Petroleum Substances Terminology

Petroleum (crude oil) and raw natural gas are naturally occurring substances sometimes containing thousands of individual chemicals called hydrocarbons. In order to make finished petroleum products, they must be separate into different fractions (i.e., gases, naphtha, distillates). Each of these fractions often requires additional processing before they can be sold or blended into finished petroleum products like gasoline, jet fuel, diesel fuel, etc.

The separated fractions are individual substances often referred to as “petroleum process streams” and are labeled according to the processing that they have undergone. If the stream has undergone multiple processing steps, it is labeled by the last process step it underwent. The chemical composition for petroleum substances can vary from refinery to refinery, and can also vary with different sources of crude oil and natural gas. There is no set chemical composition for most petroleum substances. They usually are TSCA Class II substances (Chemical Substances of Unknown or Variable Composition, Complex Reaction Products, and Biological Material or “UVCBs”). They are described generically in EPA’s Chemical Substances Inventory, and have a unique Chemical Abstracts Service (CAS) registry number. The EPA Inventory listing typically provides a brief description of the stream, with the approximate carbon number range of the hydrocarbons present, and the approximate boiling range. For example:

Distillates¹ (petroleum²), heavy catalytic cracked³
A complex combination of hydrocarbons produced by the distillation of products from a catalytic cracking process. It consists of hydrocarbons having carbon numbers predominantly in the range of C15 through C35⁴ and boiling in the range of approximately 260 °C to 500°C (500°F to 932°F)⁵. This stream is likely to contain 5 wt. % or more of 4- to 6-membered condensed ring aromatic hydrocarbons.

The substance name and definition usually contains the following information:

1. The primary hydrocarbon fraction such as Gases, Naphtha, Distillate/Gas Oil, or Residuum. Other nomenclature such as Extracts, Wax, etc. may be used for specific refinery processes.
2. The hydrocarbon source. The hydrocarbon source here is “petroleum” as opposed to ‘shale” or “coal”.
3. The last refining step.
4. The carbon number range
5. The boiling point range.

This particular definition includes some information on specific components in the substance, although this is typically not the case.

Product Categories
Petroleum HPV Testing Group sponsored substances are organized and evaluated according to product categories. Use of categories facilitates coordination of efforts to summarize existing data and develop new hazard data which will be appropriate for hazard and risk characterization worldwide and therefore, avoid unnecessary duplication of testing. The Petroleum HPV Testing Group has used the following product categories for the EPA’s High Production Volume Chemical (HPV) Challenge.

1. Aromatic Extracts (5 Substances)
2. Asphalt (6 Substances)
3. Crude Oils (1 Substance)
4. Gasoline (81 Substances)
5. Gas Oils (diesel fuels/heating oils) (29 Substances)
6. Heavy Fuel Oils (31 Substances)
7. Kerosenes/Jet Fuel (8 Substances)
8. Lubricating Grease Thickeners (11 Substances)
9. Lubricating Oil Basestocks (34 Substances)
10. Petroleum Coke (2 Substances)
11. Petroleum Gases (161 Substances)
12. Reclaimed Petroleum Substances (10 Substances)
13. Waxes and Related Products (8 Substances)

The Petroleum HPV categories are similar to the categorization of petroleum substances being used for REACH registration in Europe.

CONCAWE will prepare the common parts of the Registration Dossiers for the following “categories of substances” for REACH registration (status 21 September 2009):

1. low boiling point naphthas / gasolines
2. kerosines
3. straight run gas oils
4. vacuum gas oils, hydrocracked gas oils and distillate fuels
5. cracked gas oils
6. other gas oils
7. heavy fuel oil components
8. white mineral oils
9. unrefined / acid treated oils
10. other lubricant base oils
11. foots oils
12. paraffinic and hydrocarbon waxes
13. slack waxes
14. petrolatums
15. untreated distillate aromatic extracts
16. treated distillate aromatic extracts
17. residual aromatic extracts
18. bitumen
19. petroleum coke

CONCAWE (Conservation of Clean Air and Water in Europe) was established in 1963 by a small group of leading oil companies to carry out research on environmental issues relevant to the oil industry. Its membership has broadened to include most oil companies operating in Europe. Because of the extensive overlap of petroleum gases from refinery operation and gases from steamcrackers and/or aromatics production units CONCAWE has agreed to collaborate with by the Lower Olefins/Aromatics consortium (LOA). The common parts of the registration dossiers for petroleum gases will be prepared by LOA.

Below is a comparison of the petroleum categories used for the HPV Challenge and REACH registration.

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