ASME A13.1 Pipe Color Code Chart

Quick Answer

ASME A13.1 is the American standard for pipe marking and color coding in industrial facilities. It assigns specific color combinations (text color on background color) to pipe contents based on hazard classification. The standard covers label text, size, placement, and arrow direction for identifying the contents and flow direction of piping systems.

The ASME A13.1 pipe color code chart is the primary reference for identifying pipe contents in refineries, chemical plants, power stations, and other industrial facilities in North America. The standard was last revised in 2020 and classifies pipe contents into defined hazard categories, each with a specific color scheme.

ASME A13.1 Pipe Color Code Chart

Category	Contents	Text Color	Background Color	Examples
Flammable fluids	Gases, oils, fuels	White	Brown (Pantone 4515)	Natural gas, diesel, crude oil, LPG
Oxidizing fluids	Oxygen, oxidizers	White	Yellow (Pantone 109)	Oxygen, hydrogen peroxide
Toxic and corrosive fluids	Acids, caustics, toxics	White	Orange (Pantone 151)	H2S, sulfuric acid, caustic soda
Fire suppression	Fire protection water, foam, CO2	White	Red (Pantone 186)	Fire water, deluge, sprinkler
Compressed air	Non-hazardous gases	White	Blue (Pantone 540)	Instrument air, plant air, nitrogen
Water (non-fire)	Potable, process, cooling water	White	Green (Pantone 335)	Cooling water, potable water, condensate
User-defined	Facility-specific services	As defined by facility	As defined by facility	Steam, specialty chemicals

Label Size Requirements

ASME A13.1 specifies minimum label and letter sizes based on the pipe outside diameter:

Pipe OD Range	Minimum Letter Height	Minimum Label Length
3/4” to 1-1/4” (19-32 mm)	1/2” (13 mm)	8” (200 mm)
1-1/2” to 2” (38-50 mm)	3/4” (19 mm)	8” (200 mm)
2-1/2” to 6” (65-150 mm)	1-1/4” (32 mm)	12” (300 mm)
8” to 10” (200-250 mm)	2-1/2” (64 mm)	24” (600 mm)
Over 10” (over 250 mm)	3-1/2” (89 mm)	32” (800 mm)

Placement Rules

Labels must be placed at regular intervals and at specific locations:

• Adjacent to all valves, flanges, and inline equipment
• On both sides of wall, floor, and ceiling penetrations
• At all branch connections and direction changes
• At intervals not exceeding 25 feet (7.6 m) on straight runs
• Flow direction arrows are required alongside the content label

Pro Tip

ASME A13.1 does not assign a specific color for steam. Many facilities use facility-defined color schemes for steam piping, often using a gray or silver background. Always check the project-specific pipe marking specification, as steam color coding varies between operators and countries.

ASME A13.1 is widely adopted in the United States but is not the only standard. International projects may follow BS 1710 (UK), IS 2379 (India), or AS 1345 (Australia), each with different color assignments. See also the full pipe color coding reference for additional detail on application and international standards.

Read the full guide to pipe color coding