Next-Generation Lubricants for Marine Applications

The shipping sector’s regulatory requirements stipulate all ships must manage their pollution

In today’s world, environmental considerations are paramount across every industry. From manufacturing to maritime, the quest for sustainable solutions has given rise to the development of environmentally friendly lubricants. Among these, Environmentally Considerate Lubricants (ECL) and Environmentally Acceptable Lubricants (EALs) have gained prominence for their positive impact on both equipment performance and the planet. Let’s delve into the differences and advantages of these lubricant classifications.

Environmentally Considerate Lubricants (ECLs)

ECL, as the name suggests, signifies lubricants formulated with a consciousness towards the environment. However, the term lacks a standardized definition and doesn’t come under the oversight of scientific bodies or governmental approvals. This leaves a certain level of ambiguity, making it essential for users to exercise due diligence when choosing ECLs. Although the specifics might vary from one product to another, the general idea behind ECLs is to reduce the ecological footprint associated with lubrication.

While ECLs offer flexibility and innovation in formulation, their undefined nature can pose challenges. Without a clear guideline, users might find it harder to assess the true environmental impact and performance benefits of these lubricants. This brings us to the more regulated alternative—environmentally acceptable lubricants (EALs).

Environmentally Acceptable Lubricants (EALs)

EALs are a well-defined category of lubricants designed with a focus on biodegradability, minimal harm to aquatic ecosystems, and nonbioaccumulative properties. These lubricants are specifically crafted to ensure that they do not persist in the environment, reducing potential damage to marine life and water bodies.

One of the standout features of EALs is their mandatory use in U.S. waters since 2013. EALs are required for equipment with oil-to-sea interfaces, such as marine vessels unless technical infeasibility can be demonstrated. This proactive stance has not only fostered eco-consciousness but also fueled research and development in lubricant technology.

While ECLs offer flexibility, EALs provide a regulated framework for protecting the environment and enhancing equipment performance. The clear definition and mandated usage of EALs make them a reliable choice for industries striving to balance functionality with ecological responsibility.

Key Environmental Regulations

Vessel owners have come to understand the impact their equipment has on the environment and are seeking to reduce their environmental (carbon dioxide and oil pollution) footprint.

Legislation drove the transition to EALs. In U.S. waters, the EPA’s Vessel General Permit (VGP) 2013 was replaced by the Vessel Incidental Discharge Act (VIDA) in 2020; and for Arctic regions, the Polar Code covers environmental protection matters.

Both technical and sustainability requirements for lubricants are constantly increasing. As a result, environmental requirements and the conditions imposed by manufacturers are also becoming increasingly specific.

VIDA is essentially an updating of VGP in terms of establishing a framework for the regulation of incidental discharges to the normal operation of vessels sailing in US waters, by providing clarity on terminology. For example, specifically stating that certain deck machinery will require EALs.

Panolin Margear Designed for Dredging Gearboxes

Dredging must be carried out with extreme safety and sensitivity to the environment, so the use of safe, sustainable, and environmentally friendly lubricants is important. Panolin Margear allows customers to show a reduction in carbon dioxide emissions over the lifetime of the lubricant compared to the recommended replacement time of mineral-based oil. Panolin can readily provide vessel owners with data showing how Panolin lubricants can contribute towards their carbon dioxide reduction goals.

Greendredge, a lubricant concept developed by Panolin specifically for the dredging industry puts great emphasis on safety, environmental protection, and sustainability.
In the dredging industry, the use of reliable environmentally friendly lubricants is extremely important. Margear has been developed to provide excellent lubricant performance in dredging equipment and to ensure the applications are both operational and compliant with VIDA.

Based on fully saturated synthetic esters with additives carefully chosen to perform specific functions in marine applications, Margear has been specifically formulated for gear systems to withstand the extreme conditions regularly seen in marine operations.

Margear performance factors include:

• High thermal stability
• Shear stability
• Hydrolytic stability
• Excellent oxidation stability
• Outstanding wear protection
• Extreme corrosion protection

The above factors are extremely important for lubricants within the dredging industry. Furthermore, in an industry where vessels are utilized all year round in extreme environments, the need for functioning equipment is imperative. Margear offers customers economic benefits due to the extremely long oil-change intervals resulting in reduced downtime and maintenance costs.

Environmentally Certified and OEM Approved

Panolin Margear offers antiwear and anticorrosion properties, and has been successfully used in a variety of applications including, but not limited to:

• Gearboxes
• Roller Bearings
• Propulsion systems including bow thrusters, Azipod thrusters, azimuth thrusters
• CPPs

panolin.com

Klüber on the Way to a Clean Future in Shipping

Between 2006 and 2013, Klüber Lubrication developed EALs for stern tubes (Klüberbio RM 2 series) and thrusters (gear oils, Klüberbio EG 2 series) based on ester-oil technology. Both oil series are benchmarks for ester oil-based EALs and gained approvals from all leading propeller equipment and thruster manufacturers.

Klüber Lubrication was one of the first lubricant makers to conduct research and development in the field of readily biodegradable lubricants that are nontoxic and meet the tribological performance for lubrication of propeller shafts and thrusters.
The Problem with EALs Under High Loads

For the lubrication of the propeller shaft running in the stern tube and propeller shaft seals, the VIDA stipulates the use of EALs for the protection of the environment as an escape of oil into the sea through the propeller seal cannot be completely prevented. Biodegradable lubricants for stern-tube application from several suppliers have been available for nearly two decades. So far, however, no one has succeeded in offering an EAL with a performance capacity equaling that of a mineral oil-based product in all important performance criteria such as a strong lubricating oil film, consistency in the presence of water in the oil, and excellent seal compatibility.

Why can an insufficiently strong oil film be a problem? Under particularly high loads, for example during voyages with partially immersed propellers or at hard maneuverings, insufficient strength of a lubricant film can lead to metal-on-metal contact and higher journal bearing temperatures eventually causing bearing damage. Many commercially available EALs show insufficient resistance to oxidation and hydrolysis as well as poor lubricating capacity under high loads. Excessive shear loads may cause them to lose their viscosity and hence their ability to form a load-bearing lubricant film. High oxidation and aging can cause their viscosity to increase in an undesirable way. Chemical processes and the presence of water tend to decompose the lubricant. A failure of components and possibly even a breakdown of the propulsion system are possible. Frequent oil changes are therefore inevitable with some commercially available EALs, leading to additional operating costs.

An additional challenge in propeller shaft lubrication is that not only does lubricant leak into the water, but vice versa: The lubricant becomes contaminated with water via the same path. The insufficient resistance to hydrolysis of most commercially available ester oil–based EALs results in a rising TAN (Total Acid Number), leading to an unscheduled complete or partial oil change and a shorter service life of the seal in the stern tube. The only way to prevent early oil changes due to a rising TAN has so far been the installation of expensive filter systems and oil dryers. This, however, constitutes a major investment and increases complexity on board.

Eco-Compatibility vs. Performance

The objective of developing Klüberbio RM 8-100 was to obtain a stern tube oil that is not susceptible to hydrolysis, extends service life in comparison to conventional EALs, and meets all sustainability requirements of the EU Ecolabel and the former VPG and current VIDA for operation of ships in the United States. Besides biological eco-compatibility, the new product was designed to achieve excellent performance in terms of compatibility with seals, shear stability, wear behavior, corrosion protection, and friction. While the lubricant films formed by some EALs found in the market are not thick enough to prevent damage to stern tube bearings under unfavorable load conditions, the new product is designed to build up a load-bearing film that is close to that of a mineral oil–based product.

Next Generation of EAL Lubricants

The newly developed Klüberbio RM 8-100 successfully meets maximum environmental as well as performance requirements. Klüberbio RM 8-100 generates a lubricant film of excellent thickness that persists even under high edge loads in the propeller shaft bearing. Due to this lubricant film, the propeller bearing, and the shaft remain separated and overheating of, or damage to, the bearing is prevented. Klüberbio RM 8-100 shows very good compatibility with the elastomer material in the propeller shaft seal, providing it with optimal lubrication. This ensures a long service life and full function of the components.

Regarding TAN and resistance to hydrolysis, the new product’s performance ratings are multiples of those of ester-based EAL stern tube oils—almost up to the standard of mineral oil-based lubricants. This means the oil’s chemical composition prevents it from reacting with water getting into the stern tube through the elastomer seal. The TAN hardly rises, leading to a significantly longer life expectancy for both the propeller shaft seal and the oil.

Klüberbio RM 8-100 is the first lubricant based on a new technology Klüber Lubrication will adopt into its range of EAL gear oils designed for tunnel and azimuthing thrusters.

Two Worlds Come Together

Klüber Lubrication already showed in the past that bio in a lubricant no longer stands for a compromise of a product being green but having weaker technical performance. With the new generation of Klüberbio stern tube and gear oils, Klüber provides excellent lubricant performance, often considerably better than the direct mineral oil–based competition, and the products are also biodegradable and nontoxic.

With Klüberbio RM 8-100, users obtain a technology-leading product meeting legal environmental requirements and offering at the same time the extremely good performance ratings of a conventional, mineral oil–based lubricant. This is important for international shipping operations, where sustainable approaches are increasingly required.

klueber.com

Sidebars:

Advantages of EALs Over ECLs

1. Environmental Accountability: EALs are backed by a clear definition and regulatory framework, making their environmental benefits more transparent and dependable.

2. Ecosystem Protection: EALs’s biodegradability and nonbioaccumulative properties contribute to the protection of aquatic ecosystems. Their use aligns with global efforts to reduce pollution and maintain biodiversity.

3. Regulatory Compliance: Mandatory usage of EALs in certain regions ensures that industries are actively contributing to environmental protection.

4. Enhanced Performance: EALs are developed to match or surpass the performance of conventional lubricants, dispelling the notion that eco-friendly options compromise functionality.

5. Innovation Incentive: Regulatory demands for EALs have spurred lubricant manufacturers to innovate and develop high-performing, sustainable products.

The Role of the Stern Tube

All types of vessels, whether container ships, bulk carriers, harbor tugs, or cruise liners, have one thing in common: propulsion is by means of large propellers of varying design. With few exceptions, the shafts of fixed-pitch and controllable-pitch propellers run in journal bearings mounted inside the stern tube filled with oil. The radial movements of the propeller shaft in the bearing are larger than those of other industrial shafts and may be intensified by the force of waves or vibrations.

Radial shaft seals or mechanical seals prevent the oil from leaking into the sea and keep the stern tube tight against the engine compartment. Thrusters are filled with gear oil and must be sealed at the propeller shaft as well as at the rotating steering shaft of azimuthing thrusters to prevent leakage into the water. It is, however, not possible to seal the stern tube or the thruster 100 percent tight against exiting oil.