Definition(s)
Blind
A device such as metal plates inserted in flanged joints, blind flanges, and caps or plugs installed on the ends of pipe lines, used to prevent liquids, gases, or vapors from passing through a pipe line or nozzle. Valves are not blinds.
Source: Petroleum Safety Orders–Drilling and Production, Definitions, California Code of Regulations, 8 CCR § 6505, December 2012. Regulations