What is bright stock

This results in higher quantities of purer hydrocarbon molecules. However, this hydrofinishing process is not nearly as robust as the hydrotreating or hydrocracking that occurs in the Group II and III refining processes. Group II base oils have better antioxidation properties, since all the hydrocarbon molecules of these oils are saturated. They also have a clearer color and cost more in comparison to Group I base oils. Group III base oils are refined even more than Group II base oils and generally are severely hydrocracked with higher pressure and heat.

This longer process is designed to achieve a purer base oil. Although made from crude oil, Group III base oils are sometimes described as synthesized hydrocarbons. When examining product data sheets, you should know that the inclusion of the term "hydrofinished" could indicate that BS base stocks were utilized. Depending on the application, this may result in a higher-quality finished product than those with SN Group I base stocks.

There has been a steady decline in the number of refineries producing Group I base oils. As technology has advanced, the Group II refining process has become more efficient. In terms of piston cleanliness, the remaining candidates delivered similar performance to the reference. All oils showed good control of deposits on the piston head and piston ring grooves. The oil formulated using the Infineum thickener A delivered slightly better cylinder liner wear test results than those obtained for the other test oil and the reference.

Based on this performance, oil A, formulated with the Infineum thickener, was taken forward into the field trial. Throughout the test the candidate oil delivered similar performance to the reference in terms of wear and base number retention.

In addition, the condition of the piston and cylinder liner wall was similar across the test and reference units. The field trial confirms that using low treat rates of an advanced thickener can deliver comparable performance to a commercial MDCL blended with bright stock.

Following on from this successful research project, Infineum is now progressing with the development of a thickener for use in TPEO applications. Download this article. Marine engines All articles. Home Articles Bright stock replacement. Marine engines , Base stocks.

Group I plants produce bright stock, which means, as Group I plants continue to close, supply is becoming tighter Bright stock is a high viscosity base oil that is used in marine lubricant formulations to achieve the correct viscosity. Laboratory bench tests Five thickeners were evaluated in laboratory tests against a reference oil formulated using bright stock. All of the thickeners achieved the required viscosity at low treat rates.

The oils were tested for wear protection, detergency, oxidation, foaming and storage stability. According to Majid Safdari, commercial director for Vista Energie, about 15 percent of bright stock capacity has vanished since Safdari added, Bright stock supply is in decline and is estimated to drop further in coming years.

This is primarily due to the fact that API Group I base oil plants are the sole facilities that produce bright stock, and many of these plants are either closing or cutting production because they are being replaced by Group II and III base oils in many automotive applications. He told attendees at the ICIS World Base Oils and Lubricants Conference in London last February that the global supply of bright stock is being threatened primarily by changes in the automotive industry that promote the use of high viscosity index Group II and III base stocks to improve fuel economy and increase drain intervals.

As a result, refiners have made significant investment to increase the capacity of these base stocks at the expense of Group I refineries. Although overall demand for bright stock is declining, Safdari said that several applications still depend heavily on it, including certain automotive engine oils, marine engine oils, industrial engine oils, process oils, gear oils, greases, hydraulic fluids and metalworking fluids.

Launching a grassroots plant to manufacture bright stock is not economically viable, he noted. However, some plants, such as Luberef in Saudi Arabia, have considered making capacity expansions to produce bright stock output. This may be risky because bright stock demand in the automotive segment is declining due to the shift from monograde to multigrade oils and fill-for-life gear oils to meet fuel economy standards and market demand.

In contrast, demand for bright stock is expected to increase in marine engine, gear oil, grease, hydraulic fluid and metalworking fluid applications because of its effectiveness in the formulation from a technical and cost standpoint.

Bright stock has long been used as a high-viscosity blending tool for lubricant formulators. Henderson noted that because of its high viscosity, it can be used to blend a wide range of ISO viscosities. Bright stock also has good solvency and color characteristics, and its polarity helps disperse soap thickeners into oil for greases, he added. Safdari explained that bright stock is produced from the vacuum residuum of Group I refineries.

The vacuum distillation process separates the atmospheric residue mixture into a series of fractions, representing different molecular weight ranges or viscosity ranges. These viscosities range from neutral to neutral and above.

The neutral number is the SUS viscosity at degrees F. The residue contains the heavier base oils such as bright stocks to SUS at degrees F. The vacuum residue or bottoms is separated from asphaltenes and resins prior to introduction into the extraction process. Safdari summarized the output form the Group I refining process as shown in the table on Page Henderson explained that there are several alternatives to bright stock, including polyisobutene, polyalkalene glycol, polyalphaolefin, naphthenics and some viscosity modifiers.

He said that each alternative has advantages and disadvantages in certain applications. Therefore, formulators need to carefully match the alternative to the product and customer needs. In general, he explained that formulators have a couple of options.