OSHA 29 CFR 1910.106 (e)(2)(ii)(b):
Incidental storage or use of flammable and combustible liquids.
(b) The quantity of liquid that may be located outside of an inside storage room or storage cabinet in a building or in any one fire area of a building shall not exceed:
(1) 25 gallons of Class IA liquids in containers
(2) 120 gallons of Class IB, IC, II, or III liquids in containers
(3) 660 gallons of Class IB, IC, II, or III liquids in a single portable tank.

OSHA 29 CFR 1910.106 (d)(3)(i&ii):
Design, construction, and capacity of storage cabinets -(I) Maximum capacity. Not more than 60 gallons of Class I or Class II liquids, nor more than 120 gallons of Class III liquids may be stored in a storage cabinet.
(ii) Fire resistance. Storage cabinets shall be designed and constructed to limit the internal temperature to not more than 325°F when subjected to a 10-minute fire test using the standard time-temperature curve as set forth in Standard Methods of Fire Tests of Building Construction and Materials, NFPA 251-1969. All joints and seams shall remain tight and the door shall remain securely closed during the fire test. Cabinets shall be labeled in conspicuous lettering, FLAMMABLE-KEEP FIRE AWAY.
(a) Metal cabinets constructed in the following manner shall be deemed to be in compliance. The bottom, top, door, and sides of cabinet shall be at least No. 18 gauge sheet iron and double walled with 1½-inch air space. Joints shall be riveted, welded, or made tight by some equally effective means. The door shall be provided with a three-point lock, and a door sill shall be raised at least 2 inches above the bottom of the cabinet.

Uniform Fire Code 79.201:
(g) Storage Cabinets. 1. General. When provisions of this code require that liquid containers be stored in storage cabinets, such cabinets, and storage shall be in accordance with this section. Cabinets shall be conspicuously labeled in red letters on contrasting background FLAMMABLE - KEEP FIRE AWAY.
2. Quantities. The quantity of Class I or Class II liquids shall not exceed 60 gallons and the total quantities of all liquids in a storage cabinet shall not exceed 120 gallons.
3. Construction. Cabinets may be constructed of wood or metal. Cabinets shall be listed or constructed in accordance with the following:
A. Unlisted metal cabinets. Metal cabinets shall be of steel having a thickness of not less than 0.043 inch. The cabinet, including the door, shall be double walled with 1½-inch air space between the walls. Joints shall be riveted or welded and shall be tight fitting. Doors shall be well fitted, self-closing, and equipped with a latching device. The bottom of the cabinet shall be liquid-tight to a height of at least two inches.

Liquid Class	Maximum Storage Capacity
Flammable/Class I	60 gallons
Combustible/Class II	60 gallons
Combustible/Class III	120 gallons
Combination of Classes	120 gallons *
* Not more than 60 gallons may be Class I and Class II liquids. No more than 120 gallons of Class III liquids may be stored in a storage cabinet, according to OSHA 29 CFR 1910.106(d)(3) and NFPA 30 Section 4-3.1. Note: Not more than three such cabinets may be located in a single fire area, according to NFPA 30 Section 4-3.1.