Identifying Toxic Atmospheres
Toxic atmospheres are generally the most difficult to identify and can only be determined through testing, which should only be conducted by a qualified person (i.e., marine chemist, competent person, etc.).
The potential for a toxic atmosphere is always present and can come from several sources including:
- A space that is painted and sealed up before the paint has time to cure, causing the off-gassing of the fresh paint to release toxic levels of paint and solvent vapors into the secured space.
- A tank cover is inadvertently left open that allows nearby engine exhaust to raise the amount of carbon monoxide in the tank to dangerous levels.
- Contents from a chemical spill (deck above) enters the space.
- Multiple waste or slop is dumped into a space that creates a toxic compound.
Based on the hazards discussed above, entry into any confined/enclosed space or any space with limited ventilation space on a deck barge should be done with caution.
Real World Accident
Two riggers were capping a sulfur well in a shallow bay, working from the deck of a barge equipped with a crane with a clamshell bucket. The employees dug around the well casing and then set a caisson around the wellhead. Standard procedures required them to cut off the casing and then weld a circular plate over the end. The first employee went into the caisson to wrap a sling around the pipe end, and was asphyxiated due to hydrogen sulfide gas. The second employee entered the caisson to rescue him, and was also overcome by the gas. Neither was wearing respiratory protection (i.e., airline or Self-Contained Breathing Apparatus). Both employees died.
Knowledge Check Choose the best answer for the question.
5-3. Which of the following are generally the most difficult types of hazardous atmospheres to identify within a barges confined space?
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