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Pipemarking Regulations

ANSI/ASME A13.1 - Pipeline Labelling Requirements

The latest revision of ANSI/ASME A13.1 2007 states that pipe markers should conform to certain primary and secondary requirements which include the use of colour, arrows and text size/placement, to indicate which pipelines are dangerous, the direction of flow, and the pipe contents. Any pre-existing pipe markers (prior to 2007) should be updated to allow for consistent identification and help to ensure a safer working environment with fewer chances of employee injury and/or unexpected environmental contaminations.

Primary Identification: Marker Size & Positioning

The primary ways of identifying pipe content are by naming the pipe content and including arrows to show directional flow.

It is recommended that the pipe marker height and text size be based on the pipe diameter as depicted in the chart below:

The positioning of pipe labels is also extremely important. Labels must be placed so they can be seen from any location in the facility - if you can see a pipe, you should be able to see a label that identifies it’s contents and directional flow.  For example, if the pipe is overhead, the label should be placed below the centerline and if the pipe is below eye level, the label should be placed above the centerline.

As well, pipe labels should be placed based on the following guidelines:

  • Adjacent to all valves and flanges

  • Adjacent to all changes of direction

  • On both sides of wall or floor penetrations

  • At regular intervals on straight runs (Although 50' is the acceptable maximum spacing, closer spacing might be necessary for visibility.)

If certain valves, actuators and/or transmitters are too difficult to be marked with adhesive marking, valve tags and duratags can be used as a substitute.

Secondary Identification: Colour

The secondary way of identifying pipe content is through the colour code of the marker. The colours are based on the contents of the pipe with the most hazardous feature of the contents determining the colours to be used. Currently, the standard uses  the following colour chart which includes six standard colour combinations and four user-defined combinations.

Pipe Contents - Standard Combinations Colour Scheme
Fire-quenching fluids White text on red background
Toxic and Corrosive Fluids Black text on orange background
Flammable Fluids Black text on yellow background
Combustible fluids White text on brown background
Potable, cooling, boiler feed & other water White text on green background
Compressed air White text on blue background

Pipe Contents - User Defined Colour Scheme
User-defined White text on purple background
User-defined Black text on white background
User-defined White text on grey background
User-defined White text on black background

While the ANSI pipe marking standard does not apply to buried pipelines or electrical conduit, it classifies materials transported in above-ground piping into three categories:

  • High-Hazard Materials: Includes several hazardous materials such as; corrosive and caustic materials; substances that are toxic or capable of creating toxic gases; explosive and flammable materials; radioactive substances; and materials that, if released, would be hazardous due to extreme pressures or temperatures

  • Low-Hazard Materials: Materials that are not inherently hazardous and have a small chance of harming employees through mild temperatures and low pressures

  • Fire Suppression Materials: Fire protection materials such as foam, carbon dioxide (CO2), Halon and water.


The Occupational Health and Safety (OHS) requires labeling on pipes in compliance with the ANSI A13.1 standard. The OHS also modified the Hazard Communication Standard (HCS) to adopt the new Globally Harmonized System (GHS) which defines and classifies the hazards of chemical products, and communicates health and safety information on labels and material safety data sheets. The main purpose and benefit of GHS is that it is internationally standardized - the same set of rules to classify hazards and the same format and content for labels and safety data sheets will be adopted and used around the world. This consistency in defining and classifying hazards will improve the safety and health of workers world-wide.