March 19, 2012

Mr. Geoffrey J. Bacci
Principal
Aires Consulting Group, Inc.
1550 Hubbard Avenue
Batavia, Illinois 60510

Dear Mr. Bacci:

Thank you for your letter to Ms. Kathy Webb, Area Director, North Aurora office of the Occupational Safety and Health Administration (OSHA), on November 4, 2011. Director Webb forwarded your letter to OSHA's national office for response. This letter constitutes OSHA's interpretation only of the requirements referenced below and may not be applicable to any question not included in your original correspondence. Your inquiry is related to the application of OSHA's standard, Process Safety of Highly Hazardous Chemicals, 29 CFR 1910.119, specifically, the exemption for flammable liquids stored in atmospheric tanks.

Scenario: The company has four (4) large tanks in their flammable storage room. Tank sizes are between 2,000 and 6,000 gallons. When they make a batch, they order a flammable material. It is delivered by tank truck and pumped into one of the tanks. In some instances, quantities exceed 10,000 pounds. Other ingredients (non-flammables) are added to the tank and materials are mixed. The final mixture is pumped to fill lines, where it is transferred to containers of five (5) gallons or less.

After a batch is made (usually 1-3 days) the tanks no longer contain any flammables.

Question: Does the Process Safety Management (PSM) of Highly Hazardous Chemicals standard, 29 CFR 1910.119, apply to the above scenario?

Reply: The scenario you described has the following attributes:

• Flammable liquid is delivered to tanks;
• Flammable liquid is present in quantities greater than the 10,000 pound threshold quantity;
• Flammable liquid is blended with other, nonflammable, ingredients within the tanks to which the flammable liquid was delivered; and
• Flammable liquid finished product is pumped to a dispensing and packaging operation.

In a phone conversation with Mr. Jeffrey Wanko of my staff on December 7, 2011, you described the blending. You stated that one or more of the tanks has a permanently-mounted agitator to perform the blending. In addition, you stated that blending is also accomplished using an external pump to circulate the tank contents.

These attributes constitute a process covered by OSHA's Process Safety for Highly Hazardous Chemicals Standard (29 CFR 1910.119) for the following reasons:

• A highly hazardous chemical is present in the process in amounts greater than the threshold quantity,
• The facility conducts requisite activities that define a covered process (e.g., manufacturing and handling) including blending using agitator and pump-around methods, and
• The facility uses the tanks to perform a process operation (blending) and the exemption for flammable liquids stored in atmospheric tanks does not apply. Therefore, the tanks are subject to the requirements of the PSM standard.

Thank you for your interest in occupational safety and health. OSHA sets requirements 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. If you have any further questions, please feel free to contact the Office of General Industry Enforcement at (202) 693-1850.

Sincerely,

Thomas Galassi, Director
Directorate of Enforcement Programs