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Natural Gas – Natural gas is the predominant product found in gas distribution pipelines, and with few exceptions, is transported via pipelines in its gaseous form. Like crude oil, it is a naturally occurring resource formed millions of years ago as a result of heat and pressure acting on decayed organic material. It is extracted from wells and transported through gathering pipelines to processing facilities. From these facilities it is transported through transmission pipelines to distribution centers or distribution pipeline systems. The main ingredient in natural gas is methane (94%). Natural gas is odorless, colorless, tasteless and nontoxic in its natural state. When transported via transmission pipelines, natural gas typically does not have odorant added. An odorant (called mercaptan) is added when it is delivered to a distribution system. At ambient temperatures it remains a lighter than air gas; however, it can be compressed (CNG) under high pressure to make it convenient for use in other applications or liquefied (LNG) under extremely cold temperatures (-260° F) to facilitate transportation.

Petroleum Gas – Petroleum gas is a mixture of gaseous hydrocarbons, primarily propane, butane and ethane, which are easily liquefied under pressure and are used for residential or commercial heating and other industrial applications. Propane and butane are often stored and transported under pressure as liquid (LPG) in portable containers for use as fuel for heating and cooking applications. LPG is usually transported through hazardous liquid transmission pipelines; however, vaporized propane and butane may also be found in small distribution systems. LPG is a tasteless, colorless and odorless gas. When transported via transmission pipelines it typically will not have odorant added. Odorant is added when LPG is offloaded to a distribution pipeline system or transport tanks to facilitate leak detection.

Petroleum Liquids – Petroleum liquids is a broad term covering many products, including: crude oil, gasoline, diesel fuel, aviation gasoline, jet fuel, fuel oil, kerosene, natural gas liquids, naphtha, xylene and other refined products. Crude oil is unrefined petroleum that is extracted from beneath the earth’s surface through wells. As it comes from the well, crude oil contains a mixture of oil, gas, water and other impurities, such as metallic compounds and sulfur. Refinement of crude oil produces petroleum products that we use every day, such as motor oils and gasoline. Crude oil is normally transported from wells to refineries through gathering pipelines. Refined petroleum products are normally transported in transmission pipelines to rail or truck terminals for distribution to consumers. Odorant is not added to these products because they have a natural odor.

Anhydrous Ammonia – Anhydrous ammonia is the liquefied form of pure ammonia gas. It is a colorless gas or liquid with an extremely pungent odor. It is normally transported through transmission pipelines located in the Midwest and is used primarily as an agricultural fertilizer or industrial refrigerant.

Carbon Dioxide – Carbon dioxide is a heavy gas that is normally transported in transmission pipelines as a compressed fluid. It is a naturally occurring colorless, odorless and tasteless gas used in the petroleum industry. Under normal conditions carbon dioxide is stable, inert and nontoxic.

Ethanol – Ethanol, also called ethyl alcohol, is a colorless liquid that is widely used as an additive to automotive gasoline. It may be transported in buried transmission pipelines.

Hydrogen Gas – Hydrogen is commonly produced from the steam reforming of natural gas. It is frequently used near its production site, with the two main uses being petrochemical processing and ammonia production. It is a flammable gas that is colorless, odorless and lighter than air. It is nontoxic, but can act as a simple asphyxiant.

“Sour” Crude Oil and “Sour” Gas – Products containing little or no sulfur are often referred to as “sweet,” whereas, products containing high concentrations of sulfur and hydrogen sulfide are commonly referred to as “sour.” Hydrogen sulfide (H2S) is a toxic, corrosive contaminant found in natural gas and crude oil. Hydrogen sulfide has an odor like the smell of rotten eggs or a burnt match. Exposure to relatively low levels of hydrogen sulfide (500 ppm) can be fatal.