Understanding Hazards in the Industry. Different types of Hazards in Refining and Petrochemical Industries

Hazards are defined as having the potential to cause harm, including ill health and injury, damage to property, products or the environment, production losses or increased liabilities.

Threats – These are possible causes that could potentially release the hazard and produce and incident.

Incidents – These are defined as an unplanned event of chain of events, which have caused or could have caused injury, illness and or damage (loss), to assets, the environment, or third parties.

Causes and Types of Hazards

The hazards encountered in a hydrogen process plant are primarily due to loss in containment (i.e. leakage) of the hazardous material, which may lead to hazard. Resulting hazard can be divided into three categories:

1. Hazards resulting in fire and explosion,

2. Hazards resulting from the toxic properties of materials handled (chemical hazard), and

3. Hazards associated with the physical operations in the plant (unsafe operations).

FIRE AND EXPLOSION

By nature petroleum products are flammable to a greater or lesser degree, depending on its composition.

While handling hydrocarbons, it is essential to know the hazardous properties of the product handled. An important property is the flash point, which is defined as the lowest temperature at which the liquid gives off sufficient vapor to form a flammable gas mixture near the surface of the liquid.

It is important to recognize that the relationship between the flash point and flammability is not always straightforward. It is also to be recognized that in certain circumstances the material may be more hazardous than its flash point would indicate, e.g.

· It will ignite more easily if evaporating from soaked paper, cloth or insulation.

· High flash point material may give off flammable vapor if heated by a cutting torch

· Liquids will ignite more readily if in the form of a mist or fog.

Chemical Hazards

Major Chemical Hazards can arise from:

  Skin contact with the hydrocarbon liquid.

  Inhalation of hydrocarbon vapors.

  Accidental swallowing of liquids or solids.

A number of chemically hazardous substances are handled in the hydrocarbon industry. Hydrogen sulfide and sulfur dioxide are more common in the oil production and refining industry. In the petrochemical industry, there are numerous hazardous chemicals handled due to the multiplicity of raw materials and products. Examples of some of the toxic chemicals handled are given below:

Hydrogen Sulfide (H₂S) is a highly toxic gas. At low concentrations it has the odour of rotten gas, although this can be masked by the presence of other vapors. H₂S quickly deadens the smell at about 100 ppm and higher and this may lead to a false sense of security, since the disappearance of the smell after it has been first recognized may be due to an increase, rather than a decrease in the atmospheric concentration. All petroleum products and crude oils contain sulfur in varying amounts, usually combined with hydrogen and/or carbon. Some crude oils contain free sulfur and H S. Sulfur is an undesirable element in petroleum products and various processes exist to remove it, whereby H S is often formed during intermediate stages. Whilst the H S is subsequently removed, certain amount may still be present in the product.

Polycyclic Aromatic Hydrocarbons – Some heavy refinery streams or products may contain small amounts of polycyclic aromatic hydrocarbons (PCA’s). Typical streams are gas oils, fuel oils, catalytic cracker recycle oils and vacuum distillation residue. The toxicity of PCA’s will differ, depending on the structure. Frequent and prolonged contact with these can lead to a variety of skin disorders.

Benzene: Benzene is an aromatic hydrocarbon, which can be present in very low concentrations in some crude oils. It is often produced in certain refinery processes. It is also manufactured as a finished product in the petroleum industry. The chief route of entry by benzene into the body is by inhalation of the vapor. Whether as the pure compound or as part of a mixture such as gasoline, benzene may give rise to the following health hazards:

Inhalation of high concentrations of benzene vapor (above 700 ppm) can lead to loss of consciousness and, if allowed to continue, respiratory failure and death will result. It may also cause bone marrow damage, leading to blood disorders of varying severity which are usually reversible after removal from exposure, and more rarely, leukemia (cancer of the blood), which may occur long after exposure has ceased.

Other Toxic Chemicals

Numerous others toxic chemicals are handled in the oil, gas and petrochemical industry. Some examples are:

· Chlorine of manufacture of PVC

· Methanol

· Hydrogen Cyanide in the manufacture of acrylates etc.

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