Thursday, July 2, 2020

Boiler Survey

  • 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.
Interval:
  • Boilers require to be surveyed at 2-year intervals until they are 8 years old, thereafter they become due for survey annually.
Procedures:
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
 Before shutting down boiler
  • 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
 Shutting down 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
Preparation for 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
 Boiler Inspection
  • 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
Gas Side
  • 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
 Water side
  • 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
Safety Valve
  • 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
Closing
  • 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
Preparation flashing up:
  • 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
Flashing Up
  • 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
Starting the boiler for a normal operation:
  • 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
 EGE Safety valve
  • C/E to set the safety valve when the ship is at sea
  • Report to surveyor in writing to confirm safety valve operation

No comments:

Post a Comment

If you have any doubts.Please let me know