Base Oil

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Base oils are one of the specialty products that can be produced by a refinery.

Base oils are not a fuel. They are blendstocks used to formulate a variety of lubricating oils for use in engines and other machinery.

Base oils are produced by extracting and treating high-viscosity material from narrow distillation cuts of vacuum gasoil or vacuum resid. This requires special processing through a number of different units comprising the lubes plant.

Producing base oil is typically very profitable for a refinery, because it allows the refiner to take some of the lowest valued part of crude oil, vacuum gasoil, or vacuum resid, and sell it as a high-valued specialty product. However, base oil production facilities have a relatively high capital cost per barrel, so only a subset of refiners have installed them.

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API Base Oil Groups

 In the early 1990s, the American Petroleum Institute implemented a system for describing various base oil types.  The result was the development and introduction of base oil group numbers.

Group I base oils are the traditional older base oils created by a solvent-refining technology used to remove the weaker chemical structures or bad actors (ring structures, structures with double bonds) from the crude oil.  Solvent refining was the primary technology used in refineries built between 1940 and 1980.

Group I base oils typically range from amber to golden brown in color due to the sulphur, nitrogen and ring structures remaining in the oil.  They typically have a viscosity index (VI) from 90 to 105.  The base oils on the high end of the scale are often referred to as having a high viscosity index (HVI).

This relates to how much the viscosity changes with temperature, i.e., how much it thins out at higher temperatures and thickens at low temperatures.  Group I base oils are the most common type used for industrial oils, although increasingly more Group II base oils are being used.

Group II base oils are created by using a hydrotreating process to replace the traditional solvent-refining process.  Hydrogen gas is used to remove undesirable components from the crude oil.  This results in a clear and colorless base oil with very few sulphur, nitrogen or ring structures.

The VI is typically above 100.  In recent years, the price has become very similar to Group I base oils.  Group II base oils are still considered to be mineral oils.  They are commonly used in automotive engine oil formulations.

Group II “Plus” is a term used for Group II base oils that have a slightly higher VI of approximately 115, although this may not be an officially recognized term by the API.

Group III base oils are again created by using a hydrogen gas process to clean up the crude oil, but this time the process is more severe and is operated at higher temperatures and pressures than used for Group II base oils.  The resulting base oil is clear and colorless but also has a VI above 120.  In addition, it is more resistant to oxidation than Group I oils.

The cost of Group III base oils is higher than Group I and II.  Group III base oils are considered mineral oils by many technical people because they are derived directly from the refining of crude oil.  However, they are considered synthetic base oils by other people for marketing purposes due to the belief that the harsher hydrogen process has created new chemical oil structures that were not present before the process.  It has synthesized (created) these new hydrocarbon structures. See the section on synthetic base oils in this book.

Group I, II and III base oils basically reflect the evolution in refining technology over the past 70 or 80 years.

Group IV base oils are polyalphaolefin (PAO) synthetic base oils that have existed for more than 50 years.  They are pure chemicals created in a chemical plant as opposed to being created by distillation and refining of crude oil (as the previous groups were). 

PAOs fall into the category of synthetic hydrocarbons (SHCs).  They have a VI of greater than 120 and are significantly more expensive than Group III base oils due to the high degree of processing needed to manufacture them. 

Group V base oils comprise all base oils not included in Groups I, II, III or IV.  Therefore, naphthenic base oils, various synthetic esters, polyalkylene glycols (PAGs), phosphate esters and others fall into this group.

Note: The base oil is actually produced in an crude oil  refinery, but the main base oil material in the refineries, called Light Lub Cut and Heavy Lub Cut, is obtained from the distillation tower in the vacuum of the distillation unit. HLC, LLC are transported to the lubricants units by pipelines to obtain Mineral Base Oil of groups 1, 2 and 3 . 

Synthetic oils

Petroleum-derived lubricant can also be produced using synthetic hydrocarbons (derived ultimately from petroleum), "synthetic oils".

These include:

Types of base oils The sulfur content of mineral base oils is much higher and cheaper than synthetic base oils.

Synthetic base oils( group 4 : PAO & group 5 : ESTERS )are not contaminated due to the lack of sulfur and their life is much longer than mineral base oils.

 
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Group I base oils are classified as less than 90 percent saturates, greater than 0.03 percent sulfur and with a viscosity-index range of 80 to 120.  Group II base oils are defined as being more than 90 percent saturates, less than 0.03 percent sulfur and with a viscosity index of 80 to 120. They are often manufactured by hydrocracking, which is a more complex process than what is used for Group I base oils. Since all the hydrocarbon molecules of these oils are saturated,
Group II base oils have better antioxidation properties.  Group III base oils are greater than 90 percent saturates, less than 0.03 percent sulfur and have a viscosity index above 120. These oils are refined even more than Group II base oils and generally are severely hydrocracked (higher pressure and heat). This longer process is designed to achieve a purer base oil.

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Chemical substances – additives – are added to the base oil in order to meet the quality requirements for the end products in terms of, for example, friction and cleaning properties. Certain types of motor oils contain more than twenty percent additives.

Base Stock Physical Properties

These tests help describe key physical characteristics of new base oils:

Property Why It Is Important How It Is Determined ASTM No.
Viscosity Defines base oil viscosity grade Gravity flow capillary viscometer D445
Viscosity Index Defines viscosity-temperature
relationship
Viscosity variance between
40 degrees C and 100 degrees C,
indexed
D2270
Specific Gravity Defines density of oil relative
to water
Hydrometer D1298
Flash Point Defines high-temp volatility and
flammability properties
Flash point tester, temp. at
which flash surface flame
is achieved
D92/D93
Pour Point Defines low-temp oil
fluidity behavior
Gravity flow in test jar, temp
at which approximately
22,000 cSt is reached
D97/IP15

The Changing Use of Base Oils

A recent study on the use of base oils in today’s plants in comparison to a little more than a decade ago found a dramatic change has occurred. Present-day Group II base oils are the most commonly used base oils in plants, making up 47 percent of the capacity of plants in which the study was conducted.

This compared to 21 percent for both Group II and III base oils just a decade ago. Currently, Group III accounts for less than 1 percent of the capacity in plants. Group I base oils previously made up 56 percent of the capacity, compared to 28 percent of the capacity in today’s plants.

Remember, whichever base oil you choose, just be sure it is appropriate for the application, temperature range and conditions in your plant.

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By using hydrogenation technology, in which sulfur and aromatics are removed using hydrogen under high pressure, extremely pure base oils can be obtained, which are suitable when quality requirements are particularly stringent.

Base oils are one of the specialty products that can be produced by a refinery.
.

Producing base oil is typically very profitable for a refinery, because it allows the refiner to take some of the lowest valued part of crude oil, vacuum gasoil, or vacuum resid, and sell it as a high-valued specialty product. However, base oil production facilities have a relatively high capital cost per barrel, so only a subset of refiners have installed them.

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Base oils are not a fuel. They are blendstocks used to formulate a variety of lubricating oils for use in engines and other machinery.

Base oils are produced by extracting and treating high-viscosity material from narrow distillation cuts of vacuum gasoil or vacuum resid. This requires special processing through a number of different units comprising the lubes plant

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You, as our dear customer and as our audience, can use our products whenever you like. You can do the process of ordering your desired product according to your opinion and enjoy blending . Also, our team will contact you immediately and will provide you with the necessary advice regarding any base oils.