SAFETY SOLUTIONS: Is Your Piping Systems Properly Marked?
Understanding ANSI Pipe Marking
Welcome to the year of 2012 and I would like to
start this year off by writing about piping systems
that may be located in your facility. One of
the most overlooked items is proper pipe marking. Almost
every facility has a piping system running through it that
could be carrying dangerous substances. These pipes
need to be properly labeled to let people know what the
pipe contents are, the direction of flow, potential hazards,
and preventative measures. Another thing to think about
is what the hazardous materials located in these pipes can
have on your workers, or they can also affect the environment.
Anytime there is a spill or leak, the substance is
likely to flow into a body of water, into the soil, absorb into
the atmosphere, or come in contact with wildlife.
Marking of pipes that may hold a liquid substance must
be marked according OSHA 29CFR 1910.1200 standards.
Hazardous materials flow through miles of piping in
many industrial, commercial and institutional facilities.
Just like hazardous materials in other situations, piping
systems should be appropriately labelled to make people
aware of the materials they carry. The older versions
(1981 & 1996) of the ANSI (American National Standards
Institute) A13.1 standard have merged into the
ANSI/ASME (American Society of Testing and Materials)
A13.1 Scheme for Identification of Piping Systems. This
merged standard ANSI/ASME A13.1, addresses pipe
marking by offering a common labelling method for use in
all industrial, commercial, institutional facilities and in
buildings used for public assembly. This standard does not
apply to buried pipelines or electrical conduit.
Pipe marking labels must effectively communicate the
contents of the pipes and give additional detail if special
hazards (such as extreme temperatures or pressures)
exist. The legend should be short in length and easy to
understand. For example, the legend â€śSteam 100 PSIGâ€ť
specifies the contents as well as the additional pressure
hazard. An arrow should be used in conjunction with the
legend to show which direction the material flows. If flow
can be in both directions, arrows in both directions shall
The older versions (1981 & 1996) of ANSI A13.1 separated
materials transported in aboveground piping systems
into three categories:
- High-Hazard Materials: Encompasses several hazard
areas including 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 three hazard classes have different color-coded
labels associated with them. All high-hazard materials use
black characters on a yellow background. The low-hazard
material class is divided into two different color schemes:
liquids or liquid mixtures use white characters on a green
background; gases or gaseous mixtures use white characters
on a blue background. The fire suppression class uses
white letters on a red background. The letters on pipe
labels should be a minimum of 1/2" high, and should
increase in size as the pipe diameter increases (Table 1).
The 2007 edition of the ANSI/ASME A13.1 changed the
color scheme requirements for the labels. In this new edition
of the standard, there are 6 standard colors instead
of 4 colors. The new label color requirements are based on
the characteristic hazards of the contents. See Table 2 for
the new color requirements.
Labels should be positioned (Fig. 1) on the pipes so they
can be easily read. Proper label placement is on the lower
side of the pipe if the employee has to look up to the pipe,
on the upper side of the pipe if the employee has to look
down towards the pipe, or directly facing the employee if
on the same level as the pipe. Labels should be located
near valves, branches, where a change in direction occurs,
on entry/re-entry points through walls or floors, and on
straight segments with spacing between labels that allows
for easy identification.
Exceptions to this Standard
Other pipe labelling systems are acceptable if they are
put in writing and meet the basic ANSI requirements.
Commonly Asked Questions
Q. Can I still use my current pipe marking system based
on the older version of the standard or do I have to
change my color scheme to meet ASME A13.1 2007?
A. Existing schemes for identification shall be considered
as meeting the requirements of the standard if the
schemes are described in writing and employees are
trained in the operation and hazards of the piping system.
Q. What if I have a pipe smaller than ?
A. For pipes of less than in diameter the use of a permanently
legible tag is recommended.
Q. Are particular shades of yellow, green, red and blue
required for pipe labels?
A. Yes, ANSI/ASME A13.1- recommends the color code
featured in the ANSI Z53.1- Safety Color Code for
Marking Physical Hazards. The color shades recommended
are intended to give highest level of recognition to
employees with both normal and color-deficient vision.
Q. Has this ANSI Standard been adopted by OSHA?
A. No, it is still considered an industry consensus standard,
which is only a recommendation. Even though it has
not been specifically adopted by OSHA, industry consensus
standards may be evidence that a hazard is recognized
and there is a feasible means of correcting such a
hazard. If you do not follow a consensus standard, it is
possible to be cited under the General Duty Clause.
Should you have further questions or need safety &
health information, please feel free to visit our site at
ASME A13.1-2007 Scheme for the Identification of Piping Systems,
American Society of Mechanical Engineers, New York, NY 10016.
ANSI A13.1-1981 Scheme for the Identification of Piping Systems,
American National Standards Institute, New York, NY 10036.
ANSI Z53.1-1979 Safety Color Code for Marking Physical Hazards,
American National Standards Institute, New York, NY 10036.
ANSI Z535.1-1991 Safety Color Code, American National Standards
Institute, New York, NY 10036.
American National Standards Institute: 11 W. 42nd St. New York, NY
10036 (212) 642-4900.
Special thanks to Lab Safety Supply Company for allowing me to use
some of their information.
For more information, click on the author biography at the top of this page.