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1. The spacing between the color rings should be even to facilitate observation; generally, on straight sections, a spacing of around 5 meters is appropriate. The width of the color ring can be determined based on the pipe diameter; for an outer diameter (including the insulation layer) of up to 150 mm, the width of the color ring is 70 mm ； For those with an outer diameter of 300 mm or more, the width of the color ring is 100 mm. 2. Color rings, fluid names or chemical symbols, and arrows should be painted on pipe intersections, on the pipes on both sides of valves and penetrations, as well as on areas that need to be observed and identified. 3. If the fluid being transported flows in both directions, arrows indicating the two opposite directions should be shown. Arrows are generally painted white or yellow; on backgrounds with a light color, they are painted dark. 4. When the identification mark is painted directly on pipes with an outer diameter of less than 90 mm and is difficult to read, a label can be attached to all areas that need to be identified; such labels are usually rectangular in shape, measuring 250 mm × 150 mm. The label should indicate the name of the fluid and show the flow direction of the medium. Requirements for labeling of power pipes in the machinery industry: The paint colors for power pipes in this industry should be applied in accordance with the specifications in Table 2. The width and spacing of the color bands on the pipes should follow the rules outlined in Table 3. The pipe colors shown in the pipe diagrams shall be consistent with these specifications. Table 2: Pipe Colors and Color Rings – Pipe Name, Color; Pipe Name, Color; Pipe Name, Color. Base color, color ring, base color, color ring, base color, color ring. Superheated steam pipe: red and yellow; Rainwater pipe: green. Ammonia pipes in refrigeration systems: blue. Saturated steam pipe: red; Oil pipes: yellow. Liquid pipes: yellow. Compressed steam pipes: light blue. Acetylene pipes: white. Outlet pipes: red. Condensate water pipes: green and red. Oxygen pipes: dark blue. Oil pipes: light yellow. Hot water supply pipes: green and yellow. Natural gas pipes: yellow and black. Air pipes: white. Hot water return pipes: green and brown. High-calorific value gas pipes: yellow. Saltwater pipes: outlet pipes – green. Industrial water pipes: black. Low-calorific value gas pipes: yellow and brown. Return pipes: brown. Industrial water pipes (shared with fire-fighting water pipes): black and orange. Hydrogen pipes: yellow. Water pipes: outlet pipes – light blue. Potable water pipes: blue. Liquefied petroleum gas pipes: green. Outlet pipes: green. Return pipes: purple. Fire-fighting water pipes: orange and yellow. Note: 1. At pipe intersections, where valves are installed, or at pipe bends, arrows indicating the direction of fluid flow should be marked on the pipes. 2. For coloring equipment, silver-white is generally used for radiators and space heaters ； Compressed air storage tanks use gray ； Green or gray for ion exchangers ； Heaters, heat exchangers, etc. use red ； The water tank is green. 3. Considering the current conditions of the enterprise, on the outdoor steam pipes (which already have insulation measures in place), as well as on the gas pipes, at the points where pipes intersect, at pipe bends, and around valves, a coating with a length of 2 meters per pipe section can be applied clearly ； On straight pipes, color markings 2 meters in length should be clearly painted every 50 meters. Table 3: Width and spacing of color rings (unit: mm). Outer diameter of pipeline insulation layer, width of color rings, spacing between color rings: ＜150: 50; 50–100: 150–300: 70; 100–200: ＞300: 100; 200–400. In industries such as petroleum and chemicals, due to the specific requirements of their production processes, special regulations and standards for coloring industrial pipelines have been established; please comply with these relevant regulations.