Why is pipe marking important? Pipe marking ensures that individuals working in the facility are aware of what pipes are carrying as well as any potential hazards associated with the pipe contents.
The American National Standards Institute (ANSI/ASME) has put regulations in place that require proper marking of hazardous materials in piping systems. The requirements, though not enforced by OSHA, offer both placement and color recommendations for marking. This helps in creating a standard pipe marking system that is easy to understand and work with.
The Regulations
When determining how to mark your pipes, there are a few different elements you have to consider. These include:
- The color of the marker
- The size of the marker and letter height of the text on the marker
- Where the pipes are marked
Marker Color – Depending on what the pipe is carrying, it needs to be labeled with a specific color for quick, easy identification. Marking color categories include:
- Red Marker/White Text: Fire quenching fluids
- Orange Marker/Black Text: Toxic and corrosive fluids
- Yellow Marker/Black Text: Flammable fluids
- Brown Marker/White Text: Combustible fluids
- Green Marker/White Text: Potable, cooling, boiler feed and other water
- Blue Marker/White Text: Compressed air
Size Specifications – ANSI standards also designate what size pipe marker you should use and the letter height depending on the size of the pipe. See the chart below for these specifications.
| Outside Pipe Dia. | Marker Size | Letter Height |
| 1" or less | 1-1/8" x 4" | 1/2" |
| 1-1/4" to 2-3/8" | 1-1/8" x 8" | 3/4" |
| 2-1/2" to 7-7/8" | 2-1/4" x 12" | 1-1/2" |
| 8" and over | 4" x 20" | 3-1/2" |
Pipe Marking Locations – Finally, when marking your pipes, there are four key areas where pipes need to be marked:
- Adjacent to changes in direction
- Adjacent to all valves and flanges
- At both sides of floor or wall penetrations
- At 25- to 50-foot intervals on straight runs
Using these guidelines, marking your pipes should be a simple project. Good luck and happy pipe marking.
Christie Mendola is a pipe and valve safety specialist for Emedco. Emedco is leading supplier of safety products, including safety training and HR compliance materials, safety reminder signs, certification cards and labels, electronic scoreboards and a variety of products for motivating employees.