California Code of Regulations
Title 8 - Industrial Relations
Division 1 - Department of Industrial Relations
Chapter 4 - Division of Industrial Safety
Subchapter 2 - Boiler and Fired Pressure Vessel Safety Orders
Article 4 - Installation
Section 764 - Blowoff Valves and Tanks

(a) All boilers subject to these orders shall have blowoff valves and piping installed in accordance with the Code.

(b) All blowoff pipes shall terminate at a safe place of discharge and shall be adequately supported to prevent undue stresses on the valves or lines, and shall not be reduced in size between the blowoff valve and point of discharge.

Blowoff valves constructed with integrally threaded bonnets shall not be permitted.

No blowoff pipe shall discharge directly into a sewer. When the blowoff discharge is to be ultimately led to a sewer, local plumbing codes shall be consulted concerning requirements for discharging products into sewers.

When a blowoff tank is used, it shall be designed and constructed in accordance with good engineering practice for the maximum pressure and temperature expected during the blowdown period with a factor of safety of at least 4. All blowoff tanks shall be provided with means for cleaning and inspection.