Special Cases - Entering Tanks and Vaults

If personnel must enter a tank or vault (for example, to clean the materials off the inside of the vault or tank), OSHA recommends the following precautions prior to entry:

• Ventilate the tank or vault completely before entry.
• Disconnect any connecting pipelines.
• Take air samples (in order to prove there are no flammable or hazardous vapors and also to prove that there is ample oxygen).
• Ensure the team has all necessary respiratory protection, protective clothing, safety harnesses, and ropes.
• Designate someone as a "safety observer," and equip this person with all necessary respiratory protection, protective clothing, a safety harness, and ropes.
• Establish "lifeline signals" so that the workers and the safety observer are able to communicate via tugs on the rope.
• Designate yet another person, located in the immediate area, to provide the safety observer with help if needed.
• Make sure that the safety observer understands not to enter the tank or vault during an emergency until additional personnel arrive at the area and are able to assist with emergency response activities.

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