What colors should ammonia pipe labels be?

Pipe marking can be difficult since handling hazardous materials is no laughing matter. Ammonia labels must be correct due to the chemical's dangerous nature. To begin, there are several different colors that must accompany an ammonia label. These colors correlate with the five different parts of an ammonia label that must be visible to align with ANSI/ASME and IIAR. They are as follows:

  • The marker body: This section must be orange and include black letters spelling out “AMMONIA”.
  • The physical state section: On the immediate right from “ammonia” printed in black there should be one of two physical state markers. Yellow is for a liquid state (LIQ) and sky blue is for a vapor (VAP) state.
  • The pressure level section: This is either labeled as “LOW” in green or “HIGH” in red. Pressures above 70 psig are considered high pressure while an equal or lower pressure level is considered low pressure.
  • The abbreviation section: There is a list of 30+ abbreviations to choose from to accurately describe what the ammonia piping is for. This is very important to know when considering what to do as a part of protocol.
  • Directional arrow: An arrow is needed to specify which direction the ammonia is moving in and must be black.

Originally, ammonia pipe labels were required to be yellow because they were considered by ANSI/ASME and the IIAR to be a general hazardous material. This rule changed in 2007 when yellow became the color signifier for flammable materials and orange became the new color standard for toxic materials. Ammonia fit better into the toxic category, so it was officially changed. This new standard makes ammonia pipe labels not only described more correctly by the color classification, but it also is more recognizable, especially with the other color bars that are required to be on the label according to its specific state. There are several resources like pipe marking guides and ammonia pipe marking articles online to help you make sure that your labels are good to go regarding these regulations.


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