Why Scrubber Insulation Matters in Marine Operations
Scrubbers—exhaust gas cleaning units on ships—play a key role in meeting emission rules, but without proper insulation, they lead to various issues. This article breaks down why insulation is essential for these systems, supported by research and practical applications, and explains why removable covers often prove the best option, especially on vessels where space and weight constraints are tight.
What Scrubbers Do and Why Regulations Push for Them
Scrubbers remove pollutants like sulfur oxides (SOx) and nitrogen oxides (NOx) from engine exhaust. Under IMO’s MARPOL Annex VI, Regulation 14 sets SOx limits at 0.5% global sulfur in fuel since 2020, dropping to 0.1% in special zones. Regulation 4 allows ships to use scrubbers instead of switching to low-sulfur fuels.
Journals like Environmental Science & Technology show scrubbers enable ships to run on cheaper heavy fuel oil (HFO) while reducing emissions. A 2025 life-cycle analysis there found they can outperform low-sulfur fuels environmentally for large ocean vessels. Science of the Total Environment notes wet scrubbers excel at SOx removal but require robust designs for gases.
On-board tests confirm this. A 2020 study in Journal of Marine Science and Engineering tested a four-stroke engine on low-sulfur fuel oil (LSFO) and HFO, sampling exhaust before and after a scrubber. SO₂ was removed effectively, but particles downstream exceeded those from LSFO alone. The scrubber reduced particle mass by 32-43% from HFO, with decreases in PAHs, black carbon, organic carbon, and elemental carbon in most cases—though not as low as LSFO.
Technologies like seawater electrolysis scrubbers offer further potential. A 2006 Japanese paper examined a three-stage system with electrolyzed seawater, achieving 73% NO reduction through nitrosyl chloride, and overall 14.3% NO and 70% PM reductions at 570 L/min flow.
These systems operate at high temperatures—up to 400°C inside—making insulation necessary to control heat.
The Real Reasons Insulation is Needed on Scrubbers
Insulation for scrubber tower and pipes addresses safety, smooth operation, and compliance.
Scrubber Insulation Helps in Keeping Things Safe
Hot exhaust causes outer surfaces to exceed 60°C without insulation, risking burns or fires. IMO and organizations like DNV or ABS mandate temperatures under 60°C in crew areas under SOLAS rules. Insulation contains that heat, protecting personnel and structures.
In ships’ confined, vibrating environments, lack of insulation creates expansion stress. ABS advisories emphasize thermal control to prevent hot spots that compromise the hull.
Scrubber Insulation is Boosting Efficiency and Cutting Costs
Without insulation, heat escapes quickly, lowering scrubber performance. Effective insulation maintains temperatures for optimal pollutant capture. The 2020 study indicated 32-43% particle reductions, but stable heat improves absorption. The electrolysis system reached 70% PM reduction, where consistent temperatures are critical. A 2022 Journal of Marine Science and Engineering article states insulated scrubbers save up to 3% fuel by preserving energy—significant for extended voyages.
Handling Noise and Wear with Scrubber Insulation
Scrubbers produce noise from flows and pumps. Acoustic insulation, as outlined in a 2021 Applied Sciences article, reduces levels by 10-15 dB, improving crew conditions and complying with IMO noise standards.
Absence of insulation leads to condensation in humid air, causing corrosion—particularly problematic in retrofits with limited space.
Why Removable Insulation Covers Excel for Scrubbers
Rigid insulation struggles in dynamic ship settings. Removable jackets—custom-made from fiberglass, ceramic wool, or microporous materials, often IMO fire-rated like A-60—provide flexible, lightweight alternatives.
Light and Space-Saving for Ships
Weight affects fuel use, stability, and cargo. These covers weigh 4-11 kg/m² compared to 20-30kg/m3 for traditional insulation with metal sheet cladding. Specialist insulation materials setups achieve 31-53 mm thickness for 250-400°C, cutting mass by 50-70%. Ideal for retrofits, they avoid major alterations and install in days.
A 2020 Insulation Outlook piece highlights how they maximize engine casing space, preserving cargo capacity. For bulk carriers or cruise ships, this means better economy and reduced emissions per mile.
Simple Maintenance, Real Savings
Velcro or straps allow quick removal for inspections. In vibrating conditions, reusability avoids discarding fixed layers. Firwin analyses report 80% labor savings, with covers lasting 10-15 years.
They reduce heat loss by 90%, prevent corrosion, and deliver ROI in 12-18 months according to Mid-Mountain—quicker in high-fuel shipping.
Better Safety and Rule Compliance
Safe temperatures under 50°C protect workers from burns and provide safer workplace. Fire-resistant fabrics can also handle leaks. This maintains IMO compliance, preventing fines or halts.
Incorporating acoustic insulation materials, for example PROMASOUND® TL in towers reduces noise.
Practical Applications and Future Directions
Insulating boiler systems similar to scrubbers has cut downtime by 40%. Shipping studies in MarineLink describe 18-day installs with insulated towers for quick compliance. Emission figures—32-43% particles in standard scrubbers, 70% PM in electrolysis—indicate increasing adoption, underscoring insulation’s importance.
As IMO targets net-zero by 2050, insulated scrubbers will integrate with biofuel hybrids. For fitting or upgrading scrubber systems, removable strategies deliver optimal outcomes.
References:
Stathatou, P. M.; Petrunia, I.; Barenthin, T.; Gotsis, G.; Jeffrey, P.; Fee, C.; Bergeron, S.; Tsezos, M.; Triantafyllou, M.; Gershenfeld, N. Marine Scrubbers vs Low-Sulfur Fuels: A Comprehensive Well-To-Wake Life Cycle Assessment Supported by Measurements Aboard an Ocean-Going Vessel. Environ. Sci. Technol. 2025, 59 (14), 7066–7080. https://doi.org/10.1021/acs.est.4c10006.
Goltens Worldwide. (2017, March 24). Case Study: 18-Day Exhaust Gas Scrubber Install. MarineLink. https://www.marinelink.com/news/scrubber-exhaust-install423515