The industrial lubricant segment has been on a reformulation binge in recent years. Marketers have altered the recipes for a wide variety of existing fluids and also introduced numerous products that were altogether new. In some cases companies were trying to improve product performance. In others they switched to more highly refined base stocks for logistical reasons. Either way, end users may have expected lubricants that functioned better.
According to one industry insider, actual field experience is often not so good. Speaking in June at Rusmets second Industrial Oils for Metallurgy and Machine Building conference, OMVs Franz Novotny-Farkas said the Austrian oil company has observed a growing number of problems in industrial lube applications – most frequently involving formation of deposits. Novotny-Farkas said deposits are resulting from end users mixing lubricants that are incompatible but that also a significant number of new formulas are turning out to be not optimally balanced.
In either case, he said, machinery is not being 19 lubricated as well as it could be.
Developing New Recipes
Fluids that lubricate industrial machinery make up a huge chunk of the overall lubricant market. Novotny-Farkas cited estimates by German chemicals supplier BASF that they accounted for 34 percent of the nearly 38 million tons of lubricants consumed globally in 2010. Hydraulic fluids were the biggest part of that portion, constituting 11 percent of the total. Also included were general industrial oils with 9 percent, industrial engine oils with 8 percent and metalworking fluids with 12 percent.
Industrial lube formulators have introduced and changed products for a number of reasons, Novotny-Farkas said, the biggest being evolution in machinery. New equipment made for a broad spectrum of industry operates at higher speeds, higher temperatures and higher pressure levels than in the past – all of which increases the stress on fluids that lubricate them. In addition, many original equipment manufacturers and operators are asking for longer drain intervals.
Coping with these demands requires better temperature and oxidation stability, improved lubricity and better extreme pressure protection. On top of these challenges, lubricant suppliers are asked to satisfy environmental concerns by helping to conserve resources and reducing emissions and disposal costs. This often means switching to bio-based or synthetic base stocks.
API Group I has long been the overwhelming choice for base stocks in industrial lubricants. The majority of industrial lubes are still made with Group I, but a growing number of products are shifting to synthetics and Group II and III mineral oils – not only because of attempts to improve performance but for logistical reasons. Blenders making automotive lubes have been forced to use Group II and III oils. Incorporating those same stocks into industrial products can reduce the amount of extra storage space that they need.
As these new formulations come into the market, many older products remain, either because they continued to be manufactured or because existing volumes are working their way through the supply chain. When one supplier introduces a new product, for example a turbine oil for power generation systems, another may continue making an existing fluid.
This co-existence of [old and new] oils can be seen in various categories such as turbine and compressor oils or metalworking fluids, said Novotny-Farkas, who works in OMVs lubricants research and development competence center in Vienna. These oils might be the same products but certainly their base oils and additive formulations have different chemical characteristics.
Fickle End Users
Problems develop because end users as a group switch products frequently. When this happens, Novotny-Farkas said, Mixing of different oils is virtually inevitable, and the quality of the mixed oil is always worse than the quality of the fresh oil. There are procedures for purging a system of the old lubricant, but in practice, the amount of mixing can be significant.
Around 3 to 30 percent of the old oil could be mixed with the new, he said. Dirt and other impurities can also remain, and they influence the quality and operating ability of the lubricant going forward.
The variety of industrial lube formulas means that trouble is more likely to result when products mix. The industrial segment uses a wider range of base stocks than the automotive segment of the industry, including paraffinic and naphthenics, low-quality Group Is as well as Group II and III, not to mention numerous synthetics. The chemical differences between them are significant, and so lubricants made with different base stocks are likely to contain different chemical additives.
Different additive compositions can have contradictive chemical characteristics and could incline toward chemical interactions, Novotny-Farkas said, adding that the pace of interaction will generally be sped by the conditions that lubricants face during machine operation. The presence of moisture and air bubbles, higher temperatures and pressure accelerate the processes of chemical interaction or transformation of the additives.
Novotny-Farkas said end users switching lubricants usually cannot predict if and how the old and new products will react. Most dont know the composition of additive packages in the finished products because additive companies and lube marketers dont provide such information.
Better Base Oils?
Novotny-Farkas added that mixing of lubes is not the only reason for inadequate performance. Another is improper formulation, a problem that has become more prevalent because of the shift from Group I to Group II and III base stocks. The latter two categories have higher levels of saturates than Group I, which generally results in better oxidative stability, and Group III oils have higher viscosity indices and therefore more thermal stability.
But [Group II and III] have lower solvency and less compatibility with polar components generated as a result of the thermal-oxidative aging processes, Novotny-Farkas said. This could be overcome with higher concentrations of additives, particularly antioxidants, but certain antioxidants are causing premature sludge and deposits formation.
Making a quality industrial lube requires careful base oil selection and additives that impart the desired performance characteristics while interacting favorably with the base stock. But finding the proper mix is complicated by a lack of contemporary standards or widely adopted test methods to reliably assess lube performance.
The German DIN standard for hydraulic oils is at least 30 to 40 years old, Novotny-Farkas noted. The DIN standard for turbine oils is upgraded regularly, but Im not sure if it is developed according to the current progress of oil performance.
Novotny-Farkas said sludge and deposit formation is a serious problem that is becoming worse. It first surfaced in the United States because Americans started to use Group II and III base stocks in industrial lube formulations in the 1990s without adequately adjusting for the solubility properties of Group II and III.
Europeans reported sludge and deposit formation much later, he said, because they continued using industrial lubes based primarily on Group I stocks in the1990s and 2000s. But now OMV is seeing the same sludge and deposit problems there.
Back in the mid-2000s the industry was not able to accurately measure the thermal-oxidative implications [of using Groups II and III stocks], and the results were confusing, he said. But now it is becoming clear that mixing old and new oils in the equipment and using low-soluble Group II and III for industrial oil formulations is actually causing sludge and deposit formation.
Avoiding Deposits
To ensure adequate protection of their equipment, end users should strive to identify lubes that are formulated to provide the desired performance. In addition, Novotny-Farkas said, they should monitor the oil regularly to watch for sludge and other precursors to the formation of deposits. When weighing the costs and benefits of such programs, operators should consider the repairs and maintenance that can be avoided if they prevent deposits from forming in their machinery.
The industry as a whole would benefit from development of better methods for assessing lube performance, including tendency to form sludge and deposits, he added. Until that happens, end users of industrial lubricants will need to continue protecting themselves against the threat of sludge and deposits