Piping System Labeling Scheme
Reasons for Labeling
ASME standard suggests labeling all pipes, it is required for pipes to be labeled in the following situations:
- the contents of pipes could affect procedures during emergency situations
- the contents of pipes are hazardous
- the flow direction is unknown
- the destination of the contents is unknown
- the flow needs to be redirected for maintenance
- one or more valves need to be shut off for maintenance
| ASME A13.1 Color Scheme | |
|---|---|
| Fluid Service | Color Combinations | 
| Fire Quenching Fluids | Safety Red Background / White Legend | 
| Toxic & Corrosive Fluids | Safety Orange Background / White Legend | 
| Flammable Fluids | Safety Yellow Background / Black Legend | 
| Combustible Fluids | Safety Brown Background / White Legend | 
| Potable, Cooling, Boiler Feed, & Other Water | Safety Green Background / White Legend | 
| Compressed Air | Safety Blue Background / White Legend | 
| Defined by the User | Safety Purple Background / White Legend | 
| Defined by the User | Safety White Background / Black Legend | 
| Defined by the User | Safety Gray Background / White Legend | 
| Defined by the User | Safety Black Background / White Legend | 
| ASME A13.1 Pipe Label Size
 | ||
|---|---|---|
| Outside Pipe Diameter Including Covering | Minimum Length of Label Field Color | Minimum Height of Letters | 
| 3/4" - 1 1/4" | 8" | 1/2" | 
| 1 1/2" - 2" | 8" | 3/4" | 
| 2 1/2" - 6" | 12" | 1 1/4" | 
| 8" - 10" | 24" | 2 1/2" | 
| Over 10" | 32" | 3 1/2" | 
Standards
- ASME Standards
- ASME A13.1 - Scheme for the Identification of Piping Systems
 

