Water contamination can be a real problem when trying to keep equipment lubricated and protected. Whether the environment is at paper mills, wastewater treatment facilities, large cargo ships, or even boat trailers and recreational boats, keeping water from washing out the lubricant can be a challenge for most conventional general purpose lubricating greases. For the maintenance mechanic, it is best to take stock of the best waterproof marine grease for dealing with water contamination in your specific environment.
How to Find the Best Waterproof Marine Grease
Superior Water Resistance
The first thing to research is how the grease performed during the ASTM D 1264 Water Washout Test @79C. If the grease in question scored less than 0.4% to 0.7% water washout, then this ranks it as a superior grease for water resistance. Many conventional greases claim to be waterproof greases yet their water washout score is 2% to 5%. This may be sufficient for minor or limited exposure to water contamination. For the extreme environments where water is a constant presence, it is suggested that a grease having less than 0.7% water washout be used.
Withstanding Extreme Pressure Shock Loads
Water contamination is not the only issue to consider when choosing a superior water resistant grease. There are other factors that a grease must deal with beyond water contamination to make it an effective grease for protecting critical machinery parts.
For example, if the machine is operating in an environment where water is constantly present, yet at the same time the machine is exposed to extreme pressure and shocks loads, then these constant shock loads can ultimately affect the grease’s water resistance performance along with long term protection during shock loads.
So, we must also consider a grease’s ability to withstand extreme pressure shock loads while being constantly exposed to water contamination. The well known industry test for extreme pressure is called the Timken OK Load Test (ASTM D-2509.) A waterproof grease that scores a 75 to 100 pounds Timken OK Load would be the best choice for extreme pressure conditions. Now that you’ve found a grease with a high Timken OK Load score, the question is can this extreme pressure capability be maintained when the grease is exposed to 20% water? If so, you’ve most likely found the best waterproof marine grease.
When a piece of equipment is exposed to high shock loading and heavy load, it can be said they are functioning at peak or upper level efficiency. There are certain specialty greases on the market that were designed exclusively to score a high Timken OK Load value. Unfortunately, they do not provide the necessary protection from where when the loads are in the more normal range.
In other words, the chemistry is not balanced. It is best when looking at technical data sheets to check the score that the grease rates at during this ASTM D-2266 4 Ball Wear Test. A minimum score of 0.4 mm to 0.6 mm Scar Diameter illustrates that the grease can protect when loads are more normal.
Withstanding Extreme Operating Temperatures
Another specification that must go hand in hand when choosing a waterproof grease that will be useful in protecting critical machinery parts is the grease’s operating temperature. The first test to look for is the ASTM D-2265 Dropping Point Test. If a grease shows a dropping point “None”, then this could mean that it can withstand higher operating temperatures. It’s a good start. A more realistic higher end operating temperature would be around 440 to 500 degrees Fahrenheit. On the low end or cold operating temperature, a -20 degrees Fahrenheit would be a grease that would not harden up and still have the proper consistency to protect critical machinery parts.
The next area to consider would be whether the grease has any cohesive and adhesive characteristics. Having a tacky or stringy consistency would mean the grease would have the capability of providing a tenacious and strong barrier against any damaging contaminants such as dirt, dust, mud, moisture, and water. Also, this tacky or stringy consistency can help during extreme pressure and shock loading, allowing the grease to stay put and protect metal surfaces.
Robust Additive Package
Another area that would help a grease protect against water and other contamination would be what type of additives are used in the formulation. It is important that it have a robust volume of rust and corrosion inhibitors, anti-wear agents, extreme pressure additives, and particularly molybdenum disulfide (MoS 2) or moly.
Utilizing moly adds a protective insurance policy that if the grease lubricating the part were to disappear, then the moly additive would be still plated on the metal surfaces, providing protection until the grease has been replenished. Also, it is important to know that moly can withstand up to 500,000 psi of load.