Pipe Marking Guidelines

Latest Revision ANSI/ASME A13.1-2015:

ANSI/ASME A13.1 is the most common pipe identification standard used in the United States. The standard specifies the primary and secondary means of identifying pipe contents, as well as, the size, color and placement of the identification device.

Primary Identification:

The legend (name of pipe content) and directional flow arrow remain the primary means of identifying pipe content. The size and placement of the marker arrow has not changed. See ANSI/ASME size chart (see below) and installation guide for details (see below). 

From the official ASME A13.1-2015 guidelines on legend: "Positive identification of the contents of a piping system shall be by lettered legend, giving the name of the contents in full or abbreviated form. Arrows shall be used to indicate direction of flow. Where flow can be in both directions, arrows in both directions shall be displayed. Contents shall be identified by a legend with sufficient additional details such as temperature, pressure, etc. as are necessary to identify the hazard."

Secondary Identification:

The secondary means of identification is the color code of the marker. In addition, the terminology of inherently hazardous or non hazardous has been removed from the standards. The combination of Yellow / Black is now assigned with flammable and oxidizng fluids, and Green / White shall now identify potable, cooling, boiler feed and other waters. This means that legends such as hot water, cold water and steam will now all use the color code of Green / White.

Since 2007, the other significant color changes included the addition of Brown / White for combustible fluids and Orange/Black for toxic or corrosive fluids. The fact that the standard has identified specific colors for flammable fluids, combustible fluids and toxic or corrosive fluids means you must consult Material Safety Data Sheets before selecting a color. Further, if the pipe content contains multiple hazards (flammable and toxic) it must be determined which poses the greater risk and marked accordingly. For example, if chilled or heating systems contain toxic treatments the color combination should be Orange / Black. The standard since 2007 also identifies for the first time four additional used identified color combinations and specifically identifies all of the exact background colors to be used. The exact colors are safety colors contained in the ANSI Z535.1-2007 standard.

From the official ASME A13.1-2015 guidelines on color: "Color should be used to identify the characteristic hazards of the contents. Color should be displayed on, or contiguous to, the piping by any physical means, but its use shall be in combination with the legend."


Pipe Marking Guidelines


ANSI/ASME A13.1-1996 Colors:

ANSI/ASME A13.1-1996 Colors


ANSI/ASME A13.1-2015 Colors:

ANSI/ASME A13.1-2015 Colors


Definition of materials (from the official ASME A13.1-2015 guidelines): 

  • Flammable: This classification includes fluids, which, under ambient or expected operating conditions, are a vapor or produce vapors that can be ignited and continue to burn in air. 
  • Combustible: This classification includes fluids that can burn, but are not flammable. 
  • Oxidizing (new addition for 2015 standards): Oxidizing fluid is any gas or liquid that may, generally by providing oxygen, cause or contribute to the combustion of other material more than air does.
  • Toxic and Corrosive: This classification includes fluids that are corrosive or toxic, or will produce corrosive or toxic substances when released.
  • Fire Quenching: This classification includes water, foam, and CO2 used in sprinkler systems and fire fighting piping systems.  

Additionally, potable, cooling, boiler feed and other water includes hot water, cold water and steam. 


Installation Guide


Seton Pipe Marking Systems Meet the ASME(ANSI) A13.1-2015 Standard

Visibility Markers shall be located so that they are readily visible to plant personnel from the point of normal approach. Seton Pipe Markers instantly tell you all you need to know about pipe contents, direction of flow and whether hazardous or safe.

Pipe Marker Installation Guide


How to Properly Label Pipes


1. Obtain a legend list of all pipe contents in your plant.

2. Collect the following data on your piping systems. This may require tracing lines to determine quantities and sizes.

  • Pipe contents
  • Outside diameter of pipe (including insulation)
  • Quantity of markers needed per ASME/ANSI A13.1 or other standards
  • Pressure
  • Temperature
  • To/from information
  • Location of specific legends by area (for aid in installation)

***Note: You may be able to use blueprints or P&IDs if they are current instead of walking down all of your lines. Seton also offers Take-Off Services of which we can determine your pipe marking requirements for you.

 3. Select color of marker.


Choose The Right...



Seton Pipe Marking Systems Meet ASME (ANSI) Size Recommendations: The A13.1-2015 standard also makes recommendations as to the size of letter height and length of color field for various pipe diameters. These recommendations are shown in the table. Seton markers, used properly with arrows and banding tape or arrow tape, meet or exceed the standard.

Pipe Marker Size Chart



Seton Pipe Marking Systems Meet ASME(ANSI) Color Recommendations: Unmarked pipes mean danger to both life and property. Numerous injuries have occurred through ignorance of pipe contents, particularly when outside agencies are called in under emergency conditions.

ANSI/ASME A13.1-2015 Colors



Over 150 stock legends available! Still can't find the wording you need? No problem, we can customize markers to your exact wording.

Pipe Marker Wording


Communicate hazard information with your Pipe Markers through GHS Pictograms. ASME A13.1 2015 has incorporated the GHS pictograms into the new 2015 revision and has recommended their use as part of the legend. 

GHS Pictogram

*The applicable GHS pictogram as illustrated may be included as part of the legend. Where piping is connected to containers that are labeled in accordance with the GHS requirements, a corresponding label on the piping may be provided. The corresponding label should contain at least the product name or identifier, the pictogram, the signal word, and the physical, health and environmental hazard statements.

*GHS Pictograms available for select Pipe Markers only. 



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