California Code of Regulations
Title 8 - Industrial Relations
Division 1 - Department of Industrial Relations
Chapter 4 - Division of Industrial Safety
Subchapter 7 - General Industry Safety Orders
Group 10 - Gas Systems for Welding and Cutting
Article 85 - Service Piping for All Gases
Section 4825 - Installation-General

(a) Distribution lines shall be installed and maintained in a safe operating condition. All piping shall be run directly as practicable, protected against physical damage, proper allowance being made for expansion and contraction, jarring and vibration. Pipe laid underground in earth shall be located below the frost line and protected against corrosion. After assembly, piping shall be thoroughly blown out with air, nitrogen, or carbon dioxide to remove foreign materials. For oxygen piping, only oil-free air, oil-free nitrogen, or oil-free carbon dioxide shall be used.

(b) Oxygen piping shall never be placed in tunnel, trench, manhole or duct where it may be exposed to contact with oil.

(c) Only piping which has been welded or brazed shall be installed in tunnels, trenches or ducts. Shutoff valves shall be located outside such conduits. Oxygen piping may be placed in the same tunnel, trench or duct with fuel-gas pipelines, provided there is good natural or forced ventilation.

(d) All drip pots shall be readily accessible and provided with outlets normally closed with screw caps or plugs. No open end valves or pet-cocks shall be used.

(e) Gas cocks or valves shall be provided for all buildings at points outside the buildings where they will be readily accessible for shutting off gas supply to buildings in any emergency.