Thermal Oil Heater (for tankers)
high
6 models total
A thermal oil heater circulates heated oil rather than steam through cargo coils, letting tankers hold heavy or viscous cargoes such as fuel oil, bitumen or edible oils at pumping temperature without the corrosion and pressure risks of a live steam system.
Read more — Thermal Oil Heater (for tankers) explained ▾
What sets a thermal oil heater apart
A thermal oil heater does not raise steam. It heats a mineral or synthetic heat transfer oil in a closed loop and pumps that hot oil through coils welded or clamped inside the cargo tanks, through cargo line trace heating, and back to the furnace. Because the oil stays liquid at temperatures where water would need very high pressure to remain as saturated steam, the whole system runs close to atmospheric pressure even at oil temperatures of 250-300°C. On a tanker carrying viscous cargo — heavy fuel oil, bitumen, molasses, tallow, some vegetable oils — that combination of high temperature and low pressure is the whole point: it keeps cargo pumpable for discharge without the pressure-vessel risk of a live steam boiler sitting a few frames away from cargo tanks. Unlike an exhaust gas economiser or an auxiliary boiler, a thermal oil heater is a single-fluid, single-purpose system built around one furnace and one oil inventory, not a steam header feeding multiple consumers.
Main components
Furnace and coil
A fired furnace, usually a single coiled tube run rather than a shell-and-tube arrangement, transfers combustion heat directly into the flowing oil. Firing is by diesel oil or heavy fuel oil burners with forced draught, sized to the maximum heat duty required for the fastest planned cargo heat-up.
Expansion tank and nitrogen blanket
An elevated expansion tank absorbs the oil's thermal expansion and keeps the loop full. It is nitrogen-blanketed to keep oxygen away from the hot oil, because oxidation is what turns thermal oil into sludge and coke deposits.
Circulation pumps
Duty and standby centrifugal pumps keep oil moving through the coil at all times the furnace is fired — stopping flow to a hot coil for even a short period causes local overheating and coking at the burner end.
Cargo heating coils and control
Coils in each tank, isolating valves so unused tanks can be shut out of the circuit, and a temperature control loop that throttles firing rate or bypasses oil around the furnace to hold a set cargo temperature without overheating the oil film at the coil wall.
Selection and sizing
The heater is sized on heat duty, not on tank volume alone. The relevant figures are:
- Required heat-up time and target cargo temperature, which set the peak duty in kW or kcal/h
- Maximum oil film temperature the chosen oil grade tolerates before thermal cracking begins, usually well below its stated maximum bulk temperature
- Oil flow rate needed to keep the film-to-bulk temperature difference small at full firing
- Turndown ratio, since most of a voyage needs only trim heating, not full cargo heat-up duty
- Compatibility of the coil material and cargo heating temperature with the cargoes the ship is built to carry
Regulations and class
SOLAS Chapter II-2 governs fire protection for the furnace space and its separation from cargo tanks, since this is an open-flame heat source operating close to flammable or combustible cargo. Classification societies treat the furnace, coil and expansion tank as pressure and fire-risk equipment subject to periodic survey, including internal coil inspection for coking and wall thinning. MARPOL Annex I applies if a coil leak lets cargo or oil residues reach machinery space bilges or the sea.
Typical faults
| Fault | Cause | Consequence |
|---|---|---|
| Coking inside the coil | Local overheating from low flow or oxidised oil | Reduced heat transfer, eventually a blocked coil section |
| Expansion tank oil loss | Vent or level instrumentation fault, undetected leak | Air ingress, accelerated oxidation, fire risk near the furnace top |
| Pump seal failure | Dry running or seal wear at high oil temperature | Loss of circulation and rapid coil overheating if not tripped in time |
| Cargo coil leak into tank | Corrosion or mechanical damage to coil | Cargo contamination and loss of heating oil inventory |
What to look for in a supplier
- Documented oil film temperature at full duty, not just bulk oil temperature, against the oil grade specified
- A chemical cleaning or flushing connection built into the coil circuit for removing coke deposits without a full strip-down
- Coil material and thickness matched to the cargo range the ship will actually trade in, with margin for corrosion
- Spare parts commonality for pumps and burners with equipment already on board
Track oil film temperature trend at the coil outlet over successive voyages: a slow rise at constant duty is the earliest sign of coking, long before flow or bulk temperature readings show anything wrong.
4000h
Service Interval
20 yr
Typical Lifetime
Typical Manufacturers
Aalborg
2 manufacturers · 6 models
Alfa Laval
4
Alfa Laval Mission OL 100
100 kW thermal
· thermal oil
Boiler Type
Alfa Laval Aalborg Ölgefeuerte Schiffsdampfkessel (Water Tube / D-Type)
Thermal output (kW)
100
Max temp (°C)
300
Medium
thermal oil
Technical Specifications
- Dampfkapazität OL
- 12.500–55.000 kg/h (mit BOG-Management)
- Dampfkapazität D
- 25–120 t/h (Tanker-Hauptkessel)
- Designdrücke
- 9 or 18 bar(g)
- Konstruktion
- Zweritrommel (Dampftrommel/Wassertrommel), Membranwände, Generatorröhrenbank
- Rohrsystem
- Gerade Pin-Tubes mit Schwenk-Pins, externe Fallrohre (Aalborg D)
- Brenner-typ
- Oelgefeuert (Standard), Dual-Fuel optional, KBSD/Aalborg-Brenner
- Refraktär
- Minimal im Feuerraum, Isolations- + Formrefraktär an Rohrplatte
Product Lines
- Aalborg OL (12.5-55 t/h, 9/18 bar)
- Aalborg D (25-120 t/h, 18 bar, Tanker-Design)
- Aalborg OM (8-45 t/h, Mittelkapazität)
- Mission OS (bis 6 t/h, Vertical Auxiliary)
Common Failures & Inspection Points
- Area: Tube body leakage due to corrosion, pitting, deposits (scale/sludge) or wearCheck: 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.
- Area: Water level regulation: failure of differential pressure transmitter or feedwater control valve leads to flooding/drying outCheck: 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
- Area: Safety valve failure or incorrect opening/closing pressures — overpressure or inadequate emergency steam reliefCheck: 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
- Area: Furnace refractory damage (cracks, spalling) or soot/corrosion → heat leaks, furnace instability, drum overheatingCheck: 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
- Area: Loss of pressure integrity due to corrosion, cracks, rivets or welds → leakage, operating loss, safety riskCheck: 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
- Area: Internal corrosion (water side), scale deposits or fire side soot/flocking → tube wear, heat loss, contaminationCheck: 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-universal inspection points for Alfa Laval Aalborg oil-fired marine steam boiler (Water Tube / D-Type) (Aalborg + Class/eCFR, 2026-06). Per-model specs not auto-populated.
Alfa Laval Mission OL 250
250 kW thermal
· thermal oil
Boiler Type
Alfa Laval Aalborg Ölgefeuerte Schiffsdampfkessel (Water Tube / D-Type)
Thermal output (kW)
250
Max temp (°C)
300
Medium
thermal oil
Technical Specifications
- Dampfkapazität OL
- 12.500–55.000 kg/h (mit BOG-Management)
- Dampfkapazität D
- 25–120 t/h (Tanker-Hauptkessel)
- Designdrücke
- 9 or 18 bar(g)
- Konstruktion
- Zweritrommel (Dampftrommel/Wassertrommel), Membranwände, Generatorröhrenbank
- Rohrsystem
- Gerade Pin-Tubes mit Schwenk-Pins, externe Fallrohre (Aalborg D)
- Brenner-typ
- Oelgefeuert (Standard), Dual-Fuel optional, KBSD/Aalborg-Brenner
- Refraktär
- Minimal im Feuerraum, Isolations- + Formrefraktär an Rohrplatte
Product Lines
- Aalborg OL (12.5-55 t/h, 9/18 bar)
- Aalborg D (25-120 t/h, 18 bar, Tanker-Design)
- Aalborg OM (8-45 t/h, Mittelkapazität)
- Mission OS (bis 6 t/h, Vertical Auxiliary)
Common Failures & Inspection Points
- Area: Tube body leakage due to corrosion, pitting, deposits (scale/sludge) or wearCheck: 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.
- Area: Water level regulation: failure of differential pressure transmitter or feedwater control valve leads to flooding/drying outCheck: 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
- Area: Safety valve failure or incorrect opening/closing pressures — overpressure or inadequate emergency steam reliefCheck: 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
- Area: Furnace refractory damage (cracks, spalling) or soot/corrosion → heat leaks, furnace instability, drum overheatingCheck: 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
- Area: Loss of pressure integrity due to corrosion, cracks, rivets or welds → leakage, operating loss, safety riskCheck: 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
- Area: Internal corrosion (water side), scale deposits or fire side soot/flocking → tube wear, heat loss, contaminationCheck: 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-universal inspection points for Alfa Laval Aalborg oil-fired marine steam boiler (Water Tube / D-Type) (Aalborg + Class/eCFR, 2026-06). Per-model specs not auto-populated.
Alfa Laval Mission OL 500
500 kW thermal
· thermal oil
Boiler Type
Alfa Laval Aalborg Ölgefeuerte Schiffsdampfkessel (Water Tube / D-Type)
Thermal output (kW)
500
Max temp (°C)
300
Medium
thermal oil
Technical Specifications
- Dampfkapazität OL
- 12.500–55.000 kg/h (mit BOG-Management)
- Dampfkapazität D
- 25–120 t/h (Tanker-Hauptkessel)
- Designdrücke
- 9 or 18 bar(g)
- Konstruktion
- Zweritrommel (Dampftrommel/Wassertrommel), Membranwände, Generatorröhrenbank
- Rohrsystem
- Gerade Pin-Tubes mit Schwenk-Pins, externe Fallrohre (Aalborg D)
- Brenner-typ
- Oelgefeuert (Standard), Dual-Fuel optional, KBSD/Aalborg-Brenner
- Refraktär
- Minimal im Feuerraum, Isolations- + Formrefraktär an Rohrplatte
Product Lines
- Aalborg OL (12.5-55 t/h, 9/18 bar)
- Aalborg D (25-120 t/h, 18 bar, Tanker-Design)
- Aalborg OM (8-45 t/h, Mittelkapazität)
- Mission OS (bis 6 t/h, Vertical Auxiliary)
Common Failures & Inspection Points
- Area: Tube body leakage due to corrosion, pitting, deposits (scale/sludge) or wearCheck: 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.
- Area: Water level regulation: failure of differential pressure transmitter or feedwater control valve leads to flooding/drying outCheck: 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
- Area: Safety valve failure or incorrect opening/closing pressures — overpressure or inadequate emergency steam reliefCheck: 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
- Area: Furnace refractory damage (cracks, spalling) or soot/corrosion → heat leaks, furnace instability, drum overheatingCheck: 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
- Area: Loss of pressure integrity due to corrosion, cracks, rivets or welds → leakage, operating loss, safety riskCheck: 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
- Area: Internal corrosion (water side), scale deposits or fire side soot/flocking → tube wear, heat loss, contaminationCheck: 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-universal inspection points for Alfa Laval Aalborg oil-fired marine steam boiler (Water Tube / D-Type) (Aalborg + Class/eCFR, 2026-06). Per-model specs not auto-populated.
Alfa Laval Mission OL 1000
1000 kW thermal
· thermal oil
Boiler Type
Alfa Laval Aalborg Ölgefeuerte Schiffsdampfkessel (Water Tube / D-Type)
Thermal output (kW)
1000
Max temp (°C)
300
Medium
thermal oil
Technical Specifications
- Dampfkapazität OL
- 12.500–55.000 kg/h (mit BOG-Management)
- Dampfkapazität D
- 25–120 t/h (Tanker-Hauptkessel)
- Designdrücke
- 9 or 18 bar(g)
- Konstruktion
- Zweritrommel (Dampftrommel/Wassertrommel), Membranwände, Generatorröhrenbank
- Rohrsystem
- Gerade Pin-Tubes mit Schwenk-Pins, externe Fallrohre (Aalborg D)
- Brenner-typ
- Oelgefeuert (Standard), Dual-Fuel optional, KBSD/Aalborg-Brenner
- Refraktär
- Minimal im Feuerraum, Isolations- + Formrefraktär an Rohrplatte
Product Lines
- Aalborg OL (12.5-55 t/h, 9/18 bar)
- Aalborg D (25-120 t/h, 18 bar, Tanker-Design)
- Aalborg OM (8-45 t/h, Mittelkapazität)
- Mission OS (bis 6 t/h, Vertical Auxiliary)
Common Failures & Inspection Points
- Area: Tube body leakage due to corrosion, pitting, deposits (scale/sludge) or wearCheck: 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.
- Area: Water level regulation: failure of differential pressure transmitter or feedwater control valve leads to flooding/drying outCheck: 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
- Area: Safety valve failure or incorrect opening/closing pressures — overpressure or inadequate emergency steam reliefCheck: 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
- Area: Furnace refractory damage (cracks, spalling) or soot/corrosion → heat leaks, furnace instability, drum overheatingCheck: 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
- Area: Loss of pressure integrity due to corrosion, cracks, rivets or welds → leakage, operating loss, safety riskCheck: 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
- Area: Internal corrosion (water side), scale deposits or fire side soot/flocking → tube wear, heat loss, contaminationCheck: 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-universal inspection points for Alfa Laval Aalborg oil-fired marine steam boiler (Water Tube / D-Type) (Aalborg + Class/eCFR, 2026-06). Per-model specs not auto-populated.
Aalborg
2
TOH 4000
4000 kW thermal
· Thermal oil
· thermal‑oil heating system
Common Failures & Inspection Points
- Burner or heat-source faults reduce heat output and cause flame, temperature or pressure alarms
- Feedwater, circulation or level-control faults cause unstable operation and protective trips
- Soot, scale or internal deposits reduce heat transfer and cause poor output or abnormal temperatures
- Tube, coil, gasket or valve leakage causes visible water, steam, oil or fuel leakage and pressure loss
- Control, fan, flame-monitoring or safety-device faults cause repeated trips or failure of the normal operating sequence
Service: Inspect the burner or exhaust-heating section, pressure parts or thermal-oil coils, level or circulation controls, pumps, safety devices and refractory where fitted. Review treatment chemistry, leakage, deposits and alarm history. Function-test protective devices under the approved procedure. Refer to the manufacturer documentation for the exact figure for pressure, temperature, burner and wear limits.
Spare Parts: Carry burner and ignition parts where applicable, filters, valve and pump seal kits, level or temperature control parts, gaskets, fuses and selected control relays.
Strengths
- High thermal efficiency (≈95%) for rapid cargo heating
- Compact design saves valuable deck space on tankers
- Integrated electronic controls allow precise temperature set‑point management
- Low NOx emissions compared with conventional oil‑fired steam boilers
Weaknesses
- Sensitive to oil quality – prone to tube coking if flash point drops
- Requires regular monitoring of expansion‑tank level and oil degradation
- Higher initial capital cost than a basic steam boiler
- Longer warm‑up time after shutdown compared with instant‑fire burners
Typical Vessels:
Crude Oil TankerProduct TankerChemical Tanker
Certifications:
ABSDNV
Decision Guide: Choose if: you need efficient, space‑saving cargo heating on tankers and can maintain oil quality above the flash‑point limit. Avoid if: oil quality control is uncertain, coking risk is high, or a simpler steam boiler meets your operational profile.
Use Cases: Steam and thermal-heating service on merchant, tanker, passenger and offshore vessels.
TOH 2500
2500 kW thermal
· Thermal oil
· Thermal oil heater
Common Failures & Inspection Points
- Burner or heat-source faults reduce heat output and cause flame, temperature or pressure alarms
- Feedwater, circulation or level-control faults cause unstable operation and protective trips
- Soot, scale or internal deposits reduce heat transfer and cause poor output or abnormal temperatures
- Tube, coil, gasket or valve leakage causes visible water, steam, oil or fuel leakage and pressure loss
- Control, fan, flame-monitoring or safety-device faults cause repeated trips or failure of the normal operating sequence
Service: Inspect the burner or exhaust-heating section, pressure parts or thermal-oil coils, level or circulation controls, pumps, safety devices and refractory where fitted. Review treatment chemistry, leakage, deposits and alarm history. Function-test protective devices under the approved procedure. Refer to the manufacturer documentation for the exact figure for pressure, temperature, burner and wear limits.
Spare Parts: Carry burner and ignition parts where applicable, filters, valve and pump seal kits, level or temperature control parts, gaskets, fuses and selected control relays.
Strengths
- Compact size allows installation in confined tank spaces where larger boilers cannot fit.
- Fast heat‑up time due to low water content and direct oil circulation.
- Designed specifically for tanker cargo heating, providing stable temperature control for heavy fuel oils.
- Simplified pipe layout reduces installation complexity on new builds or retrofits.
Weaknesses
- Reported susceptibility to tube fouling from carbonisation if oil quality is not closely monitored.
- Temperature sensor failures have been noted, requiring redundant sensing in critical applications.
- Requires regular (≈3‑month) thermal‑oil sampling to detect degradation, adding maintenance workload.
Typical Vessels:
Product tankerChemical tanker
Decision Guide: Choose if the vessel needs a small‑footprint oil heating solution and can commit to regular oil quality monitoring. Avoid if space constraints are not an issue, or if the operator cannot guarantee frequent oil sampling and sensor redundancy.
Use Cases: Steam and thermal-heating service on merchant, tanker, passenger and offshore vessels.