Opening hatches to check levels in oil and gas tanks at oil refineries and other businesses can be fatal, according to a new alert issued by the US Occupational Safety and Health Administration.
Since 2010, at least nine workers have been killed as a result of hydrocarbon gases and vapors that can leak out of the tanks once openings — known as “thief hatches” — are opened. Fires and explosions are also a risk.
The federal agency — in conjunction with the National Institute for Occupational Safety and Health — have issued a new set of guidelines designed to protect workers and minimize injuries and fatalities at oil and gas extraction sites and other sites where production tanks are used.
Dangerous Blowback
Tanks that contain oil and gas can release hydrocarbon bases and vapors, oxygen-deficient atmospheres, and even fires and explosions when they are opened by workers checking levels or collecting a fluid sample, according to the OSHA warning issued this month.
When these gases are released, they can easily overwhelm workers — and in some cases, kill them.
One of the most dangerous exposures is to hydrogen sulfide, which is widely known as a severe chemical exposure hazard in the oil and gas industry. When thief hatches are open, concentrated doses of the gas that are under pressure can suddenly be released.
The gases also can displace oxygen, suffocating workers. Or they can exceed legally safe levels, rising above the 10% lower explosive level (LEL) and significantly increasing the risk of fire and explosion.
Results of Exposure
Gases and vapors can affect the eyes, lungs and central nervous system of the oil and gas tank farm workers. If enough hydrocarbon gases are present, it can cause the heart to go into abnormal rhythms and ventricular fibrillation, which can lead to instant death.
Exposures as brief as 30 seconds have led to the rapid onset of respiratory depression, hypoxia, and fatal cardiac arrest. Workers who aren’t instantly killed can experience dizziness, disorientation, and confusion that can lead to impaired judgment, sleepiness, and incapacitation. Some hydrocarbons can also increase the risk of cancer.
Decreasing Exposure Risks
OSHA and NIOSH recommended a three-pronged approach to minimize the risk of hydrocarbon vapor and gas exposure to tank workers:
- Engineering Controls — Whenever possible, gauging and sampling should be done remotely or automatically. Also, tanks should be equipped with blowdown valves, tank sampling taps, and thief hatch pressure indicators.
- Work Practices — Tank workers should always stay upwind and at a safe distance from open hatches.
- Personal Protective Equipment (PPE) –Workers should be supplied with flame retardant clothing, the appropriate respiratory protection, and impermeable gloves.
The agencies also outlined ten steps for the safe collection of fluid sample and gauging tanks, which can be found here.