ANSI Color Codes

Why are the ANSI color codes important? What does the yellow background mean?

The yellow background signifies that the piping may handle hazardous material. Unfortunately, much has changed in the typical plant over the last 70 years since this standard was originally conceived. The basic standard can be traced to the 1920's and use in the US military. Obviously, our definitions for what is "hazardous" has changed. Water, air or carbon dioxide, under certain situations (pressure, heat, mixture with other chemicals) are not always benign. How do we interpret, for example, materials that should be used for "fire quenching" that are also "hazardous"? Should we use the red or the yellow ANSI scheme? Or, how do we label a pipe that carries both the liquid (which should be green) and gas form of a chemical (which should be blue)?

Hazards, in other words, are not so easily defined. "Hazardous" may mean that the material is hazardous to a person nearby, or to the operation of the overall plant itself. Could "hazardous" mean that the materials flowing through the process piping, if not handled carefully, could contaminate the product. Or, if leaked into the atmosphere, could the chemical infect the environment or cause damage to employees after cumulative exposure over a period of years? Clearly, the ANSI standard was written for far simpler times.

Color	Std	Meaning	Example
Red	APWA	Electric Power Lines, Cables, Conduit and Lighting Cables	Buried High Voltage Line
Yellow	APWA	Gas, Oil, Steam, Petroleum or Gaseous Materials	Natural Gas Distribution Line
Orange	APWA	Communication, Alarm or Signal Lines, Cables or Conduit	Buried Fiber Optic Cable
Blue	APWA	Water, Irrigation and Slurry Lines	Buried Water Line
Green	APWA	Sewers, Drain Line	Buried Storm Sewer Line
Red	Traffic	Prohibition	STOP, Yield
Orange	Traffic	Temporary Work Zone	Construction Zone Ahead
Yellow	Traffic	Caution	Merge Ahead, Slow
Blue	Traffic	Information Signs	Hospital
Brown	Traffic	Historical or Park	Picnic Area Ahead
Green	Traffic	Directional Signs	Exit 1 Mile, Go
Red	ANSI Sign	Danger Signs, Highest Hazard	Hazardous Voltage Will Cause Death
Orange	ANSI Sign	Warning Signs, Medium Hazard	Hazardous Voltage May Cause Death
Yellow	ANSI Sign	Caution Signs, Lowest Hazard	Turn Machine Off When Not In Use
Blue	ANSI Sign	Notice Signs	Employees Only
Green	ANSI Sign	Safety First Signs	Wear Ear Plugs
Red	ANSI Pipe	Fire Quenching Materials	Fire Protection Water
Yellow	ANSI Pipe	Materials Inherently Hazardous	Chlorine
Blue	ANSI Pipe	Materials of Inherently Low Hazard, Gas	Compressed Air
Green	ANSI Pipe	Materials of Inherently Low Hazard, Liquid	Storm Drain
Blue/Red/Yellow	NFPA 701	Blue is used for Health Hazards, Red for Flammability and Yellow for reactivity

NSI Color Code for Thermocouple and Thermocouple Extension Wire
ANSI Symbol	Wire Alloys	Polarity	Thermocouple Wire Color		T/C Extension Wire Color
			Individual	Jacket	Individual	Jacket
J	Iron Constantan(TM)	+JP -JN	White Red	Brown	White Red	Black
K	CHROMEL®* ALUMEL®*	+KP -KN	Yellow Red	Brown	Yellow Red	Yellow
T	Copper Constantan(TM)	+TP -TN	Blue Red	Brown	Blue Red	Blue
E	CHROMEL®* Constantan(TM)	+EP -EN	Purple Red	Brown	Purple Red	Purple
N	Nicrosil(TM) Nisil(TM)	+NP -NN	Orange Red	Brown	Orange Red	Orange
RSX	Copper Copper Alloy	+RSP -RSN	-	-	Black Red	Green
BX	PCLW630/Copper Copper	+BP -BN	-	-	Grey Red	Grey
W3X W5X	Alloy 203; Alloy 405 Alloy 225; Alloy 426	+WP -WN	-	-	White/Red Red	White/Red

* CHROMEL® and ALUMEL® are registered rademarks of Hoskins Manufacturing Company. PMC Corporation reserves the right to substitute equivalent product to CHROMEL® and ALUMEL® at any time.
For additional information see Bare Wire Data Sheet

Variations in color-coding standards are inevitable in our complex plant and pluralistic society. While laudable, harmonization of color-codes, then, will be very difficult to achieve. Many plants use other color-coding; for example, color-code each system (i.e. Lube Oil is brown, Condensate is green, etc.>) or color code by Unit (i.e. Unit 1 is yellow, Unit 2 is blue, etc.). For most plants, we recommend either the ANSI pipe marker color codes or simply black on yellow markers. For more complex plants, we recommend a color-coding by system. For all environments, we recommend the inclusion of RTK information on the valve or on the pipe.