Line Labeling

Line labeling, another name for pipe marking, addresses the safety standards for properly labeling pipes in facilities. If done correctly, the workplace becomes more efficient and a safer environment for its employees. Line labeling can lead to a significant drop in accidents that often involve injury and damage to company property. While OSHA doesn’t require any specifics on pipe marking it does state in CFR 29 1910.261(a)(3)(ii) that the ANSI/ASME A13.1 standard is the standard to adhere to.

Oftentimes, manufacturing companies have multitudes of different chemical or water lines that need to be labeled for the safety of their employees. ANSI/ASME recommends that a company labels all of their pipes but if that can’t be done, at the very least they need to label lines if:

  • Pipes contain hazardous substances
  • Contents of pipes could impact emergency procedures
  • The flow direction/destination is unknown
  • Regular maintenance requires that valve(s) are to be shut off or the flow to be redirected

This job cannot be done haphazardly! The risk of accidentally being exposed to harmful substances due to improper labeling, or lack thereof, is too high. To quickly and accurately determine what kinds of properties a material possesses, there is a specific color code to abide by that can be found in the ANSI/ASME A13.1 standard that was mentioned above. This is to ensure that everyone who works in the building is sufficiently aware of what type of material is going through certain pipes.

Now, there isn’t just color regulations, the diameter of the pipe and where to put the labels must also be taken into consideration.

Diameter        Size of label

¾”- 1 ¾”         1”x 8” with the lettering at least ½” tall

1 ½” - 2”         1”x 8” with the lettering at ¾” tall

2 ½” - 6”         2”x 12” with the lettering at 1 ¼” tall

8” - 10”           3”x 24” with the lettering at 2 ½” tall

10” +               4” x 32” with lettering at 3 ½” tall


The goal for placing line labels is maximum visibility. To achieve this, labels must:

  • Be placed about every 25-50’ or at every direction change.
  • Be visible despite obstructions. This means if it obstructed by say, a wall, then there must be labels on either side so everyone can see it.
  • Have sufficient lighting for the label to be seen.
  • Be labeled at access points.
  • Be labeled at end points.

If these basics are achieved, then congratulations! You are doing all you can to help make hazards visible when it comes to line labeling. This information and more details are located in our pipe marking guide to help you make your workplace environment that much safer from accidents and misunderstandings.



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