OSHA Changes Policy on Covered Concentrations of Chemicals

OSHA changes its enforcement policy regarding covered concentrations of chemicals listed in Appendix A of the Process Safety Management standard

On July 21, 2016 the Occupational Safety and Health Administration (OSHA) published a letter of interpretation, with the subject “Process Safety Management of Highly Hazardous Chemicals and Covered Concentrations of Listed Appendix A Chemicals.” This letter rescinds and replaces a prior letter regarding covered concentrations of chemicals, dated June 5, 2015. The new letter clarifies OSHA’s previous memorandum, provides additional guidance, and describes OSHA’s new interim citation policy.

OSHA’s Process Safety Management standard (PSM standard) applies to processes that are highly hazardous and require additional precautions. One type of process regulated is that “which involves a chemical at or above the specified threshold quantities listed in Appendix A to this section,” which contains 137 chemicals with threshold quantities. 11 of the chemicals have a minimum concentration, and the remaining 126 chemicals do not have a listed minimum concentration.

The regulatory text and history do not indicate whether the threshold quantities apply to the chemicals in their undiluted form, or to mixtures in which the chemicals are present in some concentration.

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OSHA’s previous enforcement used the “commercial grade concentration policy,” which required employers to determine the maximum concentration at which the listed chemical was available commercially. OSHA’s new enforcement policy is the “one percent test.” When determining whether a process involves a chemical (in pure or mixture form) at or above the threshold quantities listed in Appendix A, employers must calculate:

  1. The total weight of any chemical in the process at a concentration that meets or exceeds the concentration listed for that chemical in Appendix A; and
  2. With respect to chemicals without a specified concentration, the total weight of the chemical in the process at a concentration of one percent or greater. Employers need not include the weight of such chemicals in any portion of the process in which the partial pressure of the chemical in the vapor space under handling or storage conditions is less than 10 millimeters of mercury (mm Hg). Employers must document this partial pressure determination.

When calculating the weight of a chemical present in a mixture, only the weight of the chemical itself, exclusive of any solvent, solution, or carrier is counted.

Additionally, wherever “anhydrous” is used in Appendix A, it does not cover aqueous solutions or aqueous mixtures. OSHA has also found that hydrogen chloride and hydrogen fluoride, although not listed as “anhydrous” are not covered when used in aqueous solutions or mixtures.

OSHA will not enforce the new one percent test until March 31, 2017. Until then, OSHA will still issue citations under the previous “commercial grade concentration policy.” Through March 31, 2018, facilities that were not previously covered under the maximum concentration policy, but are under the new one percent test will receive top-priority compliance assistance from OSHA.

Between April 1, 2017 and March 31, 2018, facilities that will be newly subject to the PSM standard:

  • OSHA will not conduct programmed inspections of the processes;
  • OSHA will not cite an employer under the PSM standard for any violations which the employer is making good faith efforts to comply with the standard by March 31, 2018, although this will not apply in cases of a fatality or catastrophe; and
  • Any PSM citations will be submitted to the OSHA Regional Office before issuance, to ensure consistency and clarity.

Sources :

OSHA, Memorandum to Regional Administrators, Process Safety Management of Highly Hazardous Chemicals and Covered Concentrations of Listed Appendix A Chemicals, July 21, 2016

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