- Boilers are inspected to maintain the regulatory requirement.
- Regular internal and external examination during such survey constitutes the preventive maintenance schedule the boiler goes through to have a safe working condition.
- Boilers require to be surveyed at 2-year intervals until they are 8 years old, thereafter they become due for survey annually.
Planning:
- Discuss with Master and Chief Engineer to confirm time available, manpower and time required and steam requirement for next port.
- Checks before shutting down boiler:
- Sufficient spares (joints, packing, gauge glass, etc)
- Past reports and manual for special attention need to be take care
- Special Tools required
- Meeting and brief with all engineers involved
- Mark all valves, safety valve setting and spigot clearance
- Inform Chief engineer
- Inform duty deck officer
- Top up DO service tank
- Change over M/E, A/E and boiler to Diesel oil
- Stop all purifier
- Shut all heating and tracing steam valve
- Soot blow the boiler
- Change over to manual firing
- Stop firing
- Purge boiler for 5 minutes
- Shut main steam stop valve
- Switch off power, off the circuit breaker and remove fuses for FD fan, FO pumps, feed pumps and control panel.
- Put a notice on the circuit breaker mentioned above
- Shut all fuel valve and atomizing valve and lock them in shut position, blank the line if necessary
- Allow boiler to cool down slowly
- Scum blowdown follow by bottom blowdown when the boiler cooled
- Open air vent when boiler pressure drop until 2 bar to prevent vacuum formation
- Further cooling of boiler
- Prepare to open top manhole door when boiler is cooled and at atmospheric pressure
- Slacken the dog nut and secure manhole with rope
- Knock manhole door gently with long stick. Do not open fully because hot steam or water might gush out.
- Open full when is safe
- Allow further cooling of boiler before open the bottom manhole door. This is to prevent thermal shock
- Confirm no large quantities of hot water lying in the bottom
- Open the bottom manhole door with the same precaution as with the top manhole door
- Open the furnace door slowly
- Ventilate the boiler both water and fire side for 12-24 hours
- Enclose space entry permit obtained
- Check Oxygen, flammable gas and toxic gas content
- Prepare to entry
- Prepare safety torch and safety hand lamp
- Investigate from outside make sure it is clear from obstruction before entering boiler
- Oxygen analyzer is carry with the person entered boiler
- Personnel entering must wear all safety gears
- Clear pocket contents and tools to be carried in a bag and accounted
- A responsible engineer to be standby outside with clear emergency order
- Keep breathing apparatus ready
- Remain communication
- Ensure proper lighting at all time
- Thoroughly cleaned before boiler is surveyed
- Wire brush and hose down may be sufficient to prepare for survey in well maintained boiler
- Chipping off scale is necessary
- If traces of oil are found in boiler, chemical means may have to be adopted to remove them
- Route of inspection
- Exterior of drums for signs of tube roll, leakage, corrosion, soot erosion and overheating
- Condition of outside drum insulation
- Drum seals for sign of air leakage
- Inspect drum support for crack and expansion clearance
- All blowdown connections for expansion and flexibility of support
- All piping and valve for leaks
- Water wall tubes and fins for crack
- Exterior of all tubes for corrosion, carbon build up, erosion, blisters and sagging
- Tubes near soot blowers for steam impingement
- Condition of refractory
- Around burner assembly, refractory and accumulation of soot or carbon
- Soot blower for distortion, worn bearings, rubbing of tubes, condition of nozzles, cracks, freedom of movement and effective lubrication
- Steam drum for corrosion scaling and pitting
- Manhole seats and surface
- Condition of all fee, chemical feed, blowdown lines and inside pressure parts for choking, security and leaks
- Tubes for corrosion, excessive deposits, flare cracking and pitting
- Hand hole plates and stud threads
- Condition of valve internal parts for signs of corrosion, galling and wear
- Check for pitting, crack, resiliency and condition of springs
- Check spindle for straightness and adjusting ring thread for freedom of movement
- Check discharge and drain piping
- Check dampers to ensure that linkage are secured and well greased
- Condition of burners, swirler and air register
- Wind-box dampers and vanes for sign of corrosion and erosion
- Check condition and operation of all valve
- Check feed water controller and control valve connection lines and ensure proper functioning
- Examine the foundation and bracing bolts of boiler for corrosion, fretting and rustin
- Inspect internal surface to ensure they are clean
- Counter check all tools are out from boiler
- All opening of the mounting are cleaned properly
- Mountings to be fixed back with new set of gasket/joint
- Replace the header handhole and the bottom manhole door
- Operate all mounting valves to ensure they work freely and leave all valves in close position
- Replace top manhole door
- Sootblower are correctly fitted
- Air control dampers move freely for their full travel
- Open gauge glass steam and water cocks and shut drain cock
- Open vent, alarm and pressure gauge connection valve
- Shut all drain valve
- Switch on power for control panel, feed pump, FD fan and FO pump
- Fill boiler with hot distilled treated water
- Fill until water level below normal level
- Check control air is available
- Start FD fan and purge boiler for 5 minutes
- Start FO pump and check all parameters
- Fire boiler with minimum firing ratio
- Continue firing intermittently e.g. 1min. fire, stop 10min. for 1st hour, 2min fire, stop 10min. for 2nd hour and so on….
- As boiler heats up, water level will rise to normal level, top up if necessary
- Continue fire until a continuous stream of steam comes out from air vent
- Shut air vent
- Blow through gauge glass when boiler pressure raised
- Open valve to remote level indicator
- At 7 bar, all securing buts to be retighten
- Open steam line drains to drain off condensate
- Warm up the steam line
- Gag 1 safety valve, raise the steam pressure slowly and check safety valve operation and if need adjust it.
- Repeat the procedure for other safety valve
- Ensure no condensate at the drain line
- Crack open main steam stop valve, slowly open until its full open
- Keep firing as steady as possible
- Check all safety cut outs and alarms before putting boiler on Auto
- Final round check on boiler
- Start tanks and tracing steam heating
- Open steam to all heaters
- Start all purifier
- Change over from DO to HO for boiler and Generator
- M/E change over during departure
- C/E to set the safety valve when the ship is at sea
- Report to surveyor in writing to confirm safety valve operation
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ReplyDeleteI enjoy all of your posts. I have read the entire content and procedure you outlined above. If I may, boilers are intricate pieces of machinery, and it is better to leave the service and maintenance of these to the experts. Your detailed explanation of the Boiler Repair Service material is really helpful. Are your technicians able to help us choose a new system that fits our home and way of life annual maintenance is essential for boilers of all sorts and ages and we want to make sure that neither air nor water is seeping into the system and damaging our property.
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