Purchasing Lubricants Based on Performance

Lubricants initially arrive in industrial plants usually via one of two methods:

1. New equipment generally comes with a “lubricant list” from the equipment supplier with a few recommendations for each application. Brand names are typically listed, a selection is made and, if it works satisfactorily, it is chosen.

2. Maintenance personnel express concern to a supplier or a competitor about a lubricant’s performance, and a change is made.

There are other ways lubricants are acquired, but in each case, maintenance personnel don’t know why a product does or does not work; they simply accept the outside expert’s opinion. In these situations, maintenance workers may not realize there are several products in the plant with different brand names but similar characteristics. They may be unknowingly contributing to the proliferation of products in the plant. Without understanding what makes the products work, the maintenance person may be reluctant to consolidate. In this case, there is little encouragement for competition and no reason for any oil company to lower its prices. Naturally, maintenance personnel want their equipment to have the highest quality lubricants but at a reasonable price. How can this be accomplished?

Figure 1. Common Tests for Oil and Grease

Test No.	Name	Application
Grease Tests
D-2596	4-Ball EP	Measures film strength of base oil
D-2266	4-Ball Wear	Measures wear resistance of greases
D-1742	Oil Separation	Measures tendency of grease base oil to separate from soap
D-4048	Copper Corrosion	Measures grease tendency to corrode copper, bronze and brass
D-942	Oxidation Stability	Measures grease tendency to combine with oxygen
D-217	Penetration	Measures the stiffness of grease
D-1831	Roll Stability	Measures resistance of grease to change stiffness after working
D-4049	Water Sprayoff	Measures resistance of grease to resist heavy water spray
D-2509	Timken Test	Measures film strength of base oil in grease
Oil Tests
D-445	Viscosity	Measures an oil’s resistance to flow (indicator of film strength)
D-2270	Viscosity Index	Measures change of viscosity with temperature
D-92	Flash and Fire Points	Indicates dilution by volatile fluids
D-97	Pour Point	Lowest usable temperature without heating
D-130	Copper Corrosion	Indicates corrosive action of an oil on copper, bronze or brass
D-2711	Demulsibility	Measures the ability of an oil to separate from water
D-4172	4-Ball Wear	Measures wear prevention ability of a lubricant
D-3604	Elastomer Compatibility	Measures effect of a lubricant on elastomers at static conditions
D-892	Foam Resistance	Measures the tendency of a lubricant to foam in systems

Jim Fitch’s “Hazards of Changing Lubricant Brands” article in the November-December 2013 issue of Machinery Lubrication put the maintenance person’s concerns in perspective. The article brought to mind a system that was developed and used for many years at a U.S. steel company. In order to address the concerns discussed in Fitch’s article, the company established a system whereby lubricants and hydraulic fluids were purchased by performance specifications. If a product worked in an application satisfactorily, it was tested to determine which ASTM tests (or others) it would pass that were relevant to the application. A specification was then written around those test results that could be placed out for bid by the purchasing department. If a lower bid was received, the competitor was asked to submit a sample to an independent lab to verify a few very important requirements. If successful, the lowest bidder was awarded the business for a specific period.

Lubricants are unique in that objective lab tests are available to the user that will predict field performance. Very few maintenance products have this advantage.

This article will outline the pros and cons of using a specification system, how to launch such a system and make it work, and how to handle exceptions. If a company’s lubricant purchases are substantial and could benefit from a 10- to 15-percent reduction in costs, this system may offer an advantage while assuring only the highest quality lubricants are used in the equipment.

What is a Performance Specification?

Every lubricant and hydraulic fluid has a detailed list of tests that must be passed at the oil company before it is released for shipment. The experts at the oil company know how the fluid must perform in your equipment. Several organizations (ASTM, SAE, etc.) have devised lab tests that will measure various aspects of this performance.

For instance, because viscosity and viscosity index are very important in most lubricants, numerous tests have been devised and agreed upon by industry experts to measure these parameters. Figure 1 provides a list of some of the more common tests for oil and grease.

Once a list of important performance specifications is compiled for a given product such as a gear oil, any successful product must be tested to determine the numbers or evaluation for each test. Compatibility is always a concern when switching products. The steel company’s solution was to give the competing supplier the responsibility of assuring that its product would mix properly with the incumbent product. Any problems in this area were the responsibility of the new supplier. Removal and disposal of the contaminated tank contents were also part of their job. Of course, this rarely needed to be done.

Figure 2 is a typical performance specification for a gear oil. A complete written specification from which the summary sheet is derived is too extensive to be reproduced here. A comprehensive set of summary sheets for several types of oil and grease may be obtained by contacting the author at tomlantz1@yahoo.com.

Figure 2. A Typical Performance Specification for a Gear Oil

Product: Extreme Pressure Lube Oil		Maintenance Code Number: MC - 43, 51, 87, 21, 93, 71 & 31
Test No.	Description	Test Limits	Comments
D-2270	Viscosity Index	Minimum=85
D-445	Viscosity	See Figure 3
D-92	Flash and Fire Points
D-97	Pour Point	See Figure 3
D-189	Conradson Carbon	Should contain no more than 2.5% residue
D-130	Copper Corrosion	No worse than Class1-b	3 hours at 212°F
D-874	Sulphated Ash	Matter of record
D-892	Foam Characteristics	Less than a trace after 10 minutes
D-665	Rust Prevention	No rust after 24 hours	Procedure A
D-2711	Demulsibility	See Figure 3
D-1298	API Gravity	Matter of record
D-1500	Color	Matter of record
D-3604	Elastomer Compatibility	Weight change +2% -1%; Volume change +5% -2%
D-4172	4-Ball Wear	Limit is 0.35 mm with 40 kg load
ISO 4606	ISO Cleanliness	Cleaner than 21/18 on delivery
D-2893	Oxidation Test	Viscosity increase less than 5%	312 Hours (13 days) at 100°C
D-664	Neutralization Number	Not to exceed 1.0
D-2782	Timken Test	Pass 60-pound load
D-2783	4-Ball EP	Weld=250 kg; LWI=45 kg
FZG	Gear Tooth Wear	9 stages; wear less than 10m

How a Performance Specification is Written

While the above information offers details on how to assemble the essential data, writing the specification is more involved. Plant personnel often see lubricants as their domain. They issue requisitions to the purchasing department and expect all the details to be taken care of, including the issuing of a purchase order to the supplier of the plant’s choice. The purchasing department often will talk to competitors about supplying a comparable product. This is a common source of conflict between the plant and the purchasing department. Both groups should have input into these decisions.

The steel company’s solution to this problem was to form a committee composed of both plant and purchasing personnel who worked on the specification together. The procedures for qualifying new suppliers and the bidding process were agreed on by both parties and strictly followed. Each plant in the corporation was represented on the committee, and all parties kept a three-ring binder of all the specifications.

Even after the specifications were written, meetings were held periodically to consider any new information acquired, problems encountered that might be due to a product or changes that a supplier thought was necessary.

The science of lubricant testing is constantly evolving, and staying up to date is imperative. The steel company also learned that most oil suppliers take great pride in their quality control, and problems that initially were attributed to the oil company often were the result of something the plant had done or an equipment malfunction.

Importance of Code Numbers

In order to wean everyone in the maintenance department away from brand names, it is imperative to establish a coding system. Every performance specification written may have a name, but it also needs a number.

The steel company’s system involved all maintenance products (gears, bearings, couplings, lubricants, etc.) and thus required long numbers, but the last three digits were unique to a specific product. For lubricants and hydraulic fluids, those three digits acquired the title “maintenance code” or MC number. All drums, in-plant tanks, supplier paperwork and written specifications had to have these code numbers. Although the drums and paperwork from a supplier might have brand names on them, the MC number had to appear as well.

There are four basic reasons for this strict adherence to code numbers:

1. To prevent maintenance personnel from thinking in terms of brand names.

2. To simplify computer systems that record the lubricants to be used in a given piece of equipment. If a change must be made, a new brand name is brought in under the existing code and no change in the computer is required.

3. Survey sheets and routing lists used by the lubrication technician would require constant updating if brand names were used. MC numbers eliminate this problem.

4. Tanks permanently installed in the plant may have the MC number stenciled on them if there is little chance a change will be required.

Vendor Relationships

One of the main reasons for the specification system is to prevent “cozy” relationships between vendors and plant personnel. When this situation occurs, prices tend to rise whether quality rises or not. Conflicts then occur between plant personnel and the purchasing department, as the latter attempts to stabilize prices. Using the specification system allows an “arm’s length” relationship. Looking primarily at the test results promotes objectivity. Of course, quality consistency, dependable deliveries and knowledgeable service are considered as well. No one likes vendors who provide inconsistent quality, unreliable deliveries or spotty service.

Adjusting Specifications

The performance specification should be considered a “living” document. It must be periodically adjusted to reflect new knowledge. Once written, the specification may become outdated by new developments in the field. New tests may be devised that assess a parameter better than previous versions. The consensus of opinion among industry experts might also change regarding which parameters are important or which test provides the best measurement. Therefore, vendors are encouraged to offer suggestions on ways to improve the specifications. Their input can be valuable.

Exceptions

It does not pay to employ performance specifications on low volume items. Below a certain dollar amount, the use of specifications is a waste of time. Simply find something that works and use it if the cost is not excessive. However, in a multi-plant organization, small quantities in several plants can add up to enough money to make using a specification worthwhile. Every situation is different, and good judgment must be used.

Figure 3. Examples of Maintenance Codes Assigned for Various Lubricant Tests

Maintenance Code No.	ISO VG	Viscosity Limits (cSt @ 40°C)	Viscosity Limits (SSU @ 100° F)	Pour Point °F (Maximum ASTM D-97)	Demulsibility % Water in Oil (Maximum)	Characteristics Total mL Free Water (Minimum)	ASTM D-2711 mL Emulsion (Maximum)
MC-43	68	61.2-74.8	284-347	-15° F (-26° C)	1	80	2
MC-51	150	135-165	625-764	-10° F (-23° C)	1	80	2
MC-87	220	198-242	917-1121	-10° F (-23° C)	1	80	2
MC-21	320	288-352	1334-1631	0° F (-17.8° C)	1	80	2
MC-93	460	414-506	1918-2344	0° F (-17.8° C)	1	80	4
MC-71	680	612-748	2834-3465	10° F (-12° C)	1	80	4
MC-31	1000	900-1100	4169-5095	20° F (-6.7° C)	1	80	4

One of the questions that might be asked when considering the use of specifications is: “Do we need to consolidate our products?” According to the Pareto principle (80/20 rule), 80 percent of the lubricant volume in a plant should be concentrated in 20 percent of the individual products. Take a survey of the products and the volume used of each. If the results do not conform to the 80/20 rule, your plant might be a candidate for lubricant consolidation. In other words, if relatively equal volumes of many products are in use, duplication might exist.

Benefits and Disciplines of the Specification System

The most obvious benefit of the specification system is lower prices. This can be easily seen. What goes unseen is the high-quality products you obtain while forcing oil companies to compete. However, by instituting a specification system, plant maintenance people are compelled to learn what works and why. This may be a challenge in some plants.

The willingness to perform testing is critical. You do not need to have an onsite laboratory, but you must find a quality offsite lab. While a few tests can be performed onsite with inexpensive equipment, most require expensive equipment and a qualified technician. A few ways to reduce these costs are discussed below. These two disciplines - learning what works and why, and the willingness to conduct testing - are essential.

Intangible Benefits

When you have a “system” in place for purchasing lubricants, vendors tend to be more careful with your products’ quality. Knowing that you test and won’t hesitate to complain or have a bad load pumped out at their expense will keep everyone honest. Also, those vendors who live by “sharp” practices or high costs don’t even bother to solicit your business. My personal experience has proven this to me repeatedly.

Testing

As mentioned previously, it is recommended to randomly test every truckload of bulk oil and drum shipments. The steel company did this because of the large volumes purchased. Tests are generally priced individually, and some are expensive. To lower costs, the steel company selected a few critical tests for each load and assumed the rest were OK. However, this may have been overkill. You could take a sample, label it and store it in case of future problems. As confidence in a vendor grows, this would be an acceptable practice.

Remember, buying lubricants by performance specifications puts lubrication on a professional base. Vendors would rather deal with people who understand lubricants and what makes them work. When the user’s understanding increases, the vendor may see the need to increase his or her own knowledge.

In the last 20 years, various organizations have devised certification tests to evaluate vendor and user knowledge in the lubrication field. This effort has vastly improved the knowledge of everyone involved. Now vendors know that if a problem occurs, they will receive a rational hearing rather than a screaming, emotional response. Vendors become more service-oriented and better problem-solvers instead of mere order-takers.

At the same time, customers become better problem solvers when they have records that show the important parameters have not changed. They must probe deeper to see if the problem might have been caused by something they did or did not do.

Finally, by concentrating on performance specifications, total fluid management (TFM) will take on a whole new dimension. If you choose to go this route, no longer will you be at the complete mercy of the TFM manager. The knowledge gained by focusing on the lubricant specifications will enable you to ask all the important questions and insist on critical reports.