Selecting the Proper Offshore Lubricant
Jon Pearce, Castrol Offshore. From Pumps & Systems, November 2008. www.pumpsandsystems.com
Choosing the right lubrication in the offshore industry is typically based on considerations such as performance and reliability, but this does not have to come at the expense of the environment.
For any piece of industrial machinery to run smoothly, lubrication is a key consideration. In the offshore industry, where equipment may be stranded more than 100 miles from the shore, maximum efficiency is essential, so lubrication treatment must be carefully selected to ensure reliable performance. Where spares and replacement parts may be days away, ensuring that everything is fully functional is critical to the bottom line.
Offshore operators must also carefully consider the environmental effects of the lubricant they choose. Though demand for oil has never been greater, the pressure facing companies extracting hydrocarbons from the ground is challenging in the current environmental climate. A surge in environment-related legislation in mature production zones like the North Sea has added to the complexity of offshore production. This trend is likely to continue in the North Sea and other oil-producing parts of the world.
However, operators still must weigh reliability in their lubrication decisions. The use of an environmentally responsible product that does not at least meet conventional product performance may actually be detrimental to the environment in the long-term. If one accepts a shorter service life than from conventional oil, it may reduce the immediate impact of a spillage but may increase the overall amount of oil consumed along with its attendant packaging, shipping, storage and disposal costs-all at a cost to the environment.
If the alternative fluid is more aggressive toward elastomers than mineral oil, there is actually an increased risk of a spill or leak from the seals. It is a difficult and complex balancing act between environmental responsibility and reliability that operators must perform.
Environmentally Responsible Lubricants
Fortunately, new environmentally responsible lubricants have been subjected to rigorous test programs to ensure product life, component life and system reliability are not compromised by the need for better environmental performance.
It is not only the normal aspects of lubricant performance under consideration. Other things to consider include the compatibility of the environmental alternatives with existing components and standard oils, which ensures the conversion process is simple and straightforward with no attendant risks arising from the change.
Hydraulics are among the most vulnerable systems on board a platform with high pressures, high flow rates and flexible hoses contributing to the possibility of a significant spill occurring at some time. New environmentally responsible hydraulic oils have been formulated to be stable in service, so they do not oxidize (combine with air) or hydrolyze (break down when wet) more than the traditional stable mineral oils. This means the service life can be expected to be at least as long as that of current lubricants.
New environmentally responsible base oils are compatible with the same range of elastomers used for mineral oils, so changeover is easy with no seal replacements required. Overall, the risk of a spill or leak is maintained at a low level, and the impact of any spill is reduced.
Open Gear Lubricants
Open gear lubricants used for doping the legs of jack-up drill rigs are an example of deliberately introducing the lubricant into the marine environment. The grease is applied onto wet steel, squeezed between gear teeth and is expected to stay in place on the leg when it is jacked down into the sea. Apart from selecting components with low toxicity, low tendency to bioaccumulate and good biodegradability, the main performance criteria is staying in place-it cannot have low environmental impact if it washes immediately into the sea.
A new open gear lubricant meets the demanding requirements for load carrying capability, adhesiveness and resistance to water wash-off. It was taken into the North Sea and evaluated during rig moves, where it was proven to perform as well as conventional leg dopes, was easy to apply with no stringing and provided a clean, safe working environment.
The emergence of more environmentally responsible lubricant products for the offshore industry offers a new solution at a time of mounting legislation. With the oil industry moving into increasingly challenging locations, such as the Arctic, the industry is expected to face ongoing environmental questions. The selection of new, more environmentally aware products may help in these instances. These products will only prove their value if they are robust enough to deliver the same-or better-performance as conventional lubricants, while reducing industry impact on the planet.