An R&D journey: SÄKAPHEN’s SÄKATONIT Extra AR-F and the protection of box coolers

The research, development, and commercialization of an innovative coating system is never a straight line. It is a journey defined by laboratory breakthroughs, field trials, customer feedback, and real-world validation. This was also the case with the development of our SÄKATONIT Extra AR-F nearly a decade ago.

When development began in our laboratories, the objective was to create a floodable lining system with enhanced corrosion and fouling resistance for use in demanding marine applications. The resulting product marked a genuine advance in coating technology.

SÄKATONIT Extra AR-F is a two-pack, hydrophobic epoxy hybrid coating that combines a tailored resin–hardener system with a dedicated application methodology, characterized by low solvent and VOC levels. It was designed to resist a broad range of aqueous environments, as well as acidic and alkaline solutions commonly encountered in marine service, but also to provide abrasion resistance and tolerate temperature fluctuations that typically occur during vessel operation. The goal: reducing the formation of deposits, fouling, and surface degradation over extended service periods.

Designed for box coolers
A primary target application from the outset was the protection of box coolers, specialized shipboard heat exchangers that are exposed to a combination of aggressive factors, including seawater corrosion, galvanic corrosion caused by dissimilar metals, biofouling, and mechanical loading. The new coating was especially optimized for on-site application via a flooding process, allowing both new and existing box coolers to be lined without thermal curing.

One crucial technical feature was the possibility to achieve a uniform, homogeneous film without the need for baking, thanks to its specific balance of resins, fillers, and hardeners. Unlike baked coatings, its curing process does not require elevated temperatures, streamlining logistics and reducing energy demand during application, thus also supporting more sustainable coating operations.

Early market adoption and field performance
After its market introduction in early 2018, the coating was applied to several dozen box coolers in Europe and North America within a short time. On-site application proved to be a key practical advantage, as it eliminated the need to transport large heat exchanger units to specialized coating facilities. One of the first challenging documented projects involved the cleaning, grit blasting, and re-coating of 22 box cooler units within 12 days.

At the same time, a first long-term performance evaluation was initiated with a set of box coolers re-coated in Newfoundland, Canada, for a vessel engaged in subsea activities. After more than 1 year in service and under different seawater conditions, the ship entered dry dock in Las Palmas, Canary Islands, in 2019. Visual inspections found that neither impressed current anti-fouling systems (ICAF) nor mechanical erosion had caused observable degradation of the SÄKATONIT Extra AR-F coating.

Global service and lifecycle extension
By 2020, increased attention from ship classification societies on coating quality and application procedures coincided with the expansion of Säkaphen’s partner network. A key collaboration was established with Multi Solutions (Norway), which supported several re-coating projects carried out directly at dry-docking locations. By that time, several hundred units had been re-coated across Europe, Asia, the Middle East, and South America.

Further long-term inspection data became available in 2022, when 31 box coolers originally re-coated in Norway were removed from the vessel for the 5-year class renewal. After such an extended period of continuous service, the units were pressure-washed, inspected, and pressure-tested. Marine growth was limited, and the remaining deposits were easily removed. Mechanical damage was minor and mainly attributable to routine handling. Neither ICAF systems nor erosion had caused significant coating degradation. After local repairs, the box coolers were returned to service, reducing the overall maintenance schedule from the initially planned 21 days to approximately 8 days.

In the press:
Heat Exchanger World
Corrosion Protection

Industry recognition and sustainability considerations
By 2024, the maintenance of existing heat exchanger systems through cleaning and re-coating had been gaining increased attention as part of broader sustainability strategies in shipping. At SMM, the world’s leading maritime trade fair, SÄKAPHEN presented its box cooler coating concept together with its partners, Multi Solutions and Nordic Green Products (Norway).

The exhibition confirmed growing interest in extending the typical 15-year design life of box coolers through systematic refurbishment rather than replacement. In this context, a hydrophobic, biocide-free lining system such as SÄKATONIT Extra AR-F was of particular interest, as it addresses both environmental regulations and operational performance. Equally important was the availability of regional service support, allowing inspections and re-coating to be performed at shipyards close to each vessel’s operating area.

OEM validation and a new production standard
An additional milestone in the technical qualification of SÄKATONIT Extra AR-F was reached in 2025 with its evaluation and subsequent approval by VDL Klima (Netherlands), a manufacturer of heat exchangers for maritime and industrial applications. Up to that point, SÄKATONIT Extra AR-F had primarily been used as a maintenance and refurbishment coating. However, this OEM evaluation was driven by requirements for reduced VOC emissions, lower solvent content, and the avoidance of energy-intensive thermal curing in production. Following extended testing, the coating was thus approved for use in the manufacturing of new box coolers.

In the press:
Heat Exchanger World
Journal für Oberflächentechnik
International Surface Technology

The journey continues
From its initial use as a refurbishment lining to its adoption in original equipment manufacturing, SÄKAPHEN’s SÄKATONIT Extra AR-F continues to be adapted to changing technical and regulatory requirements. With growing demands for sustainability, durability, and efficient shipyard processes, further operational data from different vessel types and service conditions will continue to shape its future development. Get in touchto be part of this!

FAQ
1) Can SÄKATONIT Extra AR-F be applied to box coolers already in service?
Yes. The coating was specifically developed for on-site application via a flooding process, allowing both new and existing box coolers to be lined without thermal curing or transport to a specialized facility.

2) How long does SÄKATONIT Extra AR-F remain in service on ship box coolers before maintenance or re-coating is required?
Field data from box coolers re-coated in Norway and inspected after 5 years of continuous service showed limited marine growth, minor mechanical damage from routine handling, and no significant coating degradation attributable to ICAF systems or erosion, with the units returned to service after local repairs only.

3) Has SÄKATONIT Extra AR-F been approved for use in the production of new box coolers, or is it primarily a refurbishment product?
Originally developed and adopted as a maintenance and refurbishment coating, SÄKATONIT Extra AR-F was approved in 2025 by VDL Klima, a Dutch heat exchanger manufacturer, for use in the production of new box coolers, following an evaluation driven by requirements for lower VOC emissions, reduced solvent content, and the elimination of energy-intensive thermal curing in manufacturing.