File:Unsealed tank car valve.jpg

English: An open valve inside of the valve housing of a tank car at a railyard in the Midwestern United States. The valve threading had been stripped, likely because someone had used a tool to attempt to seal the valve. This damaged valve could no longer seal tightly, allowing fumes and vapors from inside the tank to expose the hazardous materials inspector. The inspector notified the yard master of these noncompliant cars to prevent them from departing. This photograph was taken during a Health Hazard Evaluation, a NIOSH program by which employees, union officials, or employers can request an evaluation of possible health hazards at their workplace at no cost to them.