On 21/Mar conducted Marine boiler automation inspection service on board ship which berthed at CUD shipyard, entrusted by ship owner basing steadfast trust during long term cooperation

Present details collected from ship owner :

Boiler brand: Miura / Model: HB-15T

I. Key focus of the automation for Miura HB-15T boiler

• The Miura HB-15T is a vertical water-tube boiler with a high degree of automation and multiple safety interlocks. It is extremely hazardous once out of control. 
• There are 6 key items, all critical for safe operation:
  
  (1.) Automatic Water Level Control & Low Water Level Interlock (Most Important)
   Inspection Items: Normal operation of automatic water replenishment, high/low water level alarms, emergency boiler shutdown interlock at extremely low water level.
   Reason for Priority: As a water-tube boiler, the Miura HB-15T can suffer overheating and tube rupture immediately in case of water shortage.
  
  ( 2.) Automatic Steam Pressure Control & Overpressure Protection
   Inspection Items: Pressure sensors, pressure regulators, overpressure alarms, and linkage test of safety valves.
   Reason for Priority:Uncontrolled pressure may cause overpressure explosion and pipeline rupture.
  
  (3.) Automatic Combustion System Control (Ignition, Flame Detection, Flame Failure Protection)
   Inspection Items: Automatic ignition, flame detectors (UV / ion rod), fuel oil/gas cut-off interlock upon flame failure.
   Reason for Priority: Continuous fuel injection after flame failure can lead to fuel accumulation and deflagration, resulting in furnace explosion.
  
  ( 4.) Water Temperature/ Exhaust Gas Temperature Monitoring
  Inspection Items: Outlet water temperature monitoring and over-temperature alarm for exhaust gas.
  Reason for Priority: Abnormal temperature indicates scaling, deteriorated combustion, and imminent damage to heat transfer tubes.
  
  (5.) Automatic Blowdown / Water Quality Control
   Inspection Items: Normal operation of timed blowdown or concentration-controlled automatic blowdown.
   Reason for Priority: Lack of blowdown leads to scaling, sharp drop in thermal efficiency, and eventually tube burnout.
  
  (6.) Overall Boiler Alarm System & Control Logic
  Inspection Items: Normal function of all audible and visual alarms, reliability of shutdown logic.
  Reason for Priority: Failure to alert faults allows minor issues to escalate into major accidents.
  

II. Serious Consequences of Skipping Automatic Inspection 

(1.) Most Severe Risk: Boiler Tube Rupture / Furnace Explosion
Causes: Uncontrolled water level leading to dry firing, continuous fuel injection after flame failure.
Consequences: Injury caused by high-pressure steam ejection / Damage to the boiler structure /  Vessel outage, major accidents, and liability claims from the shipowner

( 2.) Overpressure Rupture
Causes: Failure of pressure control plus malfunction of safety valves.
Consequences: Rupture of steam pipelines, scalding injuries, and complete equipment failure.

( 3.)  Fire Hazard
Causes: Fuel oil leakage, unstable combustion, excessive high temperature.
Consequences: Engine room fire, one of the most serious accidents on board vessels.

(4.) Sudden Boiler Shutdown Causing Total Loss of Steam Supply
 Vessels rely on boiler steam for heating, cargo hold insulation, domestic hot water, and steam-driven equipment.
 Consequences: Abnormal vessel operating conditions /  Interruption of ship repair / operation / Schedule delays and huge financial losses

( 5.) Rapid Equipment Aging and Premature Retirement
Although the Miura HB-15T is highly durable: Unstable combustion causes high thermal stress /  Poor water quality leads to scaling and corrosion / Lack of automatic blowdown results in sharp decline of heat transfer efficiency
Consequence: Service life reduced from 10 years to only 3-5 years before replacement is needed.

(6.) Failure of Ship Survey / PSC Inspection and Vessel Detention
Automatic protection systems for marine boilers are mandatory inspection items.
Invalid interlocks / Missing alarms / Abnormal water level control Will directly result in PSC deficiencies→vessel detention→fines +operational suspension.

In one word: The core of automatic inspection is to uphold the three major safety bottom lines: water level, pressure and combustion.

If the inspection is omitted or carried out perfunctorily, the consequences will range from reduced efficiency and equipment damage in mild cases, to tube rupture, explosion, fire, and even vessel suspension and casualties in severe cases.

III.Our service technician stringently follow above mentioned important inspection points, along with the properly inspection procedure on board : 

STEP ONE: General summary of Boiler on board: 

• Boiler ACC health check
• Combustion tune 
• Check and clean the flame scanner 
• Water level too high/high/low/too low to shutdown boiler testing is working normal
• Flame failure testing 
• Boiler auto start/stop at 5.5kg/cm2~7.5kg/cm2. 
• Water level high alarm:190mm.
• Water level low alarm:-150mm. 
• Water level too low shutdown;-190mm. 
• Feed water pump start: 20mm. 
• Check the steam pressure transmitter. 
• Check the water level transmitter.
  
  

STEP TWO: Control panel

• Control panes is in good condition, no jumper and by-pass found.
• Control modules looks in good condition, function normal. 
•  Fire function tested under manual mode, all push buttons working and operation is fine.
•  No wire connection found loose. 
•   Check AC/DC converter working normal. Not need replaced.
  
  

STEP THREE:  Burner

• Burner is in general good condition, no leaking found. 
• Solenoid v/vs are working normally. 
• Pressure gauges are showing correct reading, matching with transmitter. 
• Burner nozzle and combustion head checked, still in good condition. 
• Burner ignition transformer and electrode checked, in good condition. 
• Air damper and oil regulator servomotor checked, in good condition. 
• Boiler starting sequence, auto start/stop function normal.
  

STEP FOUR： Feed water system

•  Water lever transmitter checked and adjusted, thereafter reading is matching with local gauge glass. 
•  Test auto feed water function, working normally condition. The pump auto start at -50mm,stop at 50mm.
  
  
  

STEP FIVE: Adjustment

• Manual start boiler, ignition and flame OK, continue running boiler and check for combustion. 
• Air/oil ratio tuned. No need adjust. 
• Check and calibration the stream pressure transmitter. actual water level same as ECR indicator. 
• Check and calibration the stream pressure transmitter. 
• Steam pressure indicator from local panel to ECR display correct.
  
  
  
  

STEP SIX: Alarm test 

• ING/FLAME FAIL testing 
• Water level high/low/too low to shutdown boiler testing is working normal 
• Water level high alarm:190mm 
• Water level low alarm:-150mm 
• Water level too low (shutdown) alarm:-190mm
• FO press. Low trip 
• FD fan failure 
• EXH.gas temp. High 
• Atomize air /steam low press. 
• All running signal light verified, working normal.
  
  
  

STEP SEVEN: Conclusion after service 

• Boiler work with AUTO and manual mode. 
• Feed water AUTO start/stop normal. 
• Combustion tuned, in good condition. No black smoke.

AT LAST