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.

March 2, 1977

Mr. Duane Anderson, Manager
Hydraulic Department
Robert Bosch Corporation
2800 South 25th Avenue
Broadview, Illinois 60153

Dear Mr. Anderson:

This is in response to your letter of December 23, 1976, addressed to Mr. Stockmeier of the Occupational Safety and Health Administration (OSHA) Chicago Regional Office, regarding OSHA standards covering hydraulic accumulators. In addition, it confirms a phone conversation to your office by a member of my staff and receipt of literature on Robert Bosch high pressure hydraulic accumulators.

The information you furnished is that Robert Bosch, Germany, supplies accumulators to manufacturers of machinery in Europe, and the machines are then exported to the United States with the Robert Bosch accumulator installed. Your question is, "What regulations does OSHA have governing such accumulator applications?" There is no clear-cut across-the-board answer to you question.

Generally, a pressure vessel shall mean a storage tank or vessel which has been designed to operate at pressures above 15 p.s.i.g.. Some OSHA standards require a pressure vessel to be built in accordance with the Code for Unfired Pressure Vessels, Section VIII of the ASME Boiler and Pressure Vessel Code 1968, e.g., 29 CFR 1910.106(b)(1)(v)(b) Flammable and Combustible Liquids. The scope of the pressure vessel code has certain exemptions, such as: Pressure containers which are integral parts or components of rotating or reciprocating mechanical devices, such as pumps, compressors, turbines, generators, engines, and hydraulic or pneumatic cylinders when the primary design considerations and/or stresses are derived from the functional requirements of the device; and, vessels having an inside diameter not exceeding 6 inches with no limitation on pressure. If your hydraulic accumulators are not covered by an OSHA standard or are exempt by the scope of the pressure vessel code, the employer is required to furnish hydraulic accumulators free from recognized hazards that are causing or are likely to cause death or serious physical harm to his employees.

OSHA has no written agreements with European safety inspection bodies, such as TUV in Germany. However, OSHA has an open-door policy of cooperation within the limits of the Occupational Safety and Health Act of 1970.

Thank you for your concern and continuing interest in occupational safety and health.


John K. Barto,
Chief Division of
Occupational Safety Programs