ANSI Pipe Marking Requirements

Hazardous materials flow through miles of piping in many industrial, commercial and institutional facilities. Just like hazardous materials in other situations, piping s ystems should be appropriately labeled to make people aware of the hazardous materials they carry. The ANSI A13.1-1981 Scheme for Identification of Piping Systems addresses this concern by offering a common labeling method for use in all facilities.

ANSI separates materials transported in above-ground piping systems into three categories:

High-Hazard Materials: Encompasses several hazard areas including corrosive and caustic materials; substances that are toxic or capable of creating toxic gases; explosive and flammable materials; radioactive substances; and materials that, if released, would be hazardous due to extreme pressures or temperatures.

Low-Hazard Materials: Materials that are not inherently hazardous and have a small chance of harming employees through mild temperatures and low pressures.

Fire Suppression Materials: Fire protection materials such as foam, carbon dioxide (CO2), Halon and water.

Label Requirements

Pipe marking labels must effectively communicate the contents of the pipes and give additional detail if special hazards (such as extreme temperatures or pressures) exist. The legend should be short in length and easy to understand. For example, the legend "Steam 100 PSIG" specifies the contents as well as the additional pressure hazard. An arrow should be used in conjunction with the legend to show which direction the material flows.

The three hazard classes have different color-coded labels associated with them. All high-hazard materials use black characters on a yellow background. T he low-hazard material class is divided into two different color schemes: liquids or liquid mixtures use white characters on a green background; gases or gaseous mixtures use white characters on a blue background. The fire suppression class uses white letters on a red background. The letters on pipe labels should be a minimum of 1/2" high, and should increase in size as the pipe diameter increases. The following table indicates ANSI-recommended letter height for various pipe sizes.

Outside Pipe Diameter	Letter Height
.75" to 1.25"	.5"
1.5" to 2"	.75"
2.5" to 6"	1.25"
8" to 10"	2.5"
over 10"	3.5"

Label Placement

Labels should be positioned on the pipes so they can be easily read. Proper label placement is on the lower side of the pipe if the employee has to look up to the pipe, on the upper side of the pipe if the employee has to look down towards the pipe, or directly facing the employee if on the same level as the pipe (see Illustration 1). Labels should be located near valves, branches, where a change in direction occurs, on entry/re-entry points through walls or floors, and on straight segments with spacing between labels that allows for easy identification (see Illustration 2).

Illustration 1

Illustration 2

References

ANSI A13.1-1981 Scheme for the Identification of Piping Systems, American National Standards Institute, New York, NY 10036.

ANSI Z53.1-1979 Safety Color Code for Marking Physical Hazards, American National Standards Institute, New York, NY 10036.

ANSI Z535.1-1991 Safety Color Code, American National Standards Institute, New York, NY 10036.

Note: The information contained on this page is intended for general information purposes only. This publication is not a substitute for review of the applicable government regulations and standards, and should not be construed as legal advice or opinion. Readers with specific questions should refer to the cited regulation or consult with an attorney.