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Subchapter 7. General Industry Safety Orders
Group 20. Flammable Liquids, Gases and Vapors
Article 145. Tank Storage

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§5583. Materials.

(a) Tanks shall be built of steel except as provided in (b) through (d).

(b) Tanks may be built of materials other than steel:

(1) If required by the properties of the liquid stored. In case of doubt, the supplier, producer of the flammable or combustible liquid, or other competent authority should be consulted as to the suitability of the material of construction to be used;

(2) For installation underground;

(3) If used for the storage of Class IIIB liquids aboveground in areas not exposed to a spill or leak of a Class I or Class II liquid. If tanks storing Class IIIB liquids are located where they are exposed to a spill or leak of a Class I or Class II liquid, they shall be constructed in accordance with Section 5585; or

(4) If used for the storage of Class IIIB liquids inside a building protected by an approved automatic fire extinguishing system.

(c) Tanks built of materials other than steel shall be designed to specifications embodying principles recognized as good engineering design for the material used.

(d) Unlined concrete tanks may be used for storing flammable or combustible liquids having a gravity of 40 degrees API or heavier. Concrete tanks with special lining may be used for other services provided the design is in accordance with sound engineering practice.

(e) Special engineering consideration shall be required if the specific gravity of the liquid to be stored exceeds that of water or if the tanks are designed to contain flammable or combustible liquids at a liquid temperature below zero degrees F.

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