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Subchapter 7. General Industry Safety Orders
Group 20. Flammable Liquids, Gases and Vapors
Article 136. Dip Tanks
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§5436. Hardening and Tempering Tanks.

(a) Tanks shall be located as far as practicable from furnaces and shall not be located on or near combustible floors.

NOTE: Combustible stock and other combustible materials should not be stored in the vicinity of dipping operations.

(b) Tanks shall be provided with a noncombustible hood and vent or other equally effective means, venting to outside of building to serve as a vent in case of fire. All such vent ducts shall be treated as flues and be kept well away from combustible roofs or materials.

(c) Tanks shall be so designed that the maximum work load is incapable of raising the temperature of the cooling medium to within 50 degrees below its flash point, or such tanks shall be equipped with circulating cooling systems which will accomplish the same result.

(d) Tanks shall be equipped with a high temperature limit switch arranged to sound an alarm when the temperature of the quenching medium reaches within 50 degrees F. below the flash point. If practical from an operating standpoint, such limit switches shall also shut down conveying equipment supplying work to the tank.

(e) The provisions of Section 5434(a) shall apply to tanks having a liquid surface area of 25 square feet or more or a capacity of 500 gallons or more.

(f) Air under pressure shall not be used to fill or to agitate oil in tanks.

(g) Drain facilities from bottom of tank may be combined with the oil circulating system or arranged independently to drain the oil to a safe location. The drain valve shall be operated automatically with approved heat actuated devices or manually, and if the latter, the valve shall be operated from a safe distance.

NOTE: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code.


1. Amendment filed 7-16-76; effective thirtieth day thereafter (Register 76, No. 29).

2. Amendment filed 12-5-86; effective thirtieth day thereafter (Register 86; No. 51).

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