Understanding On Board Lubricants – examining impact on performance and the environment, too.
Performance and sustainability—two words with growing importance in the marine industry, especially when it comes to lubricants. Performance is a must-have for a wide range of components to function properly aboard any ship, while regulatory vessel oversight and greater corporate understanding is providing an opportunity for enhanced sustainability. From bow thrusters to stern tubes, onboard lubricants are seeing the convergence of performance and sustainability. A wide range of products are available for vessel hydraulic and propulsion needs. Each category of products differs in its relative performance and ability to meet environmental regulations, such as the Vessel General Permit (VGP), in an effort to safely reduce spill impact on the environment.
Marine vessels contain a variety of equipment and machinery that require lubricants, oils or greases. The list includes bow thrusters, stabilizers, the stern tube and continuous pitch prop, deck hydraulics (wenches and cranes), stern and elevator ramps, water-tight doors and even anchor equipment. Each of these equipment type tests the performance and sustainability of onboard lubricants.
Challenges for Onboard Lubricants
Oddly enough for equipment in a marine application, the biggest challenge faced by onboard lubricants is water. The chemical makeup of many lubricants changes or is damaged by water ingress, and subsequently affects the lubricant’s performance. Another challenge for onboard lubricants is their compatibility with the variety of seal types that exist for onboard hydraulic systems. If a fluid is not compatible with the seal, the hydraulic system cannot effectively function and the equipment could be damaged or malfunction. Depending on the equipment, the downtime or end result could be very costly or damaging to the ship itself. Finally, the VGP 2013 issued from the U.S. Environmental Protection Agency (EPA) states that all vessels constructed on or after December 19, 2013, must use an environmentally acceptable lubricant in all oil-to-sea interfaces. This regulation has a significant effect on the use of onboard lubricants and provides an insurmountable challenge for petroleum-based lubricants.
The VGP outlines “environmentally acceptable lubricants” as readily biodegradable, non-toxic, and non-bioaccumulative. This definition is in close keeping with the Clean Water Act, which determines whether an oil spill may be harmful to public health or welfare. The Act reviews whether a spill causes a sheen or discoloration on the surface of a body of water, violates applicable water quality standards or causes a sludge or emulsion to be deposited beneath the surface of the water or on adjoining shorelines.
Defining Sustainable On-board Lubricants
With the advance of sustainable operations, many products claim to be “green,” but fall short, both on performance and true sustainability and do not meet the regulatory standards or the performance needs of marine applications.
In terms of degradation, claiming a product is biodegradable means next to nothing in terms of its realistic impact on the environment. Many people often say a product or substance is biodegradable, thinking that such a term indicates it is less damaging to the environment, but in fact, oil and other potentially harmful things for the environment are biodegradable too—just after a long period of time. Biodegradation is when a given substance or fluid’s chemical bonds break apart. The opposite of biodegradation is persistence, and oil-based products have a high level of persistence in the environment.
Technical terms like inherently biodegradable and readily biodegradable are used to describe the rate at which a substance or a fluid degrades and is broken up by the natural environment. That rate of biodegradation is driven by a number of factors, including the makeup of those original chemical bonds, the temperatures that the substance is being exposed to, the available natural enzymes to work against the chemical bonds and the presence of water and oxygen. All of these factors are present in biodegradation.
Readily biodegradable specifically defines a substance, fluid or composition that will degrade 60 percent or greater within 28 days or less. There are several internationally recognized tests that confirm this degrading ability of a given product and allow companies to back up a readily biodegradable claim. In fact, the Federal Trade Commission (FTC) even requires companies who use the term readily biodegradable in describing their products to state the test (for example, “ASTM 5864 or OECD 301B compliant”) in validation of the claim.
According to ISO standards for hydraulic fluids, there are four different types of lubricant oils available to meet the specification needs for environmental acceptability. With ISO 6743/4 in reference, the categories are HETG, HEPG, HEES and HEPR. While these categories may be unfamiliar to some, the typical fluids that fall into these categories will be more familiar, and it quickly becomes apparent which options are available to marine-based hydraulic applications.
This type of environmentally friendly fluid is better known as conventional vegetable oil-based fluid. While these fluids are readily biodegradable and deliver a lower impact on the environment, enhanced frictional characteristics and improved viscosity index at high temperatures, in a marine setting this category’s performance can be limited due to oxidative and hydrolytic stability. With the demands of certain applications, HETG lubricants’ limited temperature range reduces the performance they can deliver and, often, their life cycle expectancy. These types of fluids are compatible with most seal types.
Polyglycol synthethic (PAG) lubricants deliver a fire-resistant option. The downside is that they frequently are not compatible with conventional seals or filters. In switching to or from another type of lubricant, HEPG fluids are also typically not compatible with petroleum- or vegetable-based fluids, which could add significant maintenance costs to flush or remove the previous fluid before introducing the replacement fluid. These synthetic lubricants absorb water over time, which can dilute the performance and lead to the formation of rust or acid and damage equipment.
Synthetic ester-based lubricants make up the HEES type of onboard options for vessels to review in terms of ISO types. HEES fluids are also hydrolytically unstable. Their composition essentially “unzips” when water is introduced. These lubricants are also susceptible to acid formation and subsequent seal deterioration.
Poly Alpha Olefins (PAOs) and related products, in particular bio-polyalphaolefin (BPO) fluids, deliver the best option for most marine hydraulic applications. These fluids are more durable and able to operate in a wide range of temperatures, which leads to longer fluid life and often a lower total cost. HEPR-type fluids offer good seal compatibility and deal well with water ingress, as they separate from water and other contaminants without losing their performance ability or chemical make. This separation also allows for the fluid to be filtered and returned to use.
The Performance of Onboard Lubricants
From a performance standpoint, many of these eco-friendly products will meet ISO performance standards in the laboratory, but because of the operating environment in the marine industry would not perform well. These fluids or degreasers provided a trade-off between performance and sustainability. That trade-off has been eliminated by some companies, who are now able to produce readily biodegradable products that match or, in some cases, even exceed the performance of their petroleum-based counterparts in viscosity levels and wear performance, but provided the required environmentally sensitive chemical makeup. Marine original equipment manufacturers (OEMs) and hydraulic suppliers continue to give approval to these products because they meet the OEM’s outlined performance standards.
For example, the EnviroLogic 3000 series from RSC Bio Solutions is a high-performance line of readily biodegradable, nonhazardous hydraulic fluids. These HEPR fluid products can perform in extremely high temperature (250ºF), low temperature (-40ºF) and high pressure (5000+ psi) applications. With the ability to work in extreme temperatures, winter downtime can be diminished. The EnviroLogic 3000 series of products are ideal for marine hydraulic systems as they operate in environmentally sensitive areas. These types of readily biodegradable products allow marine vessels and operators to maintain or improve their performance levels with the added benefit of a safer, more sustainable product.
Bottom Line Benefits: Onboard Lubricants
Readily biodegradable fluids deliver both sustainability and performance —attributes that contribute to any company’s bottom line. These products are able to reduce the workplace hazards and environmental risks associated with spills or leaks that can not only tarnish a company’s reputation, but also lead to costly remediation involving clean-up, potential regulatory fines and equipment or employee downtime. In light of VGP regulations and the Clean Water Act, spills of readily biodegradable products are often viewed by regulatory agencies differently than petroleum-based spills, and this effect can positively impact a company’s spill response, costs and ultimately operational productivity.
As the marine industry pursues greater sustainability, companies should consider every part of their operation and equipment—from bow thrusters to stern tubes—as an opportunity for analysis and improvement. Within that equipment, readily biodegradable products stand ready to deliver those two key words that go straight to the bottom line—performance and sustainability.
(As published in the September 2013 edition of Marine News - www.marinelink.com)