Lubrication Checkup: Issues Around Copper Lines


“Dr. Lube, in your book Lubrication for Industry, specifically in the chapter ‘Selecting a Lubricant Delivery System,’ under ‘Lube Lines,’ you say that copper can deplete certain additive packages from oil. Could you explain this a bit more?”


Copper is an easy material to bend and, thus, is often favored for piping lubrication-delivery systems. One of the perceived benefits is the softness of the metal that contributes to easy installation. In fact, that very quality is a drawback when the metal is overworked during the initial bending process, causing work hardening and cracking of the line’s surface.

Hardening is accelerated as a result of subsequent machine vibration, which releases a fine copper “dust” into the fluid. As with any tubing or piping material used to carry fluid, erosion wear caused by the fluid moving over the tubing surface (i.e., think smooth rocks in a fast-moving river bed) will occur (especially at sharp bends or corners) and, over time, release copper particulate into the fluid.

How does this affect lubricants in a delivery system? Copper literally attacks the antioxidant packages in industrial and automotive oils. (It’s the primary material used in laboratory testing to accelerate oxidation when testing lubricants!) Copper’s impact on antioxidants is more common in recirculative systems than in total-loss systems. A similar effect can be seen in the cooking arena, where use of copper cleaning pads in deep fryers is known to accelerate the breakdown of oils and fats.

In areas where large temperature swings are the norm, moisture can build up in copper lines and release copper ions. This is an important issue for refineries, as distillate fuels and oils can contain sulfur-based compounds called mercaptides. Copper—like brass—is incompatible with mercaptides. Together, they form a gel similar to insoluble grease that will plug filters and lines. Additives to prevent this from occurring are available.


When choosing a premium line material for a lubrication-delivery system (any lube-delivery system, that is), the ideal choice is copper-coated (on the outside) steel. These types of lines will not only withstand heavy shock load and trauma, they’ll have a higher burst pressure—and look much neater if bent using the correct tools. MT

Lube questions? Ask Dr. Lube, aka Ken Bannister, author of the book Lubrication for Industry and the Lubrication section of the 28th edition Machinery’s Handbook. He’s also a contributing editor for Maintenance Technology and Lubrication Management & Technology. E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Newsletter Sign Up

Your First Name:

Your Last Name:

Your E-Mail Address:

Would you like our Newsletter?:

Enter verification image value

Congratulations to Our Recent Survey Winner

Paul Kimble, a Vibration Analyst for General Motors, was chosen at random to win a $100 gift card for completing our recent online MT Buying Cycle Survey. You could win, too! Watch your e-mail for our next survey request.

Featured Supplier: Brady

bradyBrady Worldwide Inc. is an international manufacturer and marketer of complete solutions that identify and protect premises, products and people. Our products include high-performance labels and signs, safety devices, printing systems and software, and precision die-cut materials. Along with being a global leader in industrial and safety printing systems and solutions, we have been the company you trust when performance matters most since 1914. We serve customers in electronics, telecommunications, manufacturing, electrical, construction, education, medical and a variety of other industries.

Click here for more.

Featured White Paper: Spraying Systems Co.

SSCo Logo Color w tag

Clean Tanks Faster and Lower Operating Costs

Understanding all the tank cleaning equipment options is difficult because not all tank cleaning nozzles are created equal. Let Spraying Systems Co. show you how to reduce cleaning time, minimize liquid consumption and improve cleaning effectiveness. 

Click here to download the White Paper.