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.

January 13, 1993

Mr. James L. Jones, III, ARM
Training Manager
Ennis, Lumsden, Boylston & Associates, Inc.
605 Eastowne Drive
Chapel Hill, North Carolina 27514

Dear Mr. Jones:

This is in response to your letter of December 1, concerning whether the use of fiberglass tanks for above and below ground storage of flammable and combustible liquids, from gasoline to asphalt, meets the intention of the Occupational Safety and Health Administration's (OSHA) 29 CFR 1910.106(b)(1), Flammable and Combustible Liquids standard.

Fiberglass storage tanks, as described in your letter, meet the intent of our 1910.106(b)(1) standard only if their use is restricted to installation underground, or required by the properties of the liquids stored, or used for the aboveground storage of Class IIIB liquids. Fiberglass is considered to be a combustible material due to the flammability of the polyester resin used as a binder for the glass, and thus its use as a type of tank for aboveground storage of Class I, II and IIIA flammable and combustible liquids would be prohibited under OSHA's 1910.106(b)(1) standard.

As you may be aware, OSHA does not regulate Class IIIB liquids. OSHA traditionally has accepted the use of aboveground fiberglass tanks for the storage of certain combustible liquids, such as crude oil, if the tanks are installed in isolated rural areas and meet the other requirements of the latest National Fire Protection Association (NFPA) 30 (1990) standard. Combustible petroleum products of the same class as crude oil may also be stored in aboveground fiberglass tanks if the tanks are also located in isolated rural areas.

We hope the information provided above will be of assistance to you.


Roger A. Clark,
Directorate of Compliance Programs