ANSI pipe marking standards are a group of rules released by the American National Standards Institute to provide uniform labels for pipes that allow instant recognition of a pipe's contents. The standards include label colors, sizes and fonts used. The standards are used for industrial, institutional, commercial and public locations.
Typical labels have informative language that identifies the flow of the material running through the pipes, any dangers from the material and the content. The listings are as short as possible, to allow for quick reading. To help with quick identification of the pipe's contents, the labels are one of six colors. Each color represents a content category. For example, a red label indicates that the pipe contains fire-quenching fluids while a yellow label is used for flammable liquids.
The ANSI standards also demand an arrow on the label to show flow direction, and that the different colored labels use a specific, easy-to-read font color. The size of the font used is determined by the outside diameter of the pipe. The diameter also determines the length of the color field of the labels. There are rules governing label placement as well, with labels located primarily at pipe junctions and at points where the pipe enters or exits a wall.