MPUSOx/U-2400 installed onboard BULGARIA (IMO: 9968475)

Common issues

• Scrubber tower internal corrosion (acid attack) at packing, demister, and shell in wash-water-wetted zones
• Demister/mist eliminator fouling or damage causing carryover into the exhaust stream
• Wash water pump or spray nozzle fouling/wear reducing spray coverage and SOx removal efficiency
• Effluent treatment unit fouling or reduced separation efficiency (hybrid-mode operation)
• CEMS sensor (pH, SO2/CO2 ratio, turbidity, PAH) drift or fouling giving unreliable compliance readings
• Overboard discharge line and valve corrosion or scaling
• Exhaust gas bypass damper seizure or leakage past the seal

Inspection checklist

• Verify CEMS calibration (SO2/CO2 ratio, PAH, turbidity, pH) is current
• Inspect scrubber tower internals (packing, demister) for corrosion/fouling at dry-dock or internal access
• Check wash water pump and spray nozzle condition and coverage pattern
• Inspect bypass damper operation and seal condition
• Check the effluent treatment unit function and sludge/residue handling arrangements (hybrid mode)
• Verify wash water discharge quality against the applicable MARPOL Annex VI Scrubber Guidelines limits
• Check coating/lining condition in wash-water-wetted areas
• Confirm the EGCS record book (operation, exceedance events) is complete and current

Service intervals

Typical intervals for this design class, not the manufacturer’s figures for your model. The manufacturer’s manual is binding.

Typical wear limits

Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.

Critical spares

• Wash water spray nozzles
• Demister/mist eliminator elements
• CEMS sensor modules (SO2, CO2, pH, turbidity, PAH)
• Wash water pump seals/impeller
• Bypass damper actuator/seal kit
• Effluent treatment consumables/filters for hybrid operation

Safety

• Acidic wash water presents a corrosive-fluid contact hazard - PPE required for internal or effluent-system work
• Confined space entry for scrubber tower internal inspection requires gas-freeing and ventilation checks
• Bypass damper failure could misroute hot, corrosive exhaust gas - verify damper interlocks before internal entry
• Unauthorised wash water discharge or sensor bypass is a MARPOL Annex VI compliance violation, not just a maintenance issue

Class survey

Exhaust gas cleaning systems are a Continuous Survey Machinery item under MARPOL Annex VI/the applicable class EGC notation: continuous monitoring of wash water discharge and CEMS parameters is reviewed, discharge exceedance events in the record book are checked, and internal survey of the scrubber unit (corrosion, lining) is carried out at renewal or dry-docking. Confirm the unit remains within the approved monitoring scheme of the applicable EGCS Guidelines revision, and that the DNV MED certificate (MEDG00001B9) matches the installed unit.

Estimated lifetime: The scrubber tower structure is generally designed for the vessel's operating life, with lining/coating renewal tied to dry-docking (typically 5-yearly); wear components (nozzles, demister elements, sensors) are renewed on a running-hours or condition basis well before that - confirm against manufacturer documentation for this specific unit.