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Subchapter 7. General Industry Safety Orders
Group 2. Safe Practices and Personal Protection
Article 7. Miscellaneous Safe Practices
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§3329. Pipe Lines.

(a) Pipe lines containing hot, poisonous, corrosive or flammable substances shall be supported and maintained so as to prevent dangerous vibration under normal operating conditions.

(b) All pressure piping shall be designed, constructed, installed, and maintained in accordance with good engineering practice. Piping which meets the requirements of the applicable ANSI B31 standard shall be considered as providing reasonable safety.

(c) Leaks from pipe lines, piping or from other equipment shall be stopped if employees are endangered by the liberated liquids, gases or vapors. If hazardous leakage cannot be stopped during plant operation, diversion shields, or other effective means, shall be installed to protect the work area and employees involved.

(d) When dismantling or opening closed pressurized or gravity fed systems, internal pressure shall be relieved or other methods utilized to prevent sudden release of pressure or spraying of liquid.

(e) At all times during the repair, modification, or maintenance work, energy within the system shall be controlled to prevent an uncontrolled release that could cause injury.

Note: Extreme care shall be taken to prevent the build-up of excessive internal pressure if external heat is used to free solid blockages within liquid pipe lines.

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


1. New section filed 10-25-74; effective thirtieth day thereafter (Register 74, No. 43).

2. Amendment of subsection (b) and new subsections (c) and (d) filed 12-19-78; effective thirtieth day thereafter (Register 79, No. 1).

3. New subsection (e) and amendment of Note filed 7-1-2013; operative 10-1-2013 (Register 2013, No. 27).

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