A Guide to Pipe Marking Standards

The prospect of labeling all of your facility’s pipes can be daunting. There’s a steep learning curve, and, since pipe marking is mandatory, there’s a lot at stake. We’ve put together a guide that will tell you what you need to know about pipe marking, and what substances call for special treatment.

For most industries, abiding by ASME/ANSI pipe marking standards will be sufficient for staying safe and OSHA compliant. There are some workplaces, though, that are required to comply with more specific requirements due to the particularly volatile nature of the substances the use in their pipes, or because of the uniquely complex environment of these workplaces.

Ammonia Pipe Marking Standards

Because ammonia is harmful to human health—it is corrosive to the eyes, skin, and lungs—any pipes carrying these ammonia-based substances must have more specific labeling than those under the ANSI/ASME standards. The International Institute of Ammonia Refrigeration (IIAR) is responsible for setting these standards for ammonia-carrying pipes.

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The standards set forth by IIAR requires facilities to label pipes carrying ammonia-based substances with the following information and color-coding:

  • Abbreviations. Abbreviations for the Ammonia System Components (black text on yellow)
  • Physical state. This refers to the form of the substance: LIQ=liquid (black or white text printed on orange), or VAP=vapor (black or white text printed on blue)
  • Pressure level. If high pressure (+70 psig), color-coding will be black or white text printed on red; if low pressure (=/-70 psig), color-coding will be black or white text printed on green

The chart below lists the common abbreviations for labeling ammonia pipes in accordance with IIAR regulations.

Ammonia Pipe Marking Abbreviations

NFPA 99/CGA C-9 Pipe Marking

Substances used for medical purposes in certain institutions and settings have their own standards as well. Since the substances used in these professional environments are highly flammable, the National Fire Prevention Association (NFPA) is the entity that regulates and sets the safety standards, and these are used by OSHA to assess compliance.

The NFPA requires that all pipes carrying medical gases such as oxygen, nitrous oxide, and nitrogen in medical facilities be labeled.

Like other labeling standards, the NFPA/CGA C-9 pipe marking standards requires that labels must include the following information:

  • Contents of pipe
  • Pressure level
  • Flow direction

See charts below for color-coding information, and for specific instructions on gas mixtures.

NFPA 99/CGA C-9 Pipe Marking colorsMedical Pipe Marking colors

ISO/DIS 14726 Sea Vessel & Marine Pipe Marking

Since marine environments are required to carry fresh water along with gases, waste media, and fire-fighting chemicals, sea-faring vessels must comply with additional pipe marking color codes. This extra pipe marking provides workers and first responders with the information they need about the contents of pipes. Because vessels travel such vast distances, these codes are internationally recognized. Whether you’re docked in Jakarta or passing through the Mozambique Channel, workers and first responders will be able to read your pipe marking easily.

Marine Pipe Marking Color Bar

Marine Pipe Marking Standards have main colors, which are defined by ISO 14726 to indicate groups of similar substances. Additional color bars (defined by ISO/DIS 14726-2) are added to indicate specific substances. The additional color should be surrounded by the main color and have a width smaller than that of the main color.

Unlike other standards, Marine Pipe Marking Standards do not require marking pipes for flow direction. Although this is not required, experts strongly advise marking the direction of flow with arrows or arrow-band tape. Additionally, using text where possible can help avoid confusion about the contents of your pipes for someone not yet familiar with the ISO/DIS standards.

Marine Pipe Marking Colors

Water Treatment Pipe Marking

There is a separate guideline for water treatment facilities. Below are some suggestions for labeling water lines, chemical lines, waste lines, and other pipes found in these special environments. The guide shows what pipes should be labeled based on their contents using the corresponding colors.

There are some exceptions to the standards of pipe marking used in water treatment settings.  Some states adhere to the 10 States Standards created by the Great Lake-Upper Mississippi River Board (GLURB). If your facility is located in one of these states, you’ll want to consult these standards in addition to the guide below.

Water Treatment Pipe Marking Colors

Commercial Building Pipe Marking

While commercial buildings fall under the ASME/ANSI A13.1 Standard, these additional guidelines listed below will help further identify common pipes found in these facilities.

These cheat sheets to pipe marking color codes will make the task go faster and feel like less of a headache. Labeling your pipes is a large responsibility, but it doesn’t have to be a huge burden.

Commercial Building Pipe Marking colors

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