Purposes of Standardization of Pipe Markings
Schemes for identification of the contents of piping systems have been developed in the past by a large number of industrial plants and organizations of various kinds. Generally speaking, the standards arrived in individual cases and have given satisfaction to those using them but they also have suffered from a lack of uniformity.
Mistakes made in turning valves on or disconnecting pipes at the wrong time or place have resulted in numerous injuries to personnel and damage to property. In particular, these sorts of mistakes have been made when outside agencies, such as municipal fire departments, were called in to assist.
Furthermore, there has been considerable confusion for people who change employment from one plant to another.
In order to promote greater safety and lessen the chances of error, confusion, or inaction, especially in times of emergency, a uniform system for the identification of piping contents has been established to warn personnel when the piping contents are inherently hazardous. Therefore, while this Standard has been prepared to specify the identification of the contents of piping systems on the basis of legends, it also suggests the use of color as a supplementary means of identifying the type of hazard of the material contained in the system.