ISO 20560-1:2024

International
Standard
ISO 20560-1
Second edition
Safety information for the content
2024-06
of piping systems and tanks —
Part 1:
Piping systems
Informations de sécurité relatives au contenu des systèmes de
tuyauteries et des reservoirs —
Partie 1: Systèmes de tuyauteries
Reference number
© ISO 2024
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Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General requirements . 2
5 Elements of safety information systems for piping . 3
5.1 General .3
5.2 Colour coding to identify the nature of the content in the piping .3
5.3 Content name .5
5.4 Flow direction indicators .6
5.5 Warning signs and GHS pictograms .6
6 Technical and operational information . 7
6.1 General .7
6.2 Additional safety information .8
6.3 Additional technical information . .8
6.4 Supplementary identification colours .8
7 Layout requirements . 9
8 Installation of safety information systems for piping .10
9 Maintenance, inspection and revision . .11
Annex A (informative) Standard colours and equivalent colour codes .12
Annex B (informative) Observation distance .13
Annex C (informative) Examples of safety information systems . 17
Annex D (informative) Firefighting systems .22
Annex E (informative) Maritime piping systems .23
Bibliography .25

iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 145, Graphical symbols, Subcommittee SC 2,
Safety identification, signs, shapes, symbols and colours.
This second edition cancels and replaces the first edition (ISO 20560-1:2020), which has been technically
revised.
The main changes are as follows:
— the colour values for yellow in Table 2 have been modified;
— the colour values for maroon and yellow in Table 5 have been modified;
— the colour values in Table A.1 have been modified.
A list of all parts in the ISO 20560 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
Introduction
Continuous growth in mobility of labour has resulted in a need to standardize safety information and form a
coherent system for non-verbal exchange of information that consists of distinct elements to identify hazards
related to the content of piping systems and tanks. Every element of the safety information system defined
in this document communicates specific information. When combined on a pipe marking, these elements
inform the viewer, in a unique and simplified way, of potential hazards so that accidents can be prevented
and an appropriate response to emergency situations can be efficiently accomplished.
The use of this document is expected to reduce risk by providing a means of improved training and
education to reduce possible confusion for people working with and near piping systems in both normal and
emergency situations.
The use of a standardized safety information system does not replace proper work methods, instructions or
accident prevention training and measures. Education is an essential part of any system that provides safety
information.
The national pipe marking standards of many different countries were reviewed during the development
of this document. Important design concepts contained in these standards were incorporated into this
document.
NOTE The statutory regulations of some countries can differ in some respect from the requirements given in this
document.
v
International Standard ISO 20560-1:2024(en)
Safety information for the content of piping systems and tanks —
Part 1:
Piping systems
IMPORTANT — The colours represented in the electronic file of this document can be neither viewed
on screen nor printed as true representations. For the purposes of colour matching, see Table 2
and Table 5, which provide colorimetric and photometric properties, and Annex A, which provides
references from colour order systems.
1 Scope
This document specifies safety information for overground piping systems related to the content of the
piping system and associated hazards for the purposes of accident prevention, reducing risks to health and
providing information for use in case of an emergency.
This document does not cover piping that is buried.
Safety signing of the hazards in an area is not part of this document.
This document does not cover risk assessment.
This document can also be used for marine structures and ships.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 7010, Graphical symbols — Safety colours and safety signs — Registered safety signs
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
additional safety information
information typically presented in the form of text, numbers or both to indicate details related to the safety
information system (3.8)
EXAMPLE Pressure or temperature.
3.2
additional technical information
technical information that is additional to the safety information system (3.8) to indicate technical details
EXAMPLE Pipe identification codes or from–to information.

3.3
basic identification colour
colour used to indicate a group of similar media
3.4
content of the pipe
medium which is transported in the pipe
EXAMPLE Gasses, liquids or solids as powder or granulate.
3.5
flow direction indicator
arrow to indicate the flow direction of the content of the pipe (3.4)
3.6
GHS hazard pictogram
graphical composition defined by the Globally harmonized system of classification and labelling of chemicals
(GHS) that can include a symbol plus other graphic elements, such as a border, background pattern or colour,
intended to convey specific information as given by the GHS
3.7
safety data sheet
SDS
standardized information template for a medium which identifies the medium and contains information
about its potential health, physical and chemical hazards, and emergency and firefighting procedures
3.8
safety information system
series of markings that consistently uses standardized elements to visually communicate information
necessary for the reliable recognition, identification and understanding of hazards
3.9
supplementary identification colour
colour used in combination with the basic identification colour (3.3) to indicate a specific purpose
3.10
warning sign
safety sign that indicates a specific source of potential harm
[SOURCE: ISO 3864-1:2011, 3.16]
4 General requirements
A safety information system for piping visually communicates information necessary for the reliable
recognition, identification and understanding of any hazard related to the type and character of the content
of a pipe. This safety information system shall be installed on site and near any place that potentially
requires operation, maintenance or manipulation of a pipe’s contents.
This safety information system provides critical information that serves to assist in:
— the correct operation and use of the piping system;
— the safe maintenance of the piping system;
— conveying critical information to trained personnel in emergency situations.
The safety information system shall, in a comprehensive and uniform manner, accurately identify the
contents and hazards associated with the content of all piping and material transport systems in conformity
with the contents’ safety data sheets (SDSs). In some cases, the safety information system shall provide, in
an integrated, coherent visual manner, specific hazard information related to the pipe contents. Examples of

this information include the exact nature of the substance, temperature, toxicity and the risk of asphyxiation
if a release of the pipe contents occurs.
The safety information system shall consistently use multiple visual elements to accurately convey its
information, including colours and colour combinations as a coding system, text, safety signs, GHS hazard
pictograms and arrows. The information conveyed by the safety information system shall be consistent
with the organization’s risk assessment and its operation and safety plans.
All elements of a safety information system shall be distinguishable and contrasting from any neighbouring
information and shall be visible from the observation distance intended for safe operation, intervention or
manipulation. When the contents of pipes include hazardous substances (see Reference [16]), the safety
information system shall include distinctive, unambiguous elements and the corresponding warning signs
or GHS hazard pictograms or both.
To avoid confusion, the same safety information system elements shall be consistently used and installed
throughout an organization’s piping system, whether it is a single unit, multiple units on the same site or a
multi-plant operation.
5 Elements of safety information systems for piping
5.1 General
The level of detail required to be displayed in a safety information system for piping will depend on many
factors, such as the type of plant, the complexity of the operation, the availability of check lists and manuals
and the competence and skills of operators. Organizations shall design safety information systems for piping
in accordance with their operational and risk communication needs as identified by their risk assessment
process.
A safety information system for piping shall consist of four key elements:
1) colour coding to identify the nature of the content in the piping;
2) content name;
3) flow direction indicators;
4) when applicable, warning signs, GHS pictograms or both.
5.2 Colour coding to identify the nature of the content in the piping
Safety information systems for piping shall incorporate colour coding that uses the basic identification
colours and the safety colour yellow for hazardous substances.
Where there is no need to further differentiate hazardous substances, the safety colour yellow may be used
alone, without the addition of a basic identification colour. See Table 1.

Table 1 — Safety colour and basic identification colours
Content of a pipe Colour
Safety colour Hazardous substances Yellow
Basic Gases in either gaseous or lique- Grey
identification fied condition
colour
Liquids and fixed materials Black
(powder, granulates)
Acids Orange
Alkalis (leaches) Violet
Firefighting medium Red
Water Green
Air Blue
The chromaticity coordinates of a basic identification colour shall fall within the relevant colour region
specified in Table 2. The luminance factor for each colour shall be as specified in Table 2. To measure the
chromaticity coordinates and luminance factor of pipe markings, the test method for ordinary materials
specified in ISO 3864-4:2011, 5.2.1 can be used. The testing shall be carried out on finished markings or
samples that are representative, with regard to the colour and surface texture, of the material used in the
finished marking.
Table 2 — Colour regions for safety colour and basic identification colours:
chromaticity coordinates and luminance factor for colours externally illuminated by CIE standard
illuminant D65
Corner points of colour region
Luminance factor
CIE standard illuminant D65
β
Colour
CIE 2° standard colorimetric observer
1 2 3 4 Minimum Maximum
Yellow x 0,467 0,514 5 0,461 0,427 0,45 0,60
y 0,516 0,472 5 0,434 0,472
Grey x 0,350 0,300 0,290 0,340 0,15 0,50
y 0,360 0,310 0,320 0,370
Black x 0,385 0,300 0,260 0,345 0,03
y 0,355 0,270 0,310 0,395
Orange x 0,590 0,538 0,508 0,550 0,25 0,4
y 0,394 0,382 0,412 0,430
NOTE 1 Measurement geometry 45°/0° or 0°/45°.
NOTE 2 All colours except yellow and red are amended from ISO 14726. Yellow and red are safety sign colours from ISO 3864-4.

TTabablele 2 2 ((ccoonnttiinnueuedd))
Corner points of colour region
Luminance factor
CIE standard illuminant D65
β
Colour
CIE 2° standard colorimetric observer
1 2 3 4 Minimum Maximum
Violet x 0,320 0,319 0,329 0,340 0,1 0,2
y 0,218 0,272 0,295 0,230
Red x 0,705 0,592 0,574 0,663 0,07 0,2
y 0,295 0,291 0,351 0,337
Green x 0,250 0,330 0,330 0,287 0,25 0,35
y 0,580 0,580 0,458 0,439
Blue x 0,160 0,196 0,218 0,205 0,15 0,25
y 0,225 0,250 0,192 0,169
NOTE 1 Measurement geometry 45°/0° or 0°/45°.
NOTE 2 All colours except yellow and red are amended from ISO 14726. Yellow and red are safety sign colours from ISO 3864-4.
NOTE Examples of identification colours are given in Annex A.
5.3 Content name
The pipe’s content name shall be displayed in text elements which can be either the content name or its
chemical formula, or by numbers in accordance with national standards.
Longer words may be abbreviated using standard approved abbreviations known by operators, as found in
the organization’s operation safety manuals.
The content name shall be centred and placed within the basic identification colour or in the yellow safety
colour using the contrast colours as defined in Table 3. Alternatively, the content name shall be the contrast
colour black on a white background.
Table 3 — Contrast colours for content name to be displayed on the safety colour and
basic identification colours
Content of a pipe Basic Contrast
identification colour
colour
Safety colour Hazardous substances Yellow Black
Basic Gases in either gaseous or lique- Grey Black
identification fied condition
colour
Liquids and fixed materials Black White
(powder, granulates)
Acids Orange Black
Alkalis (leaches) Violet White
Firefighting medium Red White
Water Green White
Air Blue White
NOTE Further information on colour systems is given in Annex A.
To increase legibility, a sans serif font in the contrast colour as defined in Table 3 shall be used. To increase
readability, upper-case and lower-case letters shall be used. See Figure 1.
Figure 1 — Example of content name “Air” in the contrast colour white on the basic identification
colour blue
5.4 Flow direction indicators
The safety information system uses arrows to indicate the flow direction of the content of the piping system.
The direction of flow shall be indicated with a single-headed arrow (see Figure 2) or, where applicable
(e.g. ring main), with a double-headed arrow (see Figure 3). The shaft of the arrow may be shortened or
lengthened as needed to improve visibility by users at the intended observation distances.
The flow direction indicator shall be black on a white background or the contrast colour on the basic
identification colour or on the safety colour, as defined in Table 3.
Key
x length of arrow point
y width of arrow point
Figure 2 — Direction of flow indicator (right)
Figure 3 — Direction of flow indicator to indicate a flow in either direction
5.5 Warning signs and GHS pictograms
Warning signs and graphical symbols are elements of the safety information system used to symbolically
communicate specific safety meanings. The SDSs, the organization’s risk assessment or both shall identify

the specific warning signs in accordance with ISO 7010 or with GHS pictograms needed to communicate
hazards associated with the contents of pipes, or with both. The safety information system’s warning signs
and GHS pictograms shall be displayed on a white background or on the yellow safety colour. See Figures 4
and 5 for examples.
Figure 4 — Examples of display of warning signs and GHS pictograms on a white background
Figure 5 — Examples of display of warning signs and GHS pictograms on the yellow safety colour
background
NOTE Ranking systems can be used to prioritize and reduce the number of GHS pictograms that need to be
displayed.
As a result of an organization’s risk assessment, safety information systems on piping may use safety signs,
supplementary text or both to communicate potentia
...