Reservoir “clogs”

Cleaning its oil reservoirs gave this company cleaner oil, dramatically longer filter life and more than $28,000 in savings

by Paul Dufresne, Senior Reliability Consultant, Trico Corporation

In most plants, when it comes to lubrication management one of the most forgotten pieces of equipment is the oil reservoir. The primary function of the oil reservoir or “lube oil tank” is to provide oil to rotating components such as roller element bearings, gears, etc.

It’s secondary function is to provide settling time for contaminants such as water, heat and metal catalysts to separate out and fall to the bottom of the reservoir before being pumped back through the filtration system and ultimately back through the equipment.

These reservoirs are often overlooked in preventive maintenance schedules and should be included just like any other piece of equipment. The following case study shows the importance of cleaning up a lube system and developing a PM schedule to prevent the system from falling back into a state of severe contamination.

Whodunnit: contaminated “clean” oil
In 2005 we were experiencing high levels of contamination on 4 out of 5 paper machine lube oil systems along with extensive filter usage. Upon further investigation we found the root cause to come from our bulk oil storage tanks that supplied these five paper machines. Upon discovery, the only option to resolve this issue was to clean out the bulk oil storage tanks and then move to the lube oil reservoirs.

At that time, our paper machine oil was costing the company just over $4 per gallon, between the two bulk oil storage tanks we had the ability to hold approximately 25,000 gallons of oil. We brought in an outside contractor who had the capability to clean out our tanks and also reclaim the new not “clean oil” in the tanks.

We transferred all our oil to one tank and then went through the proper sequences for confined space entry and proceeded to start the cleaning operation. In the first tank, we removed approximately 250 gallons of sludge and debris from the bottom of this bulk oil tank.

There is a 12-inch stand pipe in the bottom of the tank and the sludge line was approximately 1/2 inch from the top of the stand pipe. When oil is pumped to the machine reservoirs, it goes through the stand pipe. The sludge in the bottom of the oil tank was a combination of years of neglect in managing these tanks.

The oil that went into these tanks came straight from the bulk delivery tanker from the refinery where the oil was purchased. This is a key point to understand — “new oil” is not necessarily “clean oil” when it comes into your facility.

After the first tank was cleaned and we had completed reclaiming the new oil by filtering it, the new clean filtered oil was placed into the clean tank. We removed almost 300 gallons of sludge and debris from the second “primary tank” that is used to store and pump oil to our machines.

While the primary tank was being cleaned, I had a new filter bank fabricated and installed so that when our new oil would be pumped to our machine oil reservoirs it would be filtered. We installed Beta 12 = 200 micron spin on filters and then Beta 7 = 200 micron spin-on filters in-line. Down on our machines, we were filtering our oil at a Beta 3 = 200 micron level.

After we finished the bulk oil storage tanks, we moved on to our lube oil reservoirs. Following proper confined space entering procedures, we started on this next phase of our journey in cleaning up our systems.

What the... ?
What we found in these tanks was alarming and comical at the same time. From our first lube oil reservoir we removed approximately 150 gallons of sludge and build up. We also removed used oil filters, tools, nuts & bolts, rags and a few other items of the “what the hell is that?” variety.

As we moved through our other machine lube oil tanks, we removed roughly the same amount of sludge and debris.

The savings that we gained from completing this task were exponential. Upon initial start up, we found we had to change our filters immediately. After our initial change out, our filter life had increased from three to four weeks to our next filter change at six and then to nine months.

We also introduced some additional technologies such as vacuum dehydration, desiccant breathers and proper handling procedures for our lubrication practices.

It pays to be clean
The savings in dollars came out to the following:
• First, we reclaimed approximately 7,000 gallons of oil at $1.32 per gallon compared to $4.00 plus per gallon — a savings in excess of $17,000.
• Prior to the cleaning we had spent nearly $18,000 for replacement filters across five machines in the past 16 months. After the cleaning and initial filter change, our filter cost has gone from $1,200 a month to $300 a month — an estimated $11,000 dollar a year reduction in filter cost.

These savings totaled more than $28,000 by just cleaning out the systems and installing a filter header. By placing attention and some countermeasures to where our contamination problem was coming from, we were able to eliminate a lot of contamination and more damage to our equipment.

But more importantly, the true savings are our improved oil cleanliness level from 22/19/18 to a 17/15/12 on average across five machines, and an increase in the longevity of our rotating equipment.

As you can see, with a little effort in the right places you can make a great impact on the overall health of your equipment. Lube oil reservoir management must happen to ensure the reliability of your equipment. A preventive maintenance schedule should be put in place to clean out your reservoirs every three to five years depending on your individual environment.

Lubricants are the life blood of industry — the longevity of your equipment depends on the quality of the lubricants you put in them. That is why you must put into place a PM schedule that will allow you to clean out your lube oil tanks and ensure the integrity of their cleanliness is never compromised.

Paul Dufresne can be reached at pdufresne@tricocorp.com. For more information, visit the Web site: www.tricocorp.com.

This article appeared in the October/November 2007 issue of MRO Today magazine. Copyright 2007.

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