Emergency Operation
Low Water Level
A low water level, 140mm or more below the normal working level, will activate the visual and audible alarms (illumination of the alarm lamp on the control panel and sounding of the alarm buzzer).
Should the water level fall to 250mm or more below the normal working level, the fuel oil emergency trip valve will close, shutting off fuel from the boiler.
The feedwater valve and steam stop valve should be fully closed, the burner shut down completely and the forced draught fan stopped after purging the furnace.
Never attempt to supply feedwater to the boiler until the boiler has cooled sufficiently, as there is a danger of bringing comparatively cold feed into contact with hot surfaces.
When the boiler water level has been restored the boiler may be flashed up using the normal procedure.
Flame Failure
In case of flame failure, close the oil inlet valve and reduce air pressure to prevent over cooling the furnace.
Purge the furnace thoroughly before relighting the burner.
Always use the pilot burner for ignition, never attempt to relight the burner from the hot furnace refractory.
Evaporating Tube Failure
Serious tube failure where water level cannot be maintained.
a) Shut off the oil supply to the boiler and if the tube failure results from low boiler water level, shut off the feed supply, close the feedwater valve and steam stop valve.
b) If the tube failure results from a cause other than low water level, the fuel supply should be shut off but the feedwater supply should
be maintained in order to assist in the cooling down process.
When the boiler has cooled sufficiently, close the feed valve and steam stop valve and open the steam drum vent.
c) In either case of tube failure, maintain the forced draught fan so that the air draft assists in carrying away the escaping steam.
Care must be taken to avoid damage to the refractory by an excessive air supply.
d) Do not blow down the boiler unless the tube failure is so severe that personnel could be endangered.
When the boiler has cooled, the blowdown may be used to empty the boiler.
e) When the boiler has cooled enough, an inspection should be carried out to assess the situation and carry out necessary repairs.
f) If tube failure is not serious and the water level can readily be maintained, the boiler can be shut down in the normal manner.
The forced draft air supply should be maintained to carry away vapours generated by the leaking water and the water level
maintained during the cooling down period.
When boiler pressure has fallen to 2 kg/cm2, the steam drum vent valve boiler may be opened and the boiler blown down.
Putting the Boiler Out of Service
When putting a boiler out of service, the wet lay-up method is preferable, as it requires less preparation and it can be quickly returned to service.
These steps are taken if the ship is to be taken out of service for some time and are not part of normal operational routine.
Wet Lay-up
When the boiler is in the cooling down process following shutdown, appropriate quantities of boiler chemicals should be injected into the drum
using the boiler chemical injection device.
To ensure adequate protection of the boiler, follow the guidelines given by the chemical supplier.
The quantity of the chemicals required will depend upon the condition of the boiler water and a water test should be carried out prior to shutting down.
After dosing the boiler water should register pH of 12, (alkalinity 300 to 400 ppm) phosphoric acid about 50 ppm, and sodium sulphite 80 to 100 ppm.
The high alkalinity will ensure adequate protection of the boiler.
When returning the boiler to service the chemical concentrations should be returned to normal levels and this means blowing down the boiler and filling with untreated make-up feed.
a) When the pressure is approaching atmospheric pressure, open the steam drum air vent valve.
b) When the pressure is off the boiler, supply distilled water until it issues from the vent valve, then close the vent valve.
c) Put a hydrostatic pressure of 3.5 to 5kg/cm2 on the boiler.
Hold this pressure until the boiler has cooled to ambient temperature.
Bleed the boiler using the vent valve to be sure all the air is out.
Maintain a hydrostatic pressure of 2 to 3.5 kg/cm2 on the boiler.
Take a periodic boiler water sample and replenish any depleted chemicals.
Maintaining Boiler in Warm Condition
At sea, with one boiler being circulated through the waste heat economiser, the standby boiler should be maintained in a warm condition by supplying steam to the heating element in the bottom drum.
This is done by closing the heating coil drain valve and opening the inlet and outlet valves.
The boiler pressure should be maintained at 0.5 kg/cm2 or above.
When the heating element is not in use, the inlet/outlet valves are closed and the drain left open.
In port with the economiser shut down, the standby boiler is maintained at 2kg/cm2 or above by switching the burner on and off. Do not use the bottom drum heater.
Dry Lay-up
This should only be undertaken if a wet lay-up cannot be performed.
a) Whilst the boiler remains warm, drain it of all water and ensure that all headers are dry.
b) Remove the end piece of the waterwall lower header to check that no water remains.
c) Provide some dry heat, electric heaters preferably, in the furnace to promote internal drying.
d) When the boiler is completely dry, put some quick lime or calcium chloride in a shallow dish for placement in the drum and
header then close the end plate and manhole doors.
Check the moisture absorbent chemicals every week initially and replenish as required.
e) Cover the funnel outlet and close the air inlet to the furnace.
Low Water Level
A low water level, 140mm or more below the normal working level, will activate the visual and audible alarms (illumination of the alarm lamp on the control panel and sounding of the alarm buzzer).
Should the water level fall to 250mm or more below the normal working level, the fuel oil emergency trip valve will close, shutting off fuel from the boiler.
The feedwater valve and steam stop valve should be fully closed, the burner shut down completely and the forced draught fan stopped after purging the furnace.
Never attempt to supply feedwater to the boiler until the boiler has cooled sufficiently, as there is a danger of bringing comparatively cold feed into contact with hot surfaces.
When the boiler water level has been restored the boiler may be flashed up using the normal procedure.
Flame Failure
In case of flame failure, close the oil inlet valve and reduce air pressure to prevent over cooling the furnace.
Purge the furnace thoroughly before relighting the burner.
Always use the pilot burner for ignition, never attempt to relight the burner from the hot furnace refractory.
Evaporating Tube Failure
Serious tube failure where water level cannot be maintained.
a) Shut off the oil supply to the boiler and if the tube failure results from low boiler water level, shut off the feed supply, close the feedwater valve and steam stop valve.
b) If the tube failure results from a cause other than low water level, the fuel supply should be shut off but the feedwater supply should
be maintained in order to assist in the cooling down process.
When the boiler has cooled sufficiently, close the feed valve and steam stop valve and open the steam drum vent.
c) In either case of tube failure, maintain the forced draught fan so that the air draft assists in carrying away the escaping steam.
Care must be taken to avoid damage to the refractory by an excessive air supply.
d) Do not blow down the boiler unless the tube failure is so severe that personnel could be endangered.
When the boiler has cooled, the blowdown may be used to empty the boiler.
e) When the boiler has cooled enough, an inspection should be carried out to assess the situation and carry out necessary repairs.
f) If tube failure is not serious and the water level can readily be maintained, the boiler can be shut down in the normal manner.
The forced draft air supply should be maintained to carry away vapours generated by the leaking water and the water level
maintained during the cooling down period.
When boiler pressure has fallen to 2 kg/cm2, the steam drum vent valve boiler may be opened and the boiler blown down.
Putting the Boiler Out of Service
When putting a boiler out of service, the wet lay-up method is preferable, as it requires less preparation and it can be quickly returned to service.
These steps are taken if the ship is to be taken out of service for some time and are not part of normal operational routine.
Wet Lay-up
When the boiler is in the cooling down process following shutdown, appropriate quantities of boiler chemicals should be injected into the drum
using the boiler chemical injection device.
To ensure adequate protection of the boiler, follow the guidelines given by the chemical supplier.
The quantity of the chemicals required will depend upon the condition of the boiler water and a water test should be carried out prior to shutting down.
After dosing the boiler water should register pH of 12, (alkalinity 300 to 400 ppm) phosphoric acid about 50 ppm, and sodium sulphite 80 to 100 ppm.
The high alkalinity will ensure adequate protection of the boiler.
When returning the boiler to service the chemical concentrations should be returned to normal levels and this means blowing down the boiler and filling with untreated make-up feed.
a) When the pressure is approaching atmospheric pressure, open the steam drum air vent valve.
b) When the pressure is off the boiler, supply distilled water until it issues from the vent valve, then close the vent valve.
c) Put a hydrostatic pressure of 3.5 to 5kg/cm2 on the boiler.
Hold this pressure until the boiler has cooled to ambient temperature.
Bleed the boiler using the vent valve to be sure all the air is out.
Maintain a hydrostatic pressure of 2 to 3.5 kg/cm2 on the boiler.
Take a periodic boiler water sample and replenish any depleted chemicals.
Maintaining Boiler in Warm Condition
At sea, with one boiler being circulated through the waste heat economiser, the standby boiler should be maintained in a warm condition by supplying steam to the heating element in the bottom drum.
This is done by closing the heating coil drain valve and opening the inlet and outlet valves.
The boiler pressure should be maintained at 0.5 kg/cm2 or above.
When the heating element is not in use, the inlet/outlet valves are closed and the drain left open.
In port with the economiser shut down, the standby boiler is maintained at 2kg/cm2 or above by switching the burner on and off. Do not use the bottom drum heater.
Dry Lay-up
This should only be undertaken if a wet lay-up cannot be performed.
a) Whilst the boiler remains warm, drain it of all water and ensure that all headers are dry.
b) Remove the end piece of the waterwall lower header to check that no water remains.
c) Provide some dry heat, electric heaters preferably, in the furnace to promote internal drying.
d) When the boiler is completely dry, put some quick lime or calcium chloride in a shallow dish for placement in the drum and
header then close the end plate and manhole doors.
Check the moisture absorbent chemicals every week initially and replenish as required.
e) Cover the funnel outlet and close the air inlet to the furnace.
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