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Scrubbers

ABS: Lessons learned from scrubber installation and operation

ABS shares experience learned from installation and commissioning to common hardware failures for scrubbers, and the type of consumables that are typically needed.
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6 years ago

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American Bureau of Shipping (ABS) on Monday (6 April) published an article analysing some of the common troubleshooting issues with installing and operating scrubbers; it was written by Alex Huo, Manager of Technology at ABS specialising in scrubber activity: 

At the beginning of this year, the IMO’s global sulfur cap on marine fuels entered into force and shipowners who chose the SOx -scrubber pathway to compliance began the modern era of emissions reduction.

Scrubbers have been operating in marine environments for almost 30 years, so owners were not exactly entering a brave new world of technology. But any time a new technology is integra­ted into an individ­ual vessel’s operating system, lessons are learned; and these lessons create a knowledge base that operators with less experience with scrubbers can draw from.

Leading class societies have been supporting scrubber integration in the marine environment since their first application. ABS, for one, has gathered the depth of market intelligence required to help owners to improve the process of installing and operating most scrubber systems.

Lessons have been learned about everything from installation and commissioning to the most common hardware failures for operating systems, and the type of consumables that are typically needed.

In this post, we will discuss some of the key issues associated with the installation and operation of scrubbers. But for a comprehensive list, please download ABS’s guide, Practical Considerations for the Installation and Operation of Exhaust Gas Cleaning Systems.

In commissioning SOx Scrubber systems, there can be challenges associated with extensive test periods, usually the result of an owner/operator having limited test plans and/or pre-commis­sioning work. This may be relatively intuitive, but following an approved test plan and completing the pre-commissioning activities are the fastest way to avoid these problems.

Another recurrent problem we are seeing, specifically during the installation process, is when wash­water is carried over with the exhaust gas. This is commonly the result of unsuitable or inefficient flowpaths for the exhaust gas and can be resolved by optimizing the flowpath and/or modifying the design of the demister, which removes liquid droplets from the vapor stream.

Below are some more symptoms that operators are experiencing, and potential solutions:

HIGH EXHAUST BACK-PRESSURE:

This is likely due to either undersized scrubbers, sharp bends in exhaust piping, water-spray resistance, or a failure of the bypass-isolation valve interlock. Ultimately, the system’s design usually can be improved through simulations that identify the potential sources of back-pressure.

INTERRUPTED OPERATIONS:

In the case of washwater supply, the problem can be caused by clogged filters in the supply piping. But when frequent operational interruptions become problematic, it is constructive to thoroughly examine your redundancy options. A failure mode and effect analysis can support this process.

NON-COMPLIANT PERFORMANCE:

(eg., washwater pH value, SO2/CO2 ratio): These symptoms could be due to inadequacies in the washwater, low alkalinity in the water supply or simply an ineffective water-spray pattern. Improving the overall design, a process that can be verified through the use of computation fluid dynamics modeling, and verification of alkalinity levels in the water supply may resolve the issue.

POOR RELIABILITY OF MONITORING SYSTEMS:

(including instrument malfunction): These symptoms can be caused by many issues, including the simple fact that the monitoring system may not be designed for marine applications. Other possible causes include that it may not be calibrated or installed correctly. Start by ensuring that the monitoring system is approved for marine use, and then follow the manufacturer’s instructions for calibration and maintenance.

HARDWARE FAILURE:

When a SOx Scrubber system suffers a hardware failure there can be multiple causes. Below are some that industry-operating history suggests owner/operators may want to consider investigating when searching for solutions:

  • The sampling tubing may have become clogged, preventing accurate readings of SO2/CO2 ratios in the exhaust gas
  •  The pressure transducers at the bottom of the pipe run may have become clogged with debris because the sensors were located in the wrong places
  • The demister in the scrubber chamber may have malfunctioned due to a build-up of deposits
  • Defective welds on piping system could have allowed washwater to leak
  • Low-grade stainless steel (e.g. SS316 for fittings inside the scrubber chamber) may not have held up to the corrosive operating environment
  • The metallic pipe section on the side shell used to discharge washwater also may be corroded
  • The air pump that samples exhaust gases may not be working properly
  • The scrubber’s uptake damper cannot be operated in manual mode
  •  The mechanical seals for the washwater feed pumps may have failed
  • The automation controls for printed circuit boards may have failed

MAJOR INCIDENTS CAUSING ENGINE SHUTDOWN AND DAMAGE:

History has taught the industry that most costly asset failures are the result of human error. The actions may be well-intentioned, but crews need to be fully trained to operate specific systems and to discourage any efforts to operate them in a mode that would disregard the control system, or manufacturer recommendations for upkeep.

In one recent event, a main engine stalled due to high backpressure after a scrubber by-pass damper failed to open when the scrubber uptake damper was closing. The programmable logic controller that was designed to control the interlock of the by-pass and uptake dampers had failed. Regular mainten­ance and testing in accordance with manufacturer’s instructions could have identified the problem.

The incident made clear that safety features require regular maintenance and testing in accord­ance with the manufacturer’s instructions, and that crews in charge of any system need to be familiar with basic starting procedures, such as checking damper positions and safety features.

In general, the industry has learned a lot about exhaust-gas scrubbers in the 30 years since they were first used in marine applications. The average owner may have become relatively familiar with the indivi­dual systems they chose to use.

However, leading class societies such as ABS will have learned the lessons from many sys­tems, and have the depth of knowledge to help owners with any challenges they may face. 


Source: American Bureau of Shipping
Photo credit: Manifold Times
Published: 7 April, 2020

 

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ECA

VPS examines North-East Atlantic ECA on current bunker fuel mix and testing

Impact of this new ECA, will not only affect bunker fuel selection and testing, but it will also require a review of, voyage planning, bunker procurement and scrubber strategy, amongst others.

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Published

2 months ago

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May 14, 2026

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Steve Bee, Group Marketing and Strategic Projects Director, and Emilian Buksak, Decarbonisation Advisor of marine fuels testing company VPS, on Wednesday (8 April) highlighted MEPC 84 approved a new emission control area (ECA) covering the North-East Atlantic Ocean, with agreements reached on adopted amendments to MARPOL Annex VI. 

The new ECA, which will become the world’s largest emission control area, will be implemented on 1st September 2027

In a recent article, VPS outlined how VPS testing, data, CEM systems and advisory services can support vessels in both their operational and compliance challenges associated with this new ECA:

The recent International Maritime Organisation’s (IMO), Maritime Environmental Protection Committee (MEPC) meeting in London, had its main focus on setting binding greenhouse gas emission reduction targets for the global shipping sector. In keeping with the Committee’s continuing drive to decarbonise shipping and reduce the pollutant emissions from the global fleet, one major outcome from the MEPC-84 meeting was the approval of a new emission control area (ECA) covering the North East Atlantic Ocean, with agreements reached on adopted amendments to MARPOL Annex VI.

This new ECA, which will become the world’s largest emission control area, will be implemented on 1st September 2027, with the ECA requirements taking effect on 1st September 2028. It will cover the territorial seas and exclusive economic zones of Greenland, Iceland, the Faroe Islands, Ireland, the United Kingdom, France, Spain and Portugal, extending up to 200 nautical miles from their baselines:

VPS examines North-East Atlantic ECA impact on current bunker fuel mix and testing

A key advantage of the new NE Atlantic ECA is that it will close the gap between the existing ECAs in the North and Baltic Sea, plus the Mediterranean, creating an almost continuous zone of reduced shipping emissions. It will also connect to the newly approved ECAs in the Canadian Arctic and Norwegian Sea, which are scheduled for implementation in 2026 and 2027 respectively. Together these ECAs will cover almost half of all Arctic coastal waters, improving air quality, by reducing SOx, NOx and Particulate Matter (PM), protecting  public health, and reducing the environmental impacts from shipping.

The sulphur limit for the marine fuels allowed to be burnt within this new ECA will reduce from the current 0.50% to 0.10%. This will force vessels to use either effective abatement technology (scrubbers), or alternatively burn marine distillates, ultra-low-sulphur fuels (ULSFOs), or biofuels with a sulphur content of less than 0.10%.

Without doubt this new ECA will cause a significant change to the current fuel mix, probably on an even greater scale than was witnessed with the introduction of the Mediterranean ECA back in May 2025.  The fuel mix in the Mediterranean Pre-ECA implementation was,  53% VLSFO, 28% HSFO, 16% MGO, 2% ULSFO and 1% Biofuels. But from the 1st May 2025, the fuel mix changed to, 30% VLSFO, 29% HSFO, 30% MGO, 8% ULSFO and 4% Biofuels.  

So, in terms of actual tonnage, the Mediterranean ECA witnessed a decrease in VLSFOs by 23%, whilst MGO usage increased by 107%. At the same time, ULSFO and biofuels supply increased 4-fold.

Regarding fuel quality within the Mediterranean post-ECA implementation, MGO off-specification rates increased to 4%. However, the most worrying off-specification rates were for ULSFOs which saw a 10-times increase from 2% to 20% from the start of the ECA, with the main off-specification parameters being pour point, sulphur, TSP, CCAI, water and viscosity.

Therefore, it is fair to assume we’ll witness a similar dramatic fuel mix change upon the implementation of the NE Atlantic ECA, with possibly similar fuel off-specification issues, highlighting the continuing need for proactive fuel testing to protect vessels, crew and the environment.

Whilst the focus on fuel quality is essential, the multi-pollutant nature of this new ECA, covering SOx, PM and NOx, also brings the role of continuous emissions monitoring increasingly to the fore. Therefore, a further consideration relating to the impact of this new ECA relates to vessel newbuilds and the stricter NOx Tier III requirements. For newbuilds subject to the stricter NOx Tier III requirements, compliance depends not only on engine certification at delivery, but on demonstrating that exhaust after-treatment systems, typically Selective Catalytic Reduction (SCR) or Exhaust Gas Recirculation (EGR), continue to perform as designed throughout the service life of the vessel.

For scrubber-equipped ships, real-time SO₂ measurement provides the operational evidence of equivalency that Port State Control inspections increasingly expect to see. Plus, for vessels operating under multiple overlapping regulatory regimes, including the new NE Atlantic ECA, EU MRV, EU ETS and FuelEU Maritime, continuous emissions monitoring via the VPS EMSYS CEM system delivers a single, verified source of emissions data that can be applied across all of them.

As noted by DNV in their MEPC 84 technical and regulatory update, the newly adopted IMO measurement guidelines can also be used for determining actual methane and nitrous oxide under the EU ETS and FuelEU Maritime, confirming the direct route from IMO-recognised measurement to EU compliance reporting.

At an operational level, the new ECA will introduce considerable complexity in the way fuel consumption is attributed across voyage segments, with VLSFOs burnt outside the zone and compliant fuels inside, all of which carry implications for consumption reporting, charterparty allocation and EU MRV alignment. VPS Maress can provide the underlying fuel and energy data into one auditable platform, helping crews manage the operational complexity that the new ECA introduces, including voyage segmentation, fuel changeover and emissions accounting, plus providing the consolidated data foundation that feeds existing EU MRV and IMO DCS reporting obligations. 

VPS PortStats via the VPS Verisphere eco-system, (VeriSphere | VPS), further supports bunker procurement planning with port-by-port intelligence on compliant fuel availability and price spreads. Such intelligence and insights, will prove particularly valuable in the months immediately following 1st September 2028, when the supply pressure on 0.10% sulphur fuels is likely to peak.

Regarding the more strategic decisions ahead, including Tier III engine selection for newbuilds, retrofit feasibility for existing tonnage, and charterparty clauses allocating the ECA fuel cost premium between owners and charterers, VPS Advisory Services can provide the integrated commercial and technical perspective needed to navigate this transition with confidence.

Therefore, its clear the impact of this new ECA, will not only affect the choice of fuel to be burnt onboard and its subsequent quality testing, but it will also require a review of, voyage planning, bunker procurement, scrubber strategy, engine certification, compliance documentation and charterparty exposure.

Related: DNV on IMO MEPC 84: Revisiting Net‑Zero Framework

 

Photo credit: VPS
Published: 14 May, 2026

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Scrubbers

No open-loop EGCS with HSFO bunker fuel allowed in Saudi Arabian ports

Use of HSFO with an Open-Loop Exhaust Gas Cleaning System at 0.5% or 0.1% sulphur mode setting is prohibited until further notice for the ships entering Saudi Arabian ports, says GAC.

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Published

8 months ago

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December 8, 2025

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Aramco: Ras Tanura Port, Eastern Province of Saudi Arabia, on the Arabian Gulf.

The use of High Sulphur Fuel Oil (HSFO) with an Open-Loop Exhaust Gas Cleaning System (EGCS) at 0.5% or 0.1% sulphur mode setting is prohibited until further notice for the ships entering Saudi Arabian ports, according to GAC Hot Port News on Wednesday (3 December). 

All ships entering Aramco ports shall comply with one of the following options:

  • Use compliant fuel oil (≤ 0.50% m/m Sulphur, or ≤ 0.10% when operating in ECAs, if applicable).
  • Operate the EGCS in Closed-Loop mode (or Hybrid system in Closed mode), with strict prohibition on the discharge of wash water into the sea.

 

Photo credit: Aramco
Published: 8 December, 2025

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Bunker Fuel

Equatorial navigates through sanctions and green transition amid shifting bunkering landscape

Shipowners’ demand for ‘cheapest compliant fuel’ suggests a potentially more competitive and shrinking market for LSFO, forecasts Choong Sheen Mao, COO at Equatorial.

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8 months ago

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December 1, 2025

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Equatorial navigates through sanctions and green transition amid shifting bunkering landscape

Singapore-based physical bunker supplier Equatorial Marine Fuel Management Services Pte Ltd (Equatorial) is adapting to a dynamic global bunker market shaped by regulatory shifts, geopolitical tensions, and the push for decarbonisation, states its Chief Operating Officer.

Choong Sheen Mao was amongst panellists of the Bunker Sellers Panel at IBIA Annual Convention 2025 in Hong Kong on Tuesday (18 November) when he shared a significant trend of shipowners increasingly opting for high sulphur fuel oil (HSFO) paired with scrubbers, driven by the pursuit of the “cheapest compliant fuel”.

Despite a narrowing spread between high and low sulphur fuels – from approximately USD 125 to USD 80, and occasionally below USD 70 – shipowners continue to see long-term investment returns from scrubbers. This shift suggests a potentially more competitive and shrinking market for low sulphur fuel oil (LSFO).

“Geopolitical instabilities, particularly armed conflicts, sanctions and trade wars, are creating considerable market distortions. These instabilities lead to supply disruptions, cargo rerouting, and impact bunker prices,” added Choong.

“Compliance has become a paramount concern, with recent substantial fines underscoring the risks involved. The current economic slowdown, compounded by sanctions and self-sanctioning, presents a ‘double pain’ for the market.

“The market’s daily volatility is also heavily influenced by global politics, making it challenging to assess without a deep understanding of geopolitical events.”

To ensure marine fuel quality, Equatorial emphasises managing its own supply chain and operating its own fleet of bunkering vessels, allowing for direct control from delivery to the customer, he stated.

This approach prioritises transparency and security, fostering long-term relationships where quality issues can be collaboratively addressed. Knowledge sharing, especially concerning parameters from new bunker fuel testing methods such as Gas Chromatography Mass Spectrometry (GC-MS), is also deemed crucial.

Supporting the transition to alternative marine fuels, while acknowledging the uncertainty surrounding the dominant future fuel, Equatorial has strategically invested in IMO Type 2 chemical tankers capable of handling methanol, biofuel, and conventional bunker fuels.

“Biofuel is identified as the most effective short-term solution, offering favourable pricing and operational costs compared to other green alternatives,” explained Choong.

“However, challenges include feedstock availability and potential export quotas from key producing nations like China.

“The adoption of alternative marine fuels necessitates a closer, more collaborative relationship between buyers and sellers.

“This involves detailed discussions on specific fuel specifications beyond standard ISO requirements, extensive lab sampling, and long-term commitments from both parties, particularly given the absence of a liquid hedging market for biofuels.

“Collaboration across safety, quality, and commercial aspects is essential for the successful implementation of bio bunker fuels to the future maritime market.”

 

Photo credit: International Bunker Industry Association
Published: 1 December, 2025

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