OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov.

July 9, 1993

Mr. Jim Collins
Safety Manager
Helena Chemical Company
Fenn Road, P.O. Box 837
Cordele, Georgia 31015

Dear Mr. Collins:

The purpose of this letter is to correct a misinterpretation of the Process Safety Management (PSM) of Highly Hazardous Chemicals (HHC's) standard, 29 CFR 1910.119 in the September, 1992 letter to you from Patricia K. Clark, former director of the Directorate of Compliance Programs. The corrected interpretation follows.

Appendix A of the PSM standard lists toxic and reactive HHC's which are covered by the PSM standard when a process contains a threshold quantity (as delineated in Appendix A) or greater amount. Dimethylamine in aqueous solutions are not listed specifically in Appendix A. Anhydrous Dimethylamine, identified by Chemical Abstract Service (CAS) Number 124-40-3, which is listed in Appendix A, is not only a toxic and reactive HHC but also a flammable gas.

Since Anhydrous Dimethylamine is a flammable gas which is soluble in water, some Dimethylamine in aqueous solutions may also be flammable. Processes which contain threshold quantities, that is, 10,000 pounds (4535.9 kg) or greater amounts of Dimethylamine in aqueous solutions that are flammable liquids as defined in 29 CFR 1910.1200(c) are covered by the PSM standard.

Please disregard and discard the earlier correspondence. Thank you for your interest in occupational safety and health. If we can be of further assistance, please contact us.

Sincerely,



Roger A. Clark, Director
Directorate of Compliance Programs




September 15, 1992

Mr. Jim Collins
Safety Manager
Helena Chemical Company
Fenn Road, P.O. Box 837
Cordele, Georgia 31015

Dear Mr. Collins:

This is in response to your letter of August 5, requesting written confirmation that the Final Rule on Process Safety Management (PSM) of Highly Hazardous Chemicals published in Volume 57, Number 36 of the Federal Register on Monday, February 24, 1992 does not apply to solutions of Dimethylamine.

Anhydrous Dimethylamine, identified by Chemical Abstract Service (CAS) Number 124-40-3, is listed in Appendix A of the PSM Standard as a highly hazardous chemical. Dimethylamine in aqueous solutions, which is not listed in Appendix A, is not considered to be a highly hazardous chemical covered by the PSM standard.

Thank you for your interest in occupational safety and health. If we may be of further assistance, please contact us.

Sincerely,



Patricia K. Clark, Director
Directorate of Compliance Programs