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Pipe Marking Infographic

Pipe Marking Infographic

Updated on: February 12, 2026 1 MINUTE READ Published on: Feb 03, 2023

Pipe marking standards are provided by both the ASME (American Society of Mechanical Engineers) and the ANSI (American National Standards Institute) Code A13.1.

Labels on pipes and valves provide important safety information. They inform employees, contractors, customers, and emergency response teams about the contents of the pipe, the hazard it poses, and the direction of flow through the pipe.

PIPE MARKING
ANS I/ASME A13.1 2023 Standard

Infographic Transcription

COLOR CHART

Flammable/Oxidizing/Combustible
BLACK ON YELLOW
Example: HYDROGEN

Steam
BLACK ON GRAY
Example: STEAM

Toxic or Corrosive
BLACK ON ORANGE
Example: NITRIC ACID

Fire Fighting
WHITE ON RED
Example: SPRINKLER WATER

Cold/Tepid Water
WHITE ON GREEN
Example: CHILLED WATER

Compressed Air
WHITE ON BLUE
Example: COMPRESSED AIR

Abandoned Piping
BLACK ON WHITE WITH BLACK BORDER
Example: ABANDONED

Defined By User
WHITE ON BLACK
WHITE ON BROWN
WHITE ON PURPLE
BLACK ON WHITE

PIPE MARKER PLACEMENT

Adjacent to changes in direction

Adjacent to all valves & flanges

Both sides of floor/wall penetrations

Every 25'-50' on straight runs is typical

Label placement in relation to point of normal approach

SIZE CHART

OUTSIDE PIPE DIAMETER INCLUDING COVERING	RECOMMENDED MINIMUM LABEL SIZE	TEXT HEIGHT
0.7" up to 1.3" (18-33 mm)	1" x 8" (25 x 203 mm)	0.5" (13 mm)
1.4" up to 2.4" (34-61 mm)	1" x 8" (25 x 203 mm)	0.7" (18 mm)
2.5" up to 6.7" (62-170 mm)	2" x 12" (51 x 305 mm)	1.3" (33 mm)
6.8" up to 10" (171-254 mm)	3" x 24" (76 x 610 mm)	2.5" (64 mm)
10" (over 254 mm)	4" x 32" (102 x 813 mm)	3.5" (89 mm)
NOTE: It is recommended that pipes less than .7" in diameter be labeled with a permanent tag.