In the process industry, chemical industry, manufacturing industry, and other commercial and industrial contexts, pipe marking is used to identify the contents, properties and flow direction of fluids in piping. It is typically carried out by marking piping through labels and color codes. Pipe marking helps personnel and fire response teams identify the correct pipes for operational, maintenance or emergency response purposes.
Pipes are used extensively in commercial and industrial buildings and on industrial plant (e.g. oil refineries) to transfer fluids between items of plant and equipment. [1] Positive identification assists operations personnel to correctly identify plant when carrying out routine or maintenance activities, and for emergency personnel when responding to emergencies. Pipe marking is particularly important for identification where pipes run along pipe racks, through walls and bulkheads and through floors. [2]
A range of corporate, national and international codes, standards and regulations are in use around the world.
In the United States, Occupational Safety and Health Administration regulations recommend following American Society of Mechanical Engineers Standard A13.1-2015 - Scheme for the Identification of Piping Systems. [3]
The standard states that labels should be placed where easily viewed by a person standing near the pipe at any of the following points: [4]
Meaning | Background Color | Text Color | Example |
---|---|---|---|
Hazardous materials [a] | Safety Yellow | Black | Acetylene |
Non-hazardous liquids | Safety Green | White | Stormwater |
Non-hazardous gases | Safety Blue | White | Nitrogen |
Firefighting materials | Safety Red | White | Sprinkler Water |
Meaning | Background Color | Text Color | Example |
---|---|---|---|
Flammables [b] & Oxidizers [c] | Safety Yellow | Black | Acetylene |
Combustible Fluids [d] | Safety Brown | White | Lubricating Oil |
Toxic and Corrosives | Safety Orange | White | Ammonia |
Water | Safety Green | White | Stormwater |
Compressed air/Non-hazardous gases | Safety Blue | White | Compressed Air |
Firefighting materials | Safety Red | White | Sprinkler Water |
Custom - Defined by user | Safety Purple | White | Fluid Name |
Custom - Defined by user | Safety Grey | White | Fluid Name |
Custom - Defined by user | White | Black | Fluid Name |
Custom - Defined by user | Black | White | Fluid Name |
2015 revisions added oxidizing materials to the existing 'Flammables' classification. The other major change allowed and encouraged labels to incorporate the GHS signal word, hazard pictograms, and hazard statements. This addition helped identify additional dangers when dealing with materials that fit into multiple categories, like hydrogen sulfide, which is both flammable and toxic. [4]
In 2014, the International Institute of Ammonia Refrigeration introduced a specialized label design for use when marking pipes associated with refrigeration systems using ammonia, including information such as the physical state, pressure and purpose in the system. [6]
The National Fire Protection Association have a special labeling system in the standard for Health Care Facilities, such as hospitals and dentistry offices. This standard puts more emphasis on gases found in Medical gas supply systems, which consist of both oxidizing gases and gases that displace oxygen. [7]
Gas | Background Color | Text Color |
---|---|---|
Carbon Dioxide | Gray | Black or White |
Helium | Brown | White |
Medical Air | Yellow | Black |
Oxygen | Green | White [e] |
Oxygen/Carbon Mixtures | Green | White |
Nitrogen | Black | White |
Nitrous Oxide | Blue | White |
Waste Anesthetic Gas Disposal | Purple | White |
Medical Surgical Vacuum | White | Black |
Non-Medical Air | Yellow/White Diagonal Striped | Black |
Non-medical and Level 3 Vacuum | Black/White Diagonal Striped | Black (In box) |
Laboratory Air | Yellow/White Checkerboard | Black |
Laboratory Vacuum | Black/White Checkerboard | Black (In box) |
Instrument Air | Red | White |
In the United Kingdom there are three principal regulations that mandate the marking of equipment and piping:
The regulations require that vessels containing hazardous substances together with the pipes containing or transporting such substances must be labelled or marked with the relevant hazard pictograms or pipe marking. The labels used on pipes must be positioned visibly in the vicinity of the most hazardous points, such as valves and joints; at both sides of bulkheads and floor penetrations; and at reasonable intervals.
The regulations do not specify a specific marking system, but BS EN ISO 1710 Graphical symbols — Safety colours and safety signs is often used.
A widely used British Standard (BS) for marking equipment is:
The Standard stipulates the colours to be used. These are as follows: [2]
Contents | Colour | BS 4800 colour [10] |
---|---|---|
Water | Green | 12 D 45 |
Steam | Silver-grey | 10 A 03 |
Oils | Brown | 06 C 39 |
Gases | Yellow Ochre | 08 C 35 |
Acids and Alkalis | Violet | 22 C 37 |
Air | Light Blue | 20 E 51 |
Other liquids | Black | 00 E 53 |
Electrical & Ventilation | Orange | 06 E 51 |
In addition to the basic colours, certain safety colours are used:
Safety service | Colour | BS 4800 colour [10] |
---|---|---|
Fire fighting | Red | 04 E 53 |
Warning | Yellow | 08 E 51 |
Fresh water | Auxiliary Blue | 18 E 53 |
User defined | User defined |
The arrangement of markings is for the safety colour to be between bands of the basic colour. [2]
Firewater service would be:
The pipe contents must be identified adjacent to the banding. [2] This can be done by giving either:
The direction of flow should also be identified near the banding. [2]
Examples using this system are as shown.
The Indian Standard IS 2379 provides for a ground colour and a coloured band on piping to identify material. [11]
Substance | Ground colour |
---|---|
Water | Sea green |
Steam | Aluminium |
Oils and combustible liquid | Light brown |
Acids | Dark violet |
Air | Sky blue |
Gases | Canary yellow |
Alkalise | Smoke grey |
Other gases and liquids | Black |
Hydrocarbons/organic compounds | Dark aluminium grey |
Colour bands of 25 mm to 100 mm width are placed at locations such as battery limits, intersections, near valves, at walls, starting and terminating points. There is a large range of bands which define the contents of the line. For example, for oils.
Substance | Ground colour | Band colour |
---|---|---|
Light diesel | Light brown | Brilliant green |
High speed diesel | Light brown | None |
Paraffin oil | Light brown | Signal red |
Quenching oil | Light brown | Canary yellow |
Furnace fuel | Light brown | French blue |
Lubricating oil | Light brown | Light grey |
Hydraulic power | Light brown | Dark violet |
Transformer oil | Light brown | Light orange |
Pipes, ducts and conduits are identification by the Australian Standard AS 1345—1995 “Identification of the contents of pipes, conduits and ducts” [12]
Service | AS 2700 Colour |
---|---|
Water | G21 Jade |
Steam | N24 Silver Grey |
Oils, flammable liquids | X53 Golden Tan |
Gases | Y44 Sand |
Acids & alkalis | P23 Lilac |
Air | B25 Aqua |
Other Liquids | N61 Black |
Fire Services | R13 Signal Red |
Electric Power | X15 Orange |
Communication | N14 White |
Dangerous Materials | Y14 Golden Yellow + N61 Black |
Ships and marine facilities must conform to an international standard for piping systems identification. This is ISO 14726:2008 Ships and marine technology — Identification colours for the content of piping systems. [13]
This is a two-colour banded marking system. The main colour shows what the fluid is being used for. This is on either side of the secondary colour which indicates what the substance actually is. The main colours are as follows: [13]
International Standard ISO 20560-1:2020 Safety information for the content of piping systems and tanks — Part 1: Piping systems was intended to replace the variety of regulations and standards across countries and regions. Basic identification colours and warning symbols identify the pipe contents and any hazards. [14]
Pipe markers consists of 4 basic elements:
Colours and substances are typically as follows: [14]
Substance | Background colour | Text colour | ||
---|---|---|---|---|
Hazardous substances | Yellow | Black | ||
Gas (liquid or gaseous) | Grey | White | ||
Liquids & solids (powder/granulate) | Black | White | ||
Acids | Orange | Black | ||
Alkalis | Violet | White | ||
Fire fighting medium | Red | White | ||
Water | Green | White | ||
Air | Blue | White |
International Standard ISO 20560-2 Safety information for the content of piping systems and tanks — Part 2: Tanks, provides a similar colour scheme for tanks.
RAL colour standard charts are used by architects, construction industry and road safety. [15]
The pipe identification colours are as shown in the table.
Type | Reference | RAL Colour Code | Colour |
---|---|---|---|
Steam | 2114 | 9006 | White aluminium |
Air | 2123 | 5012 | Light blue |
Water | 2138 | 6010 | Grass green |
Gas | 2149 | 1004 | Golden yellow |
Acid | 2163 | 4001 | Red lilac |
Liquid Spirits | 2173 | 8001 | Ochre brown |
Other Liquids | 2179 | 9005 | Jet black |
ISO 3864 specifies international standards for safety signs and markings in workplaces and public facilities. These labels are graphical, to overcome language barriers. The standard is split into four parts.
A flange is a protruded ridge, lip or rim, either external or internal, that serves to increase strength ; for easy attachment/transfer of contact force with another object ; or for stabilizing and guiding the movements of a machine or its parts. Flanges are often attached using bolts in the pattern of a bolt circle.
A hydrostatic test is a way in which pressure vessels such as pipelines, plumbing, gas cylinders, boilers and fuel tanks can be tested for strength and leaks. The test involves filling the vessel or pipe system with a liquid, usually water, which may be dyed to aid in visual leak detection, and pressurization of the vessel to the specified test pressure. Pressure tightness can be tested by shutting off the supply valve and observing whether there is a pressure loss. The location of a leak can be visually identified more easily if the water contains a colorant. Strength is usually tested by measuring permanent deformation of the container.
A diving cylinder or diving gas cylinder is a gas cylinder used to store and transport high pressure gas used in diving operations. This may be breathing gas used with a scuba set, in which case the cylinder may also be referred to as a scuba cylinder, scuba tank or diving tank. When used for an emergency gas supply for surface supplied diving or scuba, it may be referred to as a bailout cylinder or bailout bottle. It may also be used for surface-supplied diving or as decompression gas. A diving cylinder may also be used to supply inflation gas for a dry suit or buoyancy compensator. Cylinders provide gas to the diver through the demand valve of a diving regulator or the breathing loop of a diving re-breather.
Hazard symbols are recognizable symbols designed to warn about hazardous or dangerous materials, locations, or objects, including electromagnetic fields, electric currents; harsh, toxic or unstable chemicals ; and radioactivity. The use of hazard symbols is often regulated by law and directed by standards organizations. Hazard symbols may appear with different colors, backgrounds, borders, and supplemental information in order to specify the type of hazard and the level of threat. Warning symbols are used in many places in place of or in addition to written warnings as they are quickly recognized and more universally understood, as the same symbol can be recognized as having the same meaning to speakers of different languages.
Bottled gas is a term used for substances which are gaseous at standard temperature and pressure (STP) and have been compressed and stored in carbon steel, stainless steel, aluminum, or composite containers known as gas cylinders.
A gas cylinder is a pressure vessel for storage and containment of gases at above atmospheric pressure. Gas storage cylinders may also be called bottles. Inside the cylinder the stored contents may be in a state of compressed gas, vapor over liquid, supercritical fluid, or dissolved in a substrate material, depending on the physical characteristics of the contents. A typical gas cylinder design is elongated, standing upright on a flattened or dished bottom end or foot ring, with the cylinder valve screwed into the internal neck thread at the top for connecting to the filling or receiving apparatus.
Dangerous goods (DG), are substances that are a risk to health, safety, property or the environment during transport. Certain dangerous goods that pose risks even when not being transported are known as hazardous materials. An example for dangerous goods is hazardous waste which is waste that has substantial or potential threats to public health or the environment.
A Piping and Instrumentation Diagram is a detailed diagram in the process industry which shows process equipment together with the instrumentation and control devices. It is also called as mechanical flow diagram (MFD).
The international standard IEC 60446Basic and safety principles for man-machine interface, marking and identification - Identification of equipment terminals, conductor terminations and conductors was a standard published by the International Electrotechnical Commission (IEC) that defined basic safety principles for identifying electrical conductors by colours or numerals, for example in electricity distribution wiring. The standard has been withdrawn; the fourth edition was merged in 2010 into the fifth edition of IEC 60445 along with the fourth edition, IEC 60445:2006.
In electrical and safety engineering, hazardous locations are places where fire or explosion hazards may exist. Sources of such hazards include gases, vapors, dust, fibers, and flyings, which are combustible or flammable. Electrical equipment installed in such locations can provide an ignition source, due to electrical arcing, or high temperatures. Standards and regulations exist to identify such locations, classify the hazards, and design equipment for safe use in such locations.
A pipe is a tubular section or hollow cylinder, usually but not necessarily of circular cross-section, used mainly to convey substances which can flow — liquids and gases (fluids), slurries, powders and masses of small solids. It can also be used for structural applications; a hollow pipe is far stiffer per unit weight than the solid members.
The Globally Harmonized System of Classification and Labelling of Chemicals (GHS) is an internationally agreed-upon standard managed by the United Nations that was set up to replace the assortment of hazardous material classification and labelling schemes previously used around the world. Core elements of the GHS include standardized hazard testing criteria, universal warning pictograms, and safety data sheets which provide users of dangerous goods relevant information with consistent organization. The system acts as a complement to the UN numbered system of regulated hazardous material transport. Implementation is managed through the UN Secretariat. Although adoption has taken time, as of 2017, the system has been enacted to significant extents in most major countries of the world. This includes the European Union, which has implemented the United Nations' GHS into EU law as the CLP Regulation, and United States Occupational Safety and Health Administration standards.
A pipefitter or steamfitter is a tradesman who installs, assembles, fabricates, maintains, and repairs mechanical piping systems. Pipefitters usually begin as helpers or apprentices. Journeyman pipefitters deal with industrial/commercial/marine piping and heating/cooling systems. Typical industrial process pipe is under high pressure, which requires metals such as carbon steel, stainless steel, and many different alloy metals fused together through precise cutting, threading, grooving, bending, and welding. A plumber concentrates on lower pressure piping systems for sewage and potable tap water in the industrial, commercial, institutional, or residential atmosphere. Utility piping typically consists of copper, PVC, CPVC, polyethylene, and galvanized pipe, which is typically glued, soldered, or threaded. Other types of piping systems include steam, ventilation, hydraulics, chemicals, fuel, and oil.
Plastic pipe is a tubular section, or hollow cylinder, made of plastic. It is usually, but not necessarily, of circular cross-section, used mainly to convey substances which can flow—liquids and gases (fluids), slurries, powders and masses of small solids. It can also be used for structural applications; hollow pipes are far stiffer per unit weight than solid members.
European hazard symbols for chemicals are pictograms defined by the European Union for labelling chemical packaging and containers. They are standardised currently by the CLP/GHS classification.
Transportable pressure vessels for high-pressure gases are routinely inspected and tested as part of the manufacturing process. They are generally marked as evidence of passing the tests, either individually or as part of a batch, and certified as meeting the standard of manufacture by the authorised testing agency, making them legal for import and sale. When a cylinder is manufactured, its specification, including manufacturer, working pressure, test pressure, date of manufacture, capacity and weight are stamped on the cylinder.
A safety cabinet is used for the safe storage of flammable chemical substance or compressed gas cylinders.
The Health and Safety Regulations 1996 specify the safety signs within Great Britain, Northern Ireland has a similar law. It was issued as a transposition of the European directive 92/58/EEC and replaced The Safety Signs Regulations 1980. They consist of "traditional safety signs", such as prohibitory and warning signs, hand signals, spoken and acoustic signals and hazard marking.
1910.261(a)(3)(ii) Scheme for the Identification of Piping Systems, A13.1—1956.