Pipe Labeling Requirements
(ANSI / ASME A13.1 2007)
Pipe labels in the U.S. should conform to ANSI / ASME joint standard A13.1. The most recent update to this code was published in 2007, and introduced a new color scheme. In addition to specifying colors for pipe labels, the code specifies standards for label size and placement.
Need help with pipe labels? Give us a call at 1-800-788-5572. Our knowledgeable customer service staff will be glad to answer your questions and help find the right labeling solution for your facility.
| Pipe Contents |
Color Scheme |
| Fire-quenching fluids |
White text on red |
| Toxic and corrosive fluids |
Black text on orange |
| Flammable fluids |
Black text on yellow |
| Combustible fluids |
White text on brown |
| Potable, cooling, boiler feed, and other water |
White text on green |
| Compressed air |
White text on blue |
| User-defined |
White text on purple |
| User-defined |
Black text on white |
| User-defined |
White text on grey |
| User-defined |
White text on black |
Pipe Label Design
Pipe labels should indicate both the contents of the pipe and its direction of flow. Arrows at one or both ends indicate flow; the contents are indicated by text and by a standard color scheme.
The current version of the ANSI / ASME code uses a color scheme with six standard color combinations, and four user-defined combinations, as shown in the table to the right. The colors are based on the contents of the pipe; in general, the most hazardous feature of the contents should determine the colors used. For instance, a highly-toxic mixture that was also somewhat combustible would be labeled with black text on an orange background.
Previous editions of the pipe-labeling code used a four-color scheme. The 2007 code applies only to new facilities; new labels in existing facilities should conform to the label scheme already in use to avoid confusion.
Also new to the 2007 edition is the specification of exact colors for pipe labels. Labels should use the safety colors listed in ANSI Z535.1.
Label Placement
Pipe markers should be positioned so that they can be easily seen from the normal angle of approach—for instance, below the centerline of the pipe if the pipe is overhead, and above the centerline if the pipe is below eye level. Labels are required at the following locations:
- Adjacent to all valves and flanges
- Adjacent to all changes of direction
- On both sides of wall or floor penetrations
- At regular intervals on straight runs (50' is the acceptable maximum spacing, but closer spacing might be necessary for visibility.)
Label Size
Pipe diameter determines the appropriate label and text sizes, as shown in the following table.
| Outside Pipe Diameter (including insulation) |
Minimum Length of Label Color Field |
Minimum Letter Height |
| Inches |
mm |
Inches |
mm |
Inches |
mm |
| .75–1.25* |
19–32 |
8 |
203 |
.5 |
13 |
| 1.5–2 |
38–51 |
8 |
203 |
.75 |
19 |
| 2.5–6 |
64–152 |
12 |
305 |
1.25 |
32 |
| 8–10 |
203–254 |
24 |
610 |
2.5 |
64 |
| >10 |
>254 |
32 |
813 |
3.5 |
89 |
*Pipes too small to be directly labeled should be marked with a hanging tag.
Valve Tags
Although not explicitly required by ANSI / ASME A13.1, it is a good idea to mark valves and actuators to indicate their function, normal position, and other information. Since few valves offer a flat surface for a label to adhere to, hanging tags are frequently used. Valve tags can help improve efficiency and avoid accidents by eliminating confusion, especially in crowded environments. Since few valves offer a flat surface for a label to adhere to, hanging tags are frequently used.
For more information about pipe marking practices and solutions, give us a call at
1-800-788-5572, or use the button below to send us an email. We can usually respond to questions within one business day, and would be glad to help you learn how you can meet your facility's pipe labeling needs.
