Abstract
In the oil and gas industry hydrogen sulfide is usually associated with hydrocarbon gases. This code of practice provides a way of classifying gas streams into materials where the hydrogen sulfide is the prime health hazard (high hydrogen sulfide materials, greater than 0.4% hydrogen sulfide) and where the hydrocarbons, through their ability to intoxicate and form explosive mixtures, are the prime hazard (low hydrogen sulfide materials, less than 0.4% hydrogen sulfide). This classification is based on alerting workers to the presence of hydrogen sulfide at 20 ppm in the air, or hydrocarbons at 10 percent of the lower explosive limit. Based on this classification, the code provides guidance on what type of gas monitoring is needed; exposure and evacuation standards; training requirements; respiratory protection; and working alone. The code draws attention to the way that liquids can cause hydrogen sulfide concentrations in the head space of tanks or sumps that are much higher than in the gas entering the plant. The code of practice has been successfully used for over 1 year by a major oil and gas production company operating in western Canada.