INFORMATION SHEET

Boiler operations are important in that many different conditions can exist that lead to reduced plant capability or even catastrophic failure. These conditions are the warning signs that give engineers a red flag that something is out of designed parameter or procedure. Operating the boiler in violation of established procedures can lead to an assortment of problems. Heating up or cooling down the boiler too quickly can damage the refractory, tubes and structural members. Steaming the boiler out of parameters disrupts the design operating processes and may shorten the life of the entire boiler or just specific parts. Failure to maintain boiler water within chemical limits degrades the useful life of the boiler. Improper operation of a less serious nature also contributes to poor fuel economy. Since damage to the boiler is cumulative, a series of minor problems can lead to serious ones over the long term. Fleet problems show themselves in many forms, but the most visible are chemistry, mechanical, and operation. For example, chemistry affects plant operation when boilers are improperly treated leading to boiler damage, possibly mission degrading. Only qualified personnel should treat boiler water. Mechanical reasons are PMS not properly performed/completed, wrong or missing materials or tools, unqualified personnel performing PMS, valve maintenance ineffective as a result of non-compliance with maintenance manuals (valves most ignored are below deck plates and in the overheads), lack of supply support, and logs not up to date or maintained. Operation can be more visible that the rest in that poor watch-standing procedures or the PQS program is not effective. Main propulsion boiler casualties can greatly affect a ship's ability to complete its mission. The impact of a boiler casualty can result in restricting the ships ability to maneuver quickly or its ability to get underway at all. The ultimate affect to a ship's propulsion varies with the number of shafts installed. A boiler casualty also affects electrical power generation. In a single plant ship, a loss of one of two boilers has minimal, if any, impact on electrical power generation capability. If both boilers are lost, all electrical power is lost. In a split plant ship, losing the boiler and SSTG in one plant causes the entire electrical load to be placed on the remaining SSTG(s). This may overload the SSTG(s), causing electrical power available to be reduced. In any event, casualties that occur in the fireroom require essential actions be taken in order to minimize damage and to restore propulsion services as soon as possible.

REFERENCES

(a) 600 psi Main Propulsion Boilers S-9921-A3-MMO-010

(b) Boilers NSTM Chapter 221

(d) Casualty Control, NSTM Chapter 079 Vol. Ill

INFORMATION

A. Boiler Operations

1. Different design and manufacturers of main propulsion boilers prescribe different pressures at which boilers operate. For this reason, the operating pressure is the actual setpoint which the Automatic Combustion Control (ACC) system maintains when properly calibrated. It must maintain setpoint plus or minus 5 psi.

2. Steam drum water level is sensed at the steam drum via variable and constant legs that feed a differential pressure unit that converts the signal to a readable scale on the front from +10 to -10 inches of water. Water level at steady steaming should maintain normal plus or minus 1 inch.

3. Superheater outlet temperature is sensed at the superheater outlet to indicate actual temperature. Temperature varies with the boiler design. Refer to the boiler technical manual for the allowable range. Since this is uncontrollable, it is a function of boiler load and system demand.

4. Superheater outlet pressure is sensed at the superheater outlet to indicate pressure only, not normally used as the sensing point for the ACC system. Pressure varies with boiler design. Refer to boiler technical manual for the allowable range.

5. Economizer inlet/outlet temperatures are sensed at the economizer inlet, indicating temperature in degrees F. Temperature varies with boiler design, check the Ship's Information Book (SIB), for your applicable temperatures. Temperature is sensed at the economizer outlet prior to entering the steam drum via the internal feed pipe indicated in degrees F.

6. Hydrostatic tests pose another potential danger to personnel or equipment if improperly conducted. When conducting a hydro test on the boiler, follow procedures established in NSTM 221. If possible, always use feed quality water which is not too hot because it endangers personnel. If the water is too cold, condensation may occur making leak detection difficult and cause the metal to contract enough to cause minor leaks in some of the joints or accesses. Depending on the preparation, planning, skill, and organization involved, a "hydro" may take several hours or all day.

a. The proper equipment should be used such as hydrostatic test pumps instead of main feed pumps. The hoses used must be the proper high-pressure type and not leak.

b. The pressure should be raised slowly and under positive control to avoid exceeding the test pressure. If control is lost, subsequent damage may occur. If the safety valves have not been removed or gagged, such as in a 100% hydro test for tightness, there is the risk of lifting the safety valves with water. Should this occur, then the safety valves must be tested with steam after light-off and before the boiler is ready for unrestricted use. If the safety valves have been gagged, they must also be tested with steam.

c. When the test pressure is reached, personnel should wait fifteen minutes before inspecting the boiler. This helps minimize injury if there are component failures from the pressure of the test.

d. The boiler is hydro tested to different pressures based upon the purpose of the test which is a function of the maintenance or work performed. In all cases, the last test accomplished is to 100% of the boiler steady state operating pressure to verify the tightness of the boiler. Basically, this ensures that there are no leaks from the gaskets.

7. Soot blowers - Combustion process by-products collect on tube surfaces and inhibit heat transfer, creating a potential for corrosion when the soot mixes with moisture and forms sulfuric acid. Although distillate fuels replaced older higher ash content fuels (black oil or navy special fuel oil) and has helped minimize the impact of the these problems, the soot must be blown from the tubes on a regular basis. This system uses unreduced high pressure, high temperature desuperheated steam as the motive force. The steam pressure is reduced in the soot blower elements through an orifice but the high temperature is retained. This helps minimize the moisture content of the steam and lessens the probability of corrosion and erosion. Tubes must be blown as soon as practical after conditions which produce more soot than normal. One of these is smoking heavy black. Another is steaming in port at a low firing because the exhaust gas draft is not strong enough to carry all the by-products up the stack. Therefore, after getting underway from steaming in port, tubes must be blown. Tubes are blown prior to securing a boiler, if possible, and prior to entering port to help minimize the possibility of corrosion. Routinely, tubes are blown once a week on steaming boilers. To be most effective, the boiler should be steaming at a firing rate about 50% or better. This vigorous exhaust gas flow better helps carry the soot out of the stack.

a. Properly coordinate blowing tubes with the bridge and the other departments to avoid hindering other on-going projects.

b. It takes about fifteen to twenty minutes to properly drain down and warm-up soot blower piping and at least that long to blow tubes, depending on the extent of build up.

c. Boiler Soot Blow Frequencies

(1) After leaving port

(2) Prior to entering port

(3) After smoking heavy black

(4) Prior to securing

(5) Every 168 hours of operation

8. Blowdowns maintain boiler water chemistry within limits, three types of blowdowns are conducted. They each have a specific purpose as detailed below. Bottom blowdowns must be conducted while the boiler is secured while surface blows and scum blows are conducted on steaming boilers. While surface blows are being conducted, the speed of the ship should be maintained steady with little or no changes in steam demand.

a. Surface blowdowns remove water from the steam drum, usually when the boiler is operating, to lower the concentration of contaminants in the boiler by exchanging it with water which contains no or fewer contaminants. This is a water chemistry control action and generally consists of several three inch blowdowns.

b. Scum blowdowns are conducted in conjunction with the Chelant continuous injection-continuous blowdown system. These blowdowns are conducted at prescribed intervals while steaming and are designed to remove suspended particles in the steam drum. They are generally only one inch blowdowns.

c. Bottom blowdowns are conducted to remove precipitated sludge from the water drum. These blowdowns are conducted only while the boiler is secured. A boiler must be secured for a bottom blow every 360 hours if on the Chelant system and 168 hours if on the COPHOS system. Also, if a boiler is secured for more than two hours for any reason, it must be bottom blown.

d. While a boiler is on a steam blanket lay-up, the water level may rise as the steam condenses. To control this water level, it is necessary to align the surface blow system and to lower the water level. This can be done only if the steam drum pressure is over 50 psi and is not considered a "blowdown" for water chemistry purposes.

9. Boiler Blow Down Frequencies

a. Surface blowing

(1) To maintain boiler water limits

10. Bottom Blowing

a. When the boiler will be secured for more than 2 hours

b. Every 360 hours of continuous operation

NOTE: Boiler must have at least 50 psi pressure prior to blowing over the side.

11. Effects of Load Changes

a. On an increase in load, the boiler pressure will decrease (due to increased flow to the main engines and systems) and the superheater temperature will initially decrease (due to increased flow through the superheater/combustion gas flow remains the same) until the ACC system brings pressure back to setpoint. The desuperheater temperature will initially increase (steam spends less time in the desuperheater) until the ACC system brings pressure back to setpoint.

b. On a decrease in load, the boiler pressure will increase (decreased steam flow) and the superheater temperature will initially increase until ACC system brings the pressure back to setpoint. The desuperheater temperature will initially decrease (decreased steam flow) until the ACC system brings pressure back to setpoint.

c. Limitations on boiler capacity have three limiting factors known as end points: end point of combustion, endpoint of carryover, and endpoint of circulation. The endpoint of combustion is limited by design in that the orifices in the sprayer plates or the amount of fuel allowed to the furnace, mixed with combustion air, will not allow the end point of carryover or circulation to occur by design. The end point of moisture carryover by Naval contract standards dictates the moisture carryover will not exceed 1/4 to 1 percent. Moisture carryover occurs when boiler internals are improperly installed or when the design end point of combustion is exceeded for any reason. The end point of circulation is reached when the downward flow of water in the downcomers cannot exceed the upward flow within the boiler tubes. Over sized sprayer plates or unauthorized overload plates cause the end points to occur. This condition causes boiler tubes to overheat and eventually rupture.

12. Boiler Abnormal Conditions

NOTE: Casualty prevention is the most effective form of casualty control. Effective training and continuous evaluation of all plant parameters is essential to quick identification of out of parameter indications. Out of parameter conditions in one location affects the operation of other components thus interrupting the designed heat balance and efficiency throughout the plant operation. Cause and effects when normal parameters are exceeded:

a. High water: Possible causes include failure of the 3-Element feed control system, ruptured diaphragm in the automatic feed check valve, or a bent or jammed stem in the automatic feed check valve. Possible results include carryover causing damage to the superheater, main feed pumps, ships service turbo generators, and main engines. Affects to the damaged equipment (if any) in that repairs must be made causing reduced plant capability.

b. Low Water: Possible causes include loss of feed pressure, failure of the 3-element feed control system, ruptured tubes, and a bent or jammed automatic feed check valve. Possible results include tube damage to include distorted, warped, ruptured, married, bulged or a loss of steam pressure due to ruptured tube. Effects include, the boiler must be opened for inspection causing at least a 48-72 hour repair time if no damage is sustained.

c. High Superheater Outlet Temperature: Possible causes include improper operation of the DFT producing a water discharge temperature lower than actual design, dirty firesides or a deformation of the gas baffles. Possible results in the deformation of tubes or ruptured tubes. Effects to the boiler will be catastrophic if unchecked.

d. Low Superheater Outlet Temperature: Possible causes include improper operation of the DFT which will produce a water temperature higher than design, poor combustion, insufficient combustion air, deteriorated or missing carbide baffles on the screen wall tubes, or carryover caused by either priming or foaming. Possible results include lower boiler efficiency. Effect on the boiler is generally long term and can go unnoticed if not monitored closely.

e. High Boiler Pressure: Possible causes include a malfunction of the ACC system, either in remote or local manual, inattentive watchstanders, or the throttleman not following acceleration/deceleration charts. Possible results include lifting safety valves, or a pressure part failure. Effect includes water loss or reduced plant capability.

f. Low Boiler Pressure: Possible causes include a malfunction of the ACC system, in remote or local manual control, inattentive watchstanders, or the throttleman not following the acceleration/deceleration tables. Possible results include decreased boiler efficiency, failed boiler tubes or the end point of circulation at approximately 85% of drum pressure. Effects include reduced plant capability to replace tubes or open and inspect taking a minimum of 48-72 hours.

B. CASUALTY CONTROL

1. Fireroom casualties can be broadly grouped into two categories: Casualties that have controlling actions and casualties that don't. Fireroom casualties that require securing the boiler generally follow the same procedures with few exceptions. However, casualties that require controlling actions are approached quite differently. These actions are intended to minimize damage and enhance restoring propulsion more readily.

2. Engineering operational casualty control (EOCC) procedures contain the following sections:

a. Symptoms/lndications

b. Causes

c. Possible Effects

d. Controlling Actions

e. Immediate Actions

f. Supplementary Actions

g. Restoring Actions

NOTE: Although there are six sections to the EOCC, controlling, immediate, effect on the ship, and restoring actions will be the focus of this lesson.

3. Controlling actions are actions that are performed in an effort to stabilize a plant condition while keeping it operational. Actions of this type vary in procedure to accommodate the casualty. These procedures maintain limited propulsion capability. However, immediate actions require that the plant be secured thus leading to a loss of that affected shaft. Most immediate action procedures are the same with few exceptions. An example of immediate actions would be:

a. Secure boiler

(1) Quick closing valve

(2) Shut main and auxiliary steam stops

(3) Secure auxiliary equipment

4. Casualties with controlling actions:

a. Loss of main feed control

(1) Symptoms/lndications: The inability to maintain proper boiler water level, feed pressure or feed control valve hunting, water level alarms sounding (example +7 or -6 inches of water). Water level indicators are installed at the BTOW and Engineering operating station that indicate water levels in all installed boilers.

(2) Possible causes: Failure of feed system components (main feed pumps or main feed booster pumps), operator error, feed water control system components, or loss of control air are the most common causes.

(3) Effects on the ship: Restricts the ship from quick load changes reducing maneuverability during the controlling actions. The boiler must be secured when a water level alarm sounds, prompting immediate actions to take place. Can lead to low boiler water level or high boiler water level casualties.

(4) Actions: When water level in the boiler is observed as out of parameters, the BTOW reports that there is difficulty in maintaining boiler water level. As a controlling action, the BTOW shifts feed water control to remote manual and attempts to control the water level. If the water level cannot be controlled, the mode of control is shifted to local manual and attempt to control the water level is continued at the final control element (feed water control valve). If a water level alarm sounds, the watchstanders must proceed to the immediate actions of the EOCC and secure the boiler. Securing the boiler at the sounding of a water level alarm helps prevent a high or low water condition from occurring.

(5) Restoring: Locating and correcting the problem with equipment or controls usually is relatively quick. Plant restoration will occur following repairs.

b. Low water in the DFT

(1) Symptoms/lndications: Loss of discharge pressure from the main feed booster pump or main feed pump, main feed booster low pressure alarm sounds or low water level in the DFT.

(2) Possible causes: Make-up feed misaligned, high DFT shell pressure caused by HP drain orifice failure or excessive Auxiliary Exhaust pressure, condensate pump failure or inability to handle demand, or freshwater drain tank misalignment and/or aligned to bilge due to contamination.

(3) Effects on the ship: Low water in the DFT restricts ship maneuverability during controlling and immediate actions. Ships speed shall be maintained and possibly slowed to reduce the water consumption of the boiler. If the water level in the DFT goes out of sight, the boiler will be secured IAW EOCC immediate actions, but the boiler water level will probably drop anyway, leading to a loss of main feed control or low water casualty.

(4) Actions: When a low water level condition in the DFT occurs, watchstanders shall check system alignment and operating conditions in an effort to correct the low water condition. Check the position of the makeup and excess feed valves. Makeup shall be wide open and excess shall be shut. If the DFT shell pressure is too high, check; auxiliary exhaust system pressure and HP drain pressure. If HP drain pressure is too high, isolate HP drains from the DFT. If the hotwell level is rising and the MCP can't handle the demand, place another MCP in operation. When the level reaches the bottom of the gage glass or goes out of sight, proceed to immediate actions.

(5) Restoring: Plant operation is usually quickly restored after locating and correcting the problem, particularly if no problems occurred with the boiler.

c. White smoke

(1) Symptoms/lndications: Boiler fires are incandescent, unstable or sputtering, orange glow in periscope, high superheater outlet temperature, stack gas analyzer indicating a white smoke condition or bridge reports white smoke.

(2) Possible causes: Poor-quality steam for atomization, improper fuel/air ratio, clogged fuel oil atomizer and or incorrect diffuser withdrawal setting, or component malfunction of the automatic combustion control system.

NOTE: 300 percent excess air is required for white smoke to be developed.

(3) Effects on the ship: A white smoke casualty restricts the ship's maneuverability in that if not corrected within sixty seconds of detection, the boiler must be secured. Ship's speed shall be maintained while controlling actions are in progress. If the boiler is not secured, a boiler explosion is possible.

(4) Actions: When a white smoke casualty is identified, the BTOW reports to the EOOW. As a controlling action, the BTOW shifts control of air and fuel to remote manual and reduces the air signal. If the white smoke condition still exists sixty seconds after detection, the boiler shall be secured IAW EOCC immediate actions.

(5) Restoring: Plant restoration for a white smoke casualty is quick if boiler damage has not occurred. ACC component failures can be corrected quickly, restoring propulsion if it was lost.

d. Heavy black smoke

(1) Symptoms/lndications: Periscope is dark in color or unable to see light, erratic or bright orange flame pattern in the furnace, smoke coming from boiler casing, or fire is burning on the deck of the furnace.

(2) Possible causes: An oil leak from the atomizer, component failure in the automatic combustion control system, or failure of forced draft blowers causing deficient combustion air flow.

(3) Effects on the ship: A black smoke casualty restricts the ship's maneuverability during controlling and immediate actions. Ship's speed shall be maintained while performing controlling actions. If a clear stack cannot be obtained within two minutes, the boiler will be secured IAW EOCC immediate actions.

(4) Actions: When a black smoke casualty is identified, the BTOW reports to the EOOW. As a controlling action, the BTOW shifts the air and fuel controls to remote manual and either increase air flow or decrease fuel flow signals. Immediate actions shall be initiated if stack conditions are not corrected within two minutes.

(5) Restoring: Like white smoke, this casualty is quickly restorable if boiler damage has not occurred. However, if unburned fuel is on the furnace deck prior to lighting off, the boiler must be tagged out and all traces of fuel removed prior to light off. This procedure may restrict use of the boiler for about 24 to 48 hours in a hot boiler.

e. Loss of control air

(1) Symptoms/lndications: Low pressure air system below normal operating pressure, console control air pressure drops or control air pressure alarm sounds.

(2) Possible causes: Vital/non-vital air compressor failure, ruptured air line, heavy system demand with malfunctioning priority valve failure.

(3) Effects on the ship: A loss of control air casualty which places the ABC system into airlock; restricts the ship from making speed changes until the plant can be shifted to local manual control. After that, slow changes in ship's speed can be accomplished as long as plant parameters are not exceeded

(4) Actions: When a loss of control air casualty occurs, the airlock system shall hold the plant in an airlock position for 10 minutes. The watch team shifts the final control elements into local manual and takes the boiler in local manual control. If specified parameters are exceeded, all boilers in that plant shall be secured.

(5) Restoring: If the plant is maintained within parameters until repairs are effected, the plant can be put back into automatic while still in operation. However, if the plant was secured, restoration is relatively quick when repairs have been made to the control air system or components.

f. Major machinery space flooding

(1) Symptom/lndications: Bilge level rising rapidly, inability to control bilge level by installed dewatering equipment, obvious major leak from a piping system.

(2) Possible causes: Ruptured seawater or piping system, improperly aligned drainage system, flexible expansion joint failure, or saltwater relief valve lifting.

(3) Effects to the ship: A major space flooding casualty causes a loss of propulsion capability from the affected plant. Thermal shock to space equipment (a boiler with pressure can experience pressure part failure), grounding of electrical equipment, contamination of equipment lube oil systems, and loss of ship can result.

(4) Actions: Report and aggressively isolate the leak. Align dewatering equipment to control flooding. The situation may require the use of the main circ pump for dewatering the space. When flooding out of control, proceed to immediate actions and secure the boiler and relieve all pressure by lifting safety valves manually with the hand easing gear.

(5) Restoring: Restoration from a major flooding casualty is time consuming if equipment was under water as a result of the flood. Immediate recovery is generally not possible while investigating all equipment for damage. Considerations must be made for repairing motors and other effected equipment. May require outside assistance from SIMA or a shipyard facility.

5. Casualties without controlling actions (immediate only)

a. Major steam leak

(1) Symptoms/lndications: An uncontrollable steam leak from a component or piping.

(2) Possible causes: Gasket failure, improper settings of pipe hangers, old age and deterioration, improper warm-up procedures, or incorrect isolation of pressurized systems due to improper tag-out procedures.

(3) Effects on the ship: Ship's propulsion and electrical power generation capability from the affected plant is removed until leak can be repaired of isolated. This casualty is not immediately restorable because of the extent of direct damage and collateral damage.

(4) Actions: Immediate action is required. When a major steam leak or rupture occurs, personnel shall attempt, as time permits, to locate and isolate the rupture and secure equipment. Place the affected space supply ventilation on high and the exhaust on low. If immediate evacuation is required, all personnel must don emergency escape breathing devices (EEBDs) and immediately evacuate the space mustering at the designated location.

(5) Restoring: This will be dependent on how and where the leak occurred. A flex or gasket takes little time to correct, but a pressure part failure of piping requires extensive repair procedures. If the ruptured piping can be isolated, the plant may be utilized for propulsion.

b. Low boiler water level

(1) Symptoms/Indications: An Increase feedwater control signal, an unusual drop in steam pressure, water level drops out of sight in the gage glass, or the low water level alarm sounds.

(2) Possible causes: Loss of main feed pressure, failure of the main feed pump, low water in the DFT, or ruptured main feed piping.

(3) Effects on the ship: Loss of boiler for 48-72 hours for inspection. Boiler damage may include ruptured, sagging or warped tubes. Loss of the affected shaft and turbine generators if that was the only boiler on the line until another boiler is brought on line.

(4) Actions: Secure the boiler, lift safeties to 100-200 psi below operating pressure, tag-out and inspect for damage.

(5) Restoring: The boiler must be tagged out and inspected which will delay operation for 48-72 hours. Lighting off the other boiler in the plant, if able, is required. A boiler hydro is required to check the boiler's integrity.

c. High boiler water level

(1) Symptoms/lndications: Decrease in feedwater control signal, rumbling or vibration in the steam piping, water rises out of sight in the gauge glass, or the high water level alarm sounds. Carryover can damage gaskets in the steam system piping causing steam leaks.

(2) Possible causes: Loss of feedwater control, failure of the automatic control system including the feedwater control valve and it's internals or the loss of control air.

(3) Effects on the ship: Moisture carryover, damage to boiler or turbines. Ship propulsion is restricted in the affected plant. Electrical power generation can be disrupted if this was the only boiler in operation.

(4) Actions: Immediate actions include securing the boiler. Check drains for signs of carry over, inspect main feed pump strainers for babbitt contamination.

(5) Prevent operation of the plant until the Engineer officer has determined the extent of the damage. The inspected equipment includes the main engines and SSTG(s), but is at the discretion of the Engineer Officer. This process can take 24-48 hours.

d. Ruptured boiler tube

(1) Symptoms/lndications: Loud bang from furnace, hissing noise, or loss of steam pressure, periscope fogging and steam escaping up the stack.

(2) Possible causes: Low water in the boiler, over firing the boiler, tube overheating, or improper boiler water chemistry.

(3) Effects on the ship: Loss of the boiler, damage to adjacent tubes, brickwork failure and loss of the effected shaft and electrical power generation if this was the only boiler on the line.

(4) Actions: Secure the boiler and relieve all pressure by lifting safety valves manually using the hand easing gear IAW EOCC.

(5) Restoring: The boiler must be tagged out and the tube plugged or replaced. A minimum of 48 to 72 hours will be required prior to restoring the boiler to operation.

e. Loss of boiler fires

(1) Symptoms/lndications: Fires are out, sputtering flames observed, fuel oil pump racing or stops, rapid drop in steam pressure, or a boiler explosion occurs.

(2) Possible causes: Improper stripping of fuel oil tanks, loss of the fuel oil service pump, loss of fuel oil suction or water in the fuel oil.

(3) Effects on the ship: Propulsion capability and electrical power generation from the affected plant are lost. If all boilers in the space are supplied from one fuel oil service system and the casualty affects the entire system, all boilers will lose fires.

(4) Actions: Secure the boiler using immediate actions to prevent the possibility of a boiler explosion from occurring. Investigate the fuel system for cause of the loss of fires casualty.

(5) Restoring: If water in the fuel is the cause of the casualty, stripping and purging of the fuel oil system and tanks will be required. If no boiler explosion occurred the plant may be put in operation when the cause has been corrected if the entire fuel oil service system is contaminated it must be flushed before any boiler in that space can be used. Good fuel from a satisfactory service tank must be available.

f. Fire in the boiler air casing

(1) Symptoms/lndications: Boiler air casing overheating, fire spotted in the air casing through the observation port, blistering paint, or the smell of smoke.

(2) Possible causes: Partially plugged atomizers, leaking atomizers, or boiler explosion.

(3) Effects on the ship: Warped or burned air casing, loss of boiler, propulsion and electrical power generation if this was the only boiler in operation.

(4) Actions: Immediate actions include securing the boiler and aligning steam smothering.

(5) Restoring: The boiler must be tagged out and inspected requiring at least 48 to 72 hours of down time. This time is critical in order to allow the boiler to cool for entry and inspection.

g. Major fuel oil leak

(1) Symptoms/lndications: Fuel spray, seepage or pooling, pressure drop in fuel oil system, fuel pump races or sudden increase in automatic combustion control signal, casualty while transferring or receiving fuel oil.

(2) Possible causes: Ruptured gaskets or piping, shock or excessive vibration in the plant, excessive pressure in the fuel oil system, collision, or battle damage, operator error, over flow of tanks or improper transfer of fuel.

(3) Effects on the ship: Loss of fuel oil pressure, boiler and possibly a loss of propulsion, electrical power generation and possibly a Class "B" fire.

(4) Actions: Immediately secure the boiler and break out fire fighting equipment, isolate the fuel oil leak, secure receipt or transfer of fuel if that was the cause. Refer to the main space fire doctrine.

(5) Restoring: The source of the leak must be repaired and all standing fuel oil in the space must be cleaned up prior to light off. The extent of the repair dictates when the plant can be restored to operation.

h. Boiler explosion

(1) Symptoms/lndications: Explosion in the boiler or stack.

(2) Possible causes: Temporary interruption of fuel supply, forced draft blower failure, improper fuel/air ratio, or accumulated fuel in the furnace.

(3) Effects on the ship: Damage to the boiler brickwork, injury to personnel, loss of boiler, possible loss of propulsion and electrical power generation or in the worst case a Class "B" fire

(4) Actions: Immediately secure the boiler and break out fire fighting equipment.

(5) Restoring: The boiler must be tagged out to open and inspect for damage. Minimum down time will be approximately 48 to 72 hours if repairs are not required. If repairs are required, the boiler will probably be out of commission for an extended period of time.