OSHA was asked if a company could treat a small release of ammonia as incidental releases or must all ammonia releases be treated as emergency response?
If you have had an OSHA ChemNEP inspection in the last decade, there is a pretty good chance your ammonia operators were asked “What is the difference between an incidental release and one that would require an emergency response? Read the entire interpretation response here.
A CPL published by OSHA states that emergency responses can include but is not limited to any of the following situations:
- The response comes from outside the immediate release area;
- The release requires evacuation of employees in the area;
- The release poses, or has the potential to pose, conditions that are immediately dangerous to life or health (IDLH);
- The release poses a serious threat of fire or explosion (exceeds or has the potential to exceed the lower explosive limit or lower flammable limit);
- The release requires immediate attention because of a potential imminent danger;
- The release may cause high levels of exposure to toxic substances;
- There is uncertainty about whether the employees in the work area can handle the severity of the hazard with the personal protective equipment and other equipment that has been provided and the exposure limit could easily be exceeded; and
- The situation is unclear, or data are lacking for important factors.
Another CPL from OSHA states that incidental releases are those releases that neither pose a significant safety or health hazard to employees in the immediate vicinity or to the employees cleaning it up, nor have the potential to become an emergency within a short time frame. Incidental releases are limited in quantity, exposure potential, or toxicity and present minor safety or health hazards to employees in the immediate work area or those assigned to clean them up.
Before a release occurs, the employer should consider:
- Possible release scenarios;
- The means used to detect a release;
- The means used to determine release rate, release location, and the potential for a release to become exacerbated;
- The means that will be used to correct, mitigate, or stop the release;
- Potential employee exposure while performing activities to correct, mitigate or stop the release; and
- Other relevant information, e.g., the chemical hazards in question, the training and experience of the employees who would address the release, and the presence of engineering controls.
With respect to anhydrous ammonia specifically, it is important to remember that anhydrous ammonia is a highly hazardous, toxic chemical stored in pressurized ASME or DOT vessels or containers. The OSHA permissible exposure limit (PEL) is 50 PPM and the IDLH limit is 300 PPM. Even small releases can threaten the health and safety of employees.
The response activities you describe include turning off valves and repairing or tightening leaking gaskets, seals, or fittings on the ammonia system or nurse tanks caused by environmental factors, such as temperature fluctuations. These activities have the potential to result in catastrophic releases depending on the condition of the equipment, piping supports, conditions and stress of the valves and fasteners, and many other factors. Therefore, OSHA believes it is possible, and indeed likely, that any given release of anhydrous ammonia in your scenario will necessitate an emergency response in accordance with the requirements of 29 CFR 1910.120.
Extremely small vapor releases, such as minor valve packing leakage and similar releases where exposures in the breathing zone of the employee would be less than the PEL (50 PPM) and there is no risk of a catastrophic release, may be considered incidental. Emergency Action Plan procedures should specifically address the criteria used to determine whether a particular release is incidental.
More information about Emergency Response and Incidental release in ARTS R-717 PSM/RMP course.