Book Bits
From "Lubrication Fundamentals":

An oil house should be located as centrally as possible with respect to the lubrication service activity. A study of service requirements based on total travel of lubrication service personnel to their work from the oil house can help to determine the most economical and efficient location for the oil house. Travel distances from the warehouse, unloading dock, or other storage facilities should also be taken into account. In multibuilding plants it may be advantageous to build a separate oil house in a central location within the plant area. In such cases, an oil warehouse and the oil house may be combined in one building, with consequent savings in handling and storage costs.

Today's Tip
Polyurea greases have very good oxidation resistance, because they don't contain metal soaps (such as calcium, lithium, etc.) which are pro-oxidants to varying degrees. They are therefore widely used in lubed-for-life bearings.

Q & A
"We incorporated oil analysis into our predictive maintenance program over a year ago and haven't seen much difference in our machine life. We've been able to stop catastrophic failure, but not eliminate normal wear-out failures. What are we doing wrong?"

Oil analysis is a great predictive tool, but maintenance professionals must not lose sight of the importance of proactive maintenance in terms of value generating/benefit generating potential. As such, machine operating conditions must be adjusted to new targeted levels (cleaner, dryer, cooler, better aligned/balanced, etc.) in order for these rewards to be attained.

The most widely applied approach to proactive maintenance in lubrication and hydraulic applications is making quantum improvements in fluid cleanliness. This strategy often has the greatest single impact on both lubricant and machine life at an almost insignificant cost and risk. Once well-ingrained in an organization, the "cleanliness mindset" permeates nearly all work functions and achieving stabilized fluid cleanliness levels eventually becomes the norm.

Book Bits
From "Proactive Maintenance for Mechanical Systems":

The oxidation rate and the degradation products increase not only with increasing temperature, but also with increases in agitation (turbulence) and contamination - air, water, metallic particles, dirt and dust. The oxidation stability varies not only with the viscosity grade of the oil, but the actual base stock from which the hydraulic fluid was derived and refined also affects the rate of oxidation.

Today's Tip
Oil mist is effective in protecting your stored machines. The Caltex Thailand Refinery added a new dimension to the capabilities of oil mist lubrication by using it to preserve its rotating machines while they were sitting in the construction storage yards. The machine manufacturers connected tubing from the oil mist connections on the machines to connecters on the sides of the shipping crates. A temporary system was connected to the crates upon their arrival to the yard. Typically upon startup, there are numerous bearing failures. In this case, there were virtually none. (Tip submitted by Douglas Branham, Lubrication Systems Company. Thanks Douglas!)

Q & A
"After seeing the same bearing fail several times, we had an oil analysis done. The results appeared normal, but there was a small amount of water content. The oil doesn't appear to have water in it. Could this be the problem?"

Moisture in lubricating oils can have a devastating impact on component lifecycles. According to a major bearing supplier, it is possible to shorten the life of rolling element bearings by as much as 75 percent without ever knowing that moisture is in the oil based on visual observation.

Water causes oxidation, acid formation, varnishing, sludging, foaming, viscosity problems (water first thickens and then thins the oil) and can cause an oil to become conductive. Water also creates conditions for corrosion to dramatically increase.

Water can be driven off oil by maintaining the right temperature, and through the use of absorbent media filters and vacuum dehydration. Industrial equipment that is frequently turned on and off is most susceptible to moisture from the atmosphere, particularly during the summer months when atmospheric moisture is at its peak.

Book Bits
From "Filtration Technology":

Water Exclusion is Difficult

Water is a common contaminant in hydraulic and lubricating systems. Moisture can enter these systems at several points:

Through reservoir breather caps in humid air. System fluid absorbs some of this moisture, while some is condensed on the inside surfaces of the reservoir.

Through worn seals. Besides humid air, coolant and cutting fluid sprays can enter hydraulic systems through worn rod seals as the cylinder moves. In lubricating systems, these water base fluids can enter through rotating shaft seals on pumps, machine tool spindles and gear boxes.

Through heat exchangers. Worn and damaged heat exchangers can allow cooling water to leak through seals and ruptured lines into the oil system, and vice versa.

In new oil. An oil barrel stored outside in a vertical position is likely to have rainwater collect around its bung. With changes in temperature, some of this moisture will be sucked into the barrel. Eventually, this water enters the system fluid when the reservoir is filled.

Today's Tip
The operating temperature of a static or circulated oil bath has a direct impact on the useful lifespan and effectiveness of the lubricant. Above 130°F, for every 18°F increase in temperature the rate of chemical reactivity doubles. In practical terms, if you are achieving a two-year lifecycle on a charge of hydraulic oil in a tank operating at 136°F and if you can find a way to decrease the temperature of the oil to 118°F, then you can expect to double your hydraulic fluid life.

An easy way to check to see if you have room for improvement is to lay your hand on the side of the tank. If it is hot enough that you cannot leave your hand on the tank for more than a couple seconds, then you are operating at roughly 145-150°F. A fan type heat exchanger can be installed for less than a thousand dollars, and with the right flow and ambient temperature, could reduce tank temperatures to the desired level.

Q & A
"I am preparing to upgrade the lubrication program at the mill. Do you have any suggestions for where I should begin the process?"

If is often tempting to make a clean break from poor lubrication conditions by changing suppliers, bringing in a fresh perspective and having a new lubrication survey performed as the backbone of the rejuvenating process. This is quick and clean but may not deliver appreciably different results.

We should start with a look at the maintenance objectives. What are we striving to do with the maintenance program? Have we identified the critical systems in the plant? Do we know what the failure modes for those systems are? Have we decided what courses of action will best address and correct the problems identified in the failure modes? Do we have a time table for completing these actions, prioritized from most to least critical?

The lubrication strategy should complement the overall maintenance strategy. We must first determine what we want to accomplish and where we want to accomplish it before we begin to address how the lubrication processes can help or hinder our efforts.