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 https://www.osha.gov.

December 2,1994

Mr. Glynn Rountree
Aerospace Industries Association of America, Inc.
1250 Eye Street, N.W.
Washington, D.C. 20005-3922

Dear Mr. Rountree:

This is in response to your May 25 letter, requesting that the Occupational Safety and Health Administration (OSHA) revisit current OSHA interpretations issued previously on the applicability of the Process Safety Management standard, 29 CFR 1910.119 to the manufacture of explosive devices. Please accept our apology for the delay in responding.

The paragraph (k)-Scope of the Explosives and Blasting Agents standard, 29 CFR 1910.109 was revised by adding paragraph (k)(2). By (k)(2), the manufacture of explosives as defined in 1910.109(a)(3) must meet the requirements in 1910.119. This revision was published as a final rule, a copy of which is enclosed for your use. Explosive is defined in 1910.109(a)(3) as "any chemical compound, mixture, or device, the primary or common purpose of which is to function by explosion, i.e., with substantially instantaneous release of gas and heat, unless such compound, mixture, or device is otherwise specifically classified by the U.S. Department of Transportation; see 49 CFR Chapter I ..." A copy of 1910.109(a)(3) is also enclosed for your use.

Interpretations on whether the PSM standard applies to the manufacturing of explosives at work sites are predicated on the aforementioned 1910.109 regulations. Explosive manufacturing covered by the PSM standard is discussed in the preamble to the enclosed final rule. (See page 6367, middle of the third column). The 1910.109 standard did not address the hazards associated with the manufactures of explosives before this final rule. The PSM standard is intended to apply to the explosive manufacturing process to address this gap and to address the explosive potential for producing a major accident during manufacturing.

In your letter you referenced an interpretation issued previously by OSHA (See paragraph 3 of the enclosed letter). This interpretation was intended to clarify that the manufacturing of certain explosive devices, as defined in 1910.109, would be covered by the PSM standard. This interpretation follows:

"The term explosives includes all materials which were formally classified as Class A, Class B, and Class C explosives by DOT and are now classified by number designations. See the 49 CFR 173.53 table (enclosed) which compares old and new designations. Additionally, OSHA considers the manufacture of explosives to mean: mixing, blending, extruding, synthesizing, assembling, disassembling, and other activities involved in the making of a product or device which is intended to explode or contains DOT-classified explosive materials as described above."

The phrase with which you expressed particular concern in your letter, "or contains DOT-classified explosive materials" was intended to apply to the manufacturing of explosive devices which are intended to explode. OSHA did not intend that the PSM standard apply to the installation of explosive devices, such as, explosive bolts, detonating cords, explosive actuators, squibs, heating pellets, thermal batteries, ejection seat rocket motors and similar small explosive devices (described in your letter as commonplace in the Aerospace Industry) into larger finished products or devices that are not intended to explode. The preceding installation is considered a handling activity covered by 1910.109.

We appreciate your interest in employee safety and health. If we can be of further assistance, please contact the Office of General Industry Compliance Assistance, Ron Davies on 202-219-8031 ext. 110.


John B. Miles, Jr., Director
Directorate of Compliance Programs