One of the most important decisions to make when starting a pipe marking strategy is where to place the labels. Proper positioning will ensure that people can see them, and that they will be able to provide the right information to those in the area. The best place to start when working on this is with the ANSI/ASME standards. These are the standards recommended by OSHA and are commonly used throughout the country.
Angling the Labels Properly
When applying the label you need to place it in such a way as to ensure it is readable from people looking at it from a normal angle. If the pipes are going through the ceiling, for example, then the label should be on an angle pointed toward the ground, so it can be read. Ideally there should be two labels, one pointed in each direction. Of course, of the pipes are under the floor, the labels should be pointing up toward where people will be reading it from.
Every 25-50 Feet
ANSI/ASME standards say that labels should be placed at least every 25-50 feet on long straight runs of pipe. The exact distance you choose should be made to ensure the labels are very visible. In low-light areas, for example, putting them every 25 feet, or even closer together, is a good idea.
At Every Change of Direction
Any time a pipe changes direction you will need to have a label placed on both sides of the turn. This is per the ANSI/ASME standards, and is done to help ensure people can easily follow the path of the piping. This will also help to ensure the labels are visible from all positions around the pipe.
When Going Through Walls & Floors
Pipes often have to go through small holes in the walls or floors. When this happens, a pipe marking label should be applied on both sides of the obstruction. This is necessary so that no matter which side of the wall or floor a person is on, they will be able to easily see the label.
At Any Valve
Whenever there is a valve, flange, or other change in the pipe it a label needs to be placed on each side. This is done because these valves are often quite large and can make it difficult to see the pipe on the other side. Putting a label on both sides will dramatically increase visibility for anyone who needs to be aware of what is in the pipe.
These are the main standards from ANSI/ASME and should be a good place to start. Of course, you can always go above and beyond what is set forth in these standards. Placing more labels on pipes can be a good way to keep maintenance workers, emergency responders, and others who may need to access pipes, safe.