Refineries handle a huge number of hazardous chemicals in gaseous, fluid, and solid phases. A typical refinery’s best-known products include gasoline, diesel fuel, kerosene, heating oil, liquefied petroleum gas, petroleum naptha, and asphalt base.

These products support worldwide industry, commerce, and energy needs. Of course, creating these much-needed resources comes with chemical hazards. Here are some important chemicals to handle carefully at a refinery.


WHAT THEY ARE:  Crude oil is comprised of many types of hydrocarbons, like methane, propane, butane, hydrogen sulfide, and bitumen.

RISKS INVOLVED: Hydrocarbons are flammable – able to ignite at room temperature – and combustible – capable of ignition through energy and temperature. Enclosed spaces, sparks, and temperatures are serious risks with hydrocarbons. Hydrocarbons are asphyxiants (cause suffocation). Liquid hydrocarbons and steam can cause dermatitis and thermal burns on skin. Gaseous hydrocarbons are carcinogenic with long periods of exposure.


WHAT IT IS: Sulphur is the most common inorganic material in crude oil. Its main forms are hydrogen sulphide and thiols/mercaptans, which have the characteristic foul rotten-egg smell most people associate with sulphur.

RISKS INVOLVED: Sulphur is fatal at high concentrations. Because of its smell, workers sometimes die of inhalation when they don’t smell it due to “nose-blindness,” or getting used to the odor.

Naphthenic acids

WHAT THEY ARE: Naphthenic acids are carboxylic acids present in some crude oils. Because they are in low concentrations, they do not usually present direct hazards to workers. They present indirect hazards through corrosion.

RISKS INVOLVED: As these acids dissolve equipment and seals, they pose risks of explosion, ignition, and falling or flying objects.

Organic chlorides

WHAT IT IS: These are introduced as a byproduct of the refining process. They usually don’t cause direct exposure issues but create corrosion in the system.

RISKS INVOLVED: Organic chlorides cause severe corrosion in downstream refinery equipment.


WHAT IT IS: In an industrial setting, salt combines with crude oil as it leaves underground reservoirs or sea sources.

RISKS INVOLVED: Salt water is toxic, corrosive, and can cause breathing problems, eye infections, and skin abrasions.


WHAT IT IS: Mercury is a silvery metal at normal temperatures that is found in trace amounts in oil. However, even in small amounts mercury is toxic.

RISKS INVOLVED: Workers exposed to mercury can be fatally poisoned. This sometimes occurs through overhead condensers and distillation towers, where trace amounts of mercury build up over time. Removal of deposits is hazardous.


WHAT IT IS: Normally-occurring radioactive materials (NORM) come from radioactive decay in oil. Common NORMs are radium and polonium.

RISKS INVOLVED: Not only are radioactive materials extremely harmful to people, they also destroy equipment over time. Radioactive buildup on the inside of a tank, for example, is released as toxic dust when someone attempts to remove it.

Solids and Pipescale

WHAT THEY ARE: Sand, sediment, and scale are solids that form inside pipes and equipment over time.

RISKS INVOLVED: They are either toxic on their own, or toxic when exposed to air. They form vapor clouds that are combustible at certain temperatures.

Petroleum Coke

WHAT IT IS: Petroleum coke deposits form in high-temperature areas of refineries through thermal cracking.

RISKS INVOLVED: When not kept wet, they can ignite. Workers can develop contact dermatitis over time, and suffer from carcinogenic effects.


WHAT IT IS: Nitrogen is often used to blast-clean equipment, purge it, and prepare it for the next use.

RISKS INVOLVED: When nitrogen is stored and released in confined environments, it is a major explosion hazard.


WHAT IT IS: It’s easy to forget that water and steam are also chemical hazards at refineries. Salt water and high-pressure water are both risky for people and equipment.

RISKS INVOLVED: Salt water is toxic. High-pressure steam and streams of water can burn people and knock them over. Water in overhead drums and pipes can be a serious risk to workers.

Best Practices for Handling Hazardous Refinery Chemicals:

  • Track boiling points and flash points, or the points where liquids boil and vapors ignite.
  • Beware that mists and aerosols can ignite at lower temperatures.
  • Monitor residues, deposits, scale, and sediments, which can cause unexpected ignition.
  • Beware that both containment and release from containment are high-risk periods.
  • Monitor corrosion carefully.
  • Handle radioactivity according to safety standards.
  • Limit direct exposure of workers and/or establish threshold limits for exposure times.
  • Routinely test additives that can also be hazardous.
  • Seek safe replacements whenever possible. For example, neutralize inorganic acids with safer amines, rather than toxic ammonia.
  • Provide proper safety gear and training for every worker.

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