12 Hot Work Permit Guidelines F. Are there any situations when hot work is not allowed? Non-permissible Hot Work Situations Hot work is not permitted when the following conditions exist: • In sprinklered buildings where the entire sprinkler system is impaired. • When an entire building fire detection system is shut down. • In the presence of explosive atmospheres where mixtures of flammable gases, vapors, liquids, or dusts may exist. • In tanks, drums, or other containers and equipment that contain or previously contained materials that could create explosive atmospheres.