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Subchapter 1. Unfired Pressure Vessel Safety Orders
Article 1. Scope of These Orders

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§451. Unfired Pressure Vessels Not Subject to These Safety Orders.

(a) Pressure vessels that are under the jurisdiction and inspection of the United States Government or are specifically exempted by the Labor Code.

(b) Pressure vessels subject to an internal or external pressure of not more than 15 psig except for those listed in Section 450(a)(5), with no limitation on size, and vessels having an inside diameter not exceeding 6 inches with no limitation on pressure. However, vessels excluded in this section shall be designed and constructed in accordance with recognized standards when applicable, or in accordance with good engineering practices for pressure vessel design using a factor of safety of at least 4, and shall be fitted with necessary controls and safety devices to permit safe operation.

(c) Natural gas vessels and installations and air brake tanks subject to the jurisdiction and inspection of the Public Utilities Commission, the Department of Transportation, or the Department of the California Highway Patrol, except as provided in Article 7 of these Orders.


Authority cited: Section 142.3, Labor Code. Reference: Sections 142.3 and 7624, Labor Code; and Section 13241, Health and Safety Code.


1. Amendment filed 12-8-72 as procedural and organizational; effective upon filing (Register 72, No. 50).

2. Amendment of subsection (c) filed 3-29-74; effective thirtieth day thereafter (Register 74, No. 13).

3. Amendment of subsection (b) filed 1-17-80; effective thirtieth day thereafter (Register 80, No. 3).

4. Amendment filed 1-5-88; operative 2-4-88 (Register 88, No. 4).

5. Amendment of Note filed 12-4-96; operative 1-3-97 (Register 96, No. 49).

6. Amendment of subsection (c) filed 9-25-2002 as an emergency; operative 9-25-2002 (Register 2002, No. 39). A Certificate of Compliance must be transmitted to OAL by 1-23-2003 or emergency language will be repealed by operation of law on the following day.

7. Certificate of Compliance as to 9-25-2002 order, including further amendment of subsection (c), transmitted to OAL 1-17-2003 and filed 2-24-2003 (Register 2003, No. 9).

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