever to zero position
- Close the feed of the running purifier to avoid overflow and wastage of fuel
- If auxiliary boiler was running, shut the main steam stop valve to maintain the steam pressure
- Find out the problem and reason for blackout and rectify the same
Before starting the generator set, start the pre- lubrication priming pump if the supply for the same is given from the emergency generator; if not, then use manual priming handle (provided in some generator).
Start the generator and take it on load. Then immediately start the main engine lube oil pump and main engine jacket water pump. Reset breakers and start all the other required machinery and system. Reset breakers that are included in preferential tripping sequence (Non-essential machinery).
It requires both skills and patience to tackle a situation like blackout specially when the vessel is sailing or maneuvering. However, the best way to tackle such situations is to be calm and composed; and to know your engine room and machinery very well in advance.
Scavenge Fire
For a fire to occur we need three elements which make the fire triangle. The three important elements for any type of fire are:-
Oxygen -this is available plenty in the scavenge space.
Heat source- this could happen because of blowing by of gases between piston rings and liner or as a result of any rubbing between two surfaces.
Fuel- this can be from un-burnt fuel, carbon or cylinder lubricating oil leaked into the space.
When all these elements are present in a proportion ratio and are within the flammable limit inside the scavenge space the later become a hot spot.
The fire which thus results is known as the scavenge fire.
Action taken in case of a scavenge fire depends on the type of the fire, whether small or large. In case of large fire the following signs will be easily visible – the peeling or blistering of paint, large reduction in engine rpm and surging of turbocharger.
For small fires
- Start reducing the engine rpm and reduce it to slow or dead slow
- Increase the cylinder lubrication of the affected unit. Special attention to be given to ensure it does not feed the fire. In case of increase of fire do not increase the lubrication
- The fire can be due to leaky fuel valves, so lift up the pump of the affected unit
- Keep scavenge drain closed
- Keep monitoring the scavenge and exhaust temperatures and let the fire starve and wait for it to burn itself out
- After confirming that the fire is out start increasing the rpm slowly
- Keep monitoring the scavenge temperature for any signs of re-ignition
- For large fires
- Stop the engine immediately and engage turning gear, and keep engine rotating with turning gear
- Extinguish the fire with fixed fighting system for scavenge fire. This may be by a co2 system or a steam connection
- In case fixed system is not available on very old ships an external cooling is provided to prevent distortion due to heat
- Once after confirming that the fire is extinguished, the scavenge space is allowed to cool down and later opened for inspection and cleaning
Causes of scavenge fire
There are many reasons for scavenge fire. However, the main ones are as below:
- Excessive wear of the liner
- The piston rings might be worn out or have loose ring grooves
- Broken piston rings or rings seized in the grooves
- Dirty scavenge space
- Poor combustion due to leaking fuel valves or improper timing
- Insufficient or excess cylinder lubrication
Exhaust Gas Fire
Exhaust gas fire takes place in the exhaust gas boiler because of unburnt residue of fuel and lubricating oil deposits. The response for tacking EGB fire will be different for different stages.
When there is stage 1 fire, i.e. normal soot fire:
- Stop the main engine, and thereby the oxygen supply to the fire
- Continue operating the water-circulating pump. Never stop the pump
- Never use soot blowers for fire fighting whatever type it is – Steam or Air as both will accelerate the effect of fire
- Ensure all the exhaust valves in the stopped main engine are in closed position so as to cut any chance of air supply to the soot fire
- Cover the filter of turbocharger
- Water washing, if fitted, may be used to extinguish the fire. This is normally connected to the ship’s fire fighting water system
- External boundary cooling can be done
For Major Fire:
- Stop the main engine, if it is not stopped already
- Stop the circulating water pump
- Shut all the inlet and outlet valves on the water circulation line
- Discharge the (remaining) water from the exhaust gas boiler sections by draining
- Cool down with plenty of splash water directly on the heart of the fire (Take care not to splash water)
Engine Room Flooding
Engine room flooding, as the name indicates, means filling up of the engine room space with water. Engine room flooding can affect the water tightness integrity of the ship. Reasons for engine room flooding are:
1. Leakage from Equipment and System
Engine room flooding can take place due to leakage in the engine room space from machinery or sea or fresh water system. Leakages can generally be from big sea water pump, from sea water or fresh water cooler, leakage from boiler feed water system etc.
The leak can also take place from any of the fresh or sea water pipelines due to which a lot of water can enter the engine room leakage from manhole, or crack in the water tank can also lead to engine room flooding.
Sea water or fresh water piping and system of the engine room are huge in size and thus hold large possibility for leakages.
Action to be taken in such situations:
- Call for maximum man power to tackle the situation
- The sooner you find the fault the better
- Start the other circulating system and isolate the leaking pump, pipe, cooler etc.
- Inform chief engineer regarding the leak and follow the instruction from him
- Put a notice or placard regarding leaking equipment or system and trip the breaker until repairs have been done
- In case of any tank leakage, start transferring the excess content from that tank to other tank and try to minimize it as much as possible
- Tank should not be used until cement box or welding has taken place or a repair has been done
- Close inlet and outlet valves of the effected system to stop the leak
2) In Case of Leakage from Overboard Valve
If the leakage is after the valve and if the valve is holding shut, it is better to keep the valve shut if the system to which the valve supplies water can operate without its (valve) need.
- If the valve is not holding then identify the leak. It may be from the valve stem gland or flange joint; try to repair the leak
- If the system for that valve can be isolated without disturbing the normal operation of the ship, put a blank in the valve
- If the repair is temporary then when ship reaches the port, call the divers to blank the valve opening from outside and carry out permanent repair
3) Flooding Due to Crack in the Hull or Small Hole in the Hull
- In this case, as soon as you find the leak, call for help from nearest coastal state because if the leakage is more, the ship’s stability will be affected
- By all means, the leakage has to be minimized and finally stopped
- If the leak is not big enough, then cement box is to be put in place of the leak and repairs are to be done accordingly
In case of leakage due to damage from any accident like collision or grounding, there is nothing much that can be done as the opening in the bulkhead is large and there is no chance of stopping the leak.
In such cases, the captain has to decide whether the ship is a safe place to stay or not and decision for abandoning the ship has to be made. In case of abandon ship signal being announced, the crew should muster to their respective lifeboat and abandon ship operation should be carried out.
For any of the above reasons, if the water level ingress in the engine room is very high, then open the emergency bilge ejector valve with consent of the chief engineer and pump out the water overboard. Entry of the same is to be made in oil record book (ORB) with date, time, and position of the ship and reason of direct discharge with signature of officer involved in operation, chief engineer, and master should be registered.
Chief engineer has to be reported immediately in such condition without any delay.
Procedure for Starting Emergency Steering System
An emergency steering system is used during the failure of the main steering system of the ship. Watch-keeping officers must know the procedure for operating the same.
A ship consists of electromechanical steering gear unit which steers the vessel from one port to other. Normally steering gear unit is 2 or 4 ram electro-hydraulically operated unit with two or more hydraulic motors for the ram movement.
A situation can occur in which the remote control operation may fail to work and their can be a sudden loss of steering control from the bridge. This can be due to sudden power failure, any electrical fault in the system or the control system, which includes faulty tele-motor or servo motor which is used for transferring the signal from bridge to the steering unit.
To have control for steering the ship in such emergency situation with manual measure from within the steering gear room, an emergency steering system is used.
Procedure For Emergency Steering Operation
The following points should be followed for emergency steering operation. The procedure and diagram for operating emergency steering should be displayed in steering gear room and bridge.
Even in emergency situation we cannot turn the massive rudder by hand or any other means, and that’s why a hydraulic motor is given a supply from the emergency generator directly through emergency switch board (SOLAS regulation). It should also be displayed in the steering room.
- Ensure a clear communication for emergency operation via VHF or ships telephone system
- Normally a switch is given in the power supply panel of steering gear for telemotor; switch off the supply from the panel
- Change the mode of operation by selecting the switch for the motor which is supplied emergency power
- There is a safety pin at the manual operation helms wheel so that during normal operation the manual operation always remains in cut-off mode. Remove that pin
- A helms wheel is provided which controls the flow of oil to the rams with a rudder angle indicator. Wheel can be turned clockwise or anti clockwise for going port or starboard or vice versa
- If there is a power failure, through sound power telephone receive orders from the bridge for the rudder angle. As soon as you get the orders, turn the wheel and check the rudder angle indicator
- A routine check should always be done for proper working of manual emergency system and steering gear system
An emergency steering drill should be carried out every month (prescribed duration – 3 months) in the steering gear room with proper communication with bridge to train all the ship’s staff for proper operation of the system so that in emergency situation ship’s control can be regained as soon as possible, avoiding collision or grounding.
References
A Pocket Guide To Engine Room Watchkeeping on Ships - Anish Wankhede [2013]
