Alfa Laval Aalborg-XS-TC7A-16bar
Alfa Laval Aalborg-XS-TC7A-16bar compact exhaust gas economizer (compact exhaust gas economizer). Evaporation 4800 kg/h, design pressure 16 bar, heating surface 100 m2, weight 9800 kg. Compact, vertically-mounted exhaust-gas waste heat boiler.
Inspector Detail
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Common issues
- Soot fire risk from unburned fuel deposits accumulating on the exhaust gas side
- Tube fouling on the gas side reducing heat transfer and raising exhaust back-pressure
- Tube corrosion/leakage, particularly acid dew-point corrosion during extended low-load or slow-steaming operation
- Soot blower malfunction reducing cleaning effectiveness
- Waterside scaling from inadequate feed water treatment
- Rising exhaust gas outlet temperature or differential pressure signalling fouling or an incipient soot fire
Inspection checklist
- Check exhaust gas side for soot buildup at scheduled openings
- Monitor exhaust gas differential pressure and temperature drop trend
- Inspect tubes for corrosion or leakage on both gas and water sides
- Check soot blower operation and coverage
- Verify safety valve set pressure and reseating
- Check water level control and low-water alarms
- Watch for an unexplained rise in gas outlet temperature - possible indicator of a soot fire
- Review feed water treatment and blowdown records
- Check economizer bypass damper operation if fitted
- Inspect insulation/lagging for hot spots or damage
Service intervals
| Soot blowing | daily/per running hours whenever the main engine is running |
| Exhaust gas side inspection | every 4,000-8,000 running hours or at each class survey opening |
| Safety valve function test | annually |
| Feed water treatment/TDS check | weekly |
| Internal waterside inspection | at each class survey opening |
| Bypass damper function check | per maker interval |
Typical wear limits
| Tube wall thickness | class societies require retention of a minimum percentage of original design thickness before renewal - confirm the specific figure against the vessel's classification rules and the Alfa Laval Aalborg manual, do not estimate on board |
| Low-load corrosion | acid dew-point corrosion can locally thin tubes faster than general wear - monitor via UT gauging rather than assuming a uniform rate |
Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.
Critical spares
- Soot blower nozzle/element
- Safety valve spring and seat set
- Tube plugs for isolating a leaking tube
- Manway/inspection door gasket set
- Feed check valve
- Water level gauge glass
Safety
- Soot fire risk - accumulated unburned fuel deposits on the exhaust side can ignite and cause severe damage; fixed fire-fighting/water-washing arrangements must be maintained ready for use
- Hot exhaust gas surfaces
- Pressurized steam and hot water
- Confined space entry required for internal cleaning/inspection - test atmosphere before entry
- Working at height on this vertically-mounted unit
Class survey
Exhaust gas economizers are Continuous Survey Machinery items with particular attention to soot fire prevention arrangements; class reviews internal/external inspection records and safety valve certificates, and increasingly requires enhanced inspection for vessels operating extensively at low load due to known cold-corrosion risk.
Components & Design
Component data being added…
Technical Data
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Common failures & inspection points
Visual inspection of gas side for soot buildup, exhaust temperature measurement: >10-20°C above setpoint indicates sludging; perform water flushing kit application (50 l/min, 0.4-0.6 MPa pressure); operate Soot-Blower daily 3x (caution: In case of uptake fire DO NOT blow down with steam due to H₂ fire hazard)
Internal inspection test (opening of sight glasses/hand ports): inspect tubes for wear, pitting, thinning; external inspection for soot deposits, blistering, sag; perform hydraulic pressure test at 1.25 × operating pressure for maximum 10 minutes
Class surveyor: Inspect all boilers >3.5 bar working pressure and >4.65 m² heating surface. Frequency: DNV/LLOYDS every 2 years up to 8 years old, then annually; 2 comprehensive internal inspections per 5-year period, interval maximum 36 months. Inspect internal surfaces (drums, headers) for sludging, corrosion, cracks.
Safety valve test: opening at ≤3% above working pressure; test pressure 15% above working pressure for maximum 10 minutes (feedwater only for water level safety); pressure rise during test maximum 10% above design pressure at full load firing with stop valves closed.
Sight glass visual inspection for highest, lowest, normal water level markings; protective devices without sight obstruction; test water cushion safety ball valve for function; check drain line for safety.
For Aalborg OL/D and similar burner boilers: inspect refractory material (membrane walls, furnace floor) for cracks, deformation, separation; remove carbon deposits. For XS-TC7A: clean helix tube bundle with water flush kit (7–8 hours on similar ships), if necessary add cleaning chemicals before discharge to slop tank.
Type-general inspection and maintenance points for this equipment category — not model-specific.
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