Mission OS
The Mission OS is a compact vertical auxiliary oil‑fired composite boiler delivering up to 6 t/h of steam at 9 or 18 bar, intended for port‑side operation and low‑load hotel services on merchant vessels.
Inspector Detail
▸
Common issues
- Burner flame instability or failure to light off cleanly
- Soot deposit buildup on fire-side tube surfaces reducing thermal efficiency
- Water-side scale formation from inadequate feed water treatment
- Refractory cracking or spalling around the burner throat
- Safety valve seat leakage or set pressure drift
- Low water level cutout malfunction
- Fuel oil heater or viscosity control issues when firing HFO
Inspection checklist
- Burner flame pattern and ignition sequence check, including pre-purge
- Safety valve lift and reseat test
- Low-low water level alarm and cutout function test
- Boiler water chemical treatment sampling (alkalinity, phosphate, chlorides)
- Soot blowing effectiveness on fire-side tubes
- Refractory condition at the burner throat
- Water level gauge glass cross-check against remote indication
- Exhaust gas economizer fouling check, if fitted
- Relief and vent valve operation
Service intervals
| Water treatment chemical dosing/sampling | typically weekly |
| Soot blowing | daily to weekly depending on fuel and load |
| Safety valve function test | monthly for lift check, annual for full set-pressure test |
| Internal inspection (waterside/fireside) | typically annual, tied to the class Continuous Survey Machinery scheme |
| Burner nozzle/atomiser cleaning | per OEM, commonly every few hundred running hours |
Typical wear limits
| Boiler tube wall thickness | class societies typically require renewal once wall thickness has thinned by roughly 10-15% below original design thickness for boilers of this class, but the applicable minimum must be taken from the vessel's class rules and the boiler's own drawings, not assumed |
| Safety valve set pressure drift | should not exceed the tolerance stated on the valve's test certificate |
Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.
Critical spares
- Burner nozzle/atomiser
- Ignition electrodes
- Safety valve spring and seat set
- Water level gauge glass and gaskets
- Low water alarm float or probe
- Refractory repair material for the burner throat
Safety
- Pressurised steam and hot surfaces throughout the boiler and steam lines
- Boiler damage or explosion risk from a low water condition if the cutouts fail - low water alarm testing is safety-critical
- Fuel oil under pressure and heated to high temperature on HFO firing
- Furnace/combustion chamber explosion risk if the pre-ignition purge sequence is bypassed
- Confined space hazards during internal waterside/fireside inspection
Class survey
Falls under Continuous Survey Machinery for boilers; class typically requires internal waterside/fireside examination, witnessed safety valve testing, and review of water treatment logs at each boiler survey.
Components & Design
Component data being added…
Technical Data
🤖 Ask about this model
One free question — answered like a marine engineer. No account needed.
Common failures & inspection points
Internal visual inspection of all steam/water tubes; perform pressure test if suspected; seal leaking tube with conical stop valve after steel wire brush cleaning of tube ends. Leaking tubes must be renewed.
Check DP transmitter unit (external reference/variable leg, 4–20 mA output); feedwater control valve functional test; sight glass for cracks, contamination; test alarm function in control unit
Test two safety valves under full-load steam: pressure build-up 7 min. max. +6% working pressure permissible (water tubes); pop-point of each valve max. ±3% from set pressure; class notation: perform opening + accumulation test under classifier supervision
Inspect furnace walls and refractory lining visually (min. 2x/year); check for cracks, moisture, soot deposits. Check lower tube plate (insulation + form refractory). After 3–4 weeks operation: perform blow-down, inspect/clean boiler, remove sludge
Hydrostatic test: fill boiler with water 21–65 °C (water tubes max. 71 °C). Pressure: 1.5× MAWP (non-entry) or 1.25× MAWP (entry). Secure safety valves with clamps. Check all seal surfaces, rivets, welds for leaks. Class notation: every 2 years (up to 8 years), then annually
Class survey: water side (steam drum, water drum, all tubes) check for corrosion/cracks/deposits; fire side (furnace, flue gas path) check for soot/flocking (min. 2x/year). Man holes (top/bottom) permit access. If necessary use ultrasonic/endoscope for deeper defects
Type-general inspection and maintenance points for this equipment category — not model-specific.
Service & Maintenance
Part of Mission composite boiler system. Oil section used in port. Water treatment per Alfa Laval guidelines.
Suppliers & Spare Parts
Direct links to manufacturer, datasheet, spare-parts portal and dealers — request access below.
📄 Request sourcing links & documentsCases, daily reports, timesheets and AI troubleshooting in the OceanSphere Marine app — free for 14 days.
Start free trial →Find manufacturers, repair shops and spare-part dealers in the Maritime Network — our global company directory.
Maritime Network →