ExxonMobil Environmentally Acceptable Lubricants Guide — page 1

White paper

Environmentally

acceptable lubricants:

Performance

and regulatory

compliance

Frithjof Metzner, Technology Solution Professional,

Marine and Gas Engine Oils

ExxonMobil Environmentally Acceptable Lubricants Guide — page 2

Table of contents

Introduction

01 – An evolving operational environment

02 – Industry concerns and challenges

The sheen rule

Sources of lead in used oil

03 – Environmentally Acceptable Lubricants (EAL)

EAL characteristics explained

Base stock benefits

Synthetic esters: specific properties

04 – A global drive to minimise marine pollution

05 – ExxonMobil’s EAL offering

06 – Compliance is just the start

ExxonMobil Environmentally Acceptable Lubricants Guide — page 3

Introduction

The U.S. Environmental Protection

Agency’s (EPA) Vessel General Permit (VGP)

regulation has a significant impact on marine

operators’ lubricant selection. The 2018

Vessels Incidental Discharge Act (VIDA) is

expected to replace the 2013 VGP in 2026.

If implemented, it will affect an expanded

scope of equipment.

This paper examines key industry concerns,

provides clarity regarding Environmentally

Acceptable Lubricants (EALs) and guides

EAL selection based on application.

ExxonMobil Environmentally Acceptable Lubricants Guide — page 4

An evolving

operational

environment

The combination of environmental

regulations — pressure from

manufacturers and the supply chain

— and customer demand for “green”

products, attributes and services;

continues to have a significant

impact on the marine industry.

Although the current major focus

is fuel and emission challenges,

changes are also affecting a wide

range of lubricant applications.

ExxonMobil Environmentally Acceptable Lubricants Guide — page 5

The continued application of the VGP affects almost all vessels longer

than 79 feet operating within three nautical miles of the U.S. coastline

and within U.S. jurisdiction in the Great Lakes and inland waters.

It sets out detailed rules for discharges from oil-to-sea interfaces that

affects around 70,000 vessels annually. Specifically, it mandates the use

of EALs for certain applications. Non-compliance risks a fine of up to

$25,000 per day, up to one year of imprisonment or both.

The VIDA, signed into U.S. law in December 2018, was intended to

replace the VGP and streamline the patchwork of federal, state and local

requirements for the commercial vessel community. The VIDA amend-

ment of the Clean Water Act provides for new performance standards to

be developed by the EPA and implementation regulations to be developed

by the U.S. Coast Guard; until then, the 2013 VGA applies.

The oil-to-sea

interface

Oil-to-sea interfaces include any onboard equipment where seals or

surfaces have the potential to release oil into the sea. The VGP specifically

identifies a range of equipment that has the potential for lubrication dis-

charge from an oil-to-sea interface. These include the equipment below

but is extended to any equipment on deck that reaches outboard:

•

Controllable pitch propellers

•

Thrusters

•

Stern tubes

•

Thruster bearings

•

Stabilisers

•

Rudder bearings

•

Azimuth thrusters

•

Propulsion pods

•

Wire ropes and cables

•

Equipment subject to immersion

•

Hydraulic hose-handling cranes

•

Hydraulic provision cranes

•

Hydraulic stern ramps

Certain types of seals, such as the air seals for stern tubes, are not

considered to be an oil-to-sea interface as under normal circumstances

they do not allow lubricant release.

The VIDA does not list specific applications but defines the oil-to-sea

interface as any equipment that has the potential to release oil into the

water. Contact your ExxonMobil Marine Field Engineer representative for

further details or consult the ASTM D8324 Standard Guide for Selection

of Environmentally Acceptable Lubricants for the U.S. Environmental

Protection Agency (EPA) Vessel General Permit.

ExxonMobil Environmentally Acceptable Lubricants Guide — page 6

Industry concerns

and challenges

The sheen rule

Vessels operating in U.S. inland and coastal waters are

also regulated by the Clean Water Act Discharge of

Oil regulation, which is more generally known as the

“sheen rule”. This commonly used name has given rise

to a widespread misperception that oil spills that do

not leave a sheen are acceptable. This is not the case.

The regulation requires any vessel that discharges oil

that could be “harmful to the public health or welfare

or the environment” to report the spill.

It also establishes the measures for determining whether an oil spill needs to be reported. The criteria

are discharges that:

•

Cause a sheen or discoloration on the surface of the water or adjoining shorelines

•

Violate applicable water-quality standards

•

Cause a sludge or emulsion to form below the water surface or on adjoining shorelines

According to the EPA, the use of EALs does not provide a waiver to the rule, although it may minimise

the risk of triggering the reporting requirements.

ExxonMobil Environmentally Acceptable Lubricants Guide — page 7

Sources of lead

in used oil

Another common misperception involves the presence of

lead in used stern tube oil samples, which has been accred-

ited to the lubricant’s formulation. Routine oil analysis has

recently revealed that a small percentage of vessels have in-

creased lead content in their used oil, above the Internation-

al Association of Classification Societies (IACS) guidelines

(10mg/kg). Since lead is a heavy metal and is not generated

by chemical reaction, the source of the lead could be:

•

Stern tube bearing wear, depending on composition

•

From paints or coatings within oil circulation systems

•

Acidic corrosion of the lead element within the stern

tube

•

Additives in the EAL

•

Other sources, including contamination

A significant number of the vessels that have reported

the high lead levels have tin bearings. There have been

no reported operational issues and lubricant analysis had

revealed no leaching effect as a result of oil formulation.

If high levels of lead are detected, vessel operators should

consult with their OEMs to identify the source of the

contamination in order to ensure the most appropriate

remedial action is taken.

Environmentally

Acceptable

Lubricants (EAL)

EALs are defined in

the VGP as lubricants

that are biodegradable,

minimally toxic and non-

bioaccumulative.

To meet these environmental standards, an oil must

meet all three criteria — and there are comprehen-

sive parameters for each classification. What is not

specified, however, is an oil’s chemistry. As a result,

a number of base stocks can be used, including:

•

Polyalkylene glycol

•

Triglycerides

•

Synthetic esters

It is also possible to employ sea water, in selected

and limited applications, but this requires the use

of bearings made from self-lubricating elastomeric

polymer. Practical experience of this type of

installation shows cases of rapid wear, or even

malfunctions, some of which may be caused

by insufficient lubricant flow or a buildup of

particulate matter.

Although all these options meet the criteria

of the VGP, not all EALs are created equal.

EAL characteristics

explained

Biodegradable:

As per the Organisation for Economic

Cooperation and Development (OECD)

Biodegration 301B test, the lubricant

must meet a minimum of 60% bio-

degradation within 28 days for 90% of

an oil formulation or 75% of a grease

formulation.

Minimally toxic:

The lubricant must pass the OECD 201,

202 and 203 acute toxicity tests or

OECD 210 and OECD 211 for chronic

toxicity. As an alternative, an evaluation

may be conducted on a constituent basis.

Non-bioaccumulative:

Bioaccumulation occurs when an

organism absorbs a substance at a rate

greater than the speed at which the

substance is lost. This can be assessed

using the OECD 201, 202 and 203 tests.

These tests are part of the criteria used

to determine whether a substance, like a

lubricant component, is environmentally

acceptable.

Base stock

benefits

Depending on composition, EALs based on polyal-

kylene glycol (PAG) offer good lubricity, load-bearing,

viscosity indices, oxidation characteristics and hydro-

lytic stability. However, they are typically highly incom-

patible with conventional seals and filters, as well as hy-

drocarbon, vegetable and ester-based oils. This makes

switching to a PAG-based EAL lubricant both complex

and costly, as solvent washing of lubricant tanks and

associated systems may be necessary and seals may

need to be replaced.

Triglycerides, naturally derived vegetable-based lubri-

cants, are readily biodegradable and offer excellent

lubricity but are prone to hydrolysis. They also have

poor resistance to temperature extremes, low oxidative

stability and a short operational life.

The most effective and balanced EAL lubricants are

based on synthetic ester base stocks They perform

well across a wide range of temperatures, have a high

viscosity index, possess good lubricity, provide excellent

corrosion protection and have high oxidative stability.

They also offer excellent biodegradability and can have

good hydrolytic stability depending on the ester.

They have a history of proven

performance, long operational

life and are generally compat-

ible with mineral oils, making

changeovers straightforward.

For more detailed guidance,

consult a Mobil expert.

ExxonMobil Environmentally Acceptable Lubricants Guide — page 10

Synthetic esters:

specific properties

Volatility:

The polarity of ester molecules causes them to be

attracted to one another and because of this more energy (heat)

is required to get them to move from a liquid to a gaseous state.

As a result, the synthetic ester lubricants have a high flash point

and a low rate of evaporation.

Lubricity:

Polarity also causes the ester molecules to be attracted

to positively charged metal surfaces. As a result, the molecules tend

to create a film that requires additional energy (load) to wipe it off.

The result is high lubricity and low energy consumption in lubricant

applications.

Detergency/Dispersancy:

The polar nature of esters makes them

good solvents and dispersants. This allows the esters to dissolve

or disperse oil degradation byproducts that might otherwise be

deposited as varnish or sludge.

Biodegradability:

The character of ester linkage provides

vulnerability for microbes to biodegrade the ester molecule.

This results in high biodegradability rates for ester lubricants,

which enables the formulation of environmentally friendly products.

Although base stock is important, the lubricant’s additive package also plays an

important part in an EAL’s overall performance. For example, the demands placed on

hydraulic and gear oils are quite different. Gear oils often have to deal with below-the-

waterline applications, such as thrusters and pitch propellers. Hydraulic oils are most

commonly found in deck equipment, such as cranes, ramps and hatches.

Vessel operators are therefore advised to

select lubricants best suited for individual tasks.

This will not only ensure optimum operation,

it can also help maintain lubricant performance,

which can help reduce maintenance costs and

enhance overall efficiencies.

ExxonMobil Environmentally Acceptable Lubricants Guide — page 11

A global drive

to minimise

marine pollution

The VGP’s ruling is part of a wider trend driven by a growing awareness of

environmental issues and the demand from business to better understand

potential impacts from supply chains. For example, the International Maritime

Organization (IMO) Polar Code, which entered into effect 1 January 2017,

recommends the use of EALs in polar waters.

There are also national and regional schemes that impose environmental

standards for marine lubricants, including the European Union’s Ecolabel,

Germany’s Blue Angel scheme, Sweden’s SS 155434 ruling on hydraulic fluids

and greases, and the Nordic Swan, which was jointly developed by Norway,

Sweden, Iceland, Finland and Denmark. The Nordic Swan is generally consid-

ered to be the most demanding and comprehensive programme as it sets out

criteria for biodegradability, toxicity, renewability and technical performance.

These types of regulations are an everyday reality for vessel operators and

their scope and frequency are likely to increase. China, for instance, has been

incrementally tightening its maritime emissions regulations and the IMO has

indicated further changes.

ExxonMobil Environmentally Acceptable Lubricants Guide — page 12

Mobil’s EAL

offering

In order to ensure that vessel operators have access to lubricants that not

only comply with the VGP (and future VIDA requirements) but also help to

extend equipment life (compared with industry-standard mineral products),

ExxonMobil has developed

the

Mobil SHC™ Aware™ family

of high-performance synthetic

ester-based EALs.

These include

hydraulic oils, synthetic gear oils,

greases and stern tube oils.

The type of ester is selected by the application’s requirements. We chose

saturated ester for Mobil SHC™ Aware™ Gear Oil, Mobil SHC Aware™

H and Mobil SHC™ Aware™ Grease to ensure good resistance to

temperature-related degradation and stability in the presence of water

to protect against hydrolytic breakdown.

The presence of water in stern tubes can be unavoidable, so unsaturated

esters are used in the formulation of Mobil SHC™ Aware™ ST Series

lubricants. This ensures that the stern tube oils readily emulsify with water

while providing outstanding lubrication and rust/corrosion protection,

even with up to 20% water in a stable emulsion. For users who prefer

draining off water from the stern tube system, SHC™ Aware™ Gear Series

is a viable demulsifying alternative in Mobil’s EAL offer.

ExxonMobil Environmentally Acceptable Lubricants Guide — page 13

Regulatory Compliance

is just the start

When it comes to EAL selection, regulatory

compliance is just the starting point. Vessel

operators should also look for lubricants that

are most suitable for the application and can

help to enhance operational efficiencies.

Conversion from existing mineral oils to EALs requires time in dry dock for some appli-

cations. It is therefore essential that the changeover process is as easy to manage as

possible. Vessel operators will want to avoid the need for solvent flushing, as required for

PAGs, while also ensuring that their EALs are up to the job. The optimal solution is an EAL

based on synthetic esters, coupled with EAL-compliant performance additive technology.

Used oil analysis

A condition-based maintenance approach, such as used oil analysis, offers a range

of benefits. Properly implemented, it can help vessel operators:

Improve

equipment

reliability

Cut lubricant

consumption/

expenditure

Reduce

maintenance

costs

Enhance

equipment

life

ExxonMobil’s Mobil™ Lubricant Analysis simplifies this process by producing reliable

results and clear guidance that can help vessel operators identify issues before they

become problems. Its insights into the condition of equipment and lubricants are

backed by ExxonMobil’s extensive marine industry experience and expertise.

ExxonMobil Environmentally Acceptable Lubricants Guide — page 14

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