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Subchapter 1. Unfired Pressure Vessel Safety Orders
Article 10. Safe Practices

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Appendix B

3301.1 Use of Compressed Air or Gases.

(a) Compressed air and other compressed gases in excess of 10 pounds per square inch gauge shall not be used to blow dirt, chips, or dust from clothing while it is being worn.

(b) Compressed air or gases shall not be used to empty containers of liquids where the pressure can exceed the safe working pressure of the container.

(c) The use of compressed air shall be so controlled, and proper personal protective equipment or safeguards utilized, as to protect against the possibility of eye or body injury to the operator or other workers.

(d) Abrasive blast cleaning nozzles shall be equipped with an operating valve which must be held open manually. A support shall be provided on which the nozzle may be mounted when it is not in use.

(e) Compressed gases shall not be used to elevate or otherwise transfer any hazardous substance from one container to another unless the containers are designed to withstand, with a factor of safety of at least four, the maximum possible pressure that may be applied.

NOTE: For further guidance in the utilization of compressed gases in cylinders see Group 10; for portable tanks, rail tank cars, or motor vehicle cargo tanks, see Compressed Gas Association Pamphlet P-1-1965.

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1Reprint General Industry Safety Order, Section 3301, Use of Compressed Air or Gases, from the California Administrative Code, Title 8, Subchapter 7 (Register 75, No. 29).

3304.2 Miscellaneous Use of Compressed Cylinder Gas.

(a) Employers shall not permit the use of compressed cylinder gas for testing pressure vessels unless there is installed in the compressed gas supply line or on the vessel being tested a pressure relief device set to function at a pressure not to exceed the safe working pressure of the vessel.

(b) Compressed gas shall never be used from a cylinder or cylinder manifold where pressures dangerous to employees may develop unless an accepted pressure regulating device is installed on the cylinder valve or manifold. The term "accepted" here means that the pressure regulating device is listed by Underwriters' Laboratories or some other recognized authority of equivalent standing.

NOTE: Cylinder as used in this order means an Interstate Commerce Commission compressed gas cylinder.

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2Reprint General Industry Safety Order, Section 3304, Miscellaneous Use of Compressed Cylinder Gas, from the California Administrative Code, Title 8, Subchapter 7 (Register 72, No. 23).

3312.3 Entering Combustion Chambers, Flues, Boilers or Unfired Steam Pressure Vessels.

(a) Before employees are allowed to enter, through a manhole, the shell or drum of a steam boiler or an unfired steam pressure vessel for maintenance or repair, where such a boiler or pressure vessel is one of a battery of two or more boilers or vessels or is connected to another source of steam, the valves connecting to the steam header or other source of steam shall be closed and effectively blinded or two valves shall be installed with a bleeder between them and the valves shall be closed and bleeder open. Blow down valves and other valves on lines through which harmful material might accidentally flow back to the boiler or vessel shall be either sealed or closed and locked and the key retained by the employee or his supervisor while the employee is in the boiler or vessel. When lines are effectively blinded the valves need not be locked or sealed.

(b) Employees shall not enter or be required to enter the fire boxes, flues or combustion chambers of fired apparatus until:

(1) The pilot light, fuel and steam lines to burners entering the fire box or combustion chamber have been blinded, disconnected or effectively closed by the use of two block valves with an open bleeder between them.

(2) All probability of ignition of any solid combustibles in the fire box or combustion chamber has been removed.

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3Reprint of General Industry Safety Order, Section 3312, Entering Combustion Chambers, Flues, Boilers or Unfired Steam Pressure Vessels, from the California Administrative Code, Title 8, Subchapter 7 (Register 72, No. 23).

3518.4 Air Compressors.

(a) Air compressor discharge lines having a block valve between the air receiver and compressor shall have a pressure relieving safety device installed in the line between the compressor and block valve. The pressure relieving safety device shall be set to open at a pressure not to exceed the rated working pressure of the cylinder. The relieving capacity of the pressure relieving safety devices shall be such as to prevent a rise of pressure in the compressor cylinder of more than 10 percent above its maximum allowable working pressure, and the discharge shall be to a safe place.

The installation of this pressure relieving safety device is not to be considered as providing the required safety relief valve for the protection of the air receiver.

(b) Air compressor intake lines shall not be located in atmospheres containing explosive concentrations of flammable gases or vapors.

HISTORY:

  1. New Appendix B (Sections 3301, 3304, 3312, and 3518) filed 12-14-76; effective thirtieth day thereafter (Register 76, No. 51).

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4Reprint of General Industry Safety Order, Section 3518, Air Compressors, from the California Administrative Code, Title 8, Subchapter 7 (Register 72, No. 23).

NOTE: Authority cited: Section 142.3, Labor Code.

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