Regulations on pipeline coloring and marking

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In industrial enterprises, a large number of pipes for transporting various gases and liquids are often installed inside buildings and on the factory premises. This is done to facilitate the identification of the type and state of the fluids flowing within these pipes, as well as to support the management, maintenance, and safety of such pipes. Generally, the following three methods are used for painting and marking pipelines. 1. Generally, paints of different colors are applied to the surface of pipes containing various fluids or on the outer surface of the pipe insulation; sometimes arrows are also painted to indicate the flow direction of the fluid as a marker. 2. If the temperature or composition of the fluid being transported differs and differentiation is required, a color corresponding to a specific temperature or composition can be applied as a marker on the painted surface of the pipeline. 3. If the properties or parameters of the fluid inside the pipe cannot still be determined using the above two methods, it is possible to apply the name or chemical symbol of the fluid onto the outer surface of the pipe, or indicate the fluid’s temperature and pressure as identifiers. Due to the varying nature of pipeline projects and the wide range of fluids that flow within pipelines, the coloring and labeling of these pipelines should be determined based on the specific requirements of each project, with the aim of facilitating operation, management, and maintenance. Therefore, the regulations vary across different systems; in engineering projects, coloring should be carried out in accordance with the design specifications when such specifications exist, and otherwise, the colors listed in the table below can be used. Table 1: Classification of Pipe Coloring
| Serial Number | Pipe Name | Color | Remarks | Base Color Ring |
|----------------|------------|-------|---------|-----------------|
| 1 | Superheated steam pipe | Red, Yellow | | |
| 2 | Saturated steam pipe | Red | | |
| 3 | Waste gas pipe | Red, Green | | |
| 4 | Condensate pipe | Green, Red | Self-priming | |
| 5 | Hot water supply pipe | Green, Yellow | | |
| 6 | Hot water return pipe | Green, Brown | | |
| 7 | Refrigeration system pipes | Ammonia pipe: Inlet – Blue; Liquid pipe – Yellow; Outlet – Red; Oil pipe – Light yellow; Air pipe – White; Safety pipe – Brown; Saltwater pipe: Outlet – Green; Return pipe – Brown; Water pipe: Outlet – Light blue; Return pipe – Purple | | |
| 8 | Drain pipe | Green, Black | | |
| 9 | Industrial water pipe | Black | | |
| 10 | Industrial and fire-fighting combined water pipe | Black, Orange, Yellow | | |
| 11 | Potable water pipe | Blue | | |
| 12 | Fire-fighting water pipe | Orange, Yellow | | |
| 13 | Central water pipe | Light Green | | |
| 14 | Rainwater pipe | Black, Green | | |
| 15 | Sewer pipe | Green, Blue | | |
| 16 | Oil pipe | Orange, Yellow | | |
| 17 | High-calorific value gas pipe | Yellow | | |
| 18 | Low-calorific value gas pipe | Yellow, Brown | | |
| 19 | Liquefied petroleum gas pipe | Yellow, Green | | |
| 20 | Compressed air pipe | Light Blue | | |
| 21 | Purified compressed air pipe | Light Blue, Yellow | | |
| 22 | Acetylene pipe | White | | |
| 23 | Oxygen pipe | Blue | | |
| 24 | Hydrogen pipe | White, Red | | |
| 25 | Nitrogen pipe | Brown | | |
| 26 | Oil pipe | Orange, Yellow | | |
| 27 | Exhaust pipe | Red, Black | | |
| 28 | Softened (supply) water pipe | Green, White | | |
| 29 | Salt water pipe | Light Yellow | | |—